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-rw-r--r--.gitignore1
-rw-r--r--CMakeLists.txt141
-rw-r--r--MacOSXBundleInfo.plist.in36
-rw-r--r--asset.h72
-rw-r--r--cards/.gitignore5
-rw-r--r--cards/CMakeLists.txt18
-rw-r--r--cards/LICENSE661
-rw-r--r--cards/cards.3 (renamed from cards.3)0
-rw-r--r--cards/cards.c (renamed from cards.c)0
-rw-r--r--cards/cards.h (renamed from cards.h)0
-rw-r--r--cards/dump.1 (renamed from dump.1)0
-rw-r--r--cards/dump.c (renamed from dump.c)0
-rw-r--r--cards/example.c (renamed from example.c)0
-rw-r--r--cards/exefmt.txt (renamed from exefmt.txt)0
-rw-r--r--freecell.c635
-rw-r--r--layout.h110
-rw-r--r--sol.c397
-rw-r--r--stack.h122
-rw-r--r--tools/exe2ico.c170
-rw-r--r--tools/ico2png.c251
20 files changed, 2610 insertions, 9 deletions
diff --git a/.gitignore b/.gitignore
index eb62ecc..4629025 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,4 +1,3 @@
-*.bmp
 CARDS.DLL
 FREECELL.EXE
 SOL.EXE
diff --git a/CMakeLists.txt b/CMakeLists.txt
index 9a40c37..4836b88 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -1,18 +1,143 @@
-cmake_minimum_required(VERSION 3.10)
+cmake_minimum_required(VERSION 3.13)
 
-project(cards C)
+project(WEP VERSION 0 LANGUAGES C)
 
 find_package(SDL2 REQUIRED)
 
+add_subdirectory(cards)
+include_directories(cards)
+
 if(NOT MSVC)
 	add_compile_options(-Wall -Wextra -pedantic)
 endif()
 
-add_library(cards STATIC cards.c)
-target_link_libraries(cards SDL2::SDL2)
+set(games sol freecell)
+set(tools exe2ico ico2png)
+
+foreach(game ${games})
+	add_executable(${game} MACOSX_BUNDLE ${game}.c)
+	target_link_libraries(${game} cards)
+
+	# Work around possible bugs in SDL2Config.cmake
+	if(MINGW)
+		target_link_libraries(${game} mingw32)
+		set_target_properties(${game} PROPERTIES WIN32_EXECUTABLE 1)
+	endif()
+
+	target_link_libraries(${game} SDL2::SDL2main SDL2::SDL2)
+
+	# Avoid conflicting with SOL.EXE, FREECELL.EXE on Windows
+	if(WIN32)
+		set_target_properties(${game} PROPERTIES OUTPUT_NAME wep${game})
+	endif()
+
+	set_target_properties(
+		${game} PROPERTIES
+		MACOSX_BUNDLE_INFO_PLIST
+			${CMAKE_CURRENT_SOURCE_DIR}/MacOSXBundleInfo.plist.in
+		MACOSX_BUNDLE_GUI_IDENTIFIER agency.causal.wep.${game}
+		MACOSX_BUNDLE_SHORT_VERSION_STRING "Version ${CMAKE_PROJECT_VERSION}"
+		MACOSX_BUNDLE_COPYRIGHT "Copyright 2019 June McEnroe"
+	)
+endforeach()
+
+if(APPLE)
+	set_target_properties(
+		sol PROPERTIES
+		OUTPUT_NAME Solitaire
+		MACOSX_BUNDLE_BUNDLE_NAME Solitaire
+	)
+	set_target_properties(
+		freecell PROPERTIES
+		OUTPUT_NAME FreeCell
+		MACOSX_BUNDLE_BUNDLE_NAME FreeCell
+	)
+endif()
+
+foreach(tool ${tools})
+	add_executable(${tool} EXCLUDE_FROM_ALL tools/${tool}.c)
+	target_link_libraries(${tool} SDL2::SDL2)
+endforeach()
+
+set(
+	WEP_DIRECTORY ${CMAKE_CURRENT_SOURCE_DIR} CACHE PATH
+	"Directory containing WEP DLLs and EXEs"
+)
+set(
+	SOL_DIRECTORY ${WEP_DIRECTORY} CACHE PATH
+	"Directory containing SOL.EXE"
+)
+
+set(cards_dll ${WEP_DIRECTORY}/CARDS.DLL)
+if(NOT EXISTS ${cards_dll})
+	set(cards_dll ${SOL_DIRECTORY}/SOL.EXE)
+endif()
+if(EXISTS ${cards_dll})
+	foreach(game ${games})
+		target_sources(${game} PRIVATE ${cards_dll})
+		set_target_properties(${game} PROPERTIES RESOURCE ${cards_dll})
+	endforeach()
+endif()
+
+set(freecell_exe ${WEP_DIRECTORY}/FREECELL.EXE)
+if(EXISTS ${freecell_exe})
+	target_sources(freecell PRIVATE ${freecell_exe})
+	set_target_properties(
+		freecell PROPERTIES RESOURCE "${cards_dll};${freecell_exe}"
+	)
+endif()
+
+foreach(game ${games})
+	string(TOUPPER ${game} shouting)
+	set(game_exe ${WEP_DIRECTORY}/${shouting}.EXE)
+	if(NOT EXISTS ${game_exe})
+		continue()
+	endif()
 
-add_executable(example EXCLUDE_FROM_ALL example.c)
-target_link_libraries(example cards SDL2::SDL2main)
+	add_custom_command(
+		OUTPUT ${shouting}.ICO
+		COMMAND exe2ico ${game_exe}
+		DEPENDS ${game_exe}
+		VERBATIM
+	)
+	if(APPLE)
+		file(MAKE_DIRECTORY ${CMAKE_CURRENT_BINARY_DIR}/${game}.iconset)
+		foreach(scale 1 2 4 8 16)
+			math(EXPR size "32 * ${scale}")
+			add_custom_command(
+				OUTPUT ${game}.iconset/icon_${size}x${size}.png
+				COMMAND ico2png
+					${shouting}.ICO ${scale}x
+					${game}.iconset/icon_${size}x${size}.png
+				DEPENDS ${shouting}.ICO
+				VERBATIM
+			)
+		endforeach()
+		add_custom_command(
+			OUTPUT ${game}.icns
+			COMMAND iconutil -c icns ${game}.iconset
+			DEPENDS
+				${game}.iconset/icon_32x32.png
+				${game}.iconset/icon_64x64.png
+				${game}.iconset/icon_128x128.png
+				${game}.iconset/icon_256x256.png
+				${game}.iconset/icon_512x512.png
+			VERBATIM
+		)
+		target_sources(${game} PRIVATE ${game}.icns)
+		get_property(game_resource TARGET ${game} PROPERTY RESOURCE)
+		set_target_properties(
+			${game} PROPERTIES
+			RESOURCE "${game_resource};${game}.icns"
+			MACOSX_BUNDLE_ICON_FILE ${game}.icns
+		)
+	elseif(WIN32)
+		file(
+			GENERATE OUTPUT ${game}.rc
+			CONTENT "IDI_ICON1 ICON DISCARDABLE \"${shouting}.ICO\"\n"
+		)
+		target_sources(${game} PRIVATE ${game}.rc ${shouting}.ICO)
+	endif()
+endforeach()
 
-add_executable(dump EXCLUDE_FROM_ALL dump.c)
-target_link_libraries(dump cards)
+install(TARGETS ${games} BUNDLE DESTINATION /Applications)
diff --git a/MacOSXBundleInfo.plist.in b/MacOSXBundleInfo.plist.in
new file mode 100644
index 0000000..b144709
--- /dev/null
+++ b/MacOSXBundleInfo.plist.in
@@ -0,0 +1,36 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!DOCTYPE plist PUBLIC "-//Apple Computer//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
+<plist version="1.0">
+<dict>
+	<key>CFBundleDevelopmentRegion</key>
+	<string>English</string>
+	<key>CFBundleExecutable</key>
+	<string>${MACOSX_BUNDLE_EXECUTABLE_NAME}</string>
+	<key>CFBundleGetInfoString</key>
+	<string>${MACOSX_BUNDLE_INFO_STRING}</string>
+	<key>CFBundleIconFile</key>
+	<string>${MACOSX_BUNDLE_ICON_FILE}</string>
+	<key>CFBundleIdentifier</key>
+	<string>${MACOSX_BUNDLE_GUI_IDENTIFIER}</string>
+	<key>CFBundleInfoDictionaryVersion</key>
+	<string>6.0</string>
+	<key>CFBundleLongVersionString</key>
+	<string>${MACOSX_BUNDLE_LONG_VERSION_STRING}</string>
+	<key>CFBundleName</key>
+	<string>${MACOSX_BUNDLE_BUNDLE_NAME}</string>
+	<key>CFBundlePackageType</key>
+	<string>APPL</string>
+	<key>CFBundleShortVersionString</key>
+	<string>${MACOSX_BUNDLE_SHORT_VERSION_STRING}</string>
+	<key>CFBundleSignature</key>
+	<string>????</string>
+	<key>CFBundleVersion</key>
+	<string>${MACOSX_BUNDLE_BUNDLE_VERSION}</string>
+	<key>CSResourcesFileMapped</key>
+	<true/>
+	<key>NSHumanReadableCopyright</key>
+	<string>${MACOSX_BUNDLE_COPYRIGHT}</string>
+	<key>NSHighResolutionCapable</key>
+	<string>True</string>
+</dict>
+</plist>
diff --git a/asset.h b/asset.h
new file mode 100644
index 0000000..cc37709
--- /dev/null
+++ b/asset.h
@@ -0,0 +1,72 @@
+/* Copyright (C) 2019  C. 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/>.
+ */
+
+#ifndef ASSET_H
+#define ASSET_H
+
+#include <SDL_filesystem.h>
+#include <SDL_rwops.h>
+#include <stdio.h>
+#include <stdlib.h>
+
+struct Paths {
+	char *base;
+	char *pref;
+};
+
+static inline int assetPaths(struct Paths *paths) {
+	paths->base = SDL_GetBasePath();
+	if (!paths->base) return -1;
+	paths->pref = SDL_GetPrefPath("Causal Agency", "Entertainment Pack");
+	if (!paths->pref) return -1;
+	return 0;
+}
+
+static inline SDL_RWops *
+assetOpen(const struct Paths *paths, const char *names[], size_t len) {
+	const char *dirs[3] = { paths->pref, paths->base, "" };
+	for (size_t i = 0; i < 3; ++i) {
+		for (size_t j = 0; j < len; ++j) {
+			char path[1024];
+			snprintf(path, sizeof(path), "%s%s", dirs[i], names[j]);
+			SDL_RWops *rw = SDL_RWFromFile(path, "rb");
+			if (rw) return rw;
+		}
+	}
+	return NULL;
+}
+
+static inline SDL_RWops *assetOpenCards(const struct Paths *paths) {
+	const char *names[3] = { "CARDS.DLL", "SOL.EXE", "cards.dll" };
+	SDL_RWops *rw = assetOpen(paths, names, 3);
+	if (rw) return rw;
+	char msg[4096];
+	snprintf(
+		msg, sizeof(msg), "%s or %s not found in:\n%s\n%s",
+		names[0], names[1], paths->pref, paths->base
+	);
+	SDL_ShowSimpleMessageBox(
+		SDL_MESSAGEBOX_ERROR, "Entertainment Pack", msg, NULL
+	);
+	return NULL;
+}
+
+static inline SDL_RWops *assetOpenFreeCell(const struct Paths *paths) {
+	const char *names[2] = { "FREECELL.EXE", "freecell.exe" };
+	return assetOpen(paths, names, 2);
+}
+
+#endif
diff --git a/cards/.gitignore b/cards/.gitignore
new file mode 100644
index 0000000..eb62ecc
--- /dev/null
+++ b/cards/.gitignore
@@ -0,0 +1,5 @@
+*.bmp
+CARDS.DLL
+FREECELL.EXE
+SOL.EXE
+build/
diff --git a/cards/CMakeLists.txt b/cards/CMakeLists.txt
new file mode 100644
index 0000000..9a40c37
--- /dev/null
+++ b/cards/CMakeLists.txt
@@ -0,0 +1,18 @@
+cmake_minimum_required(VERSION 3.10)
+
+project(cards C)
+
+find_package(SDL2 REQUIRED)
+
+if(NOT MSVC)
+	add_compile_options(-Wall -Wextra -pedantic)
+endif()
+
+add_library(cards STATIC cards.c)
+target_link_libraries(cards SDL2::SDL2)
+
+add_executable(example EXCLUDE_FROM_ALL example.c)
+target_link_libraries(example cards SDL2::SDL2main)
+
+add_executable(dump EXCLUDE_FROM_ALL dump.c)
+target_link_libraries(dump cards)
diff --git a/cards/LICENSE b/cards/LICENSE
new file mode 100644
index 0000000..dba13ed
--- /dev/null
+++ b/cards/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
+
+  The GNU Affero General Public License is a free, copyleft license for
+software and other kinds of works, specifically designed to ensure
+cooperation with the community in the case of network server software.
+
+  The licenses for most software and other practical works are designed
+to take away your freedom to share and change the works.  By contrast,
+our General Public Licenses are intended to guarantee your freedom to
+share and change all versions of a program--to make sure it remains free
+software for all its users.
+
+  When we speak of free software, we are referring to freedom, not
+price.  Our General Public Licenses are designed to make sure that you
+have the freedom to distribute copies of free software (and charge for
+them if you wish), that you receive source code or can get it if you
+want it, that you can change the software or use pieces of it in new
+free programs, and that you know you can do these things.
+
+  Developers that use our General Public Licenses protect your rights
+with two steps: (1) assert copyright on the software, and (2) offer
+you this License which gives you legal permission to copy, distribute
+and/or modify the software.
+
+  A secondary benefit of defending all users' freedom is that
+improvements made in alternate versions of the program, if they
+receive widespread use, become available for other developers to
+incorporate.  Many developers of free software are heartened and
+encouraged by the resulting cooperation.  However, in the case of
+software used on network servers, this result may fail to come about.
+The GNU General Public License permits making a modified version and
+letting the public access it on a server without ever releasing its
+source code to the public.
+
+  The GNU Affero General Public License is designed specifically to
+ensure that, in such cases, the modified source code becomes available
+to the community.  It requires the operator of a network server to
+provide the source code of the modified version running there to the
+users of that server.  Therefore, public use of a modified version, on
+a publicly accessible server, gives the public access to the source
+code of the modified version.
+
+  An older license, called the Affero General Public License and
+published by Affero, was designed to accomplish similar goals.  This is
+a different license, not a version of the Affero GPL, but Affero has
+released a new version of the Affero GPL which permits relicensing under
+this license.
+
+  The precise terms and conditions for copying, distribution and
+modification follow.
+
+                       TERMS AND CONDITIONS
+
+  0. Definitions.
+
+  "This License" refers to version 3 of the GNU Affero General Public License.
+
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+  12. No Surrender of Others' Freedom.
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+
+  13. Remote Network Interaction; Use with the GNU General Public License.
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+  14. Revised Versions of this License.
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+                     END OF TERMS AND CONDITIONS
+
+            How to Apply These Terms to Your New Programs
+
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+    <one line to give the program's name and a brief idea of what it does.>
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+    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
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+Also add information on how to contact you by electronic and paper mail.
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+For more information on this, and how to apply and follow the GNU AGPL, see
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diff --git a/cards.3 b/cards/cards.3
index fd46051..fd46051 100644
--- a/cards.3
+++ b/cards/cards.3
diff --git a/cards.c b/cards/cards.c
index c9467f3..c9467f3 100644
--- a/cards.c
+++ b/cards/cards.c
diff --git a/cards.h b/cards/cards.h
index 89baf5d..89baf5d 100644
--- a/cards.h
+++ b/cards/cards.h
diff --git a/dump.1 b/cards/dump.1
index a7fc3db..a7fc3db 100644
--- a/dump.1
+++ b/cards/dump.1
diff --git a/dump.c b/cards/dump.c
index 3e39292..3e39292 100644
--- a/dump.c
+++ b/cards/dump.c
diff --git a/example.c b/cards/example.c
index 036a44a..036a44a 100644
--- a/example.c
+++ b/cards/example.c
diff --git a/exefmt.txt b/cards/exefmt.txt
index 51fa9a7..51fa9a7 100644
--- a/exefmt.txt
+++ b/cards/exefmt.txt
diff --git a/freecell.c b/freecell.c
new file mode 100644
index 0000000..a346277
--- /dev/null
+++ b/freecell.c
@@ -0,0 +1,635 @@
+/* Copyright (C) 2019  June 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 <stdbool.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <time.h>
+
+#include <SDL.h>
+#include <cards.h>
+
+#include "asset.h"
+#include "stack.h"
+
+typedef unsigned uint;
+
+enum {
+	Foundation1,
+	Foundation2,
+	Foundation3,
+	Foundation4,
+	Cell1,
+	Cell2,
+	Cell3,
+	Cell4,
+	Tableau1,
+	Tableau2,
+	Tableau3,
+	Tableau4,
+	Tableau5,
+	Tableau6,
+	Tableau7,
+	Tableau8,
+	StacksLen,
+};
+
+static struct Stack stacks[StacksLen];
+
+static uint kingIndex = Cards_KingRight;
+
+struct Move {
+	uint dst;
+	uint src;
+};
+
+enum { QueueLen = 16 };
+static struct {
+	struct Move moves[QueueLen];
+	uint r, w, u;
+} queue;
+
+static void enqueue(uint dst, uint src) {
+	queue.moves[queue.w % QueueLen].dst = dst;
+	queue.moves[queue.w % QueueLen].src = src;
+	queue.w++;
+}
+
+static void dequeue(void) {
+	struct Move move = queue.moves[queue.r++ % QueueLen];
+	push(&stacks[move.dst], pop(&stacks[move.src]));
+	if (move.dst <= Foundation4) {
+		kingIndex = Cards_KingRight;
+	} else if (move.dst <= Cell4) {
+		kingIndex = Cards_KingLeft;
+	}
+}
+
+static bool undo(void) {
+	uint len = queue.w - queue.u;
+	if (!len || len > QueueLen) return false;
+	for (uint i = len - 1; i < len; --i) {
+		struct Move move = queue.moves[(queue.u + i) % QueueLen];
+		push(&stacks[move.src], pop(&stacks[move.dst]));
+	}
+	queue.r = queue.w = queue.u;
+	return true;
+}
+
+static uint lcgState = 1;
+static uint lcgRand(void) {
+	lcgState = (214013 * lcgState + 2531011) % (1 << 31);
+	return lcgState / (1 << 16);
+}
+
+// <https://rosettacode.org/wiki/Deal_cards_for_FreeCell>
+static void deal(uint game) {
+	lcgState = game;
+
+	queue.r = queue.w = queue.u = 0;
+	for (uint i = 0; i < StacksLen; ++i) {
+		clear(&stacks[i]);
+	}
+	kingIndex = Cards_KingRight;
+
+	struct Stack deck = {0};
+	for (Card i = Cards_A; i <= Cards_K; ++i) {
+		push(&deck, Cards_Club + i);
+		push(&deck, Cards_Diamond + i);
+		push(&deck, Cards_Heart + i);
+		push(&deck, Cards_Spade + i);
+	}
+
+	uint stack = 0;
+	while (deck.len) {
+		uint i = lcgRand() % deck.len;
+		Card card = deck.cards[i];
+		deck.cards[i] = deck.cards[--deck.len];
+		push(&stacks[Tableau1 + stack++ % 8], card);
+	}
+}
+
+static bool win(void) {
+	for (uint i = Foundation1; i <= Foundation4; ++i) {
+		if (stacks[i].len != 13) return false;
+	}
+	return true;
+}
+
+static bool valid(uint dst, Card card) {
+	Card top = peek(&stacks[dst]);
+	if (dst <= Foundation4) {
+		if (!top) return rank(card) == Cards_A;
+		return suit(card) == suit(top)
+			&& rank(card) == rank(top) + 1;
+	}
+	if (!top) return true;
+	if (dst >= Tableau1) {
+		return color(card) != color(top)
+			&& rank(card) == rank(top) - 1;
+	}
+	return false;
+}
+
+static void autoEnqueue(void) {
+	Card min[] = { Cards_K, Cards_K };
+	for (uint i = Cell1; i <= Tableau8; ++i) {
+		for (uint j = 0; j < stacks[i].len; ++j) {
+			Card card = stacks[i].cards[j];
+			if (rank(card) < min[color(card)]) {
+				min[color(card)] = rank(card);
+			}
+		}
+	}
+
+	for (uint src = Cell1; src <= Tableau8; ++src) {
+		Card card = peek(&stacks[src]);
+		if (!card) continue;
+		if (rank(card) > Cards_2) {
+			if (min[!color(card)] < rank(card)) continue;
+		}
+		for (uint dst = Foundation1; dst <= Foundation4; ++dst) {
+			if (valid(dst, card)) {
+				enqueue(dst, src);
+				return;
+			}
+		}
+	}
+}
+
+static void moveSingle(uint dst, uint src) {
+	if (valid(dst, peek(&stacks[src]))) {
+		queue.u = queue.w;
+		enqueue(dst, src);
+	}
+}
+
+static uint moveDepth(uint src) {
+	struct Stack stack = stacks[src];
+	if (stack.len < 2) return stack.len;
+	uint n = 1;
+	for (uint i = stack.len - 2; i < stack.len; --i, ++n) {
+		if (color(stack.cards[i]) == color(stack.cards[i + 1])) break;
+		if (rank(stack.cards[i]) != rank(stack.cards[i + 1]) + 1) break;
+	}
+	return n;
+}
+
+static uint freeCells(uint cells[]) {
+	uint len = 0;
+	for (uint i = Cell1; i <= Cell4; ++i) {
+		if (!stacks[i].len) cells[len++] = i;
+	}
+	return len;
+}
+
+static void moveColumn(uint dst, uint src) {
+	uint cells[4];
+	uint free = freeCells(cells);
+
+	uint depth;
+	for (depth = moveDepth(src); depth; --depth) {
+		if (free < depth - 1) continue;
+		if (valid(dst, stacks[src].cards[stacks[src].len - depth])) break;
+	}
+	if (depth < 2 || dst <= Cell4) {
+		moveSingle(dst, src);
+		return;
+	}
+
+	queue.u = queue.w;
+	for (uint i = 0; i < depth - 1; ++i) {
+		enqueue(cells[i], src);
+	}
+	enqueue(dst, src);
+	for (uint i = depth - 2; i < depth - 1; --i) {
+		enqueue(dst, cells[i]);
+	}
+}
+
+enum {
+	CardWidth = Cards_CardWidth,
+	CardHeight = Cards_CardHeight,
+
+	CellX = 0,
+	CellY = 0,
+
+	KingMarginX = 13,
+	KingX = CellX + 4 * CardWidth + KingMarginX,
+	KingY = 18,
+	KingPadX = 3,
+	KingPadY = 3,
+	KingWidth = Cards_KingWidth + 2 * KingPadX,
+	KingHeight = Cards_KingHeight + 2 * KingPadY,
+
+	FoundationX = KingX + KingWidth + KingMarginX,
+	FoundationY = CellY,
+
+	StackMarginX = 7,
+	StackMarginY = 10,
+	StackDeltaY = 17,
+
+	TableauX = StackMarginX,
+	TableauY = CellY + CardHeight + StackMarginY,
+
+	KingWinMarginX = 10,
+	KingWinMarginY = 10,
+	KingWinX = KingWinMarginX,
+	KingWinY = CellY + CardHeight + KingWinMarginY,
+	KingWinWidth = 320,
+	KingWinHeight = 320,
+
+	WindowWidth = 8 * CardWidth + 9 * StackMarginX + 1,
+	WindowHeight = KingWinY + KingWinHeight + KingWinMarginY,
+};
+
+static struct SDL_Rect rects[StacksLen];
+
+static void initRects(void) {
+	SDL_Rect rect = { CellX, CellY, CardWidth, CardHeight };
+	for (uint i = Cell1; i <= Cell4; ++i) {
+		rects[i] = rect;
+		rect.x += CardWidth;
+	}
+
+	rect.x = FoundationX;
+	rect.y = FoundationY;
+	for (uint i = Foundation1; i <= Foundation4; ++i) {
+		rects[i] = rect;
+		rect.x += CardWidth;
+	}
+
+	rect.x = TableauX;
+	rect.y = TableauY;
+	rect.h = WindowHeight - TableauY;
+	for (uint i = Tableau1; i <= Tableau8; ++i) {
+		rects[i] = rect;
+		rect.x += CardWidth + StackMarginX;
+	}
+}
+
+static uint pointStack(SDL_Point point) {
+	uint i;
+	for (i = 0; i < StacksLen; ++i) {
+		if (SDL_PointInRect(&point, &rects[i])) break;
+	}
+	return i;
+}
+
+static SDL_Window *window;
+
+static void err(const char *title) {
+	int error = SDL_ShowSimpleMessageBox(
+		SDL_MESSAGEBOX_ERROR, title, SDL_GetError(), window
+	);
+	if (error) fprintf(stderr, "%s\n", SDL_GetError());
+	exit(EXIT_FAILURE);
+}
+
+static bool playAgain(void) {
+	SDL_MessageBoxButtonData buttons[] = {
+		{ SDL_MESSAGEBOX_BUTTON_RETURNKEY_DEFAULT, true, "Yes" },
+		{ SDL_MESSAGEBOX_BUTTON_ESCAPEKEY_DEFAULT, false, "No" },
+	};
+	SDL_MessageBoxData data = {
+		.window = window,
+		.title = "Game Over",
+		.message = "Congratulations, you win!\n\nDo you want to play again?",
+		.buttons = buttons,
+		.numbuttons = SDL_arraysize(buttons),
+	};
+	int choice;
+	if (SDL_ShowMessageBox(&data, &choice) < 0) err("SDL_ShowMessageBox");
+	return choice;
+}
+
+enum Choice {
+	Cancel,
+	Column,
+	Single,
+};
+
+static enum Choice chooseMove(void) {
+	SDL_MessageBoxButtonData buttons[] = {
+		{ SDL_MESSAGEBOX_BUTTON_RETURNKEY_DEFAULT, Column, "Move column" },
+		{ 0, Single, "Move single card" },
+		{ SDL_MESSAGEBOX_BUTTON_ESCAPEKEY_DEFAULT, Cancel, "Cancel" },
+	};
+	SDL_MessageBoxData data = {
+		.window = window,
+		.title = "Move to Empty Column...",
+		.message = "",
+		.buttons = buttons,
+		.numbuttons = SDL_arraysize(buttons),
+	};
+	int choice;
+	if (SDL_ShowMessageBox(&data, &choice) < 0) err("SDL_ShowMessageBox");
+	return choice;
+}
+
+static uint currentGame;
+static void newGame(uint game) {
+	if (!game) game = 1 + randUniform(32000);
+	deal(game);
+	char buf[sizeof("FreeCell Game #32000")];
+	snprintf(buf, sizeof(buf), "FreeCell Game #%u", game);
+	SDL_SetWindowTitle(window, buf);
+	currentGame = game;
+}
+
+static Card hiliteRank;
+static SDL_Point revealPoint;
+static uint fromStack = StacksLen;
+
+static bool keyDown(SDL_KeyboardEvent key) {
+	switch (key.keysym.sym) {
+		case SDLK_F2: newGame(0); return true;
+		case SDLK_F5: newGame(currentGame); return true;
+		case SDLK_BACKSPACE: return undo();
+	}
+	if (key.repeat) return false;
+	switch (key.keysym.sym) {
+		break; case SDLK_a: hiliteRank = Cards_A;
+		break; case SDLK_2: hiliteRank = Cards_2;
+		break; case SDLK_3: hiliteRank = Cards_3;
+		break; case SDLK_4: hiliteRank = Cards_4;
+		break; case SDLK_5: hiliteRank = Cards_5;
+		break; case SDLK_6: hiliteRank = Cards_6;
+		break; case SDLK_7: hiliteRank = Cards_7;
+		break; case SDLK_8: hiliteRank = Cards_8;
+		break; case SDLK_9: hiliteRank = Cards_9;
+		break; case SDLK_1: hiliteRank = Cards_10;
+		break; case SDLK_0: hiliteRank = Cards_10;
+		break; case SDLK_j: hiliteRank = Cards_J;
+		break; case SDLK_q: hiliteRank = Cards_Q;
+		break; case SDLK_k: hiliteRank = Cards_K;
+		break; default: return false;
+	}
+	return true;
+}
+
+static bool keyUp(SDL_KeyboardEvent key) {
+	(void)key;
+	if (hiliteRank) {
+		hiliteRank = 0;
+		return true;
+	}
+	return false;
+}
+
+static bool mouseButtonDown(SDL_MouseButtonEvent button) {
+	if (button.button == SDL_BUTTON_RIGHT) {
+		revealPoint.x = button.x;
+		revealPoint.y = button.y;
+		return true;
+	}
+	return false;
+}
+
+static bool mouseButtonUp(SDL_MouseButtonEvent button) {
+	if (win() && playAgain()) {
+		newGame(0);
+		return true;
+	}
+
+	if (button.button == SDL_BUTTON_RIGHT && revealPoint.x) {
+		revealPoint.x = 0;
+		revealPoint.y = 0;
+		return true;
+	}
+
+	SDL_Point point = { button.x, button.y };
+	uint stack = pointStack(point);
+	if (button.clicks % 2 == 0) {
+		for (stack = Cell1; stack <= Cell4; ++stack) {
+			if (!stacks[stack].len) break;
+		}
+	}
+
+	if (fromStack < StacksLen && stack < StacksLen) {
+		if (moveDepth(fromStack) > 1 && stack > Cell4 && !stacks[stack].len) {
+			switch (chooseMove()) {
+				break; case Single: moveSingle(stack, fromStack);
+				break; case Column: moveColumn(stack, fromStack);
+				break; case Cancel: break;
+			}
+		} else {
+			moveColumn(stack, fromStack);
+		}
+	}
+
+	if (fromStack < StacksLen) {
+		fromStack = StacksLen;
+		return true;
+	}
+	if (stack < StacksLen && stack > Foundation4 && stacks[stack].len) {
+		fromStack = stack;
+		return true;
+	}
+
+	return false;
+}
+
+static SDL_Renderer *render;
+static struct {
+	SDL_Texture *cards[Cards_Empty];
+	SDL_Texture *hilites[Cards_Empty];
+	SDL_Texture *kings[Cards_FreeCellCount];
+} tex;
+
+static void renderOutline(SDL_Rect rect, bool out) {
+	int right = rect.x + rect.w - 1;
+	int bottom = rect.y + rect.h - 1;
+	SDL_Point topLeft[3] = {
+		{ rect.x, bottom - 1 },
+		{ rect.x, rect.y },
+		{ right - 1, rect.y },
+	};
+	SDL_Point bottomRight[3] = {
+		{ rect.x + 1, bottom },
+		{ right, bottom },
+		{ right, rect.y + 1 },
+	};
+	SDL_SetRenderDrawColor(render, 0x00, 0x00, 0x00, 0xFF);
+	SDL_RenderDrawLines(render, out ? bottomRight : topLeft, 3);
+	SDL_SetRenderDrawColor(render, 0x00, 0xFF, 0x00, 0xFF);
+	SDL_RenderDrawLines(render, out ? topLeft : bottomRight, 3);
+}
+
+static void renderOutlines(void) {
+	for (uint i = Foundation1; i <= Cell4; ++i) {
+		renderOutline(rects[i], false);
+	}
+}
+
+static void renderKing(void) {
+	SDL_Rect box = { KingX, KingY, KingWidth, KingHeight };
+	renderOutline(box, true);
+	if (win()) {
+		SDL_Rect king = { KingWinX, KingWinY, KingWinWidth, KingWinHeight };
+		SDL_RenderCopy(render, tex.kings[Cards_KingWin], NULL, &king);
+	} else {
+		SDL_Rect king = {
+			KingX + KingPadX, KingY + KingPadY,
+			Cards_KingWidth, Cards_KingHeight,
+		};
+		SDL_RenderCopy(render, tex.kings[kingIndex], NULL, &king);
+	}
+}
+
+static void renderCard(SDL_Rect rect, Card card, bool hilite) {
+	SDL_Texture *texture = (hilite ? tex.hilites : tex.cards)[card];
+	SDL_RenderCopy(render, texture, NULL, &rect);
+}
+
+static void renderStack(uint stack) {
+	Card revealCard = 0;
+	SDL_Rect revealRect = {0};
+	SDL_Rect rect = { rects[stack].x, rects[stack].y, CardWidth, CardHeight };
+	for (uint i = 0; i < stacks[stack].len; ++i) {
+		Card card = stacks[stack].cards[i];
+		if (SDL_PointInRect(&revealPoint, &rect)) {
+			revealCard = card;
+			revealRect = rect;
+		}
+		bool hilite = (stack == fromStack && i == stacks[stack].len - 1);
+		renderCard(rect, card, hilite || rank(card) == hiliteRank);
+		rect.y += StackDeltaY;
+	}
+	if (revealCard) {
+		renderCard(revealRect, revealCard, false);
+	}
+}
+
+static void renderStacks(void) {
+	for (uint i = Foundation1; i <= Cell4; ++i) {
+		Card card = peek(&stacks[i]);
+		if (!card) continue;
+		bool hilite = (i == fromStack || rank(card) == hiliteRank);
+		renderCard(rects[i], card, hilite);
+	}
+	for (uint i = Tableau1; i <= Tableau8; ++i) {
+		renderStack(i);
+	}
+}
+
+int main(int argc, char *argv[]) {
+	int error;
+
+	if (SDL_Init(SDL_INIT_VIDEO) < 0) err("SDL_Init");
+	atexit(SDL_Quit);
+
+	SDL_SetHint(SDL_HINT_VIDEO_ALLOW_SCREENSAVER, "1");
+	SDL_SetHint(SDL_HINT_MAC_CTRL_CLICK_EMULATE_RIGHT_CLICK, "1");
+
+	struct Paths paths;
+	if (assetPaths(&paths) < 0) err("SDL_GetPrefPath");
+
+	bool haveFreeCell = false;
+	struct {
+		SDL_Surface *cards[Cards_Empty];
+		SDL_Surface *freeCell[Cards_FreeCellCount];
+	} res;
+
+	SDL_RWops *rw = assetOpenCards(&paths);
+	if (!rw) return EXIT_FAILURE;
+	error = Cards_LoadCards(
+		res.cards, Cards_Empty, rw,
+		Cards_AlphaCorners | Cards_BlackBorders
+	);
+	if (error) err("Cards_LoadCards");
+	SDL_RWclose(rw);
+
+	rw = assetOpenFreeCell(&paths);
+	if (rw) {
+		haveFreeCell = true;
+		error = Cards_LoadFreeCell(
+			res.freeCell, Cards_FreeCellCount, rw,
+			Cards_ColorKey
+		);
+		if (error) err("Cards_LoadFreeCell");
+		SDL_RWclose(rw);
+	}
+
+	error = SDL_CreateWindowAndRenderer(
+		WindowWidth, WindowHeight, SDL_WINDOW_ALLOW_HIGHDPI,
+		&window, &render
+	);
+	if (error) err("SDL_CreateWindowAndRenderer");
+	SDL_SetWindowTitle(window, "FreeCell");
+
+	SDL_RenderSetIntegerScale(render, SDL_TRUE);
+	SDL_RenderSetLogicalSize(render, WindowWidth, WindowHeight);
+
+	for (uint i = 0; i < Cards_Empty; ++i) {
+		if (!res.cards[i]) continue;
+
+		tex.cards[i] = SDL_CreateTextureFromSurface(render, res.cards[i]);
+		if (!tex.cards[i]) err("SDL_CreateTextureFromSurface");
+
+		if (Cards_InvertSurface(res.cards[i]) < 0) err("Cards_hilitesurface");
+		tex.hilites[i] = SDL_CreateTextureFromSurface(render, res.cards[i]);
+		if (!tex.hilites[i]) err("SDL_CreateTextureFromSurface");
+
+		SDL_FreeSurface(res.cards[i]);
+	}
+
+	if (haveFreeCell) {
+		for (uint i = 0; i < Cards_FreeCellCount; ++i) {
+			if (!res.freeCell[i]) continue;
+			tex.kings[i] = SDL_CreateTextureFromSurface(render, res.freeCell[i]);
+			if (!tex.kings[i]) err("SDL_CreateTextureFromSurface");
+			SDL_FreeSurface(res.freeCell[i]);
+		}
+	}
+
+	srand(time(NULL));
+	newGame(argc > 1 ? strtoul(argv[1], NULL, 10) : 0);
+	
+	initRects();
+	for (;;) {
+		SDL_SetRenderDrawColor(render, 0x00, 0xAA, 0x55, 0xFF);
+		SDL_RenderClear(render);
+		renderOutlines();
+		renderStacks();
+		if (haveFreeCell) renderKing();
+		SDL_RenderPresent(render);
+
+		if (queue.r < queue.w) {
+			dequeue();
+			if (queue.r == queue.w) autoEnqueue();
+			if (queue.r < queue.w) SDL_Delay(50);
+			continue;
+		}
+
+		bool update = false;
+		while (!update) {
+			SDL_Event event;
+			SDL_WaitEvent(&event);
+			switch (event.type) {
+				break; case SDL_QUIT: return EXIT_SUCCESS;
+				break; case SDL_KEYDOWN: update = keyDown(event.key);
+				break; case SDL_KEYUP: update = keyUp(event.key);
+				break; case SDL_MOUSEBUTTONDOWN: {
+					update = mouseButtonDown(event.button);
+				}
+				break; case SDL_MOUSEBUTTONUP: {
+					update = mouseButtonUp(event.button);
+				}
+			}
+		}
+	}
+}
diff --git a/layout.h b/layout.h
new file mode 100644
index 0000000..cbff6df
--- /dev/null
+++ b/layout.h
@@ -0,0 +1,110 @@
+/* Copyright (C) 2019  C. 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/>.
+ */
+
+#ifndef LAYOUT_H
+#define LAYOUT_H
+
+#include <SDL_rect.h>
+#include <assert.h>
+
+#include "stack.h"
+
+#ifndef LAYOUT_CAP
+#define LAYOUT_CAP 64
+#endif
+
+typedef unsigned uint;
+
+struct Item {
+	SDL_Rect rect;
+	Card card;
+};
+
+struct List {
+	uint len;
+	struct Item items[LAYOUT_CAP];
+};
+
+static inline void listClear(struct List *list) {
+	list->len = 0;
+}
+
+static inline void
+listPush(struct List *list, const struct SDL_Rect *rect, Card card) {
+	assert(list->len < LAYOUT_CAP);
+	struct Item item = { *rect, card };
+	list->items[list->len++] = item;
+}
+
+static inline struct Item *listFind(struct List *list, const SDL_Point *point) {
+	for (uint i = list->len - 1; i < list->len; --i) {
+		if (SDL_PointInRect(point, &list->items[i].rect)) {
+			return &list->items[i];
+		}
+	}
+	return NULL;
+}
+
+struct Layout {
+	struct List main;
+	struct List drag;
+	struct Item dragItem;
+};
+
+static inline void layoutClear(struct Layout *layout) {
+	listClear(&layout->main);
+	listClear(&layout->drag);
+}
+
+struct Style {
+	uint increment;
+	int deltaXBack;
+	int deltaYBack;
+	int deltaXFront;
+	int deltaYFront;
+};
+
+enum {
+	SquareIncrement = 24 / 3,
+	SquareDeltaX = 2,
+	SquareDeltaY = 1,
+};
+static const struct Style Flat = { 1, 0, 0, 0, 0 };
+static const struct Style Square = {
+	SquareIncrement, SquareDeltaX, SquareDeltaY, SquareDeltaX, SquareDeltaY,
+};
+
+static inline void
+layoutStack(
+	struct Layout *layout, SDL_Rect *rect,
+	const struct Stack *stack, const struct Style *style
+) {
+	struct List *list = &layout->main;
+	for (uint i = 0; i < stack->len; ++i) {
+		Card card = stack->cards[i];
+		if (card == layout->dragItem.card) {
+			list = &layout->drag;
+			*rect = layout->dragItem.rect;
+		}
+		listPush(list, rect, card);
+		if ((i + 1) % style->increment == 0) {
+			rect->x += (card > 0 ? style->deltaXFront : style->deltaXBack);
+			rect->y += (card > 0 ? style->deltaYFront : style->deltaYBack);
+		}
+	}
+}
+
+#endif
diff --git a/sol.c b/sol.c
new file mode 100644
index 0000000..890ad89
--- /dev/null
+++ b/sol.c
@@ -0,0 +1,397 @@
+/* Copyright (C) 2019  C. 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 <stdbool.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <time.h>
+
+#include <SDL.h>
+#include <cards.h>
+
+#include "asset.h"
+#include "layout.h"
+#include "stack.h"
+
+#define ARRAY_LEN(a) (sizeof(a) / sizeof((a)[0]))
+
+enum {
+	Stock,
+	Waste1,
+	Waste3,
+	Foundation1,
+	Foundation2,
+	Foundation3,
+	Foundation4,
+	Tableau1,
+	Tableau2,
+	Tableau3,
+	Tableau4,
+	Tableau5,
+	Tableau6,
+	Tableau7,
+	StacksLen,
+};
+
+static struct Stack stacks[StacksLen];
+
+// TODO: Scoring method, score, time.
+static struct {
+	uint draw;
+} game = {
+	.draw = 3,
+};
+
+typedef void StackFn(struct Stack *dst, struct Stack *src, Uint8 len);
+
+static struct {
+	StackFn *fn;
+	uint dst;
+	uint src;
+	uint len;
+} undo;
+
+static void gameDo(StackFn *fn, uint dst, uint src, uint len) {
+	undo.fn = fn;
+	undo.dst = src;
+	undo.src = dst;
+	undo.len = len;
+	fn(&stacks[dst], &stacks[src], len);
+}
+
+static bool gameUndo(void) {
+	if (!undo.fn) return false;
+	undo.fn(&stacks[undo.dst], &stacks[undo.src], undo.len);
+	undo.fn = NULL;
+	return true;
+}
+
+static void gameDeal(void) {
+	undo.fn = NULL;
+	for (uint i = 0; i < StacksLen; ++i) {
+		clear(&stacks[i]);
+	}
+	stacks[Stock] = Deck;
+	shuffle(&stacks[Stock]);
+	for (uint i = Tableau1; i <= Tableau7; ++i) {
+		moveTo(&stacks[i], &stacks[Stock], i - Tableau1);
+		flipTo(&stacks[i], &stacks[Stock], 1);
+	}
+}
+
+static void gameDraw(void) {
+	moveTo(&stacks[Waste1], &stacks[Waste3], stacks[Waste3].len);
+	if (stacks[Stock].len) {
+		if (game.draw > 1) {
+			gameDo(flipTo, Waste3, Stock, game.draw);
+		} else {
+			gameDo(flipTo, Waste1, Stock, 1);
+		}
+	} else {
+		gameDo(flipTo, Stock, Waste1, stacks[Waste1].len);
+	}
+}
+
+static bool gameFind(uint *stack, uint *index, Card card) {
+	for (*stack = 0; *stack < StacksLen; ++*stack) {
+		for (*index = 0; *index < stacks[*stack].len; ++*index) {
+			if (stacks[*stack].cards[*index] == card) return true;
+		}
+	}
+	return false;
+}
+
+static bool gameAvail(Card card) {
+	uint stack, index;
+	if (card < 0) return false;
+	if (!gameFind(&stack, &index, card)) return false;
+
+	bool top = (card == peek(&stacks[stack]));
+	if (stack == Waste1) {
+		return top && !stacks[Waste3].len;
+	} else if (stack == Waste3) {
+		return top;
+	} else if (stack >= Foundation1 && stack <= Foundation4) {
+		return top;
+	} else if (stack >= Tableau1 && stack <= Tableau7) {
+		return true;
+	} else {
+		return false;
+	}
+}
+
+static bool gameReveal(Card card) {
+	uint stack, index;
+	if (!gameFind(&stack, &index, card)) return false;
+	if (stack < Tableau1 || stack > Tableau7) return false;
+	if (card != peek(&stacks[stack])) return false;
+	if (card > 0) return false;
+	gameDo(flipTo, stack, stack, 1);
+	return true;
+}
+
+static bool gameMove(uint dest, Card card) {
+	uint source, index;
+	if (!gameFind(&source, &index, card)) return false;
+	if (source == dest) return false;
+
+	uint count = stacks[source].len - index;
+	Card destTop = peek(&stacks[dest]);
+
+	if (dest >= Foundation1 && dest <= Foundation4) {
+		if (count > 1) return false;
+		if (!destTop && rank(card) != Cards_A) return false;
+		if (destTop && suit(card) != suit(destTop)) return false;
+		if (destTop && rank(card) != rank(destTop) + 1) return false;
+		gameDo(moveTo, dest, source, 1);
+		return true;
+	}
+
+	if (dest >= Tableau1 && dest <= Tableau7) {
+		if (!destTop && rank(card) != Cards_K) return false;
+		if (destTop && color(card) == color(destTop)) return false;
+		if (destTop && rank(card) != rank(destTop) - 1) return false;
+		gameDo(moveTo, dest, source, count);
+		return true;
+	}
+
+	return false;
+}
+
+enum {
+	CardWidth = Cards_CardWidth,
+	CardHeight = Cards_CardHeight,
+
+	StackMarginX = 11,
+	StackMarginY = 6,
+
+	StockX = StackMarginX,
+	StockY = StackMarginY,
+
+	WasteX = StockX + CardWidth + StackMarginX,
+	WasteY = StackMarginY,
+
+	FoundationX = WasteX + 2 * (CardWidth + StackMarginX),
+	FoundationY = StackMarginY,
+
+	TableauX = StackMarginX,
+	TableauY = StockY + CardHeight + StackMarginY,
+
+	FanRightDeltaX = 14,
+	FanDownDeltaYBack = 3,
+	FanDownDeltaYFront = 15,
+
+	WindowWidth = 7 * CardWidth + 8 * StackMarginX,
+	WindowHeight = 2 * (StackMarginY + CardHeight)
+		+ 6 * FanDownDeltaYBack
+		+ 12 * FanDownDeltaYFront
+		+ StackMarginY,
+};
+
+static const struct Style FanRight = {
+	1, 0, 0, FanRightDeltaX, SquareDeltaY
+};
+static const struct Style FanDown = {
+	1, 0, FanDownDeltaYBack, 0, FanDownDeltaYFront
+};
+
+static struct SDL_Rect stackRects[StacksLen];
+static struct Layout layout;
+static uint backTexture = Cards_Back1;
+
+static void updateLayout(void) {
+	layoutClear(&layout);
+
+	SDL_Rect stock = { StockX, StockY, CardWidth, CardHeight };
+	stackRects[Stock] = stock;
+	listPush(&layout.main, &stock, Cards_O);
+	layoutStack(&layout, &stock, &stacks[Stock], &Square);
+
+	SDL_Rect waste = { WasteX, WasteY, CardWidth, CardHeight };
+	layoutStack(&layout, &waste, &stacks[Waste1], &Square);
+	layoutStack(&layout, &waste, &stacks[Waste3], &FanRight);
+
+	SDL_Rect found = { FoundationX, FoundationY, CardWidth, CardHeight };
+	for (uint i = Foundation1; i <= Foundation4; ++i) {
+		stackRects[i] = found;
+		listPush(&layout.main, &found, Cards_Empty);
+		SDL_Rect rect = found;
+		layoutStack(&layout, &rect, &stacks[i], &Square);
+		found.x += CardWidth + StackMarginX;
+	}
+
+	SDL_Rect table = { TableauX, TableauY, CardWidth, CardHeight };
+	for (uint i = Tableau1; i <= Tableau7; ++i) {
+		stackRects[i] = table;
+		stackRects[i].h = WindowHeight;
+		SDL_Rect rect = table;
+		layoutStack(&layout, &rect, &stacks[i], &FanDown);
+		table.x += CardWidth + StackMarginX;
+	}
+}
+
+static bool keyDown(SDL_KeyboardEvent key) {
+	switch (key.keysym.sym) {
+		case SDLK_F2: gameDeal(); return true;
+		case SDLK_BACKSPACE: return gameUndo();
+		case SDLK_b: {
+			backTexture -= Cards_Back1;
+			backTexture += 1;
+			backTexture %= 12;
+			backTexture += Cards_Back1;
+			return true;
+		}
+		case SDLK_d: {
+			game.draw = (game.draw == 1 ? 3 : 1);
+			gameDeal();
+			return true;
+		}
+		default: return false;
+	}
+}
+
+static bool mouseButtonDown(SDL_MouseButtonEvent button) {
+	struct SDL_Point point = { button.x, button.y };
+	if (SDL_PointInRect(&point, &stackRects[Stock])) {
+		gameDraw();
+		return true;
+	}
+	struct Item *item = listFind(&layout.main, &point);
+	if (!item) return false;
+	if (!gameAvail(item->card)) return gameReveal(item->card);
+	if (button.clicks % 2 == 0) {
+		for (uint dest = Foundation1; dest <= Foundation4; ++dest) {
+			if (gameMove(dest, item->card)) return true;
+		}
+		return false;
+	}
+	layout.dragItem = *item;
+	return true;
+}
+
+static bool mouseButtonUp(SDL_MouseButtonEvent button) {
+	(void)button;
+	if (!layout.dragItem.card) return false;
+	for (uint dest = 0; dest < StacksLen; ++dest) {
+		if (SDL_HasIntersection(&layout.dragItem.rect, &stackRects[dest])) {
+			if (gameMove(dest, layout.dragItem.card)) break;
+		}
+	}
+	layout.dragItem.card = 0;
+	return true;
+}
+
+static bool mouseMotion(SDL_MouseMotionEvent motion) {
+	if (!motion.state) return false;
+	layout.dragItem.rect.x += motion.xrel;
+	layout.dragItem.rect.y += motion.yrel;
+	return true;
+}
+
+static SDL_Renderer *render;
+static SDL_Texture *textures[Cards_CardCount];
+
+static void renderList(const struct List *list) {
+	for (uint i = 0; i < list->len; ++i) {
+		int tex = list->items[i].card;
+		if (tex < 0) tex = backTexture;
+		SDL_RenderCopy(render, textures[tex], NULL, &list->items[i].rect);
+	}
+}
+
+static void err(const char *title) {
+	int error = SDL_ShowSimpleMessageBox(
+		SDL_MESSAGEBOX_ERROR, title, SDL_GetError(), NULL
+	);
+	if (error) fprintf(stderr, "%s\n", SDL_GetError());
+	exit(EXIT_FAILURE);
+}
+
+int main(int argc, char *argv[]) {
+	(void)argc;
+	(void)argv;
+
+	if (SDL_Init(SDL_INIT_VIDEO) < 0) err("SDL_Init");
+	atexit(SDL_Quit);
+
+	SDL_SetHint(SDL_HINT_VIDEO_ALLOW_SCREENSAVER, "1");
+
+	struct Paths paths;
+	if (assetPaths(&paths) < 0) err("SDL_GetPrefPath");
+
+	SDL_RWops *rw = assetOpenCards(&paths);
+	if (!rw) return EXIT_FAILURE;
+
+	SDL_Surface *surfaces[Cards_CardCount];
+	int error = Cards_LoadCards(
+		surfaces, Cards_CardCount,
+		rw, Cards_ColorKey | Cards_AlphaCorners | Cards_BlackBorders
+	);
+	if (error) err("Cards_LoadCards");
+	SDL_RWclose(rw);
+
+	SDL_Window *window;
+	error = SDL_CreateWindowAndRenderer(
+		WindowWidth, WindowHeight, SDL_WINDOW_ALLOW_HIGHDPI,
+		&window, &render
+	);
+	if (error) err("SDL_CreateWindowAndRenderer");
+	SDL_SetWindowTitle(window, "Solitaire");
+
+	SDL_RenderSetIntegerScale(render, SDL_TRUE);
+	SDL_RenderSetLogicalSize(render, WindowWidth, WindowHeight);
+
+	for (uint i = 0; i < Cards_CardCount; ++i) {
+		textures[i] = NULL;
+		if (!surfaces[i]) continue;
+		textures[i] = SDL_CreateTextureFromSurface(render, surfaces[i]);
+		if (!textures[i]) err("SDL_CreateTextureFromSurface");
+		SDL_FreeSurface(surfaces[i]);
+	}
+
+	srand(time(NULL));
+	backTexture = Cards_Back1 + randUniform(12);
+	gameDeal();
+
+	for (;;) {
+		updateLayout();
+
+		SDL_SetRenderDrawColor(render, 0x00, 0xAA, 0x55, 0xFF);
+		SDL_RenderClear(render);
+		renderList(&layout.main);
+		renderList(&layout.drag);
+		SDL_RenderPresent(render);
+
+		SDL_Event event;
+		for (;;) {
+			SDL_WaitEvent(&event);
+			if (event.type == SDL_QUIT) {
+				goto quit;
+			} else if (event.type == SDL_KEYDOWN) {
+				if (keyDown(event.key)) break;
+			} else if (event.type == SDL_MOUSEBUTTONDOWN) {
+				if (mouseButtonDown(event.button)) break;
+			} else if (event.type == SDL_MOUSEBUTTONUP) {
+				if (mouseButtonUp(event.button)) break;
+			} else if (event.type == SDL_MOUSEMOTION) {
+				if (mouseMotion(event.motion)) break;
+			}
+		}
+	}
+
+quit:
+	SDL_Quit();
+}
diff --git a/stack.h b/stack.h
new file mode 100644
index 0000000..c315729
--- /dev/null
+++ b/stack.h
@@ -0,0 +1,122 @@
+/* Copyright (C) 2019  C. 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/>.
+ */
+
+#ifndef STACK_H
+#define STACK_H
+
+#include <assert.h>
+#include <stdlib.h>
+
+#include <SDL_stdinc.h>
+#include <cards.h>
+
+#ifndef STACK_CAP
+#define STACK_CAP 52
+#endif
+
+#if STACK_CAP < 52
+#error "Stack capacity too small for deck"
+#endif
+
+typedef Sint8 Card;
+
+static inline int suit(Card card) {
+	card = abs(card);
+	if (card > Cards_Spade) {
+		return Cards_Spade;
+	} else if (card > Cards_Heart) {
+		return Cards_Heart;
+	} else if (card > Cards_Diamond) {
+		return Cards_Diamond;
+	} else {
+		return Cards_Club;
+	}
+}
+
+static inline int color(Card card) {
+	return suit(card) == Cards_Diamond || suit(card) == Cards_Heart;
+}
+
+static inline int rank(Card card) {
+	return abs(card) - suit(card);
+}
+
+struct Stack {
+	Uint8 len;
+	Card cards[STACK_CAP];
+};
+
+static const struct Stack Deck = {
+	.len = 52,
+	.cards = {
+		-1, -2, -3, -4, -5, -6, -7, -8, -9, -10, -11, -12, -13,
+		-14, -15, -16, -17, -18, -19, -20, -21, -22, -23, -24, -25, -26,
+		-27, -28, -29, -30, -31, -32, -33, -34, -35, -36, -37, -38, -39,
+		-40, -41, -42, -43, -44, -45, -46, -47, -48, -49, -50, -51, -52,
+	},
+};
+
+static inline void clear(struct Stack *stack) {
+	stack->len = 0;
+}
+
+static inline void push(struct Stack *stack, Card card) {
+	assert(stack->len < STACK_CAP);
+	stack->cards[stack->len++] = card;
+}
+
+static inline Card pop(struct Stack *stack) {
+	if (!stack->len) return 0;
+	return stack->cards[--stack->len];
+}
+
+static inline Card peek(const struct Stack *stack) {
+	if (!stack->len) return 0;
+	return stack->cards[stack->len - 1];
+}
+
+static inline void flipTo(struct Stack *dst, struct Stack *src, Uint8 n) {
+	if (n > src->len) n = src->len;
+	for (Uint8 i = 0; i < n; ++i) {
+		push(dst, -pop(src));
+	}
+}
+
+static inline void moveTo(struct Stack *dst, struct Stack *src, Uint8 n) {
+	if (n > src->len) n = src->len;
+	for (Uint8 i = 0; i < n; ++i) {
+		push(dst, src->cards[src->len - n + i]);
+	}
+	src->len -= n;
+}
+
+static inline int randUniform(int bound) {
+	for (;;) {
+		int r = rand();
+		if (r >= RAND_MAX % bound) return r % bound;
+	}
+}
+
+static inline void shuffle(struct Stack *stack) {
+	for (Uint8 i = stack->len - 1; i > 0; --i) {
+		Uint8 j = randUniform(i + 1);
+		Card x = stack->cards[i];
+		stack->cards[i] = stack->cards[j];
+		stack->cards[j] = x;
+	}
+}
+
+#endif
diff --git a/tools/exe2ico.c b/tools/exe2ico.c
new file mode 100644
index 0000000..5cf0483
--- /dev/null
+++ b/tools/exe2ico.c
@@ -0,0 +1,170 @@
+/* Copyright (C) 2022  June 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 <SDL_rwops.h>
+#include <stdarg.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+static void errx(int eval, const char *fmt, ...) {
+	va_list ap;
+	va_start(ap, fmt);
+	vfprintf(stderr, fmt, ap);
+	va_end(ap);
+	putc('\n', stderr);
+	exit(eval);
+}
+static void err(int eval, const char *fmt, ...) {
+	va_list ap;
+	va_start(ap, fmt);
+	vfprintf(stderr, fmt, ap);
+	va_end(ap);
+	fprintf(stderr, ": %s\n", SDL_GetError());
+	exit(eval);
+}
+
+int main(int argc, char *argv[]) {
+	if (argc < 2) return 1;
+	const char *exePath = argv[1];
+	const char *name = strrchr(exePath, '/');
+	name = (name ? &name[1] : exePath);
+	char icoPath[256];
+	snprintf(
+		icoPath, sizeof(icoPath), "%.*s.ICO", (int)strcspn(name, "."), name
+	);
+
+	SDL_RWops *exe = SDL_RWFromFile(exePath, "rb");
+	if (!exe) err(1, "%s", exePath);
+
+	// Read the EXE header
+	if (SDL_ReadU8(exe) != 'M' || SDL_ReadU8(exe) != 'Z') {
+		errx(1, "%s: invalid MZ signature", exePath);
+	}
+	SDL_RWseek(exe, 0x3C, RW_SEEK_SET);
+	Uint16 neOffset = SDL_ReadLE16(exe);
+	SDL_RWseek(exe, neOffset, RW_SEEK_SET);
+	Uint8 sig[2] = { SDL_ReadU8(exe), SDL_ReadU8(exe) };
+	if (sig[0] == 'P' && sig[1] == 'E') {
+		errx(1, "%s: not implemented for PE", exePath);
+	}
+	if (sig[0] != 'N' || sig[1] != 'E') {
+		errx(1, "%s: invalid NE/PE signature", exePath);
+	}
+
+	// Read the NE header
+	SDL_RWseek(exe, neOffset + 0x24, RW_SEEK_SET);
+	Uint16 resourceTableOffset = neOffset + SDL_ReadLE16(exe);
+
+	// Find the RT_GROUP_ICON resource
+	SDL_RWseek(exe, resourceTableOffset, RW_SEEK_SET);
+	Uint16 alignmentShift = SDL_ReadLE16(exe);
+	for (;;) {
+		Uint16 typeID = SDL_ReadLE16(exe);
+		Uint16 count = SDL_ReadLE16(exe);
+		SDL_ReadLE32(exe); // reserved
+		if (!typeID) {
+			errx(1, "%s: no group icon resource", exePath);
+		}
+		if (typeID == 0x800E) break;
+		SDL_RWseek(exe, 0x0C * count, RW_SEEK_CUR);
+	}
+
+	SDL_RWops *ico = SDL_RWFromFile(icoPath, "wb");
+	if (!ico) err(1, "%s", icoPath);
+
+	// Copy the ICONHEADER
+	// https://devblogs.microsoft.com/oldnewthing/20101018-00/?p=12513
+	SDL_RWseek(exe, (Uint32)SDL_ReadLE16(exe) << alignmentShift, RW_SEEK_SET);
+	SDL_WriteLE16(ico, SDL_ReadLE16(exe)); // reserved
+	SDL_WriteLE16(ico, SDL_ReadLE16(exe)); // type
+	Uint16 iconDirCount = SDL_ReadLE16(exe);
+	SDL_WriteLE16(ico, iconDirCount);
+
+	// Copy ICONDIRENTRY's. The entries in the RT_GROUP_ICON resource differ
+	// from those in ICO in their last field. In ICO, it is a 32-bit offset
+	// of the icon data in the ICO file. In the resource, it is a 16-bit
+	// resource ID of an RT_ICON resource. Here we assume the resources are
+	// in the same order as the entries referencing them. We translate the
+	// resource IDs into data offsets by simply tallying up the data lengths
+	// so far. The data offsets need to be aligned to alignmentShift to match
+	// up with the lengths of the icon resources.
+	Uint32 iconDirLength = 0x06 + 0x10 * iconDirCount;
+	Uint32 dataOffset = iconDirLength;
+	dataOffset += -dataOffset & ((1 << alignmentShift) - 1);
+	for (Uint16 i = 0; i < iconDirCount; ++i) {
+		SDL_WriteU8(ico, SDL_ReadU8(exe)); // width
+		SDL_WriteU8(ico, SDL_ReadU8(exe)); // height
+		SDL_WriteU8(ico, SDL_ReadU8(exe)); // colors
+		SDL_WriteU8(ico, SDL_ReadU8(exe)); // reserved
+		SDL_WriteLE16(ico, SDL_ReadLE16(exe)); // color planes
+		SDL_WriteLE16(ico, SDL_ReadLE16(exe)); // bits per pixel
+		Uint32 dataLength = SDL_ReadLE32(exe);
+		SDL_ReadLE16(exe); // resource ID, assumed sequential
+		SDL_WriteLE32(ico, dataLength);
+		SDL_WriteLE32(ico, dataOffset);
+		dataOffset += dataLength;
+		dataOffset += -dataOffset & ((1 << alignmentShift) - 1);
+	}
+	// Padding before the first aligned data offset
+	for (
+		Uint32 i = 0;
+		i < (-iconDirLength & ((1 << alignmentShift) - 1));
+		++i
+	) {
+		SDL_WriteU8(ico, 0);
+	}
+
+	// Find the RT_ICON resources
+	SDL_RWseek(exe, resourceTableOffset + 0x02, RW_SEEK_SET);
+	Uint16 resourceCount;
+	for (;;) {
+		Uint16 typeID = SDL_ReadLE16(exe);
+		resourceCount = SDL_ReadLE16(exe);
+		SDL_ReadLE32(exe); // reserved
+		if (!typeID) {
+			errx(1, "%s: no icon resources", exePath);
+		}
+		if (typeID == 0x8003) break;
+		SDL_RWseek(exe, 0x0C * resourceCount, RW_SEEK_CUR);
+	}
+
+	// Copy all icon data sequentially
+	Uint8 *data = NULL;
+	for (Uint16 i = 0; i < resourceCount; ++i) {
+		Uint32 dataOffset = (Uint32)SDL_ReadLE16(exe) << alignmentShift;
+		Uint32 dataLength = (Uint32)SDL_ReadLE16(exe) << alignmentShift;
+		SDL_ReadLE16(exe); // flags
+		SDL_ReadLE16(exe); // resource ID
+		SDL_ReadLE32(exe); // reserved
+		Sint64 nextResource = SDL_RWtell(exe);
+		if (nextResource < 0) err(1, "%s", exePath);
+
+		SDL_RWseek(exe, dataOffset, RW_SEEK_SET);
+		data = realloc(data, dataLength);
+		if (!data) errx(1, "malloc failed");
+		size_t num = SDL_RWread(exe, data, dataLength, 1);
+		if (!num) err(1, "%s", exePath);
+		num = SDL_RWwrite(ico, data, dataLength, 1);
+		if (!num) err(1, "%s", icoPath);
+
+		SDL_RWseek(exe, nextResource, RW_SEEK_SET);
+	}
+	free(data);
+
+	SDL_RWclose(ico);
+	SDL_RWclose(exe);
+}
diff --git a/tools/ico2png.c b/tools/ico2png.c
new file mode 100644
index 0000000..9065f6f
--- /dev/null
+++ b/tools/ico2png.c
@@ -0,0 +1,251 @@
+/* Copyright (C) 2022  June 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 <SDL_rwops.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <stdarg.h>
+#include <string.h>
+
+static void errx(int eval, const char *fmt, ...) {
+	va_list ap;
+	va_start(ap, fmt);
+	vfprintf(stderr, fmt, ap);
+	va_end(ap);
+	putc('\n', stderr);
+	exit(eval);
+}
+static void err(int eval, const char *fmt, ...) {
+	va_list ap;
+	va_start(ap, fmt);
+	vfprintf(stderr, fmt, ap);
+	va_end(ap);
+	fprintf(stderr, ": %s\n", SDL_GetError());
+	exit(eval);
+}
+
+static Uint32 crcTable(Uint8 n) {
+	static Uint32 table[256];
+	if (table[1]) return table[n];
+	for (int i = 0; i < 256; ++i) {
+		table[i] = i;
+		for (int j = 0; j < 8; ++j) {
+			table[i] = (table[i] >> 1) ^ (table[i] & 1 ? 0xEDB88320 : 0);
+		}
+	}
+	return table[n];
+}
+
+static Uint32 pngCRC;
+static void pngWrite(SDL_RWops *rw, const Uint8 *ptr, Uint32 len) {
+	if (!SDL_RWwrite(rw, ptr, len, 1)) err(1, "pngWrite");
+	for (Uint32 i = 0; i < len; ++i) {
+		pngCRC = crcTable(pngCRC ^ ptr[i]) ^ (pngCRC >> 8);
+	}
+}
+static void pngUint32(SDL_RWops *rw, Uint32 n) {
+	Uint8 bytes[4] = { n >> 24, n >> 16, n >> 8, n  };
+	pngWrite(rw, bytes, sizeof(bytes));
+}
+static void pngChunk(SDL_RWops *rw, const char *type, Uint32 len) {
+	pngUint32(rw, len);
+	pngCRC = ~0;
+	pngWrite(rw, (const Uint8 *)type, 4);
+}
+
+// Write out image data as DEFLATE literal blocks
+static void pngData(SDL_RWops *rw, const Uint8 *data, Uint32 len) {
+	Uint32 adler1 = 1, adler2 = 0;
+	for (Uint32 i = 0; i < len; ++i) {
+		adler1 = (adler1 + data[i]) % 65521;
+		adler2 = (adler1 + adler2) % 65521;
+	}
+	Uint32 zlen = 2 + 5 * ((len + 0xFFFE) / 0xFFFF) + len + 4;
+	pngChunk(rw, "IDAT", zlen);
+	Uint8 zlib[2] = { 0x08, 0x1D };
+	pngWrite(rw, zlib, sizeof(zlib));
+	for (; len > 0xFFFF; data += 0xFFFF, len -= 0xFFFF) {
+		Uint8 block[5] = { 0x00, 0xFF, 0xFF, 0x00, 0x00 };
+		pngWrite(rw, block, sizeof(block));
+		pngWrite(rw, data, 0xFFFF);
+	}
+	Uint8 block[5] = { 0x01, len, len >> 8, ~len, ~len >> 8 };
+	pngWrite(rw, block, sizeof(block));
+	pngWrite(rw, data, len);
+	pngUint32(rw, adler2 << 16 | adler1);
+	pngUint32(rw, ~pngCRC);
+}
+
+int main(int argc, char *argv[]) {
+	if (argc < 4) return 1;
+	const char *icoPath = argv[1];
+	const char *pngPath = argv[3];
+	Uint32 scale = strtoul(argv[2], NULL, 10);
+	if (!scale) return 1;
+
+	SDL_RWops *ico = SDL_RWFromFile(icoPath, "rb");
+	if (!ico) err(1, "%s", icoPath);
+
+	// Read the ICONHEADER
+	// https://devblogs.microsoft.com/oldnewthing/20101018-00/?p=12513
+	SDL_ReadLE16(ico); // reserved
+	if (SDL_ReadLE16(ico) != 0x0001) {
+		errx(1, "%s: not an ICO", icoPath);
+	}
+	Uint16 count = SDL_ReadLE16(ico);
+
+	// Find the best icon
+	Uint32 bestScore = 0;
+	struct Icon {
+		Uint8 width;
+		Uint8 height;
+		Uint8 colors;
+		Uint16 planes;
+		Uint16 bpp;
+		Uint32 length;
+		Uint32 offset;
+	} bestIcon = {0};
+	for (Uint16 i = 0; i < count; ++i) {
+		struct Icon icon = {0};
+		icon.width = SDL_ReadU8(ico);
+		icon.height = SDL_ReadU8(ico);
+		icon.colors = SDL_ReadU8(ico);
+		SDL_ReadU8(ico); // reserved
+		icon.planes = SDL_ReadLE16(ico);
+		icon.bpp = SDL_ReadLE16(ico); // some ICOs lie about this...
+		icon.length = SDL_ReadLE32(ico);
+		icon.offset = SDL_ReadLE32(ico);
+		Uint32 score = icon.width * icon.height * icon.colors;
+		if (score > bestScore) {
+			bestScore = score;
+			bestIcon = icon;
+		}
+	}
+	if (!bestScore) errx(1, "%s: no icons found", icoPath);
+	if (bestIcon.planes != 1) {
+		errx(1, "%s: non-indexed bitmap not implemented", icoPath);
+	}
+
+	SDL_RWops *png = SDL_RWFromFile(pngPath, "wb");
+	if (!png) err(1, "%s", pngPath);
+
+	// Write the PNG header
+	SDL_RWwrite(png, "\x89PNG\r\n\x1A\n", 8, 1);
+	pngChunk(png, "IHDR", 13);
+	pngUint32(png, bestIcon.width * scale);
+	pngUint32(png, bestIcon.height * scale);
+	Uint8 depth = 8;
+	Uint8 color = 3; // indexed
+	Uint8 zero[3] = {0};
+	pngWrite(png, &depth, 1);
+	pngWrite(png, &color, 1);
+	pngWrite(png, zero, 3);
+	pngUint32(png, ~pngCRC);
+
+	// Read the real bpp and palette count from the DIB header
+	SDL_RWseek(ico, bestIcon.offset, RW_SEEK_SET);
+	Uint32 dibHeaderLength = SDL_ReadLE32(ico);
+	if (dibHeaderLength != 0x28) {
+		errx(
+			1, "%s: unrecognized DIB header length %u",
+			icoPath, dibHeaderLength
+		);
+	}
+	SDL_RWseek(ico, 0x0A, RW_SEEK_CUR);
+	bestIcon.bpp = SDL_ReadLE16(ico); // the truth
+	SDL_RWseek(ico, 0x10, RW_SEEK_CUR);
+	Uint32 paletteCount = SDL_ReadLE32(ico);
+	if (!paletteCount) paletteCount = 1 << bestIcon.bpp;
+
+	// Copy the palette, reserving index 0 for transparency. We assume at most
+	// 255 colors will be used by the icon.
+	Uint8 *palette = calloc(1 + paletteCount, 3);
+	if (!palette) errx(1, "calloc failed");
+	SDL_RWseek(ico, bestIcon.offset + dibHeaderLength, RW_SEEK_SET);
+	for (Uint32 i = 0; i < paletteCount; ++i) {
+		palette[3 * (i + 1) + 2] = SDL_ReadU8(ico);
+		palette[3 * (i + 1) + 1] = SDL_ReadU8(ico);
+		palette[3 * (i + 1) + 0] = SDL_ReadU8(ico);
+		SDL_ReadU8(ico);
+	}
+	pngChunk(png, "PLTE", 3 * (1 + paletteCount));
+	pngWrite(png, palette, 3 * (1 + paletteCount));
+	pngUint32(png, ~pngCRC);
+	pngChunk(png, "tRNS", 1);
+	pngWrite(png, zero, 1);
+	pngUint32(png, ~pngCRC);
+	free(palette);
+
+	Uint32 pngStride = 1 + bestIcon.width;
+	Uint8 *lines = calloc(bestIcon.height, pngStride);
+	if (!lines) errx(1, "calloc failed");
+
+	// Copy and expand the icon pixels to 8 bpp, adding 1 for the transparency
+	// index.
+	Uint32 icoPPByte = 8 / bestIcon.bpp;
+	Uint32 icoStride = bestIcon.width / icoPPByte;
+	icoStride += -icoStride & 0x03;
+	for (Uint32 y = bestIcon.height - 1; y < bestIcon.height; --y) {
+		Uint8 *ptr = &lines[y * pngStride + 1];
+		Uint8 *end = &lines[(y + 1) * pngStride];
+		for (Uint32 x = 0; x < icoStride; ++x) {
+			Uint8 byte = SDL_ReadU8(ico);
+			for (Uint8 i = icoPPByte - 1; i < icoPPByte; --i) {
+				if (ptr == end) break;
+				*ptr = (byte >> (i * bestIcon.bpp)) & ((1 << bestIcon.bpp) - 1);
+				*ptr++ += 1;
+			}
+		}
+	}
+
+	// Read the 1 bpp transparency mask, setting PNG pixels to index 0.
+	// https://devblogs.microsoft.com/oldnewthing/20101019-00/?p=12503
+	icoPPByte = 8;
+	icoStride = bestIcon.width / icoPPByte;
+	icoStride += -icoStride & 0x03;
+	for (Uint32 y = bestIcon.height - 1; y < bestIcon.height; --y) {
+		Uint8 *ptr = &lines[y * pngStride + 1];
+		Uint8 *end = &lines[(y + 1) * pngStride];
+		for (Uint32 x = 0; x < icoStride; ++x) {
+			Uint8 byte = SDL_ReadU8(ico);
+			for (Uint8 i = icoPPByte - 1; i < icoPPByte; --i) {
+				if (ptr == end) break;
+				if ((byte >> i) & 1) *ptr = 0;
+				ptr++;
+			}
+		}
+	}
+
+	// Upscale with nearest neighbor
+	Uint32 scaledWidth = bestIcon.width * scale;
+	Uint32 scaledHeight = bestIcon.height * scale;
+	Uint32 scaledStride = 1 + scaledWidth;
+	Uint8 *scaled = calloc(scaledHeight, scaledStride);
+	for (Uint32 y = 0; y < scaledHeight; ++y) {
+		for (Uint32 x = 0; x < scaledWidth; ++x) {
+			scaled[y * scaledStride + 1 + x] =
+				lines[(y / scale) * pngStride + 1 + (x / scale)];
+		}
+	}
+	pngData(png, scaled, scaledHeight * scaledStride);
+	pngChunk(png, "IEND", 0);
+	pngUint32(png, ~pngCRC);
+
+	free(scaled);
+	free(lines);
+	SDL_RWclose(png);
+	SDL_RWclose(ico);
+}