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#include <assert.h>
#include <err.h>
#include <fcntl.h>
#include <linux/fb.h>
#include <stdint.h>
#include <stdlib.h>
#include <string.h>
#include <sys/ioctl.h>
#include <sys/mman.h>
#include <sysexits.h>
#include <termios.h>
#include <unistd.h>
extern void init(int argc, char *argv[]);
extern void draw(uint32_t *buf, uint32_t xres, uint32_t yres);
extern void input(char in);
static size_t bufLen;
static uint32_t *buf;
static uint32_t *saveBuf;
static struct termios saveTerm;
static void restoreBuf(void) {
memcpy(buf, saveBuf, bufLen);
}
static void restoreTerm(void) {
tcsetattr(STDERR_FILENO, TCSADRAIN, &saveTerm);
}
int main(int argc, char *argv[]) {
int error;
char *path = getenv("FRAMEBUFFER");
if (!path) path = "/dev/fb0";
int fd = open(path, O_RDWR);
if (fd < 0) err(EX_OSFILE, "%s", path);
struct fb_fix_screeninfo fixInfo;
error = ioctl(fd, FBIOGET_FSCREENINFO, &fixInfo);
if (error) err(EX_IOERR, "%s", path);
struct fb_var_screeninfo varInfo;
error = ioctl(fd, FBIOGET_VSCREENINFO, &varInfo);
if (error) err(EX_IOERR, "%s", path);
assert(!varInfo.xoffset);
assert(!varInfo.yoffset);
assert(varInfo.bits_per_pixel == 32);
assert(!varInfo.grayscale);
assert(varInfo.red.offset == 16);
assert(varInfo.green.offset == 8);
assert(varInfo.blue.offset == 0);
assert(fixInfo.line_length == varInfo.xres * 4);
bufLen = varInfo.xres * varInfo.yres * 4;
buf = mmap(NULL, bufLen, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
if (buf == MAP_FAILED) err(EX_IOERR, "%s", path);
saveBuf = malloc(bufLen);
if (!saveBuf) err(EX_OSERR, "malloc(%zu)", bufLen);
memcpy(saveBuf, buf, bufLen);
atexit(restoreBuf);
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");
init(argc, argv);
for(;;) {
draw(buf, varInfo.xres, varInfo.yres);
char in;
ssize_t len = read(STDIN_FILENO, &in, 1);
if (len < 0) err(EX_IOERR, "read");
if (!len) return EX_DATAERR;
if (in == CTRL('C')) return EX_USAGE;
input(in);
}
}
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