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-rw-r--r--bin/.gitignore20
-rw-r--r--bin/LICENSE661
-rw-r--r--bin/Makefile48
-rw-r--r--bin/README156
-rw-r--r--bin/bri.c83
-rw-r--r--bin/dtch.c247
-rw-r--r--bin/fbatt.c127
-rw-r--r--bin/fbclock.c131
-rw-r--r--bin/gfx/cocoa.m162
-rw-r--r--bin/gfx/fb.c87
-rw-r--r--bin/gfx/gfx.h24
-rw-r--r--bin/gfx/none.c24
-rw-r--r--bin/gfx/x11.c135
-rw-r--r--bin/gfxx.c492
-rw-r--r--bin/glitch.c488
-rw-r--r--bin/hnel.c118
-rw-r--r--bin/klon.c357
-rw-r--r--bin/pbd.c136
-rw-r--r--bin/pngo.c717
-rw-r--r--bin/scheme.c219
-rw-r--r--bin/wake.c53
-rw-r--r--bin/watch.c93
-rw-r--r--bin/xx.c133
23 files changed, 4711 insertions, 0 deletions
diff --git a/bin/.gitignore b/bin/.gitignore
new file mode 100644
index 00000000..d3450745
--- /dev/null
+++ b/bin/.gitignore
@@ -0,0 +1,20 @@
+*.o
+tags
+atch
+dtch
+gfxx
+glitch
+hnel
+pbcopy
+pbd
+pbpaste
+pngo
+scheme
+wake
+xx
+klon
+watch
+bri
+fbatt
+fbclock
+scheme.png
diff --git a/bin/LICENSE b/bin/LICENSE
new file mode 100644
index 00000000..dba13ed2
--- /dev/null
+++ b/bin/LICENSE
@@ -0,0 +1,661 @@
+                    GNU AFFERO GENERAL PUBLIC LICENSE
+                       Version 3, 19 November 2007
+
+ Copyright (C) 2007 Free Software Foundation, Inc. <http://fsf.org/>
+ Everyone is permitted to copy and distribute verbatim copies
+ of this license document, but changing it is not allowed.
+
+                            Preamble
+
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+software and other kinds of works, specifically designed to ensure
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+  When we speak of free software, we are referring to freedom, not
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+  14. Revised Versions of this License.
+
+  The Free Software Foundation may publish revised and/or new versions of
+the GNU Affero General Public License from time to time.  Such new versions
+will be similar in spirit to the present version, but may differ in detail to
+address new problems or concerns.
+
+  Each version is given a distinguishing version number.  If the
+Program specifies that a certain numbered version of the GNU Affero General
+Public License "or any later version" applies to it, you have the
+option of following the terms and conditions either of that numbered
+version or of any later version published by the Free Software
+Foundation.  If the Program does not specify a version number of the
+GNU Affero General Public License, you may choose any version ever published
+by the Free Software Foundation.
+
+  If the Program specifies that a proxy can decide which future
+versions of the GNU Affero General Public License can be used, that proxy's
+public statement of acceptance of a version permanently authorizes you
+to choose that version for the Program.
+
+  Later license versions may give you additional or different
+permissions.  However, no additional obligations are imposed on any
+author or copyright holder as a result of your choosing to follow a
+later version.
+
+  15. Disclaimer of Warranty.
+
+  THERE IS NO WARRANTY FOR THE PROGRAM, TO THE EXTENT PERMITTED BY
+APPLICABLE LAW.  EXCEPT WHEN OTHERWISE STATED IN WRITING THE COPYRIGHT
+HOLDERS AND/OR OTHER PARTIES PROVIDE THE PROGRAM "AS IS" WITHOUT WARRANTY
+OF ANY KIND, EITHER EXPRESSED OR IMPLIED, INCLUDING, BUT NOT LIMITED TO,
+THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
+PURPOSE.  THE ENTIRE RISK AS TO THE QUALITY AND PERFORMANCE OF THE PROGRAM
+IS WITH YOU.  SHOULD THE PROGRAM PROVE DEFECTIVE, YOU ASSUME THE COST OF
+ALL NECESSARY SERVICING, REPAIR OR CORRECTION.
+
+  16. Limitation of Liability.
+
+  IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW OR AGREED TO IN WRITING
+WILL ANY COPYRIGHT HOLDER, OR ANY OTHER PARTY WHO MODIFIES AND/OR CONVEYS
+THE PROGRAM AS PERMITTED ABOVE, BE LIABLE TO YOU FOR DAMAGES, INCLUDING ANY
+GENERAL, SPECIAL, INCIDENTAL OR CONSEQUENTIAL DAMAGES ARISING OUT OF THE
+USE OR INABILITY TO USE THE PROGRAM (INCLUDING BUT NOT LIMITED TO LOSS OF
+DATA OR DATA BEING RENDERED INACCURATE OR LOSSES SUSTAINED BY YOU OR THIRD
+PARTIES OR A FAILURE OF THE PROGRAM TO OPERATE WITH ANY OTHER PROGRAMS),
+EVEN IF SUCH HOLDER OR OTHER PARTY HAS BEEN ADVISED OF THE POSSIBILITY OF
+SUCH DAMAGES.
+
+  17. Interpretation of Sections 15 and 16.
+
+  If the disclaimer of warranty and limitation of liability provided
+above cannot be given local legal effect according to their terms,
+reviewing courts shall apply local law that most closely approximates
+an absolute waiver of all civil liability in connection with the
+Program, unless a warranty or assumption of liability accompanies a
+copy of the Program in return for a fee.
+
+                     END OF TERMS AND CONDITIONS
+
+            How to Apply These Terms to Your New Programs
+
+  If you develop a new program, and you want it to be of the greatest
+possible use to the public, the best way to achieve this is to make it
+free software which everyone can redistribute and change under these terms.
+
+  To do so, attach the following notices to the program.  It is safest
+to attach them to the start of each source file to most effectively
+state the exclusion of warranty; and each file should have at least
+the "copyright" line and a pointer to where the full notice is found.
+
+    <one line to give the program's name and a brief idea of what it does.>
+    Copyright (C) <year>  <name of author>
+
+    This program is free software: you can redistribute it and/or modify
+    it under the terms of the GNU Affero General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    This program is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU Affero General Public License for more details.
+
+    You should have received a copy of the GNU Affero General Public License
+    along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+Also add information on how to contact you by electronic and paper mail.
+
+  If your software can interact with users remotely through a computer
+network, you should also make sure that it provides a way for users to
+get its source.  For example, if your program is a web application, its
+interface could display a "Source" link that leads users to an archive
+of the code.  There are many ways you could offer source, and different
+solutions will be better for different programs; see section 13 for the
+specific requirements.
+
+  You should also get your employer (if you work as a programmer) or school,
+if any, to sign a "copyright disclaimer" for the program, if necessary.
+For more information on this, and how to apply and follow the GNU AGPL, see
+<http://www.gnu.org/licenses/>.
diff --git a/bin/Makefile b/bin/Makefile
new file mode 100644
index 00000000..bbcc8c4b
--- /dev/null
+++ b/bin/Makefile
@@ -0,0 +1,48 @@
+ANY_BINS = atch dtch gfxx glitch hnel pbcopy pbd pbpaste pngo scheme wake xx
+BSD_BINS = klon watch
+LIN_BINS = bri fbatt fbclock
+ALL_BINS = $(ANY_BINS) $(BSD_BINS) $(LIN_BINS)
+GFX ?= none
+
+CFLAGS += -Wall -Wextra -Wpedantic
+LDLIBS = -ledit -lncurses -lutil -lz
+LDLIBS_cocoa = -framework Cocoa
+LDLIBS_x11 = -lX11
+
+any: .gitignore tags $(ANY_BINS)
+
+bsd: any $(BSD_BINS)
+
+linux: any $(LIN_BINS)
+
+.gitignore: Makefile
+	echo '*.o' tags $(ALL_BINS) scheme.png | tr ' ' '\n' > .gitignore
+
+tags: *.c
+	ctags -w *.c
+
+atch: dtch
+	ln -f dtch atch
+
+gfxx: gfxx.o gfx/$(GFX).o
+	$(CC) $(LDFLAGS) gfxx.o gfx/$(GFX).o $(LDLIBS) $(LDLIBS_$(GFX)) -o $@
+
+pbcopy pbpaste: pbd
+	ln -f pbd $@
+
+scheme.png: scheme
+	./scheme -t -g > scheme.png
+
+setuid: bri
+	chown root bri
+	chmod u+s bri
+
+clean:
+	rm -f tags *.o gfx/*.o $(ALL_BINS)
+
+link:
+	mkdir -p ~/.local/bin
+	ln -s -f $(ALL_BINS:%=$(PWD)/%) ~/.local/bin
+
+unlink:
+	rm -f $(ALL_BINS:%=~/.local/bin/%)
diff --git a/bin/README b/bin/README
new file mode 100644
index 00000000..c15f6f5a
--- /dev/null
+++ b/bin/README
@@ -0,0 +1,156 @@
+
+Tools primarily targetting Darwin and FreeBSD. Some don't build on Linux
+and some only build on Linux. All code licensed AGPLv3. See LICENSE.
+
+                                  bri
+
+Backlight brightness control for Linux through /sys/class/backlight.
+
+    bri 255
+    bri ---
+    bri ++
+
+                               dtch/atch
+
+Session detach and attach. Simple implementation of part of screen(1) by
+lending out the master end of a PTY over a UNIX domain socket. Detach
+with ^Q.
+
+    dtch a nvim & disown
+    atch a
+
+                                 fbatt
+
+Battery charge indicator panel for the Linux framebuffer through
+/sys/class/power_supply.
+
+                                fbclock
+
+Clock panel for the Linux framebuffer. Renders PSF2 bitmap fonts.
+
+                                  gfxx
+
+Graphics data explorer. Build with GFX={cocoa,fb,x11}. Dumps PNGs.
+
+    -c {indexed,grayscale,rgb}    set color space
+    -p PATH                       load palette
+    -e {l,b}                      set byte order
+    -E {l,b}                      set bit order
+    -b NNNN                       set pad, R, G, B bits
+    -n N                          set offset
+    -f                            flip
+    -m                            mirror
+    -w N                          set width
+    -z N                          set scale
+    -o PREFIX                     set output prefix
+
+    q      quit
+    x      dump one frame
+    X      dump each frame
+    o      print options
+    []     switch color spaces
+    p      sample palette
+    P      dump palette
+    {}     switch bits presets
+    e      swap byte order
+    E      swap bit order
+    hl     offset by byte
+    jk     offset by pixel
+    HL     offset by row
+    JK     offset by square
+    ,.     adjust width
+    <>     half/double width
+    f      flip
+    m      mirror
+    -+     zoom
+    0-9    set bits
+
+                                 glitch
+
+PNG glitcher based on pngo.
+
+    -c         write to stdout
+    -o PATH    write to file
+    -p         broken Paeth predictor
+    -f         filter when reconstructing
+    -r         reconstruct when filtering
+    -d LIST    declare pattern of comma-separated filters
+    -a LIST    apply pattern of comma-separated filters
+
+                                  hnel
+
+The tr(1) of PTYs, for remapping keys. Originally for preserving HJKL in
+alternate keyboard layouts. Toggle remapping with ^S.
+
+    hnel '[]{}' '{}[]' vi
+
+                                  klon
+
+Klondike solitaire for curses. BSD-only for arc4random_uniform.
+
+    q   quit
+    u   undo
+    ' ' draw
+    w   waste
+    a-d foundations
+    1-7 tableau
+    ^M  auto-foundation
+
+                           pbd/pbcopy/pbpaste
+
+TCP server which pipes into macOS pbcopy(1) and from pbpaste(1), and
+pbcopy and pbpaste implementations that connect to it. Used to share
+the macOS pasteboard over SSH with RemoteForward 7062 127.0.0.1:7062.
+This used to make nvim's "+ register work but they seem to have changed
+their detection.
+
+    pbd & disown
+    ssh tux.local
+    pbpaste
+
+                                  pngo
+
+PNG optimizer. Does not support interlaced PNGs.
+
+ - Discards ancillary chunks
+ - Discards unnecessary alpha channel
+ - Converts unnecessary truecolor to grayscale
+ - Indexes color if possible
+ - Reduces bit depth if possible
+ - Applies a simple filter type heuristic
+ - Applies zlib's best compression
+
+    pngo foo.png
+    pngo -o bar.png foo.png
+    pngo -c foo.png | xx
+
+                                 scheme
+
+Color scheme for terminals.
+
+    -a  generate ANSI palette
+    -t  generate Terminal.app palette
+    -x  output hex
+    -g  output PNG
+
+                                  wake
+
+Broadcasts a wake-on-LAN packet to one of my machines.
+
+                                 watch
+
+Executes a command each time files change. BSD-only for kqueue(2).
+
+    watch watch.c make
+    watch wake.c watch.c -- make wake watch
+
+                                   xx
+
+Hexdump tool.
+
+    -a          toggle ASCII
+    -c N        set columns
+    -g N        set grouping
+    -r          reverse hexdump
+    -s          toggle offsets
+    -z          skip zeros
diff --git a/bin/bri.c b/bin/bri.c
new file mode 100644
index 00000000..c3ec723c
--- /dev/null
+++ b/bin/bri.c
@@ -0,0 +1,83 @@
+/* Copyright (c) 2017, Curtis McEnroe <programble@gmail.com>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <dirent.h>
+#include <err.h>
+#include <errno.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sysexits.h>
+#include <unistd.h>
+
+static const char *CLASS = "/sys/class/backlight";
+
+int main(int argc, char *argv[]) {
+    int error;
+
+    const char *input = (argc > 1) ? argv[1] : NULL;
+
+    error = chdir(CLASS);
+    if (error) err(EX_OSFILE, "%s", CLASS);
+
+    DIR *dir = opendir(".");
+    if (!dir) err(EX_OSFILE, "%s", CLASS);
+
+    struct dirent *entry;
+    while (NULL != (errno = 0, entry = readdir(dir))) {
+        if (entry->d_name[0] == '.') continue;
+
+        error = chdir(entry->d_name);
+        if (error) err(EX_OSFILE, "%s/%s", CLASS, entry->d_name);
+        break;
+    }
+    if (!entry) {
+        if (errno) err(EX_IOERR, "%s", CLASS);
+        errx(EX_CONFIG, "%s: empty", CLASS);
+    }
+
+    FILE *actual = fopen("actual_brightness", "r");
+    if (!actual) err(EX_OSFILE, "%s/actual_brightness", CLASS);
+
+    unsigned value;
+    int match = fscanf(actual, "%u", &value);
+    if (match == EOF) err(EX_IOERR, "%s/actual_brightness", CLASS);
+    if (match < 1) errx(EX_DATAERR, "%s/actual_brightness", CLASS);
+
+    if (!input) {
+        printf("%u\n", value);
+        return EX_OK;
+    }
+
+    if (input[0] == '+' || input[0] == '-') {
+        size_t count = strnlen(input, 16);
+        if (input[0] == '+') {
+            value += 16 * count;
+        } else {
+            value -= 16 * count;
+        }
+    } else {
+        value = strtoul(input, NULL, 0);
+    }
+
+    FILE *brightness = fopen("brightness", "w");
+    if (!brightness) err(EX_OSFILE, "%s/brightness", CLASS);
+
+    int size = fprintf(brightness, "%u", value);
+    if (size < 0) err(EX_IOERR, "brightness");
+
+    return EX_OK;
+}
diff --git a/bin/dtch.c b/bin/dtch.c
new file mode 100644
index 00000000..17bbf118
--- /dev/null
+++ b/bin/dtch.c
@@ -0,0 +1,247 @@
+/* Copyright (c) 2017, Curtis McEnroe <programble@gmail.com>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <err.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <poll.h>
+#include <pwd.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <sys/ioctl.h>
+#include <sys/socket.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+#include <sys/un.h>
+#include <sys/wait.h>
+#include <sysexits.h>
+#include <termios.h>
+#include <unistd.h>
+
+#if defined __FreeBSD__
+#include <libutil.h>
+#elif defined __linux__
+#include <pty.h>
+#else
+#include <util.h>
+#endif
+
+static struct passwd *getUser(void) {
+    uid_t uid = getuid();
+    struct passwd *user = getpwuid(uid);
+    if (!user) err(EX_OSFILE, "/etc/passwd");
+    return user;
+}
+
+static struct sockaddr_un sockAddr(const char *home, const char *name) {
+    struct sockaddr_un addr = { .sun_family = AF_LOCAL };
+    snprintf(addr.sun_path, sizeof(addr.sun_path), "%s/.dtch/%s", home, name);
+    return addr;
+}
+
+static char z;
+static struct iovec iov = { .iov_base = &z, .iov_len = 1 };
+
+static ssize_t sendFd(int sock, int fd) {
+    size_t size = CMSG_LEN(sizeof(int));
+    char buf[size];
+    struct msghdr msg = {
+        .msg_iov = &iov,
+        .msg_iovlen = 1,
+        .msg_control = buf,
+        .msg_controllen = size,
+    };
+
+    struct cmsghdr *cmsg = CMSG_FIRSTHDR(&msg);
+    cmsg->cmsg_len = size;
+    cmsg->cmsg_level = SOL_SOCKET;
+    cmsg->cmsg_type = SCM_RIGHTS;
+    *(int *)CMSG_DATA(cmsg) = fd;
+
+    return sendmsg(sock, &msg, 0);
+}
+
+static int recvFd(int sock) {
+    size_t size = CMSG_LEN(sizeof(int));
+    char buf[size];
+    struct msghdr msg = {
+        .msg_iov = &iov,
+        .msg_iovlen = 1,
+        .msg_control = buf,
+        .msg_controllen = size,
+    };
+
+    ssize_t n = recvmsg(sock, &msg, 0);
+    if (n < 0) return -1;
+
+    struct cmsghdr *cmsg = CMSG_FIRSTHDR(&msg);
+    if (!cmsg || cmsg->cmsg_type != SCM_RIGHTS) {
+        errno = ENOMSG;
+        return -1;
+    }
+
+    return *(int *)CMSG_DATA(cmsg);
+}
+
+static struct sockaddr_un addr;
+static void unlinkAddr(void) {
+    unlink(addr.sun_path);
+}
+
+static int dtch(int argc, char *argv[]) {
+    int error;
+
+    const struct passwd *user = getUser();
+
+    const char *name = user->pw_name;
+    if (argc > 1) {
+        name = argv[1];
+        argv++;
+        argc--;
+    }
+    if (argc > 1) {
+        argv++;
+    } else {
+        argv[0] = user->pw_shell;
+    }
+
+    int home = open(user->pw_dir, 0);
+    if (home < 0) err(EX_CANTCREAT, "%s", user->pw_dir);
+
+    error = mkdirat(home, ".dtch", 0700);
+    if (error && errno != EEXIST) err(EX_CANTCREAT, "%s/.dtch", user->pw_dir);
+
+    close(home);
+
+    int server = socket(PF_LOCAL, SOCK_STREAM, 0);
+    if (server < 0) err(EX_OSERR, "socket");
+
+    addr = sockAddr(user->pw_dir, name);
+    error = bind(server, (struct sockaddr *)&addr, sizeof(addr));
+    if (error) err(EX_CANTCREAT, "%s", addr.sun_path);
+    fcntl(server, F_SETFD, FD_CLOEXEC);
+    atexit(unlinkAddr);
+
+    int pty;
+    pid_t pid = forkpty(&pty, NULL, NULL, NULL);
+    if (pid < 0) err(EX_OSERR, "forkpty");
+
+    if (!pid) {
+        execvp(*argv, argv);
+        err(EX_NOINPUT, "%s", *argv);
+    }
+
+    error = listen(server, 0);
+    if (error) err(EX_OSERR, "listen");
+
+    for (;;) {
+        int client = accept(server, NULL, NULL);
+        if (client < 0) err(EX_IOERR, "accept");
+
+        ssize_t size = sendFd(client, pty);
+        if (size < 0) warn("sendmsg");
+
+        size = recv(client, &z, sizeof(z), 0);
+        if (size < 0) warn("recv");
+
+        close(client);
+
+        int status;
+        pid_t dead = waitpid(pid, &status, WNOHANG);
+        if (dead < 0) err(EX_OSERR, "waitpid(%d)", pid);
+        if (dead) return WIFEXITED(status) ? WEXITSTATUS(status) : EX_SOFTWARE;
+    }
+}
+
+static struct termios saveTerm;
+static void restoreTerm(void) {
+    tcsetattr(STDIN_FILENO, TCSADRAIN, &saveTerm);
+    printf(
+        "\x1b[?1049l" // rmcup
+        "\x1b\x63\x1b[!p\x1b[?3;4l\x1b[4l\x1b>" // reset
+    );
+}
+
+static int atch(int argc, char *argv[]) {
+    int error;
+
+    const struct passwd *user = getUser();
+    const char *name = (argc > 1) ? argv[1] : user->pw_name;
+
+    int client = socket(PF_LOCAL, SOCK_STREAM, 0);
+    if (client < 0) err(EX_OSERR, "socket");
+
+    struct sockaddr_un addr = sockAddr(user->pw_dir, name);
+    error = connect(client, (struct sockaddr *)&addr, sizeof(addr));
+    if (error) err(EX_NOINPUT, "%s", addr.sun_path);
+
+    int pty = recvFd(client);
+    if (pty < 0) err(EX_IOERR, "recvmsg");
+
+    struct winsize window;
+    error = ioctl(STDIN_FILENO, TIOCGWINSZ, &window);
+    if (error) err(EX_IOERR, "TIOCGWINSZ");
+
+    struct winsize redraw = { .ws_row = 1, .ws_col = 1 };
+    error = ioctl(pty, TIOCSWINSZ, &redraw);
+    if (error) err(EX_IOERR, "TIOCSWINSZ");
+
+    error = ioctl(pty, TIOCSWINSZ, &window);
+    if (error) err(EX_IOERR, "TIOCSWINSZ");
+
+    error = tcgetattr(STDIN_FILENO, &saveTerm);
+    if (error) err(EX_IOERR, "tcgetattr");
+    atexit(restoreTerm);
+
+    struct termios raw;
+    cfmakeraw(&raw);
+    error = tcsetattr(STDIN_FILENO, TCSADRAIN, &raw);
+    if (error) err(EX_IOERR, "tcsetattr");
+
+    char buf[4096];
+    struct pollfd fds[2] = {
+        { .fd = STDIN_FILENO, .events = POLLIN },
+        { .fd = pty, .events = POLLIN },
+    };
+    while (0 < poll(fds, 2, -1)) {
+        if (fds[0].revents) {
+            ssize_t size = read(STDIN_FILENO, buf, sizeof(buf));
+            if (size < 0) err(EX_IOERR, "read(%d)", STDIN_FILENO);
+
+            if (size == 1 && buf[0] == CTRL('Q')) return EX_OK;
+
+            size = write(pty, buf, size);
+            if (size < 0) err(EX_IOERR, "write(%d)", pty);
+        }
+
+        if (fds[1].revents) {
+            ssize_t size = read(pty, buf, sizeof(buf));
+            if (size < 0) err(EX_IOERR, "read(%d)", pty);
+
+            size = write(STDOUT_FILENO, buf, size);
+            if (size < 0) err(EX_IOERR, "write(%d)", STDOUT_FILENO);
+        }
+    }
+    err(EX_IOERR, "poll");
+}
+
+int main(int argc, char *argv[]) {
+    switch (argv[0][0]) {
+        case 'd': return dtch(argc, argv);
+        case 'a': return atch(argc, argv);
+        default:  return EX_USAGE;
+    }
+}
diff --git a/bin/fbatt.c b/bin/fbatt.c
new file mode 100644
index 00000000..6c0052e4
--- /dev/null
+++ b/bin/fbatt.c
@@ -0,0 +1,127 @@
+/* Copyright (c) 2018, Curtis McEnroe <programble@gmail.com>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <dirent.h>
+#include <err.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <linux/fb.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <sys/ioctl.h>
+#include <sys/mman.h>
+#include <sysexits.h>
+#include <unistd.h>
+
+static const char *CLASS = "/sys/class/power_supply";
+
+static const uint32_t RIGHT  = 5 * 8 + 1; // fbclock width.
+static const uint32_t WIDTH  = 8;
+static const uint32_t HEIGHT = 16;
+
+static const uint32_t BG     = 0x1D2021;
+static const uint32_t BORDER = 0xA99A84;
+static const uint32_t GRAY   = 0x938374;
+static const uint32_t YELLOW = 0xD89A22;
+static const uint32_t RED    = 0xCC241D;
+
+int main() {
+    int error;
+
+    DIR *dir = opendir(CLASS);
+    if (!dir) err(EX_OSFILE, "%s", CLASS);
+
+    FILE *chargeFull = NULL;
+    FILE *chargeNow = NULL;
+
+    const struct dirent *entry;
+    while (NULL != (errno = 0, entry = readdir(dir))) {
+        if (entry->d_name[0] == '.') continue;
+
+        error = chdir(CLASS);
+        if (error) err(EX_OSFILE, "%s", CLASS);
+
+        error = chdir(entry->d_name);
+        if (error) err(EX_OSFILE, "%s/%s", CLASS, entry->d_name);
+
+        chargeFull = fopen("charge_full", "r");
+        chargeNow = fopen("charge_now", "r");
+        if (chargeFull && chargeNow) break;
+    }
+    if (!chargeFull || !chargeNow) {
+        if (errno) err(EX_OSFILE, "%s", CLASS);
+        errx(EX_CONFIG, "%s: empty", CLASS);
+    }
+    closedir(dir);
+
+    const char *path = getenv("FRAMEBUFFER");
+    if (!path) path = "/dev/fb0";
+
+    int fb = open(path, O_RDWR);
+    if (fb < 0) err(EX_OSFILE, "%s", path);
+
+    struct fb_var_screeninfo info;
+    error = ioctl(fb, FBIOGET_VSCREENINFO, &info);
+    if (error) err(EX_IOERR, "%s", path);
+
+    size_t size = 4 * info.xres * info.yres;
+    uint32_t *buf = mmap(NULL, size, PROT_READ | PROT_WRITE, MAP_SHARED, fb, 0);
+    if (buf == MAP_FAILED) err(EX_IOERR, "%s", path);
+
+    for (;;) {
+        int match;
+
+        rewind(chargeFull);
+        fflush(chargeFull);
+        uint32_t full;
+        match = fscanf(chargeFull, "%u", &full);
+        if (match == EOF) err(EX_IOERR, "charge_full");
+        if (match < 1) errx(EX_DATAERR, "charge_full");
+
+        rewind(chargeNow);
+        fflush(chargeNow);
+        uint32_t now;
+        match = fscanf(chargeNow, "%u", &now);
+        if (match == EOF) err(EX_IOERR, "charge_now");
+        if (match < 1) errx(EX_DATAERR, "charge_now");
+
+        uint32_t percent = 100 * now / full;
+        uint32_t height = 16 * now / full;
+
+        for (int i = 0; i < 60; ++i, sleep(1)) {
+            uint32_t left = info.xres - RIGHT - WIDTH;
+
+            for (uint32_t y = 0; y <= HEIGHT; ++y) {
+                buf[y * info.xres + left - 1] = BORDER;
+                buf[y * info.xres + left + WIDTH] = BORDER;
+            }
+            for (uint32_t x = left; x < left + WIDTH; ++x) {
+                buf[HEIGHT * info.xres + x] = BORDER;
+            }
+
+            for (uint32_t y = 0; y < HEIGHT; ++y) {
+                for (uint32_t x = left; x < left + WIDTH; ++x) {
+                    buf[y * info.xres + x] =
+                        (HEIGHT - 1 - y > height) ? BG
+                        : (percent <= 10) ? RED
+                        : (percent <= 30) ? YELLOW
+                        : GRAY;
+                }
+            }
+        }
+    }
+}
diff --git a/bin/fbclock.c b/bin/fbclock.c
new file mode 100644
index 00000000..605fa4e0
--- /dev/null
+++ b/bin/fbclock.c
@@ -0,0 +1,131 @@
+/* Copyright (c) 2018, Curtis McEnroe <programble@gmail.com>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <assert.h>
+#include <err.h>
+#include <fcntl.h>
+#include <linux/fb.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <sys/ioctl.h>
+#include <sys/mman.h>
+#include <sysexits.h>
+#include <time.h>
+#include <unistd.h>
+#include <zlib.h>
+
+static const uint32_t PSF2_MAGIC = 0x864AB572;
+struct Psf2Header {
+    uint32_t magic;
+    uint32_t version;
+    uint32_t headerSize;
+    uint32_t flags;
+    uint32_t glyphCount;
+    uint32_t glyphSize;
+    uint32_t glyphHeight;
+    uint32_t glyphWidth;
+};
+
+static const uint32_t BG = 0x1D2021;
+static const uint32_t FG = 0xA99A84;
+
+int main() {
+    size_t len;
+
+    const char *fontPath = getenv("FONT");
+    if (!fontPath) {
+        fontPath = "/usr/share/kbd/consolefonts/Lat2-Terminus16.psfu.gz";
+    }
+
+    gzFile font = gzopen(fontPath, "r");
+    if (!font) err(EX_NOINPUT, "%s", fontPath);
+
+    struct Psf2Header header;
+    len = gzfread(&header, sizeof(header), 1, font);
+    if (!len && gzeof(font)) errx(EX_DATAERR, "%s: missing header", fontPath);
+    if (!len) errx(EX_IOERR, "%s", gzerror(font, NULL));
+
+    if (header.magic != PSF2_MAGIC) {
+        errx(
+            EX_DATAERR, "%s: invalid header magic %08x",
+            fontPath, header.magic
+        );
+    }
+    if (header.headerSize != sizeof(struct Psf2Header)) {
+        errx(
+            EX_DATAERR, "%s: weird header size %d",
+            fontPath, header.headerSize
+        );
+    }
+
+    uint8_t glyphs[128][header.glyphSize];
+    len = gzfread(glyphs, header.glyphSize, 128, font);
+    if (!len && gzeof(font)) errx(EX_DATAERR, "%s: missing glyphs", fontPath);
+    if (!len) errx(EX_IOERR, "%s", gzerror(font, NULL));
+
+    gzclose(font);
+
+    const char *fbPath = getenv("FRAMEBUFFER");
+    if (!fbPath) fbPath = "/dev/fb0";
+
+    int fb = open(fbPath, O_RDWR);
+    if (fb < 0) err(EX_OSFILE, "%s", fbPath);
+
+    struct fb_var_screeninfo info;
+    int error = ioctl(fb, FBIOGET_VSCREENINFO, &info);
+    if (error) err(EX_IOERR, "%s", fbPath);
+
+    size_t size = 4 * info.xres * info.yres;
+    uint32_t *buf = mmap(NULL, size, PROT_READ | PROT_WRITE, MAP_SHARED, fb, 0);
+    if (buf == MAP_FAILED) err(EX_IOERR, "%s", fbPath);
+
+    for (;;) {
+        time_t t = time(NULL);
+        if (t < 0) err(EX_OSERR, "time");
+        const struct tm *local = localtime(&t);
+        if (!local) err(EX_OSERR, "localtime");
+
+        char str[64];
+        len = strftime(str, sizeof(str), "%H:%M", local);
+        assert(len);
+
+        for (int i = 0; i < (60 - local->tm_sec); ++i, sleep(1)) {
+            uint32_t left = info.xres - header.glyphWidth * len;
+            uint32_t bottom = header.glyphHeight;
+
+            for (uint32_t y = 0; y < bottom; ++y) {
+                buf[y * info.xres + left - 1] = FG;
+            }
+            for (uint32_t x = left - 1; x < info.xres; ++x) {
+                buf[bottom * info.xres + x] = FG;
+            }
+
+            for (const char *s = str; *s; ++s) {
+                const uint8_t *glyph = glyphs[(unsigned)*s];
+                uint32_t stride = header.glyphSize / header.glyphHeight;
+                for (uint32_t y = 0; y < header.glyphHeight; ++y) {
+                    for (uint32_t x = 0; x < header.glyphWidth; ++x) {
+                        uint8_t bits = glyph[y * stride + x / 8];
+                        uint8_t bit = bits >> (7 - x % 8) & 1;
+                        buf[y * info.xres + left + x] = bit ? FG : BG;
+                    }
+                }
+                left += header.glyphWidth;
+            }
+        }
+    }
+}
diff --git a/bin/gfx/cocoa.m b/bin/gfx/cocoa.m
new file mode 100644
index 00000000..4837a386
--- /dev/null
+++ b/bin/gfx/cocoa.m
@@ -0,0 +1,162 @@
+/* Copyright (c) 2018, Curtis McEnroe <programble@gmail.com>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#import <Cocoa/Cocoa.h>
+#import <err.h>
+#import <stdbool.h>
+#import <stdint.h>
+#import <stdlib.h>
+#import <sysexits.h>
+
+#import "gfx.h"
+
+#define UNUSED __attribute__((unused))
+
+@interface BufferView : NSView {
+    size_t bufSize;
+    uint32_t *buf;
+    CGColorSpaceRef colorSpace;
+    CGDataProviderRef dataProvider;
+}
+@end
+
+@implementation BufferView
+- (instancetype) initWithFrame: (NSRect) frameRect {
+    colorSpace = CGColorSpaceCreateDeviceRGB();
+    return [super initWithFrame: frameRect];
+}
+
+- (void) setWindowTitle {
+    [[self window] setTitle: [NSString stringWithUTF8String: status()]];
+}
+
+- (void) draw {
+    draw(buf, [self frame].size.width, [self frame].size.height);
+    [self setNeedsDisplay: YES];
+}
+
+- (void) setFrameSize: (NSSize) newSize {
+    [super setFrameSize: newSize];
+    size_t newBufSize = 4 * newSize.width * newSize.height;
+    if (newBufSize > bufSize) {
+        bufSize = newBufSize;
+        buf = malloc(bufSize);
+        if (!buf) err(EX_OSERR, "malloc(%zu)", bufSize);
+        CGDataProviderRelease(dataProvider);
+        dataProvider = CGDataProviderCreateWithData(NULL, buf, bufSize, NULL);
+    }
+    [self draw];
+}
+
+- (void) drawRect: (NSRect) UNUSED dirtyRect {
+    NSSize size = [self frame].size;
+    CGContextRef ctx = [[NSGraphicsContext currentContext] CGContext];
+    CGImageRef image = CGImageCreate(
+        size.width, size.height,
+        8, 32, 4 * size.width,
+        colorSpace, kCGBitmapByteOrder32Little | kCGImageAlphaNoneSkipFirst,
+        dataProvider,
+        NULL, false, kCGRenderingIntentDefault
+    );
+    CGContextDrawImage(ctx, [self frame], image);
+    CGImageRelease(image);
+}
+
+- (BOOL) acceptsFirstResponder {
+    return YES;
+}
+
+- (void) keyDown: (NSEvent *) event {
+    char in;
+    BOOL converted = [
+        [event characters]
+        getBytes: &in
+        maxLength: 1
+        usedLength: NULL
+        encoding: NSASCIIStringEncoding
+        options: 0
+        range: NSMakeRange(0, 1)
+        remainingRange: NULL
+    ];
+    if (converted) {
+        if (!input(in)) {
+            [NSApp terminate: self];
+        }
+        [self setWindowTitle];
+        [self draw];
+    }
+}
+@end
+
+@interface Delegate : NSObject <NSApplicationDelegate>
+@end
+
+@implementation Delegate
+- (BOOL) applicationShouldTerminateAfterLastWindowClosed:
+    (NSApplication *) UNUSED sender {
+    return YES;
+}
+@end
+
+int main(int argc, char *argv[]) {
+    int error = init(argc, argv);
+    if (error) return error;
+
+    [NSApplication sharedApplication];
+    [NSApp setActivationPolicy: NSApplicationActivationPolicyRegular];
+    [NSApp setDelegate: [Delegate new]];
+
+    NSString *name = [[NSProcessInfo processInfo] processName];
+    NSMenu *menu = [NSMenu new];
+    [
+        menu
+        addItemWithTitle: @"Close Window"
+        action: @selector(performClose:)
+        keyEquivalent: @"w"
+    ];
+    [menu addItem: [NSMenuItem separatorItem]];
+    [
+        menu
+        addItemWithTitle: [@"Quit " stringByAppendingString: name]
+        action: @selector(terminate:)
+        keyEquivalent: @"q"
+    ];
+    NSMenuItem *menuItem = [NSMenuItem new];
+    [menuItem setSubmenu: menu];
+    [NSApp setMainMenu: [NSMenu new]];
+    [[NSApp mainMenu] addItem: menuItem];
+
+    NSUInteger style = NSTitledWindowMask
+        | NSClosableWindowMask
+        | NSMiniaturizableWindowMask
+        | NSResizableWindowMask;
+    NSWindow *window = [
+        [NSWindow alloc]
+        initWithContentRect: NSMakeRect(0, 0, 800, 600)
+        styleMask: style
+        backing: NSBackingStoreBuffered
+        defer: YES
+    ];
+    [window center];
+
+    BufferView *view = [[BufferView alloc] initWithFrame: [window frame]];
+    [window setContentView: view];
+    [view setWindowTitle];
+
+    [window makeKeyAndOrderFront: nil];
+    [NSApp activateIgnoringOtherApps: YES];
+    [NSApp run];
+}
diff --git a/bin/gfx/fb.c b/bin/gfx/fb.c
new file mode 100644
index 00000000..94a3245e
--- /dev/null
+++ b/bin/gfx/fb.c
@@ -0,0 +1,87 @@
+/* Copyright (c) 2018, Curtis McEnroe <programble@gmail.com>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <err.h>
+#include <fcntl.h>
+#include <linux/fb.h>
+#include <stdbool.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/ioctl.h>
+#include <sys/mman.h>
+#include <sysexits.h>
+#include <termios.h>
+#include <unistd.h>
+
+#include "gfx.h"
+
+static struct termios saveTerm;
+static void restoreTerm(void) {
+    tcsetattr(STDERR_FILENO, TCSADRAIN, &saveTerm);
+}
+
+int main(int argc, char *argv[]) {
+    int error;
+
+    error = init(argc, argv);
+    if (error) return error;
+
+    const char *path = getenv("FRAMEBUFFER");
+    if (!path) path = "/dev/fb0";
+
+    int fb = open(path, O_RDWR);
+    if (fb < 0) err(EX_OSFILE, "%s", path);
+
+    struct fb_var_screeninfo info;
+    error = ioctl(fb, FBIOGET_VSCREENINFO, &info);
+    if (error) err(EX_IOERR, "%s", path);
+
+    size_t size = 4 * info.xres * info.yres;
+    uint32_t *buf = mmap(NULL, size, PROT_READ | PROT_WRITE, MAP_SHARED, fb, 0);
+    if (buf == MAP_FAILED) err(EX_IOERR, "%s", path);
+
+    error = tcgetattr(STDERR_FILENO, &saveTerm);
+    if (error) err(EX_IOERR, "tcgetattr");
+    atexit(restoreTerm);
+
+    struct termios term = saveTerm;
+    term.c_lflag &= ~(ICANON | ECHO);
+    error = tcsetattr(STDERR_FILENO, TCSADRAIN, &term);
+    if (error) err(EX_IOERR, "tcsetattr");
+
+    uint32_t saveBg = buf[0];
+
+    uint32_t back[info.xres * info.yres];
+    for (;;) {
+        draw(back, info.xres, info.yres);
+        memcpy(buf, back, size);
+
+        char in;
+        ssize_t len = read(STDERR_FILENO, &in, 1);
+        if (len < 0) err(EX_IOERR, "read");
+        if (!len) return EX_DATAERR;
+
+        if (!input(in)) {
+            for (uint32_t i = 0; i < info.xres * info.yres; ++i) {
+                buf[i] = saveBg;
+            }
+            fprintf(stderr, "%s\n", status());
+            return EX_OK;
+        }
+    }
+}
diff --git a/bin/gfx/gfx.h b/bin/gfx/gfx.h
new file mode 100644
index 00000000..cd59ea3d
--- /dev/null
+++ b/bin/gfx/gfx.h
@@ -0,0 +1,24 @@
+/* Copyright (c) 2018, Curtis McEnroe <programble@gmail.com>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <stdbool.h>
+#include <stdint.h>
+#include <stdlib.h>
+
+extern int init(int argc, char *argv[]);
+extern const char *status(void);
+extern void draw(uint32_t *buf, size_t width, size_t height);
+extern bool input(char in);
diff --git a/bin/gfx/none.c b/bin/gfx/none.c
new file mode 100644
index 00000000..6decb24b
--- /dev/null
+++ b/bin/gfx/none.c
@@ -0,0 +1,24 @@
+/* Copyright (c) 2018, Curtis McEnroe <programble@gmail.com>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <err.h>
+#include <sysexits.h>
+
+#include "gfx.h"
+
+int main() {
+    errx(EX_CONFIG, "no gfx frontend");
+}
diff --git a/bin/gfx/x11.c b/bin/gfx/x11.c
new file mode 100644
index 00000000..108d6459
--- /dev/null
+++ b/bin/gfx/x11.c
@@ -0,0 +1,135 @@
+/* Copyright (c) 2018, Curtis McEnroe <programble@gmail.com>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <X11/Xlib.h>
+#include <err.h>
+#include <sysexits.h>
+#include <stdint.h>
+#include <stdlib.h>
+#include <stdbool.h>
+
+#include "gfx.h"
+
+static size_t width = 800;
+static size_t height = 600;
+
+static Display *display;
+static Window window;
+static Atom WM_DELETE_WINDOW;
+static GC windowGc;
+static XImage *image;
+
+static size_t bufSize;
+static uint32_t *buf;
+
+static size_t pixmapWidth;
+static size_t pixmapHeight;
+static Pixmap pixmap;
+
+static void createWindow(void) {
+    display = XOpenDisplay(NULL);
+    if (!display) errx(EX_UNAVAILABLE, "XOpenDisplay: %s", XDisplayName(NULL));
+
+    Window root = DefaultRootWindow(display);
+    window = XCreateSimpleWindow(display, root, 0, 0, width, height, 0, 0, 0);
+
+    WM_DELETE_WINDOW = XInternAtom(display, "WM_DELETE_WINDOW", false);
+    XSetWMProtocols(display, window, &WM_DELETE_WINDOW, 1);
+
+    windowGc = XCreateGC(display, window, 0, NULL);
+
+    image = XCreateImage(display, NULL, 24, ZPixmap, 0, NULL, width, height, 32, 0);
+}
+
+static void resizePixmap(void) {
+    size_t newSize = 4 * width * height;
+    if (newSize > bufSize) {
+        bufSize = newSize;
+        free(buf);
+        buf = malloc(bufSize);
+        if (!buf) err(EX_OSERR, "malloc(%zu)", bufSize);
+    }
+
+    image->data = (char *)buf;
+    image->width = width;
+    image->height = height;
+    image->bytes_per_line = 4 * width;
+
+    if (width > pixmapWidth || height > pixmapHeight) {
+        pixmapWidth = width;
+        pixmapHeight = height;
+        if (pixmap) XFreePixmap(display, pixmap);
+        pixmap = XCreatePixmap(display, window, pixmapWidth, pixmapHeight, 24);
+    }
+}
+
+static void drawWindow(void) {
+    draw(buf, width, height);
+    XPutImage(display, pixmap, windowGc, image, 0, 0, 0, 0, width, height);
+    XCopyArea(display, pixmap, window, windowGc, 0, 0, width, height, 0, 0);
+}
+
+int main(int argc, char *argv[]) {
+    int error = init(argc, argv);
+    if (error) return error;
+
+    createWindow();
+    resizePixmap();
+    drawWindow();
+
+    XStoreName(display, window, status());
+    XMapWindow(display, window);
+
+    XEvent event;
+    XSelectInput(display, window, ExposureMask | StructureNotifyMask | KeyPressMask);
+    for (;;) {
+        XNextEvent(display, &event);
+
+        switch (event.type) {
+            case KeyPress: {
+                XKeyEvent key = event.xkey;
+                KeySym sym = XLookupKeysym(&key, key.state & ShiftMask);
+                if (sym > 0x80) break;
+                if (!input(sym)) return EX_OK;
+                XStoreName(display, window, status());
+                drawWindow();
+            } break;
+
+            case ConfigureNotify: {
+                XConfigureEvent configure = event.xconfigure;
+                width = configure.width;
+                height = configure.height;
+                resizePixmap();
+                drawWindow();
+            } break;
+
+            case Expose: {
+                XExposeEvent expose = event.xexpose;
+                XCopyArea(
+                    display, pixmap, window, windowGc,
+                    expose.x, expose.y,
+                    expose.width, expose.height,
+                    expose.x, expose.y
+                );
+            } break;
+
+            case ClientMessage: {
+                XClientMessageEvent client = event.xclient;
+                if ((Atom)client.data.l[0] == WM_DELETE_WINDOW) return EX_OK;
+            } break;
+        }
+    }
+}
diff --git a/bin/gfxx.c b/bin/gfxx.c
new file mode 100644
index 00000000..8a43fd2f
--- /dev/null
+++ b/bin/gfxx.c
@@ -0,0 +1,492 @@
+/* Copyright (c) 2018, Curtis McEnroe <programble@gmail.com>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <arpa/inet.h>
+#include <err.h>
+#include <fcntl.h>
+#include <math.h>
+#include <stdbool.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/mman.h>
+#include <sys/stat.h>
+#include <sysexits.h>
+#include <unistd.h>
+#include <zlib.h>
+
+#include "gfx/gfx.h"
+
+#define MAX(a, b) ((a) > (b) ? (a) : (b))
+#define MASK(b) ((1 << (b)) - 1)
+
+#define RGB(r, g, b) ((uint32_t)(r) << 16 | (uint32_t)(g) << 8 | (uint32_t)(b))
+#define GRAY(n) RGB(n, n, n)
+
+static enum {
+    COLOR_INDEXED,
+    COLOR_GRAYSCALE,
+    COLOR_RGB,
+    COLOR__COUNT,
+} space = COLOR_RGB;
+static const char *COLOR__STR[COLOR__COUNT] = { "indexed", "grayscale", "rgb" };
+static uint32_t palette[256];
+
+static enum {
+    ENDIAN_LITTLE,
+    ENDIAN_BIG,
+} byteOrder, bitOrder;
+
+enum { PAD, R, G, B };
+static uint8_t bits[4] = { 8, 8, 8, 8 };
+#define BITS_COLOR (bits[R] + bits[G] + bits[B])
+#define BITS_TOTAL (bits[PAD] + BITS_COLOR)
+
+static size_t offset;
+static size_t width = 16;
+static bool flip;
+static bool mirror;
+static size_t scale = 1;
+
+static const char *prefix = "gfxx";
+
+static size_t size;
+static uint8_t *data;
+
+int init(int argc, char *argv[]) {
+    const char *pal = NULL;
+    const char *path = NULL;
+
+    int opt;
+    while (0 < (opt = getopt(argc, argv, "c:p:b:e:E:n:fmw:z:o:"))) {
+        switch (opt) {
+            case 'c': switch (optarg[0]) {
+                case 'i': space = COLOR_INDEXED; break;
+                case 'g': space = COLOR_GRAYSCALE; break;
+                case 'r': space = COLOR_RGB; break;
+                default: return EX_USAGE;
+            } break;
+            case 'p': pal = optarg; break;
+            case 'e': switch (optarg[0]) {
+                case 'l': byteOrder = ENDIAN_LITTLE; break;
+                case 'b': byteOrder = ENDIAN_BIG; break;
+                default: return EX_USAGE;
+            } break;
+            case 'E': switch (optarg[0]) {
+                case 'l': bitOrder = ENDIAN_LITTLE; break;
+                case 'b': bitOrder = ENDIAN_BIG; break;
+                default: return EX_USAGE;
+            } break;
+            case 'b': {
+                if (strlen(optarg) < 4) return EX_USAGE;
+                for (int i = 0; i < 4; ++i) {
+                    bits[i] = optarg[i] - '0';
+                }
+            } break;
+            case 'n': offset  = strtoul(optarg, NULL, 0); break;
+            case 'f': flip   ^= true; break;
+            case 'm': mirror ^= true; break;
+            case 'w': width   = strtoul(optarg, NULL, 0); break;
+            case 'z': scale   = strtoul(optarg, NULL, 0); break;
+            case 'o': prefix  = optarg; break;
+            default: return EX_USAGE;
+        }
+    }
+    if (argc > optind) path = argv[optind];
+    if (!width || !scale) return EX_USAGE;
+
+    if (pal) {
+        FILE *file = fopen(pal, "r");
+        if (!file) err(EX_NOINPUT, "%s", pal);
+        fread(palette, 4, 256, file);
+        if (ferror(file)) err(EX_IOERR, "%s", pal);
+        fclose(file);
+    } else {
+        for (int i = 0; i < 256; ++i) {
+            double h = i / 256.0 * 6.0;
+            double x = 1.0 - fabs(fmod(h, 2.0) - 1.0);
+            double r = 255.0, g = 255.0, b = 255.0;
+            if      (h <= 1.0) { g *= x; b = 0.0; }
+            else if (h <= 2.0) { r *= x; b = 0.0; }
+            else if (h <= 3.0) { r = 0.0; b *= x; }
+            else if (h <= 4.0) { r = 0.0; g *= x; }
+            else if (h <= 5.0) { r *= x; g = 0.0; }
+            else if (h <= 6.0) { g = 0.0; b *= x; }
+            palette[i] = (uint32_t)r << 16 | (uint32_t)g << 8 | (uint32_t)b;
+        }
+    }
+
+    if (path) {
+        int fd = open(path, O_RDONLY);
+        if (fd < 0) err(EX_NOINPUT, "%s", path);
+
+        struct stat stat;
+        int error = fstat(fd, &stat);
+        if (error) err(EX_IOERR, "%s", path);
+        size = stat.st_size;
+
+        data = mmap(NULL, size, PROT_READ, MAP_SHARED, fd, 0);
+        if (data == MAP_FAILED) err(EX_IOERR, "%s", path);
+
+    } else {
+        size = 1024 * 1024;
+        data = malloc(size);
+        if (!data) err(EX_OSERR, "malloc(%zu)", size);
+
+        size = fread(data, 1, size, stdin);
+        if (ferror(stdin)) err(EX_IOERR, "(stdin)");
+    }
+
+    return EX_OK;
+}
+
+static char options[128];
+static void formatOptions(void) {
+    snprintf(
+        options, sizeof(options),
+        "gfxx -c %s -e%c -E%c -b %hhu%hhu%hhu%hhu -n %#zx %s%s-w %zu -z %zu",
+        COLOR__STR[space],
+        "lb"[byteOrder],
+        "lb"[bitOrder],
+        bits[PAD], bits[R], bits[G], bits[B],
+        offset,
+        flip ? "-f " : "",
+        mirror ? "-m " : "",
+        width,
+        scale
+    );
+}
+
+const char *status(void) {
+    formatOptions();
+    return options;
+}
+
+struct Iter {
+    uint32_t *buf;
+    size_t bufWidth;
+    size_t bufHeight;
+    size_t left;
+    size_t x;
+    size_t y;
+};
+
+static struct Iter iter(uint32_t *buf, size_t bufWidth, size_t bufHeight) {
+    struct Iter it = { .buf = buf, .bufWidth = bufWidth, .bufHeight = bufHeight };
+    if (mirror) it.x = width - 1;
+    if (flip) it.y = bufHeight / scale - 1;
+    return it;
+}
+
+static bool nextX(struct Iter *it) {
+    if (mirror) {
+        if (it->x == it->left) return false;
+        it->x--;
+    } else {
+        it->x++;
+        if (it->x == it->left + width) return false;
+    }
+    return true;
+}
+
+static bool nextY(struct Iter *it) {
+    if (flip) {
+        if (it->y == 0) {
+            it->left += width;
+            it->y = it->bufHeight / scale;
+        }
+        it->y--;
+    } else {
+        it->y++;
+        if (it->y == it->bufHeight / scale) {
+            it->left += width;
+            it->y = 0;
+        }
+    }
+    it->x = it->left;
+    if (mirror) it->x += width - 1;
+    return (it->left < it->bufWidth / scale);
+}
+
+static bool next(struct Iter *it) {
+    return nextX(it) || nextY(it);
+}
+
+static void put(const struct Iter *it, uint32_t pixel) {
+    size_t scaledX = it->x * scale;
+    size_t scaledY = it->y * scale;
+    for (size_t fillY = scaledY; fillY < scaledY + scale; ++fillY) {
+        if (fillY >= it->bufHeight) break;
+        for (size_t fillX = scaledX; fillX < scaledX + scale; ++fillX) {
+            if (fillX >= it->bufWidth) break;
+            it->buf[fillY * it->bufWidth + fillX] = pixel;
+        }
+    }
+}
+
+static uint8_t interp(uint8_t b, uint32_t n) {
+    if (b == 8) return n;
+    if (b == 0) return 0;
+    return n * MASK(8) / MASK(b);
+}
+
+static uint32_t interpolate(uint32_t rgb) {
+    uint32_t r, g, b;
+    if (bitOrder == ENDIAN_LITTLE) {
+        b = rgb & MASK(bits[B]);
+        g = (rgb >>= bits[B]) & MASK(bits[G]);
+        r = (rgb >>= bits[G]) & MASK(bits[R]);
+    } else {
+        r = rgb & MASK(bits[R]);
+        g = (rgb >>= bits[R]) & MASK(bits[G]);
+        b = (rgb >>= bits[G]) & MASK(bits[B]);
+    }
+    return RGB(interp(bits[R], r), interp(bits[G], g), interp(bits[B], b));
+}
+
+static void drawBits(struct Iter *it) {
+    for (size_t i = offset; i < size; ++i) {
+        for (uint8_t b = 0; b < 8; b += BITS_TOTAL) {
+            uint8_t n;
+            if (byteOrder == ENDIAN_BIG) {
+                n = data[i] >> (8 - BITS_TOTAL - b) & MASK(BITS_TOTAL);
+            } else {
+                n = data[i] >> b & MASK(BITS_TOTAL);
+            }
+
+            if (space == COLOR_INDEXED) {
+                put(it, palette[n]);
+            } else if (space == COLOR_GRAYSCALE) {
+                put(it, GRAY(interp(BITS_COLOR, n & MASK(BITS_COLOR))));
+            } else if (space == COLOR_RGB) {
+                put(it, interpolate(n));
+            }
+
+            if (!next(it)) return;
+        }
+    }
+}
+
+static void drawBytes(struct Iter *it) {
+    uint8_t bytes = (BITS_TOTAL + 7) / 8;
+    for (size_t i = offset; i + bytes <= size; i += bytes) {
+        uint32_t n = 0;
+        for (size_t b = 0; b < bytes; ++b) {
+            n <<= 8;
+            n |= (byteOrder == ENDIAN_BIG) ? data[i + b] : data[i + bytes - b - 1];
+        }
+
+        if (space == COLOR_INDEXED) {
+            put(it, palette[n & 0xFF]);
+        } else if (space == COLOR_GRAYSCALE) {
+            put(it, GRAY(interp(BITS_COLOR, n & MASK(BITS_COLOR))));
+        } else if (space == COLOR_RGB) {
+            put(it, interpolate(n));
+        }
+
+        if (!next(it)) return;
+    }
+}
+
+static struct {
+    unsigned counter;
+    char path[FILENAME_MAX];
+    FILE *file;
+} out;
+static void outOpen(const char *ext) {
+    snprintf(out.path, sizeof(out.path), "%s%04u.%s", prefix, ++out.counter, ext);
+    out.file = fopen(out.path, "wx");
+    if (out.file) {
+        printf("%s\n", out.path);
+    } else {
+        warn("%s", out.path);
+    }
+}
+
+static uint32_t crc;
+static void pngWrite(const void *ptr, size_t size) {
+    fwrite(ptr, size, 1, out.file);
+    if (ferror(out.file)) err(EX_IOERR, "%s", out.path);
+    crc = crc32(crc, ptr, size);
+}
+static void pngUint(uint32_t host) {
+    uint32_t net = htonl(host);
+    pngWrite(&net, 4);
+}
+static void pngChunk(const char *type, uint32_t size) {
+    pngUint(size);
+    crc = crc32(0, Z_NULL, 0);
+    pngWrite(type, 4);
+}
+
+static void pngDump(uint32_t *src, size_t srcWidth, size_t srcHeight) {
+    int error;
+
+    size_t stride = 1 + 3 * srcWidth;
+    uint8_t data[stride * srcHeight];
+    for (size_t y = 0; y < srcHeight; ++y) {
+        data[y * stride] = 0;
+        for (size_t x = 0; x < srcWidth; ++x) {
+            uint8_t *p = &data[y * stride + 1 + 3 * x];
+            p[0] = src[y * srcWidth + x] >> 16;
+            p[1] = src[y * srcWidth + x] >> 8;
+            p[2] = src[y * srcWidth + x];
+        }
+    }
+
+    uLong deflateSize = compressBound(sizeof(data));
+    uint8_t deflate[deflateSize];
+    error = compress(deflate, &deflateSize, data, sizeof(data));
+    if (error != Z_OK) errx(EX_SOFTWARE, "compress: %d", error);
+
+    outOpen("png");
+    if (!out.file) return;
+
+    const uint8_t SIGNATURE[] = { 0x89, 'P', 'N', 'G', '\r', '\n', 0x1A, '\n' };
+    const uint8_t HEADER[] = { 8, 2, 0, 0, 0 }; // 8-bit truecolor
+    const char SOFTWARE[] = "Software";
+    formatOptions();
+    uint8_t sbit[3] = { MAX(bits[R], 1), MAX(bits[G], 1), MAX(bits[B], 1) };
+
+    pngWrite(SIGNATURE, sizeof(SIGNATURE));
+
+    pngChunk("IHDR", 4 + 4 + sizeof(HEADER));
+    pngUint(srcWidth);
+    pngUint(srcHeight);
+    pngWrite(HEADER, sizeof(HEADER));
+    pngUint(crc);
+
+    pngChunk("tEXt", sizeof(SOFTWARE) + strlen(options));
+    pngWrite(SOFTWARE, sizeof(SOFTWARE));
+    pngWrite(options, strlen(options));
+    pngUint(crc);
+
+    pngChunk("sBIT", sizeof(sbit));
+    pngWrite(sbit, sizeof(sbit));
+    pngUint(crc);
+
+    pngChunk("IDAT", deflateSize);
+    pngWrite(deflate, deflateSize);
+    pngUint(crc);
+
+    pngChunk("IEND", 0);
+    pngUint(crc);
+
+    error = fclose(out.file);
+    if (error) err(EX_IOERR, "%s", out.path);
+}
+
+static enum {
+    DUMP_NONE,
+    DUMP_ONE,
+    DUMP_ALL,
+} dump;
+
+void draw(uint32_t *buf, size_t bufWidth, size_t bufHeight) {
+    memset(buf, 0, 4 * bufWidth * bufHeight);
+    struct Iter it = iter(buf, bufWidth, bufHeight);
+    if (BITS_TOTAL >= 8) {
+        drawBytes(&it);
+    } else {
+        drawBits(&it);
+    }
+    if (dump) pngDump(buf, bufWidth, bufHeight);
+    if (dump == DUMP_ONE) dump = DUMP_NONE;
+}
+
+static void palSample(void) {
+    size_t temp = scale;
+    scale = 1;
+    draw(palette, 256, 1);
+    scale = temp;
+}
+
+static void palDump(void) {
+    outOpen("dat");
+    if (!out.file) return;
+
+    fwrite(palette, 4, 256, out.file);
+    if (ferror(out.file)) err(EX_IOERR, "%s", out.path);
+
+    int error = fclose(out.file);
+    if (error) err(EX_IOERR, "%s", out.path);
+}
+
+static const uint8_t PRESETS[][4] = {
+    { 0, 0, 1, 0 },
+    { 0, 1, 1, 0 },
+    { 1, 1, 1, 1 },
+    { 2, 2, 2, 2 },
+    { 0, 3, 3, 2 },
+    { 4, 4, 4, 4 },
+    { 1, 5, 5, 5 },
+    { 0, 5, 6, 5 },
+    { 0, 8, 8, 8 },
+    { 8, 8, 8, 8 },
+};
+#define PRESETS_LEN (sizeof(PRESETS) / sizeof(PRESETS[0]))
+
+static uint8_t preset = PRESETS_LEN - 1;
+static void setPreset(void) {
+    bits[PAD] = PRESETS[preset][PAD];
+    bits[R] = PRESETS[preset][R];
+    bits[G] = PRESETS[preset][G];
+    bits[B] = PRESETS[preset][B];
+}
+
+static void setBit(char in) {
+    static uint8_t bit = 0;
+    bits[bit++] = in - '0';
+    bit &= 3;
+}
+
+bool input(char in) {
+    size_t pixel = (BITS_TOTAL + 7) / 8;
+    size_t row = width * BITS_TOTAL / 8;
+    switch (in) {
+        case 'q': return false;
+        break; case 'x': dump = DUMP_ONE;
+        break; case 'X': dump ^= DUMP_ALL;
+        break; case 'o': formatOptions(); printf("%s\n", options);
+        break; case '[': if (!space--) space = COLOR__COUNT - 1;
+        break; case ']': if (++space == COLOR__COUNT) space = 0;
+        break; case 'p': palSample();
+        break; case 'P': palDump();
+        break; case '{': if (!preset--) preset = PRESETS_LEN - 1; setPreset();
+        break; case '}': if (++preset == PRESETS_LEN) preset = 0; setPreset();
+        break; case 'e': byteOrder ^= ENDIAN_BIG;
+        break; case 'E': bitOrder ^= ENDIAN_BIG;
+        break; case 'h': if (offset) offset--;
+        break; case 'j': offset += pixel;
+        break; case 'k': if (offset >= pixel) offset -= pixel;
+        break; case 'l': offset++;
+        break; case 'H': if (offset >= row) offset -= row;
+        break; case 'J': offset += width * row;
+        break; case 'K': if (offset >= width * row) offset -= width * row;
+        break; case 'L': offset += row;
+        break; case '.': width++;
+        break; case ',': if (width > 1) width--;
+        break; case '>': width *= 2;
+        break; case '<': if (width > 1) width /= 2;
+        break; case 'f': flip ^= true;
+        break; case 'm': mirror ^= true;
+        break; case '+': scale++;
+        break; case '-': if (scale > 1) scale--;
+        break; default: if (in >= '0' && in <= '9') setBit(in);
+    }
+    return true;
+}
diff --git a/bin/glitch.c b/bin/glitch.c
new file mode 100644
index 00000000..ea9c083d
--- /dev/null
+++ b/bin/glitch.c
@@ -0,0 +1,488 @@
+/* Copyright (c) 2018, Curtis McEnroe <programble@gmail.com>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <arpa/inet.h>
+#include <assert.h>
+#include <err.h>
+#include <stdbool.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sysexits.h>
+#include <unistd.h>
+#include <zlib.h>
+
+#define PACKED __attribute__((packed))
+
+#define CRC_INIT (crc32(0, Z_NULL, 0))
+
+static const char *path;
+static FILE *file;
+static uint32_t crc;
+
+static void readExpect(void *ptr, size_t size, const char *expect) {
+    fread(ptr, size, 1, file);
+    if (ferror(file)) err(EX_IOERR, "%s", path);
+    if (feof(file)) errx(EX_DATAERR, "%s: missing %s", path, expect);
+    crc = crc32(crc, ptr, size);
+}
+
+static void writeExpect(const void *ptr, size_t size) {
+    fwrite(ptr, size, 1, file);
+    if (ferror(file)) err(EX_IOERR, "%s", path);
+    crc = crc32(crc, ptr, size);
+}
+
+static const uint8_t SIGNATURE[8] = {
+    0x89, 'P', 'N', 'G', '\r', '\n', 0x1A, '\n'
+};
+
+static void readSignature(void) {
+    uint8_t signature[8];
+    readExpect(signature, 8, "signature");
+    if (0 != memcmp(signature, SIGNATURE, 8)) {
+        errx(EX_DATAERR, "%s: invalid signature", path);
+    }
+}
+
+static void writeSignature(void) {
+    writeExpect(SIGNATURE, sizeof(SIGNATURE));
+}
+
+struct PACKED Chunk {
+    uint32_t size;
+    char type[4];
+};
+
+static const char *typeStr(struct Chunk chunk) {
+    static char buf[5];
+    memcpy(buf, chunk.type, 4);
+    return buf;
+}
+
+static struct Chunk readChunk(void) {
+    struct Chunk chunk;
+    readExpect(&chunk, sizeof(chunk), "chunk");
+    chunk.size = ntohl(chunk.size);
+    crc = crc32(CRC_INIT, (Byte *)chunk.type, sizeof(chunk.type));
+    return chunk;
+}
+
+static void writeChunk(struct Chunk chunk) {
+    chunk.size = htonl(chunk.size);
+    writeExpect(&chunk, sizeof(chunk));
+    crc = crc32(CRC_INIT, (Byte *)chunk.type, sizeof(chunk.type));
+}
+
+static void readCrc(void) {
+    uint32_t expected = crc;
+    uint32_t found;
+    readExpect(&found, sizeof(found), "CRC32");
+    found = ntohl(found);
+    if (found != expected) {
+        errx(
+            EX_DATAERR, "%s: expected CRC32 %08X, found %08X",
+            path, expected, found
+        );
+    }
+}
+
+static void writeCrc(void) {
+    uint32_t net = htonl(crc);
+    writeExpect(&net, sizeof(net));
+}
+
+static void skipChunk(struct Chunk chunk) {
+    uint8_t discard[chunk.size];
+    readExpect(discard, sizeof(discard), "chunk data");
+    readCrc();
+}
+
+static struct PACKED {
+    uint32_t width;
+    uint32_t height;
+    uint8_t depth;
+    enum PACKED {
+        GRAYSCALE       = 0,
+        TRUECOLOR       = 2,
+        INDEXED         = 3,
+        GRAYSCALE_ALPHA = 4,
+        TRUECOLOR_ALPHA = 6,
+    } color;
+    uint8_t compression;
+    uint8_t filter;
+    uint8_t interlace;
+} header;
+
+static size_t lineSize(void) {
+    switch (header.color) {
+        case GRAYSCALE:       return (header.width * 1 * header.depth + 7) / 8;
+        case TRUECOLOR:       return (header.width * 3 * header.depth + 7) / 8;
+        case INDEXED:         return (header.width * 1 * header.depth + 7) / 8;
+        case GRAYSCALE_ALPHA: return (header.width * 2 * header.depth + 7) / 8;
+        case TRUECOLOR_ALPHA: return (header.width * 4 * header.depth + 7) / 8;
+        default: abort();
+    }
+}
+
+static size_t dataSize(void) {
+    return (1 + lineSize()) * header.height;
+}
+
+static void readHeader(void) {
+    struct Chunk ihdr = readChunk();
+    if (0 != memcmp(ihdr.type, "IHDR", 4)) {
+        errx(EX_DATAERR, "%s: expected IHDR, found %s", path, typeStr(ihdr));
+    }
+    if (ihdr.size != sizeof(header)) {
+        errx(
+            EX_DATAERR, "%s: expected IHDR size %zu, found %u",
+            path, sizeof(header), ihdr.size
+        );
+    }
+    readExpect(&header, sizeof(header), "header");
+    readCrc();
+    header.width = ntohl(header.width);
+    header.height = ntohl(header.height);
+    if (!header.width) errx(EX_DATAERR, "%s: invalid width 0", path);
+    if (!header.height) errx(EX_DATAERR, "%s: invalid height 0", path);
+}
+
+static void writeHeader(void) {
+    struct Chunk ihdr = { .size = sizeof(header), .type = "IHDR" };
+    writeChunk(ihdr);
+    header.width = htonl(header.width);
+    header.height = htonl(header.height);
+    writeExpect(&header, sizeof(header));
+    writeCrc();
+    header.width = ntohl(header.width);
+    header.height = ntohl(header.height);
+}
+
+static struct {
+    uint32_t len;
+    uint8_t entries[256][3];
+} palette;
+
+static void readPalette(void) {
+    struct Chunk chunk;
+    for (;;) {
+        chunk = readChunk();
+        if (0 == memcmp(chunk.type, "PLTE", 4)) break;
+        skipChunk(chunk);
+    }
+    palette.len = chunk.size / 3;
+    readExpect(palette.entries, chunk.size, "palette data");
+    readCrc();
+}
+
+static void writePalette(void) {
+    struct Chunk plte = { .size = 3 * palette.len, .type = "PLTE" };
+    writeChunk(plte);
+    writeExpect(palette.entries, plte.size);
+    writeCrc();
+}
+
+static uint8_t *data;
+
+static void readData(void) {
+    data = malloc(dataSize());
+    if (!data) err(EX_OSERR, "malloc(%zu)", dataSize());
+
+    struct z_stream_s stream = { .next_out = data, .avail_out = dataSize() };
+    int error = inflateInit(&stream);
+    if (error != Z_OK) errx(EX_SOFTWARE, "%s: inflateInit: %s", path, stream.msg);
+
+    for (;;) {
+        struct Chunk chunk = readChunk();
+        if (0 == memcmp(chunk.type, "IDAT", 4)) {
+            uint8_t idat[chunk.size];
+            readExpect(idat, sizeof(idat), "image data");
+            readCrc();
+
+            stream.next_in = idat;
+            stream.avail_in = sizeof(idat);
+            int error = inflate(&stream, Z_SYNC_FLUSH);
+            if (error == Z_STREAM_END) break;
+            if (error != Z_OK) errx(EX_DATAERR, "%s: inflate: %s", path, stream.msg);
+
+        } else if (0 == memcmp(chunk.type, "IEND", 4)) {
+            errx(EX_DATAERR, "%s: missing IDAT chunk", path);
+        } else {
+            skipChunk(chunk);
+        }
+    }
+
+    inflateEnd(&stream);
+    if (stream.total_out != dataSize()) {
+        errx(
+            EX_DATAERR, "%s: expected data size %zu, found %lu",
+            path, dataSize(), stream.total_out
+        );
+    }
+}
+
+static void writeData(void) {
+    uLong size = compressBound(dataSize());
+    uint8_t deflate[size];
+    int error = compress2(deflate, &size, data, dataSize(), Z_BEST_SPEED);
+    if (error != Z_OK) errx(EX_SOFTWARE, "%s: compress2: %d", path, error);
+
+    struct Chunk idat = { .size = size, .type = "IDAT" };
+    writeChunk(idat);
+    writeExpect(deflate, size);
+    writeCrc();
+}
+
+static void writeEnd(void) {
+    struct Chunk iend = { .size = 0, .type = "IEND" };
+    writeChunk(iend);
+    writeCrc();
+}
+
+enum PACKED Filter {
+    NONE,
+    SUB,
+    UP,
+    AVERAGE,
+    PAETH,
+};
+#define FILTER_COUNT (PAETH + 1)
+
+static struct {
+    bool brokenPaeth;
+    bool filt;
+    bool recon;
+    uint8_t declareFilter;
+    uint8_t applyFilter;
+    enum Filter declareFilters[255];
+    enum Filter applyFilters[255];
+} options;
+
+struct Bytes {
+    uint8_t x;
+    uint8_t a;
+    uint8_t b;
+    uint8_t c;
+};
+
+static uint8_t paethPredictor(struct Bytes f) {
+    int32_t p = (int32_t)f.a + (int32_t)f.b - (int32_t)f.c;
+    int32_t pa = abs(p - (int32_t)f.a);
+    int32_t pb = abs(p - (int32_t)f.b);
+    int32_t pc = abs(p - (int32_t)f.c);
+    if (pa <= pb && pa <= pc) return f.a;
+    if (options.brokenPaeth) {
+        if (pb < pc) return f.b;
+    } else {
+        if (pb <= pc) return f.b;
+    }
+    return f.c;
+}
+
+static uint8_t recon(enum Filter type, struct Bytes f) {
+    switch (type) {
+        case NONE:    return f.x;
+        case SUB:     return f.x + f.a;
+        case UP:      return f.x + f.b;
+        case AVERAGE: return f.x + ((uint32_t)f.a + (uint32_t)f.b) / 2;
+        case PAETH:   return f.x + paethPredictor(f);
+        default:      abort();
+    }
+}
+
+static uint8_t filt(enum Filter type, struct Bytes f) {
+    switch (type) {
+        case NONE:    return f.x;
+        case SUB:     return f.x - f.a;
+        case UP:      return f.x - f.b;
+        case AVERAGE: return f.x - ((uint32_t)f.a + (uint32_t)f.b) / 2;
+        case PAETH:   return f.x - paethPredictor(f);
+        default:      abort();
+    }
+}
+
+static struct Line {
+    enum Filter type;
+    uint8_t data[];
+} **lines;
+
+static void scanlines(void) {
+    lines = calloc(header.height, sizeof(*lines));
+    if (!lines) err(EX_OSERR, "calloc(%u, %zu)", header.height, sizeof(*lines));
+
+    size_t stride = 1 + lineSize();
+    for (uint32_t y = 0; y < header.height; ++y) {
+        lines[y] = (struct Line *)&data[y * stride];
+        if (lines[y]->type >= FILTER_COUNT) {
+            errx(EX_DATAERR, "%s: invalid filter type %hhu", path, lines[y]->type);
+        }
+    }
+}
+
+static struct Bytes origBytes(uint32_t y, size_t i) {
+    size_t pixelSize = lineSize() / header.width;
+    if (!pixelSize) pixelSize = 1;
+    bool a = (i >= pixelSize), b = (y > 0), c = (a && b);
+    return (struct Bytes) {
+        .x = lines[y]->data[i],
+        .a = a ? lines[y]->data[i - pixelSize] : 0,
+        .b = b ? lines[y - 1]->data[i] : 0,
+        .c = c ? lines[y - 1]->data[i - pixelSize] : 0,
+    };
+}
+
+static void reconData(void) {
+    for (uint32_t y = 0; y < header.height; ++y) {
+        for (size_t i = 0; i < lineSize(); ++i) {
+            if (options.filt) {
+                lines[y]->data[i] = filt(lines[y]->type, origBytes(y, i));
+            } else {
+                lines[y]->data[i] = recon(lines[y]->type, origBytes(y, i));
+            }
+        }
+        lines[y]->type = NONE;
+    }
+}
+
+static void filterData(void) {
+    for (uint32_t y = header.height - 1; y < header.height; --y) {
+        uint8_t filter[FILTER_COUNT][lineSize()];
+        uint32_t heuristic[FILTER_COUNT] = {0};
+        enum Filter minType = NONE;
+        for (enum Filter type = NONE; type < FILTER_COUNT; ++type) {
+            for (size_t i = 0; i < lineSize(); ++i) {
+                if (options.recon) {
+                    filter[type][i] = recon(type, origBytes(y, i));
+                } else {
+                    filter[type][i] = filt(type, origBytes(y, i));
+                }
+                heuristic[type] += abs((int8_t)filter[type][i]);
+            }
+            if (heuristic[type] < heuristic[minType]) minType = type;
+        }
+
+        if (options.declareFilter) {
+            lines[y]->type = options.declareFilters[y % options.declareFilter];
+        } else {
+            lines[y]->type = minType;
+        }
+
+        if (options.applyFilter) {
+            enum Filter type = options.applyFilters[y % options.applyFilter];
+            memcpy(lines[y]->data, filter[type], lineSize());
+        } else {
+            memcpy(lines[y]->data, filter[minType], lineSize());
+        }
+    }
+}
+
+static void glitch(const char *inPath, const char *outPath) {
+    if (inPath) {
+        path = inPath;
+        file = fopen(path, "r");
+        if (!file) err(EX_NOINPUT, "%s", path);
+    } else {
+        path = "(stdin)";
+        file = stdin;
+    }
+
+    readSignature();
+    readHeader();
+    if (header.color == INDEXED) readPalette();
+    readData();
+    fclose(file);
+
+    scanlines();
+    reconData();
+    filterData();
+    free(lines);
+
+    if (outPath) {
+        path = outPath;
+        file = fopen(path, "w");
+        if (!file) err(EX_CANTCREAT, "%s", path);
+    } else {
+        path = "(stdout)";
+        file = stdout;
+    }
+
+    writeSignature();
+    writeHeader();
+    if (header.color == INDEXED) writePalette();
+    writeData();
+    writeEnd();
+    free(data);
+
+    int error = fclose(file);
+    if (error) err(EX_IOERR, "%s", path);
+}
+
+static enum Filter parseFilter(const char *s) {
+    switch (s[0]) {
+        case 'N': case 'n': return NONE;
+        case 'S': case 's': return SUB;
+        case 'U': case 'u': return UP;
+        case 'A': case 'a': return AVERAGE;
+        case 'P': case 'p': return PAETH;
+        default: errx(EX_USAGE, "invalid filter type %s", s);
+    }
+}
+
+static uint8_t parseFilters(enum Filter *filters, const char *s) {
+    uint8_t len = 0;
+    do {
+        filters[len++] = parseFilter(s);
+        s = strchr(s, ',');
+    } while (s++);
+    return len;
+}
+
+int main(int argc, char *argv[]) {
+    bool stdio = false;
+    char *output = NULL;
+
+    int opt;
+    while (0 < (opt = getopt(argc, argv, "a:cd:fo:pr"))) {
+        switch (opt) {
+            case 'a': {
+                options.applyFilter = parseFilters(options.applyFilters, optarg);
+            } break;
+            case 'c': stdio = true; break;
+            case 'd': {
+                options.declareFilter = parseFilters(options.declareFilters, optarg);
+            } break;
+            case 'f': options.filt = true; break;
+            case 'o': output = optarg; break;
+            case 'p': options.brokenPaeth = true; break;
+            case 'r': options.recon = true; break;
+            default: return EX_USAGE;
+        }
+    }
+
+    if (argc - optind == 1 && (output || stdio)) {
+        glitch(argv[optind], output);
+    } else if (optind < argc) {
+        for (int i = optind; i < argc; ++i) {
+            glitch(argv[i], argv[i]);
+        }
+    } else {
+        glitch(NULL, output);
+    }
+
+    return EX_OK;
+}
diff --git a/bin/hnel.c b/bin/hnel.c
new file mode 100644
index 00000000..709ea2fc
--- /dev/null
+++ b/bin/hnel.c
@@ -0,0 +1,118 @@
+/* Copyright (c) 2017, Curtis McEnroe <programble@gmail.com>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <err.h>
+#include <poll.h>
+#include <stdbool.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/ioctl.h>
+#include <sys/wait.h>
+#include <sysexits.h>
+#include <termios.h>
+#include <unistd.h>
+
+#if defined __FreeBSD__
+#include <libutil.h>
+#elif defined __linux__
+#include <pty.h>
+#else
+#include <util.h>
+#endif
+
+static struct termios saveTerm;
+static void restoreTerm(void) {
+    tcsetattr(STDIN_FILENO, TCSADRAIN, &saveTerm);
+}
+
+int main(int argc, char *argv[]) {
+    int error;
+
+    if (argc < 4) return EX_USAGE;
+
+    char table[256] = {0};
+    if (strlen(argv[1]) != strlen(argv[2])) return EX_USAGE;
+    for (const char *from = argv[1], *to = argv[2]; *from; ++from, ++to) {
+        table[(unsigned)*from] = *to;
+    }
+
+    error = tcgetattr(STDERR_FILENO, &saveTerm);
+    if (error) err(EX_IOERR, "tcgetattr");
+    atexit(restoreTerm);
+
+    struct termios raw;
+    cfmakeraw(&raw);
+    error = tcsetattr(STDERR_FILENO, TCSADRAIN, &raw);
+    if (error) err(EX_IOERR, "tcsetattr");
+
+    struct winsize window;
+    error = ioctl(STDERR_FILENO, TIOCGWINSZ, &window);
+    if (error) err(EX_IOERR, "TIOCGWINSZ");
+
+    int pty;
+    pid_t pid = forkpty(&pty, NULL, NULL, &window);
+    if (pid < 0) err(EX_OSERR, "forkpty");
+
+    if (!pid) {
+        execvp(argv[3], &argv[3]);
+        err(EX_NOINPUT, "%s", argv[3]);
+    }
+
+    bool enable = true;
+
+    char buf[4096];
+    struct pollfd fds[2] = {
+        { .fd = STDIN_FILENO, .events = POLLIN },
+        { .fd = pty, .events = POLLIN },
+    };
+    while (0 < poll(fds, 2, -1)) {
+        if (fds[0].revents & POLLIN) {
+            ssize_t readSize = read(STDIN_FILENO, buf, sizeof(buf));
+            if (readSize < 0) err(EX_IOERR, "read(%d)", STDIN_FILENO);
+
+            if (readSize == 1) {
+                if (buf[0] == CTRL('S')) {
+                    enable ^= true;
+                    continue;
+                }
+
+                unsigned char c = buf[0];
+                if (enable && table[c]) buf[0] = table[c];
+            }
+
+            ssize_t writeSize = write(pty, buf, readSize);
+            if (writeSize < 0) err(EX_IOERR, "write(%d)", pty);
+            if (writeSize < readSize) errx(EX_IOERR, "short write(%d)", pty);
+        }
+
+        if (fds[1].revents & POLLIN) {
+            ssize_t readSize = read(pty, buf, sizeof(buf));
+            if (readSize < 0) err(EX_IOERR, "read(%d)", pty);
+
+            ssize_t writeSize = write(STDOUT_FILENO, buf, readSize);
+            if (writeSize < 0) err(EX_IOERR, "write(%d)", STDOUT_FILENO);
+            if (writeSize < readSize) {
+                errx(EX_IOERR, "short write(%d)", STDOUT_FILENO);
+            }
+        }
+
+        int status;
+        pid_t dead = waitpid(pid, &status, WNOHANG);
+        if (dead < 0) err(EX_OSERR, "waitpid(%d)", pid);
+        if (dead) return WIFEXITED(status) ? WEXITSTATUS(status) : EX_SOFTWARE;
+    }
+    err(EX_IOERR, "poll");
+}
diff --git a/bin/klon.c b/bin/klon.c
new file mode 100644
index 00000000..40469290
--- /dev/null
+++ b/bin/klon.c
@@ -0,0 +1,357 @@
+/* Copyright (c) 2018, Curtis McEnroe <programble@gmail.com>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <assert.h>
+#include <curses.h>
+#include <locale.h>
+#include <stdbool.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+typedef uint8_t Card;
+
+#define MASK_RANK   (0x0F)
+#define MASK_SUIT   (0x30)
+#define MASK_COLOR  (0x10)
+#define MASK_UP     (0x40)
+#define MASK_SELECT (0x80)
+
+enum {
+    SUIT_CLUB    = 0x00,
+    SUIT_DIAMOND = 0x10,
+    SUIT_SPADE   = 0x20,
+    SUIT_HEART   = 0x30,
+};
+
+struct Stack {
+    Card data[52];
+    uint8_t index;
+};
+#define EMPTY { .data = {0}, .index = 52 }
+
+static void push(struct Stack *stack, Card card) {
+    assert(stack->index > 0);
+    stack->data[--stack->index] = card;
+}
+
+static Card pop(struct Stack *stack) {
+    assert(stack->index < 52);
+    return stack->data[stack->index++];
+}
+
+static Card get(const struct Stack *stack, uint8_t i) {
+    if (stack->index + i > 51) return 0;
+    return stack->data[stack->index + i];
+}
+
+static uint8_t len(const struct Stack *stack) {
+    return 52 - stack->index;
+}
+
+struct State {
+    struct Stack stock;
+    struct Stack waste;
+    struct Stack found[4];
+    struct Stack table[7];
+};
+
+static struct State g = {
+    .stock = {
+        .data = {
+            0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07,
+            0x08, 0x09, 0x0A, 0x0B, 0x0C, 0x0D,
+            0x11, 0x12, 0x13, 0x14, 0x15, 0x16, 0x17,
+            0x18, 0x19, 0x1A, 0x1B, 0x1C, 0x1D,
+            0x21, 0x22, 0x23, 0x24, 0x25, 0x26, 0x27,
+            0x28, 0x29, 0x2A, 0x2B, 0x2C, 0x2D,
+            0x31, 0x32, 0x33, 0x34, 0x35, 0x36, 0x37,
+            0x38, 0x39, 0x3A, 0x3B, 0x3C, 0x3D,
+        },
+        .index = 0,
+    },
+    .waste = EMPTY,
+    .found = { EMPTY, EMPTY, EMPTY, EMPTY },
+    .table = {
+        EMPTY, EMPTY, EMPTY, EMPTY, EMPTY, EMPTY, EMPTY
+    },
+};
+
+static struct State save;
+
+static void checkpoint(void) {
+    memcpy(&save, &g, sizeof(struct State));
+}
+
+static void undo(void) {
+    memcpy(&g, &save, sizeof(struct State));
+}
+
+static void shuffle(void) {
+    for (int i = 51; i > 0; --i) {
+        int j = arc4random_uniform(i + 1);
+        uint8_t x = g.stock.data[i];
+        g.stock.data[i] = g.stock.data[j];
+        g.stock.data[j] = x;
+    }
+}
+
+static void deal(void) {
+    for (int i = 0; i < 7; ++i) {
+        for (int j = i; j < 7; ++j) {
+            push(&g.table[j], pop(&g.stock));
+        }
+    }
+}
+
+static void reveal(void) {
+    for (int i = 0; i < 7; ++i) {
+        if (get(&g.table[i], 0)) {
+            push(&g.table[i], pop(&g.table[i]) | MASK_UP);
+        }
+    }
+}
+
+static void draw(void) {
+    if (get(&g.stock, 0)) push(&g.waste, pop(&g.stock) | MASK_UP);
+    if (get(&g.stock, 0)) push(&g.waste, pop(&g.stock) | MASK_UP);
+    if (get(&g.stock, 0)) push(&g.waste, pop(&g.stock) | MASK_UP);
+}
+
+static void wasted(void) {
+    uint8_t n = len(&g.waste);
+    for (int i = 0; i < n; ++i) {
+        push(&g.stock, pop(&g.waste) & ~MASK_UP);
+    }
+}
+
+static void transfer(struct Stack *dest, struct Stack *src, uint8_t n) {
+    struct Stack temp = EMPTY;
+    for (int i = 0; i < n; ++i) {
+        push(&temp, pop(src));
+    }
+    for (int i = 0; i < n; ++i) {
+        push(dest, pop(&temp));
+    }
+}
+
+static bool canFound(const struct Stack *found, Card card) {
+    if (!get(found, 0)) return (card & MASK_RANK) == 1;
+    if ((card & MASK_SUIT) != (get(found, 0) & MASK_SUIT)) return false;
+    return (card & MASK_RANK) == (get(found, 0) & MASK_RANK) + 1;
+}
+
+static bool canTable(const struct Stack *table, Card card) {
+    if (!get(table, 0)) return (card & MASK_RANK) == 13;
+    if ((card & MASK_COLOR) == (get(table, 0) & MASK_COLOR)) return false;
+    return (card & MASK_RANK) == (get(table, 0) & MASK_RANK) - 1;
+}
+
+enum {
+    PAIR_EMPTY = 1,
+    PAIR_BACK,
+    PAIR_BLACK,
+    PAIR_RED,
+};
+
+static void curse(void) {
+    setlocale(LC_CTYPE, "");
+
+    initscr();
+    cbreak();
+    noecho();
+    keypad(stdscr, true);
+    set_escdelay(100);
+    curs_set(0);
+
+    start_color();
+    assume_default_colors(-1, -1);
+    init_pair(PAIR_EMPTY, COLOR_WHITE, COLOR_BLACK);
+    init_pair(PAIR_BACK,  COLOR_WHITE, COLOR_BLUE);
+    init_pair(PAIR_BLACK, COLOR_BLACK, COLOR_WHITE);
+    init_pair(PAIR_RED,   COLOR_RED,   COLOR_WHITE);
+}
+
+static const char rank[] = "\0A23456789TJQK";
+static const char *suit[] = {
+    [SUIT_HEART]   = "♥",
+    [SUIT_CLUB]    = "♣",
+    [SUIT_DIAMOND] = "♦",
+    [SUIT_SPADE]   = "â™ ",
+};
+
+static void renderCard(int y, int x, Card card) {
+    if (card & MASK_UP) {
+        bkgdset(
+            COLOR_PAIR(card & MASK_COLOR ? PAIR_RED : PAIR_BLACK)
+            | (card & MASK_SELECT ? A_REVERSE : A_NORMAL)
+        );
+
+        move(y, x);
+        addch(rank[card & MASK_RANK]);
+        addstr(suit[card & MASK_SUIT]);
+        addch(' ');
+
+        move(y + 1, x);
+        addstr(suit[card & MASK_SUIT]);
+        addch(' ');
+        addstr(suit[card & MASK_SUIT]);
+
+        move(y + 2, x);
+        addch(' ');
+        addstr(suit[card & MASK_SUIT]);
+        addch(rank[card & MASK_RANK]);
+
+    } else {
+        bkgdset(COLOR_PAIR(card ? PAIR_BACK : PAIR_EMPTY));
+        mvaddstr(y, x, "   ");
+        mvaddstr(y + 1, x, "   ");
+        mvaddstr(y + 2, x, "   ");
+    }
+}
+
+static void render(void) {
+    bkgdset(COLOR_PAIR(0));
+    erase();
+
+    int x = 2;
+    int y = 1;
+
+    renderCard(y, x, get(&g.stock, 0));
+
+    x += 5;
+    renderCard(y, x++, get(&g.waste, 2));
+    renderCard(y, x++, get(&g.waste, 1));
+    renderCard(y, x, get(&g.waste, 0));
+
+    x += 5;
+    for (int i = 0; i < 4; ++i) {
+        renderCard(y, x, get(&g.found[i], 0));
+        x += 4;
+    }
+
+    x = 2;
+    for (int i = 0; i < 7; ++i) {
+        y = 5;
+        renderCard(y, x, 0);
+        for (int j = len(&g.table[i]); j > 0; --j) {
+            renderCard(y, x, get(&g.table[i], j - 1));
+            y++;
+        }
+        x += 4;
+    }
+}
+
+static struct {
+    struct Stack *stack;
+    uint8_t depth;
+} input;
+
+static void deepen(void) {
+    assert(input.stack);
+    if (input.depth == len(input.stack)) return;
+    if (!(get(input.stack, input.depth) & MASK_UP)) return;
+    input.stack->data[input.stack->index + input.depth] |= MASK_SELECT;
+    input.depth++;
+}
+
+static void select(struct Stack *stack) {
+    if (!get(stack, 0)) return;
+    input.stack = stack;
+    input.depth = 0;
+    deepen();
+}
+
+static void commit(struct Stack *dest) {
+    assert(input.stack);
+    for (int i = 0; i < input.depth; ++i) {
+        input.stack->data[input.stack->index + i] &= ~MASK_SELECT;
+    }
+    if (dest) {
+        checkpoint();
+        transfer(dest, input.stack, input.depth);
+    }
+    input.stack = NULL;
+    input.depth = 0;
+}
+
+int main() {
+    curse();
+
+    shuffle();
+    deal();
+    checkpoint();
+
+    for (;;) {
+        reveal();
+        render();
+
+        int c = getch();
+        if (!input.stack) {
+            if (c == 'q') {
+                break;
+            } else if (c == 'u') {
+                undo();
+            } else if (c == 's' || c == ' ') {
+                if (get(&g.stock, 0)) {
+                    checkpoint();
+                    draw();
+                } else {
+                    wasted();
+                }
+            } else if (c == 'w') {
+                select(&g.waste);
+            } else if (c >= 'a' && c <= 'd') {
+                select(&g.found[c - 'a']);
+            } else if (c >= '1' && c <= '7') {
+                select(&g.table[c - '1']);
+            }
+
+        } else {
+            if (c >= '1' && c <= '7') {
+                struct Stack *table = &g.table[c - '1'];
+                if (input.stack == table) {
+                    deepen();
+                } else if (canTable(table, get(input.stack, input.depth - 1))) {
+                    commit(table);
+                } else {
+                    commit(NULL);
+                }
+            } else if (input.depth == 1 && c >= 'a' && c <= 'd') {
+                struct Stack *found = &g.found[c - 'a'];
+                if (canFound(found, get(input.stack, 0))) {
+                    commit(found);
+                } else {
+                    commit(NULL);
+                }
+            } else if (input.depth == 1 && (c == 'f' || c == '\n')) {
+                struct Stack *found;
+                for (int i = 0; i < 4; ++i) {
+                    found = &g.found[i];
+                    if (canFound(found, get(input.stack, 0))) break;
+                    found = NULL;
+                }
+                commit(found);
+            } else {
+                commit(NULL);
+            }
+        }
+    }
+
+    endwin();
+    return 0;
+}
diff --git a/bin/pbd.c b/bin/pbd.c
new file mode 100644
index 00000000..80ab036f
--- /dev/null
+++ b/bin/pbd.c
@@ -0,0 +1,136 @@
+/* Copyright (c) 2017, Curtis McEnroe <programble@gmail.com>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <arpa/inet.h>
+#include <err.h>
+#include <fcntl.h>
+#include <netinet/in.h>
+#include <stdbool.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <sys/socket.h>
+#include <sys/wait.h>
+#include <sysexits.h>
+#include <unistd.h>
+
+#define UNUSED __attribute__((unused))
+
+static void spawn(const char *cmd, int dest, int src) {
+    pid_t pid = fork();
+    if (pid < 0) err(EX_OSERR, "fork");
+
+    if (pid) {
+        int status;
+        pid_t dead = waitpid(pid, &status, 0);
+        if (dead < 0) err(EX_OSERR, "waitpid(%d)", pid);
+        if (status) warnx("%s: status %d", cmd, status);
+
+    } else {
+        int fd = dup2(src, dest);
+        if (fd < 0) err(EX_OSERR, "dup2");
+
+        execlp(cmd, cmd, NULL);
+        err(EX_UNAVAILABLE, "%s", cmd);
+    }
+}
+
+static int pbd(void) {
+    int error;
+
+    int server = socket(PF_INET, SOCK_STREAM, 0);
+    if (server < 0) err(EX_OSERR, "socket");
+
+    error = fcntl(server, F_SETFD, FD_CLOEXEC);
+    if (error) err(EX_IOERR, "fcntl");
+
+    struct sockaddr_in addr = {
+        .sin_family = AF_INET,
+        .sin_port = htons(7062),
+        .sin_addr = { .s_addr = htonl(0x7f000001) },
+    };
+    error = bind(server, (struct sockaddr *)&addr, sizeof(addr));
+    if (error) err(EX_UNAVAILABLE, "bind");
+
+    error = listen(server, 0);
+    if (error) err(EX_UNAVAILABLE, "listen");
+
+    for (;;) {
+        int client = accept(server, NULL, NULL);
+        if (client < 0) err(EX_IOERR, "accept");
+
+        error = fcntl(client, F_SETFD, FD_CLOEXEC);
+        if (error) err(EX_IOERR, "fcntl");
+
+        spawn("pbpaste", STDOUT_FILENO, client);
+
+        char p;
+        ssize_t peek = recv(client, &p, 1, MSG_PEEK);
+        if (peek < 0) err(EX_IOERR, "recv");
+
+        if (peek) spawn("pbcopy", STDIN_FILENO, client);
+
+        close(client);
+    }
+}
+
+static int pbdClient(void) {
+    int client = socket(PF_INET, SOCK_STREAM, 0);
+    if (client < 0) err(EX_OSERR, "socket");
+
+    struct sockaddr_in addr = {
+        .sin_family = AF_INET,
+        .sin_port = htons(7062),
+        .sin_addr = { .s_addr = htonl(0x7f000001) },
+    };
+    int error = connect(client, (struct sockaddr *)&addr, sizeof(addr));
+    if (error) err(EX_UNAVAILABLE, "connect");
+
+    return client;
+}
+
+static void copy(int out, int in) {
+    char buf[4096];
+    ssize_t readSize;
+    while (0 < (readSize = read(in, buf, sizeof(buf)))) {
+        ssize_t writeSize = write(out, buf, readSize);
+        if (writeSize < 0) err(EX_IOERR, "write(%d)", out);
+        if (writeSize < readSize) errx(EX_IOERR, "short write(%d)", out);
+    }
+    if (readSize < 0) err(EX_IOERR, "read(%d)", in);
+}
+
+static int pbcopy(void) {
+    int client = pbdClient();
+    copy(client, STDIN_FILENO);
+    return EX_OK;
+}
+
+static int pbpaste(void) {
+    int client = pbdClient();
+    shutdown(client, SHUT_WR);
+    copy(STDOUT_FILENO, client);
+    return EX_OK;
+}
+
+int main(int argc UNUSED, char *argv[]) {
+    if (!argv[0][0] || !argv[0][1]) return EX_USAGE;
+    switch (argv[0][2]) {
+        case 'd': return pbd();
+        case 'c': return pbcopy();
+        case 'p': return pbpaste();
+        default:  return EX_USAGE;
+    }
+}
diff --git a/bin/pngo.c b/bin/pngo.c
new file mode 100644
index 00000000..c34ec7d1
--- /dev/null
+++ b/bin/pngo.c
@@ -0,0 +1,717 @@
+/* Copyright (c) 2018, Curtis McEnroe <programble@gmail.com>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <arpa/inet.h>
+#include <assert.h>
+#include <err.h>
+#include <stdbool.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sysexits.h>
+#include <unistd.h>
+#include <zlib.h>
+
+#define PACKED __attribute__((packed))
+#define PAIR(a, b) ((uint16_t)(a) << 8 | (uint16_t)(b))
+
+#define CRC_INIT (crc32(0, Z_NULL, 0))
+
+static bool verbose;
+static const char *path;
+static FILE *file;
+static uint32_t crc;
+
+static void readExpect(void *ptr, size_t size, const char *expect) {
+    fread(ptr, size, 1, file);
+    if (ferror(file)) err(EX_IOERR, "%s", path);
+    if (feof(file)) errx(EX_DATAERR, "%s: missing %s", path, expect);
+    crc = crc32(crc, ptr, size);
+}
+
+static void writeExpect(const void *ptr, size_t size) {
+    fwrite(ptr, size, 1, file);
+    if (ferror(file)) err(EX_IOERR, "%s", path);
+    crc = crc32(crc, ptr, size);
+}
+
+static const uint8_t SIGNATURE[8] = {
+    0x89, 'P', 'N', 'G', '\r', '\n', 0x1A, '\n'
+};
+
+static void readSignature(void) {
+    uint8_t signature[8];
+    readExpect(signature, 8, "signature");
+    if (0 != memcmp(signature, SIGNATURE, 8)) {
+        errx(EX_DATAERR, "%s: invalid signature", path);
+    }
+}
+
+static void writeSignature(void) {
+    writeExpect(SIGNATURE, sizeof(SIGNATURE));
+}
+
+struct PACKED Chunk {
+    uint32_t size;
+    char type[4];
+};
+
+static const char *typeStr(struct Chunk chunk) {
+    static char buf[5];
+    memcpy(buf, chunk.type, 4);
+    return buf;
+}
+
+static struct Chunk readChunk(void) {
+    struct Chunk chunk;
+    readExpect(&chunk, sizeof(chunk), "chunk");
+    chunk.size = ntohl(chunk.size);
+    crc = crc32(CRC_INIT, (Byte *)chunk.type, sizeof(chunk.type));
+    return chunk;
+}
+
+static void writeChunk(struct Chunk chunk) {
+    chunk.size = htonl(chunk.size);
+    writeExpect(&chunk, sizeof(chunk));
+    crc = crc32(CRC_INIT, (Byte *)chunk.type, sizeof(chunk.type));
+}
+
+static void readCrc(void) {
+    uint32_t expected = crc;
+    uint32_t found;
+    readExpect(&found, sizeof(found), "CRC32");
+    found = ntohl(found);
+    if (found != expected) {
+        errx(
+            EX_DATAERR, "%s: expected CRC32 %08X, found %08X",
+            path, expected, found
+        );
+    }
+}
+
+static void writeCrc(void) {
+    uint32_t net = htonl(crc);
+    writeExpect(&net, sizeof(net));
+}
+
+static void skipChunk(struct Chunk chunk) {
+    if (!(chunk.type[0] & 0x20)) {
+        errx(EX_CONFIG, "%s: unsupported critical chunk %s", path, typeStr(chunk));
+    }
+    uint8_t discard[chunk.size];
+    readExpect(discard, sizeof(discard), "chunk data");
+    readCrc();
+}
+
+static struct PACKED {
+    uint32_t width;
+    uint32_t height;
+    uint8_t depth;
+    enum PACKED {
+        GRAYSCALE       = 0,
+        TRUECOLOR       = 2,
+        INDEXED         = 3,
+        GRAYSCALE_ALPHA = 4,
+        TRUECOLOR_ALPHA = 6,
+    } color;
+    enum PACKED { DEFLATE } compression;
+    enum PACKED { ADAPTIVE } filter;
+    enum PACKED { PROGRESSIVE, ADAM7 } interlace;
+} header;
+
+static size_t lineSize(void) {
+    switch (header.color) {
+        case GRAYSCALE:       return (header.width * 1 * header.depth + 7) / 8;
+        case TRUECOLOR:       return (header.width * 3 * header.depth + 7) / 8;
+        case INDEXED:         return (header.width * 1 * header.depth + 7) / 8;
+        case GRAYSCALE_ALPHA: return (header.width * 2 * header.depth + 7) / 8;
+        case TRUECOLOR_ALPHA: return (header.width * 4 * header.depth + 7) / 8;
+        default: abort();
+    }
+}
+
+static size_t dataSize(void) {
+    return (1 + lineSize()) * header.height;
+}
+
+static const char *COLOR_STR[] = {
+    [GRAYSCALE] = "grayscale",
+    [TRUECOLOR] = "truecolor",
+    [INDEXED] = "indexed",
+    [GRAYSCALE_ALPHA] = "grayscale alpha",
+    [TRUECOLOR_ALPHA] = "truecolor alpha",
+};
+static void printHeader(void) {
+    fprintf(
+        stderr,
+        "%s: %ux%u %hhu-bit %s\n",
+        path,
+        header.width, header.height,
+        header.depth, COLOR_STR[header.color]
+    );
+}
+
+static void readHeader(void) {
+    struct Chunk ihdr = readChunk();
+    if (0 != memcmp(ihdr.type, "IHDR", 4)) {
+        errx(EX_DATAERR, "%s: expected IHDR, found %s", path, typeStr(ihdr));
+    }
+    if (ihdr.size != sizeof(header)) {
+        errx(
+            EX_DATAERR, "%s: expected IHDR size %zu, found %u",
+            path, sizeof(header), ihdr.size
+        );
+    }
+    readExpect(&header, sizeof(header), "header");
+    readCrc();
+
+    header.width = ntohl(header.width);
+    header.height = ntohl(header.height);
+
+    if (!header.width) errx(EX_DATAERR, "%s: invalid width 0", path);
+    if (!header.height) errx(EX_DATAERR, "%s: invalid height 0", path);
+    switch (PAIR(header.color, header.depth)) {
+        case PAIR(GRAYSCALE, 1):
+        case PAIR(GRAYSCALE, 2):
+        case PAIR(GRAYSCALE, 4):
+        case PAIR(GRAYSCALE, 8):
+        case PAIR(GRAYSCALE, 16):
+        case PAIR(TRUECOLOR, 8):
+        case PAIR(TRUECOLOR, 16):
+        case PAIR(INDEXED, 1):
+        case PAIR(INDEXED, 2):
+        case PAIR(INDEXED, 4):
+        case PAIR(INDEXED, 8):
+        case PAIR(GRAYSCALE_ALPHA, 8):
+        case PAIR(GRAYSCALE_ALPHA, 16):
+        case PAIR(TRUECOLOR_ALPHA, 8):
+        case PAIR(TRUECOLOR_ALPHA, 16):
+            break;
+        default:
+            errx(
+                EX_DATAERR, "%s: invalid color type %hhu and bit depth %hhu",
+                path, header.color, header.depth
+            );
+    }
+    if (header.compression != DEFLATE) {
+        errx(
+            EX_DATAERR, "%s: invalid compression method %hhu",
+            path, header.compression
+        );
+    }
+    if (header.filter != ADAPTIVE) {
+        errx(EX_DATAERR, "%s: invalid filter method %hhu", path, header.filter);
+    }
+    if (header.interlace > ADAM7) {
+        errx(EX_DATAERR, "%s: invalid interlace method %hhu", path, header.interlace);
+    }
+
+    if (verbose) printHeader();
+}
+
+static void writeHeader(void) {
+    if (verbose) printHeader();
+
+    struct Chunk ihdr = { .size = sizeof(header), .type = "IHDR" };
+    writeChunk(ihdr);
+    header.width = htonl(header.width);
+    header.height = htonl(header.height);
+    writeExpect(&header, sizeof(header));
+    writeCrc();
+
+    header.width = ntohl(header.width);
+    header.height = ntohl(header.height);
+}
+
+static struct {
+    uint32_t len;
+    uint8_t entries[256][3];
+} palette;
+
+static uint16_t paletteIndex(const uint8_t *rgb) {
+    uint16_t i;
+    for (i = 0; i < palette.len; ++i) {
+        if (0 == memcmp(palette.entries[i], rgb, 3)) break;
+    }
+    return i;
+}
+
+static bool paletteAdd(const uint8_t *rgb) {
+    uint16_t i = paletteIndex(rgb);
+    if (i < palette.len) return true;
+    if (i == 256) return false;
+    memcpy(palette.entries[palette.len++], rgb, 3);
+    return true;
+}
+
+static void readPalette(void) {
+    struct Chunk chunk;
+    for (;;) {
+        chunk = readChunk();
+        if (0 == memcmp(chunk.type, "PLTE", 4)) break;
+        skipChunk(chunk);
+    }
+    if (chunk.size % 3) {
+        errx(EX_DATAERR, "%s: PLTE size %u not divisible by 3", path, chunk.size);
+    }
+
+    palette.len = chunk.size / 3;
+    readExpect(palette.entries, chunk.size, "palette data");
+    readCrc();
+
+    if (verbose) fprintf(stderr, "%s: palette length %u\n", path, palette.len);
+}
+
+static void writePalette(void) {
+    if (verbose) fprintf(stderr, "%s: palette length %u\n", path, palette.len);
+    struct Chunk plte = { .size = 3 * palette.len, .type = "PLTE" };
+    writeChunk(plte);
+    writeExpect(palette.entries, plte.size);
+    writeCrc();
+}
+
+static uint8_t *data;
+
+static void allocData(void) {
+    data = malloc(dataSize());
+    if (!data) err(EX_OSERR, "malloc(%zu)", dataSize());
+}
+
+static void readData(void) {
+    if (verbose) fprintf(stderr, "%s: data size %zu\n", path, dataSize());
+
+    struct z_stream_s stream = { .next_out = data, .avail_out = dataSize() };
+    int error = inflateInit(&stream);
+    if (error != Z_OK) errx(EX_SOFTWARE, "%s: inflateInit: %s", path, stream.msg);
+
+    for (;;) {
+        struct Chunk chunk = readChunk();
+        if (0 == memcmp(chunk.type, "IDAT", 4)) {
+            uint8_t idat[chunk.size];
+            readExpect(idat, sizeof(idat), "image data");
+            readCrc();
+
+            stream.next_in = idat;
+            stream.avail_in = sizeof(idat);
+            int error = inflate(&stream, Z_SYNC_FLUSH);
+            if (error == Z_STREAM_END) break;
+            if (error != Z_OK) errx(EX_DATAERR, "%s: inflate: %s", path, stream.msg);
+
+        } else if (0 == memcmp(chunk.type, "IEND", 4)) {
+            errx(EX_DATAERR, "%s: missing IDAT chunk", path);
+        } else {
+            skipChunk(chunk);
+        }
+    }
+
+    inflateEnd(&stream);
+    if (stream.total_out != dataSize()) {
+        errx(
+            EX_DATAERR, "%s: expected data size %zu, found %lu",
+            path, dataSize(), stream.total_out
+        );
+    }
+
+    if (verbose) fprintf(stderr, "%s: deflate size %lu\n", path, stream.total_in);
+}
+
+static void writeData(void) {
+    if (verbose) fprintf(stderr, "%s: data size %zu\n", path, dataSize());
+
+    uLong size = compressBound(dataSize());
+    uint8_t deflate[size];
+    int error = compress2(deflate, &size, data, dataSize(), Z_BEST_COMPRESSION);
+    if (error != Z_OK) errx(EX_SOFTWARE, "%s: compress2: %d", path, error);
+
+    struct Chunk idat = { .size = size, .type = "IDAT" };
+    writeChunk(idat);
+    writeExpect(deflate, size);
+    writeCrc();
+
+    if (verbose) fprintf(stderr, "%s: deflate size %lu\n", path, size);
+}
+
+static void writeEnd(void) {
+    struct Chunk iend = { .size = 0, .type = "IEND" };
+    writeChunk(iend);
+    writeCrc();
+}
+
+enum PACKED Filter {
+    NONE,
+    SUB,
+    UP,
+    AVERAGE,
+    PAETH,
+};
+#define FILTER_COUNT (PAETH + 1)
+
+struct Bytes {
+    uint8_t x;
+    uint8_t a;
+    uint8_t b;
+    uint8_t c;
+};
+
+static uint8_t paethPredictor(struct Bytes f) {
+    int32_t p = (int32_t)f.a + (int32_t)f.b - (int32_t)f.c;
+    int32_t pa = abs(p - (int32_t)f.a);
+    int32_t pb = abs(p - (int32_t)f.b);
+    int32_t pc = abs(p - (int32_t)f.c);
+    if (pa <= pb && pa <= pc) return f.a;
+    if (pb <= pc) return f.b;
+    return f.c;
+}
+
+static uint8_t recon(enum Filter type, struct Bytes f) {
+    switch (type) {
+        case NONE:    return f.x;
+        case SUB:     return f.x + f.a;
+        case UP:      return f.x + f.b;
+        case AVERAGE: return f.x + ((uint32_t)f.a + (uint32_t)f.b) / 2;
+        case PAETH:   return f.x + paethPredictor(f);
+        default:      abort();
+    }
+}
+
+static uint8_t filt(enum Filter type, struct Bytes f) {
+    switch (type) {
+        case NONE:    return f.x;
+        case SUB:     return f.x - f.a;
+        case UP:      return f.x - f.b;
+        case AVERAGE: return f.x - ((uint32_t)f.a + (uint32_t)f.b) / 2;
+        case PAETH:   return f.x - paethPredictor(f);
+        default:      abort();
+    }
+}
+
+static struct Line {
+    enum Filter type;
+    uint8_t data[];
+} **lines;
+
+static void allocLines(void) {
+    lines = calloc(header.height, sizeof(*lines));
+    if (!lines) err(EX_OSERR, "calloc(%u, %zu)", header.height, sizeof(*lines));
+}
+
+static void scanlines(void) {
+    size_t stride = 1 + lineSize();
+    for (uint32_t y = 0; y < header.height; ++y) {
+        lines[y] = (struct Line *)&data[y * stride];
+        if (lines[y]->type >= FILTER_COUNT) {
+            errx(EX_DATAERR, "%s: invalid filter type %hhu", path, lines[y]->type);
+        }
+    }
+}
+
+static struct Bytes origBytes(uint32_t y, size_t i) {
+    size_t pixelSize = lineSize() / header.width;
+    if (!pixelSize) pixelSize = 1;
+    bool a = (i >= pixelSize), b = (y > 0), c = (a && b);
+    return (struct Bytes) {
+        .x = lines[y]->data[i],
+        .a = a ? lines[y]->data[i - pixelSize] : 0,
+        .b = b ? lines[y - 1]->data[i] : 0,
+        .c = c ? lines[y - 1]->data[i - pixelSize] : 0,
+    };
+}
+
+static void reconData(void) {
+    for (uint32_t y = 0; y < header.height; ++y) {
+        for (size_t i = 0; i < lineSize(); ++i) {
+            lines[y]->data[i] =
+                recon(lines[y]->type, origBytes(y, i));
+        }
+        lines[y]->type = NONE;
+    }
+}
+
+static void filterData(void) {
+    if (header.color == INDEXED || header.depth < 8) return;
+    for (uint32_t y = header.height - 1; y < header.height; --y) {
+        uint8_t filter[FILTER_COUNT][lineSize()];
+        uint32_t heuristic[FILTER_COUNT] = {0};
+        enum Filter minType = NONE;
+        for (enum Filter type = NONE; type < FILTER_COUNT; ++type) {
+            for (size_t i = 0; i < lineSize(); ++i) {
+                filter[type][i] = filt(type, origBytes(y, i));
+                heuristic[type] += abs((int8_t)filter[type][i]);
+            }
+            if (heuristic[type] < heuristic[minType]) minType = type;
+        }
+        lines[y]->type = minType;
+        memcpy(lines[y]->data, filter[minType], lineSize());
+    }
+}
+
+static void discardAlpha(void) {
+    if (header.color != GRAYSCALE_ALPHA && header.color != TRUECOLOR_ALPHA) return;
+    size_t sampleSize = header.depth / 8;
+    size_t pixelSize = sampleSize * (header.color == GRAYSCALE_ALPHA ? 2 : 4);
+    size_t colorSize = pixelSize - sampleSize;
+    for (uint32_t y = 0; y < header.height; ++y) {
+        for (uint32_t x = 0; x < header.width; ++x) {
+            for (size_t i = 0; i < sampleSize; ++i) {
+                if (lines[y]->data[x * pixelSize + colorSize + i] != 0xFF) return;
+            }
+        }
+    }
+
+    uint8_t *ptr = data;
+    for (uint32_t y = 0; y < header.height; ++y) {
+        *ptr++ = lines[y]->type;
+        for (uint32_t x = 0; x < header.width; ++x) {
+            memmove(ptr, &lines[y]->data[x * pixelSize], colorSize);
+            ptr += colorSize;
+        }
+    }
+    header.color = (header.color == GRAYSCALE_ALPHA) ? GRAYSCALE : TRUECOLOR;
+    scanlines();
+}
+
+static void discardColor(void) {
+    if (header.color != TRUECOLOR && header.color != TRUECOLOR_ALPHA) return;
+    size_t sampleSize = header.depth / 8;
+    size_t pixelSize = sampleSize * (header.color == TRUECOLOR ? 3 : 4);
+    for (uint32_t y = 0; y < header.height; ++y) {
+        for (uint32_t x = 0; x < header.width; ++x) {
+            uint8_t *r = &lines[y]->data[x * pixelSize];
+            uint8_t *g = r + sampleSize;
+            uint8_t *b = g + sampleSize;
+            if (0 != memcmp(r, g, sampleSize)) return;
+            if (0 != memcmp(g, b, sampleSize)) return;
+        }
+    }
+
+    uint8_t *ptr = data;
+    for (uint32_t y = 0; y < header.height; ++y) {
+        *ptr++ = lines[y]->type;
+        for (uint32_t x = 0; x < header.width; ++x) {
+            uint8_t *pixel = &lines[y]->data[x * pixelSize];
+            memmove(ptr, pixel, sampleSize);
+            ptr += sampleSize;
+            if (header.color == TRUECOLOR_ALPHA) {
+                memmove(ptr, pixel + 3 * sampleSize, sampleSize);
+                ptr += sampleSize;
+            }
+        }
+    }
+    header.color = (header.color == TRUECOLOR) ? GRAYSCALE : GRAYSCALE_ALPHA;
+    scanlines();
+}
+
+static void indexColor(void) {
+    if (header.color != TRUECOLOR || header.depth != 8) return;
+    for (uint32_t y = 0; y < header.height; ++y) {
+        for (uint32_t x = 0; x < header.width; ++x) {
+            if (!paletteAdd(&lines[y]->data[x * 3])) return;
+        }
+    }
+
+    uint8_t *ptr = data;
+    for (uint32_t y = 0; y < header.height; ++y) {
+        *ptr++ = lines[y]->type;
+        for (uint32_t x = 0; x < header.width; ++x) {
+            *ptr++ = paletteIndex(&lines[y]->data[x * 3]);
+        }
+    }
+    header.color = INDEXED;
+    scanlines();
+}
+
+static void reduceDepth8(void) {
+    if (header.color != GRAYSCALE && header.color != INDEXED) return;
+    if (header.depth != 8) return;
+    if (header.color == GRAYSCALE) {
+        for (uint32_t y = 0; y < header.height; ++y) {
+            for (size_t i = 0; i < lineSize(); ++i) {
+                uint8_t a = lines[y]->data[i];
+                if ((a >> 4) != (a & 0x0F)) return;
+            }
+        }
+    } else if (palette.len > 16) {
+        return;
+    }
+
+    uint8_t *ptr = data;
+    for (uint32_t y = 0; y < header.height; ++y) {
+        *ptr++ = lines[y]->type;
+        for (size_t i = 0; i < lineSize(); i += 2) {
+            uint8_t iByte = lines[y]->data[i];
+            uint8_t jByte = (i + 1 < lineSize()) ? lines[y]->data[i + 1] : 0;
+            uint8_t a = iByte & 0x0F;
+            uint8_t b = jByte & 0x0F;
+            *ptr++ = a << 4 | b;
+        }
+    }
+    header.depth = 4;
+    scanlines();
+}
+
+static void reduceDepth4(void) {
+    if (header.depth != 4) return;
+    if (header.color == GRAYSCALE) {
+        for (uint32_t y = 0; y < header.height; ++y) {
+            for (size_t i = 0; i < lineSize(); ++i) {
+                uint8_t a = lines[y]->data[i] >> 4;
+                uint8_t b = lines[y]->data[i] & 0x0F;
+                if ((a >> 2) != (a & 0x03)) return;
+                if ((b >> 2) != (b & 0x03)) return;
+            }
+        }
+    } else if (palette.len > 4) {
+        return;
+    }
+
+    uint8_t *ptr = data;
+    for (uint32_t y = 0; y < header.height; ++y) {
+        *ptr++ = lines[y]->type;
+        for (size_t i = 0; i < lineSize(); i += 2) {
+            uint8_t iByte = lines[y]->data[i];
+            uint8_t jByte = (i + 1 < lineSize()) ? lines[y]->data[i + 1] : 0;
+            uint8_t a = iByte >> 4 & 0x03, b = iByte & 0x03;
+            uint8_t c = jByte >> 4 & 0x03, d = jByte & 0x03;
+            *ptr++ = a << 6 | b << 4 | c << 2 | d;
+        }
+    }
+    header.depth = 2;
+    scanlines();
+}
+
+static void reduceDepth2(void) {
+    if (header.depth != 2) return;
+    if (header.color == GRAYSCALE) {
+        for (uint32_t y = 0; y < header.height; ++y) {
+            for (size_t i = 0; i < lineSize(); ++i) {
+                uint8_t a = lines[y]->data[i] >> 6;
+                uint8_t b = lines[y]->data[i] >> 4 & 0x03;
+                uint8_t c = lines[y]->data[i] >> 2 & 0x03;
+                uint8_t d = lines[y]->data[i] & 0x03;
+                if ((a >> 1) != (a & 0x01)) return;
+                if ((b >> 1) != (b & 0x01)) return;
+                if ((c >> 1) != (c & 0x01)) return;
+                if ((d >> 1) != (d & 0x01)) return;
+            }
+        }
+    } else if (palette.len > 2) {
+        return;
+    }
+
+    uint8_t *ptr = data;
+    for (uint32_t y = 0; y < header.height; ++y) {
+        *ptr++ = lines[y]->type;
+        for (size_t i = 0; i < lineSize(); i += 2) {
+            uint8_t iByte = lines[y]->data[i];
+            uint8_t jByte = (i + 1 < lineSize()) ? lines[y]->data[i + 1] : 0;
+            uint8_t a = iByte >> 6 & 0x01, b = iByte >> 4 & 0x01;
+            uint8_t c = iByte >> 2 & 0x01, d = iByte & 0x01;
+            uint8_t e = jByte >> 6 & 0x01, f = jByte >> 4 & 0x01;
+            uint8_t g = jByte >> 2 & 0x01, h = jByte & 0x01;
+            *ptr++ = a << 7 | b << 6 | c << 5 | d << 4 | e << 3 | f << 2 | g << 1 | h;
+        }
+    }
+    header.depth = 1;
+    scanlines();
+}
+
+static void reduceDepth(void) {
+    reduceDepth8();
+    reduceDepth4();
+    reduceDepth2();
+}
+
+static void optimize(const char *inPath, const char *outPath) {
+    if (inPath) {
+        path = inPath;
+        file = fopen(path, "r");
+        if (!file) err(EX_NOINPUT, "%s", path);
+    } else {
+        path = "(stdin)";
+        file = stdin;
+    }
+
+    readSignature();
+    readHeader();
+    if (header.interlace != PROGRESSIVE) {
+        errx(
+            EX_CONFIG, "%s: unsupported interlace method %hhu",
+            path, header.interlace
+        );
+    }
+    if (header.color == INDEXED) readPalette();
+    allocData();
+    readData();
+    fclose(file);
+
+    allocLines();
+    scanlines();
+    reconData();
+
+    discardAlpha();
+    discardColor();
+    indexColor();
+    reduceDepth();
+    filterData();
+    free(lines);
+
+    if (outPath) {
+        path = outPath;
+        file = fopen(path, "w");
+        if (!file) err(EX_CANTCREAT, "%s", path);
+    } else {
+        path = "(stdout)";
+        file = stdout;
+    }
+
+    writeSignature();
+    writeHeader();
+    if (header.color == INDEXED) writePalette();
+    writeData();
+    writeEnd();
+    free(data);
+
+    int error = fclose(file);
+    if (error) err(EX_IOERR, "%s", path);
+}
+
+int main(int argc, char *argv[]) {
+    bool stdio = false;
+    char *output = NULL;
+
+    int opt;
+    while (0 < (opt = getopt(argc, argv, "co:v"))) {
+        switch (opt) {
+            case 'c': stdio = true; break;
+            case 'o': output = optarg; break;
+            case 'v': verbose = true; break;
+            default: return EX_USAGE;
+        }
+    }
+
+    if (argc - optind == 1 && (output || stdio)) {
+        optimize(argv[optind], output);
+    } else if (optind < argc) {
+        for (int i = optind; i < argc; ++i) {
+            optimize(argv[i], argv[i]);
+        }
+    } else {
+        optimize(NULL, output);
+    }
+
+    return EX_OK;
+}
diff --git a/bin/scheme.c b/bin/scheme.c
new file mode 100644
index 00000000..162192fc
--- /dev/null
+++ b/bin/scheme.c
@@ -0,0 +1,219 @@
+/* Copyright (C) 2018  Curtis McEnroe <june@causal.agency>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <arpa/inet.h>
+#include <err.h>
+#include <math.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sysexits.h>
+#include <unistd.h>
+#include <zlib.h>
+
+static const struct Hsv { double h, s, v; }
+    R = {   0.0, 1.0, 1.0 },
+    Y = {  60.0, 1.0, 1.0 },
+    G = { 120.0, 1.0, 1.0 },
+    C = { 180.0, 1.0, 1.0 },
+    B = { 240.0, 1.0, 1.0 },
+    M = { 300.0, 1.0, 1.0 };
+
+static struct Hsv x(struct Hsv o, double hd, double sf, double vf) {
+    return (struct Hsv) {
+        fmod(o.h + hd, 360.0),
+        fmin(o.s * sf, 1.0),
+        fmin(o.v * vf, 1.0),
+    };
+}
+
+struct Ansi {
+    enum { BLACK, RED, GREEN, YELLOW, BLUE, MAGENTA, CYAN, WHITE };
+    struct Hsv dark[8];
+    struct Hsv light[8];
+};
+
+struct Terminal {
+    struct Ansi ansi;
+    struct Hsv background, text, bold, selection, cursor;
+};
+
+#define HSV_LEN(x) (sizeof(x) / sizeof(struct Hsv))
+struct Scheme {
+    size_t len;
+    union {
+        struct Hsv hsv;
+        struct Ansi ansi;
+        struct Terminal terminal;
+    };
+};
+
+static struct Scheme ansi(void) {
+    struct Ansi a = {
+        .light = {
+            [BLACK]   = x(R, +45.0, 0.3, 0.3),
+            [RED]     = x(R, +10.0, 0.9, 0.8),
+            [GREEN]   = x(G, -55.0, 0.8, 0.6),
+            [YELLOW]  = x(Y, -20.0, 0.8, 0.8),
+            [BLUE]    = x(B, -55.0, 0.4, 0.5),
+            [MAGENTA] = x(M, +45.0, 0.4, 0.6),
+            [CYAN]    = x(C, -60.0, 0.3, 0.6),
+            [WHITE]   = x(R, +45.0, 0.3, 0.8),
+        },
+    };
+    a.dark[BLACK] = x(a.light[BLACK], 0.0, 1.0, 0.3);
+    a.dark[WHITE] = x(a.light[WHITE], 0.0, 1.0, 0.6);
+    for (int i = RED; i < WHITE; ++i) {
+        a.dark[i] = x(a.light[i], 0.0, 1.0, 0.8);
+    }
+    return (struct Scheme) { .len = HSV_LEN(a), .ansi = a };
+}
+
+static struct Scheme terminal(void) {
+    struct Ansi a = ansi().ansi;
+    struct Terminal t = {
+        .ansi       = a,
+        .background = x(a.dark[BLACK],    0.0, 1.0, 0.9),
+        .text       = x(a.light[WHITE],   0.0, 1.0, 0.9),
+        .bold       = x(a.light[WHITE],   0.0, 1.0, 1.0),
+        .selection  = x(a.light[RED],   +10.0, 1.0, 0.8),
+        .cursor     = x(a.dark[WHITE],    0.0, 1.0, 0.8),
+    };
+    return (struct Scheme) { .len = HSV_LEN(t), .terminal = t };
+}
+
+static void hsv(const struct Hsv *hsv, size_t len) {
+    for (size_t i = 0; i < len; ++i) {
+        printf("%g,%g,%g\n", hsv[i].h, hsv[i].s, hsv[i].v);
+    }
+}
+
+struct Rgb { uint8_t r, g, b; };
+static struct Rgb toRgb(struct Hsv hsv) {
+    double c = hsv.v * hsv.s;
+    double h = hsv.h / 60.0;
+    double x = c * (1.0 - fabs(fmod(h, 2.0) - 1.0));
+    double m = hsv.v - c;
+    double r = m, g = m, b = m;
+    if      (h <= 1.0) { r += c; g += x; }
+    else if (h <= 2.0) { r += x; g += c; }
+    else if (h <= 3.0) { g += c; b += x; }
+    else if (h <= 4.0) { g += x; b += c; }
+    else if (h <= 5.0) { r += x; b += c; }
+    else if (h <= 6.0) { r += c; b += x; }
+    return (struct Rgb) { r * 255.0, g * 255.0, b * 255.0 };
+}
+
+static void hex(const struct Hsv *hsv, size_t len) {
+    for (size_t i = 0; i < len; ++i) {
+        struct Rgb rgb = toRgb(hsv[i]);
+        printf("%02x%02x%02x\n", rgb.r, rgb.g, rgb.b);
+    }
+}
+
+static void linux(const struct Hsv *hsv, size_t len) {
+    if (len > 16) len = 16;
+    for (size_t i = 0; i < len; ++i) {
+        struct Rgb rgb = toRgb(hsv[i]);
+        printf("\x1B]P%zx%02x%02x%02x", i, rgb.r, rgb.g, rgb.b);
+    }
+}
+
+static uint32_t crc;
+static void pngWrite(const void *ptr, size_t size) {
+    fwrite(ptr, size, 1, stdout);
+    if (ferror(stdout)) err(EX_IOERR, "(stdout)");
+    crc = crc32(crc, ptr, size);
+}
+static void pngInt(uint32_t host) {
+    uint32_t net = htonl(host);
+    pngWrite(&net, 4);
+}
+static void pngChunk(const char *type, uint32_t size) {
+    pngInt(size);
+    crc = crc32(0, Z_NULL, 0);
+    pngWrite(type, 4);
+}
+
+static void png(const struct Hsv *hsv, size_t len) {
+    if (len > 256) len = 256;
+    uint32_t swatchWidth = 64;
+    uint32_t swatchHeight = 64;
+    uint32_t columns = 8;
+    uint32_t rows = (len + columns - 1) / columns;
+    uint32_t width = swatchWidth * columns;
+    uint32_t height = swatchHeight * rows;
+
+    pngWrite("\x89PNG\r\n\x1A\n", 8);
+
+    pngChunk("IHDR", 13);
+    pngInt(width);
+    pngInt(height);
+    pngWrite("\x08\x03\0\0\0", 5);
+    pngInt(crc);
+
+    pngChunk("PLTE", 3 * len);
+    for (size_t i = 0; i < len; ++i) {
+        struct Rgb rgb = toRgb(hsv[i]);
+        pngWrite(&rgb, 3);
+    }
+    pngInt(crc);
+
+    uint8_t data[height][1 + width];
+    memset(data, 0, sizeof(data));
+    for (uint32_t y = 0; y < height; ++y) {
+        enum { NONE, SUB, UP, AVERAGE, PAETH };
+        data[y][0] = (y % swatchHeight) ? UP : SUB;
+    }
+    for (size_t i = 0; i < len; ++i) {
+        uint32_t y = swatchHeight * (i / columns);
+        uint32_t x = swatchWidth * (i % columns);
+        data[y][1 + x] = x ? 1 : i;
+    }
+
+    uLong size = compressBound(sizeof(data));
+    uint8_t deflate[size];
+    int error = compress(deflate, &size, (Byte *)data, sizeof(data));
+    if (error != Z_OK) errx(EX_SOFTWARE, "compress: %d", error);
+
+    pngChunk("IDAT", size);
+    pngWrite(deflate, size);
+    pngInt(crc);
+
+    pngChunk("IEND", 0);
+    pngInt(crc);
+}
+
+int main(int argc, char *argv[]) {
+    struct Scheme (*gen)(void) = ansi;
+    void (*out)(const struct Hsv *, size_t len) = hex;
+    int opt;
+    while (0 < (opt = getopt(argc, argv, "aghltx"))) {
+        switch (opt) {
+            case 'a': gen = ansi; break;
+            case 'g': out = png; break;
+            case 'h': out = hsv; break;
+            case 'l': out = linux; break;
+            case 't': gen = terminal; break;
+            case 'x': out = hex; break;
+            default: return EX_USAGE;
+        }
+    }
+    struct Scheme scheme = gen();
+    out(&scheme.hsv, scheme.len);
+    return EX_OK;
+}
diff --git a/bin/wake.c b/bin/wake.c
new file mode 100644
index 00000000..c81c5ede
--- /dev/null
+++ b/bin/wake.c
@@ -0,0 +1,53 @@
+/* Copyright (c) 2017, Curtis McEnroe <programble@gmail.com>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <sys/types.h>
+
+#include <err.h>
+#include <netinet/in.h>
+#include <stdint.h>
+#include <stdlib.h>
+#include <sys/socket.h>
+#include <sysexits.h>
+
+#define MAC 0x04, 0x7D, 0x7B, 0xD5, 0x6A, 0x53
+static const uint8_t payload[102] = {
+    0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
+    MAC, MAC, MAC, MAC, MAC, MAC, MAC, MAC,
+    MAC, MAC, MAC, MAC, MAC, MAC, MAC, MAC,
+};
+
+int main() {
+    int sock = socket(PF_INET, SOCK_DGRAM, 0);
+    if (sock < 0) err(EX_OSERR, "socket");
+
+    int on = 1;
+    int error = setsockopt(sock, SOL_SOCKET, SO_BROADCAST, &on, sizeof(on));
+    if (error) err(EX_OSERR, "setsockopt");
+
+    struct sockaddr_in addr = {
+        .sin_family = AF_INET,
+        .sin_port = 9,
+        .sin_addr.s_addr = INADDR_BROADCAST,
+    };
+    ssize_t size = sendto(
+        sock, payload, sizeof(payload), 0,
+        (struct sockaddr *)&addr, sizeof(addr)
+    );
+    if (size < 0) err(EX_IOERR, "sendto");
+
+    return EX_OK;
+}
diff --git a/bin/watch.c b/bin/watch.c
new file mode 100644
index 00000000..ed499652
--- /dev/null
+++ b/bin/watch.c
@@ -0,0 +1,93 @@
+/* Copyright (c) 2017, Curtis McEnroe <programble@gmail.com>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <sys/types.h>
+
+#include <err.h>
+#include <fcntl.h>
+#include <stdlib.h>
+#include <sys/event.h>
+#include <sys/wait.h>
+#include <sysexits.h>
+#include <unistd.h>
+
+static void watch(int kq, char *path) {
+    int fd = open(path, O_CLOEXEC);
+    if (fd < 0) err(EX_NOINPUT, "%s", path);
+
+    struct kevent event = {
+        .ident = fd,
+        .filter = EVFILT_VNODE,
+        .flags = EV_ADD | EV_CLEAR,
+        .fflags = NOTE_WRITE | NOTE_DELETE,
+        .udata = path,
+    };
+    int nevents = kevent(kq, &event, 1, NULL, 0, NULL);
+    if (nevents < 0) err(EX_OSERR, "kevent");
+}
+
+static void exec(char *const argv[]) {
+    pid_t pid = fork();
+    if (pid < 0) err(EX_OSERR, "fork");
+
+    if (!pid) {
+        execvp(*argv, argv);
+        err(EX_NOINPUT, "%s", *argv);
+    }
+
+    int status;
+    pid = wait(&status);
+    if (pid < 0) err(EX_OSERR, "wait");
+
+    if (WIFEXITED(status)) {
+        warnx("exit %d\n", WEXITSTATUS(status));
+    } else if (WIFSIGNALED(status)) {
+        warnx("signal %d\n", WTERMSIG(status));
+    } else {
+        warnx("status %d\n", status);
+    }
+}
+
+int main(int argc, char *argv[]) {
+    if (argc < 3) return EX_USAGE;
+
+    int kq = kqueue();
+    if (kq < 0) err(EX_OSERR, "kqueue");
+
+    int i;
+    for (i = 1; i < argc - 1; ++i) {
+        if (argv[i][0] == '-') {
+            i++;
+            break;
+        }
+        watch(kq, argv[i]);
+    }
+
+    exec(&argv[i]);
+
+    for (;;) {
+        struct kevent event;
+        int nevents = kevent(kq, NULL, 0, &event, 1, NULL);
+        if (nevents < 0) err(EX_OSERR, "kevent");
+
+        if (event.fflags & NOTE_DELETE) {
+            close(event.ident);
+            watch(kq, event.udata);
+        }
+
+        exec(&argv[i]);
+    }
+}
diff --git a/bin/xx.c b/bin/xx.c
new file mode 100644
index 00000000..688db8bc
--- /dev/null
+++ b/bin/xx.c
@@ -0,0 +1,133 @@
+/* Copyright (c) 2017, Curtis McEnroe <programble@gmail.com>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <ctype.h>
+#include <err.h>
+#include <stdbool.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <sysexits.h>
+#include <unistd.h>
+
+static bool zero(const uint8_t *ptr, size_t size) {
+    for (size_t i = 0; i < size; ++i) {
+        if (ptr[i]) return false;
+    }
+    return true;
+}
+
+static struct {
+    size_t cols;
+    size_t group;
+    bool ascii;
+    bool offset;
+    bool skip;
+} options = { 16, 8, true, true, false };
+
+static void dump(FILE *file) {
+    bool skip = false;
+
+    uint8_t buf[options.cols];
+    size_t offset = 0;
+    for (
+        size_t size;
+        (size = fread(buf, 1, sizeof(buf), file));
+        offset += size
+    ) {
+        if (options.skip) {
+            if (zero(buf, size)) {
+                if (!skip) printf("*\n");
+                skip = true;
+                continue;
+            } else {
+                skip = false;
+            }
+        }
+
+        if (options.offset) {
+            printf("%08zx:  ", offset);
+        }
+
+        for (size_t i = 0; i < sizeof(buf); ++i) {
+            if (options.group) {
+                if (i && !(i % options.group)) {
+                    printf(" ");
+                }
+            }
+            if (i < size) {
+                printf("%02hhx ", buf[i]);
+            } else {
+                printf("   ");
+            }
+        }
+
+        if (options.ascii) {
+            printf(" ");
+            for (size_t i = 0; i < size; ++i) {
+                if (options.group) {
+                    if (i && !(i % options.group)) {
+                        printf(" ");
+                    }
+                }
+                printf("%c", isprint(buf[i]) ? buf[i] : '.');
+            }
+        }
+
+        printf("\n");
+    }
+}
+
+static void undump(FILE *file) {
+    uint8_t byte;
+    int match;
+    while (0 < (match = fscanf(file, " %hhx", &byte))) {
+        printf("%c", byte);
+    }
+    if (!match) errx(EX_DATAERR, "invalid input");
+}
+
+int main(int argc, char *argv[]) {
+    bool reverse = false;
+    const char *path = NULL;
+
+    int opt;
+    while (0 < (opt = getopt(argc, argv, "ac:g:rsz"))) {
+        switch (opt) {
+            case 'a': options.ascii ^= true; break;
+            case 'c': options.cols = strtoul(optarg, NULL, 0); break;
+            case 'g': options.group = strtoul(optarg, NULL, 0); break;
+            case 'r': reverse = true; break;
+            case 's': options.offset ^= true; break;
+            case 'z': options.skip ^= true; break;
+            default: return EX_USAGE;
+        }
+    }
+    if (argc > optind) path = argv[optind];
+    if (!options.cols) return EX_USAGE;
+
+    FILE *file = path ? fopen(path, "r") : stdin;
+    if (!file) err(EX_NOINPUT, "%s", path);
+
+    if (reverse) {
+        undump(file);
+    } else {
+        dump(file);
+    }
+    if (ferror(file)) err(EX_IOERR, "%s", path);
+
+    return EX_OK;
+}