Merge branch 'sdl_gui' into libretro_core

# Conflicts:
#	Makefile
#	SDL/main.c

BootROMs/cgb_boot.asm

@@ -504,7 +504,7 @@ Palettes:
   dw $7FFF, $1BEF, $6180, $0000
   ; Sameboy "Exclusives"
   dw $7FFF, $7FEA, $7D5F, $0000 ; CGA 1
-  dw $1B77, $0AD2, $25E9, $1545 ; DMG LCD
+  dw $4778, $3290, $1D87, $0861 ; DMG LCD
 
 KeyCombinationPalettes
   db 1 ; Right

Core/apu.c

@@ -94,6 +94,7 @@ static void render(GB_gameboy_t *gb)
             {left_volume * (1 - gb->apu_output.highpass_rate) + gb->apu_output.highpass_diff.left * gb->apu_output.highpass_rate,
                 right_volume * (1 - gb->apu_output.highpass_rate) + gb->apu_output.highpass_diff.right * gb->apu_output.highpass_rate};
             
+        case GB_HIGHPASS_MAX:;
         }
             
     }

Core/apu.h

@@ -103,6 +103,7 @@ typedef enum {
     GB_HIGHPASS_OFF, // Do not apply any filter, keep DC offset
     GB_HIGHPASS_ACCURATE, // Apply a highpass filter similar to the one used on hardware
     GB_HIGHPASS_REMOVE_DC_OFFSET, // Remove DC Offset without affecting the waveform
+    GB_HIGHPASS_MAX
 } GB_highpass_mode_t;
 
 typedef struct {

Core/display.c

@@ -279,7 +279,7 @@ uint32_t GB_convert_rgb15(GB_gameboy_t *gb, uint16_t color)
 
 void GB_palette_changed(GB_gameboy_t *gb, bool background_palette, uint8_t index)
 {
-    if (!gb->rgb_encode_callback) return;
+    if (!gb->rgb_encode_callback || !gb->is_cgb) return;
     uint8_t *palette_data = background_palette? gb->background_palettes_data : gb->sprite_palettes_data;
     uint16_t color = palette_data[index & ~1] | (palette_data[index | 1] << 8);
 

Core/save_state.c

@@ -303,6 +303,11 @@ int GB_load_state_from_buffer(GB_gameboy_t *gb, const uint8_t *buffer, size_t le
         gb->rumble_callback(gb, gb->rumble_state);
     }
     
+    for (unsigned i = 0; i < 32; i++) {
+        GB_palette_changed(gb, false, i * 2);
+        GB_palette_changed(gb, true, i * 2);
+    }
+    
     return 0;
 }
 

Core/z80_cpu.c

@@ -1064,7 +1064,7 @@ static void ld_a_da16(GB_gameboy_t *gb, uint8_t opcode)
 static void di(GB_gameboy_t *gb, uint8_t opcode)
 {
     /* DI is NOT delayed, not even on a CGB. Mooneye's di_timing-GS test fails on a CGB
-       for different reasons.*/
+       for different reasons. */
     GB_advance_cycles(gb, 4);
     gb->ime = false;
 }
@@ -1073,8 +1073,9 @@ static void ei(GB_gameboy_t *gb, uint8_t opcode)
 {
     /* ei is actually "disable interrupts for one instruction, then enable them". */
     GB_advance_cycles(gb, 4);
-    gb->ime = false;
+    if (!gb->ime && !gb->ime_toggle) {
         gb->ime_toggle = true;
+    }
 }
 
 static void ld_hl_sp_r8(GB_gameboy_t *gb, uint8_t opcode)

Makefile

@@ -43,10 +43,11 @@ endif
 # Set compilation and linkage flags based on target, platform and configuration
 
 CFLAGS += -Werror -Wall -std=gnu11 -D_GNU_SOURCE -DVERSION="$(VERSION)" -I. -D_USE_MATH_DEFINES
-SDL_LDFLAGS := -lSDL2
+SDL_LDFLAGS := -lSDL2 -lGL
 ifeq ($(PLATFORM),windows32)
 CFLAGS += -IWindows
 LDFLAGS += -lmsvcrt -lSDL2main -Wl,/MANIFESTFILE:NUL
+SDL_LDFLAGS := -lSDL2 -lopengl32
 else
 LDFLAGS += -lc -lm
 endif
@@ -56,7 +57,7 @@ SYSROOT := $(shell xcodebuild -sdk macosx -version Path 2> /dev/null)
 CFLAGS += -F/Library/Frameworks
 OCFLAGS += -x objective-c -fobjc-arc -Wno-deprecated-declarations -isysroot $(SYSROOT) -mmacosx-version-min=10.9
 LDFLAGS += -framework AppKit -framework PreferencePanes -framework Carbon -framework QuartzCore
-SDL_LDFLAGS := -F/Library/Frameworks -framework SDL2
+SDL_LDFLAGS := -F/Library/Frameworks -framework SDL2 -framework OpenGL
 endif
 CFLAGS += -Wno-deprecated-declarations
 ifeq ($(PLATFORM),windows32)
@@ -88,7 +89,7 @@ endif
 
 cocoa: $(BIN)/SameBoy.app
 quicklook: $(BIN)/SameBoy.qlgenerator
-sdl: $(SDL_TARGET) $(BIN)/SDL/dmg_boot.bin $(BIN)/SDL/cgb_boot.bin $(BIN)/SDL/LICENSE $(BIN)/SDL/registers.sym $(BIN)/SDL/drop.bmp
+sdl: $(SDL_TARGET) $(BIN)/SDL/dmg_boot.bin $(BIN)/SDL/cgb_boot.bin $(BIN)/SDL/LICENSE $(BIN)/SDL/registers.sym $(BIN)/SDL/background.bmp $(BIN)/SDL/Shaders
 bootroms: $(BIN)/BootROMs/cgb_boot.bin $(BIN)/BootROMs/dmg_boot.bin
 tester: $(TESTER_TARGET) $(BIN)/tester/dmg_boot.bin $(BIN)/tester/cgb_boot.bin
 all: cocoa sdl tester libretro
@@ -262,14 +263,21 @@ $(BIN)/SameBoy.app/Contents/Resources/%.bin: $(BOOTROMS_DIR)/%.bin
 	cp -f $^ $@
 	
 $(BIN)/SDL/LICENSE: LICENSE
+	-@$(MKDIR) -p $(dir $@)
 	cp -f $^ $@
 
 $(BIN)/SDL/registers.sym: Misc/registers.sym
+	-@$(MKDIR) -p $(dir $@)
 	cp -f $^ $@
 	
-$(BIN)/SDL/drop.bmp: SDL/drop.bmp
+$(BIN)/SDL/background.bmp: SDL/background.bmp
+	-@$(MKDIR) -p $(dir $@)
 	cp -f $^ $@
 
+$(BIN)/SDL/Shaders: Shaders
+	-@$(MKDIR) -p $(dir $@)
+	cp -rf $^ $@
+
 # Boot ROMs
 
 $(BIN)/BootROMs/%.bin: BootROMs/%.asm

SDL/font.h

@@ -0,0 +1,16 @@
+#ifndef font_h
+#define font_h
+
+#include <stdint.h>
+extern uint8_t font[];
+extern const uint8_t font_max;
+#define GLYPH_HEIGHT 8
+#define GLYPH_WIDTH 6
+#define LEFT_ARROW_STRING "\x86"
+#define RIGHT_ARROW_STRING "\x7f"
+#define SELECTION_STRING RIGHT_ARROW_STRING
+#define CTRL_STRING "\x80\x81\x82"
+#define SHIFT_STRING "\x83"
+#define CMD_STRING "\x84\x85"
+#endif /* font_h */
+

SDL/gui.c

@@ -0,0 +1,903 @@
+#include <SDL2/SDL.h>
+#include <stdbool.h>
+#include "utils.h"
+#include "gui.h"
+#include "font.h"
+
+static const SDL_Color gui_palette[4] = {{8, 24, 16,}, {57, 97, 57,}, {132, 165, 99}, {198, 222, 140}};
+static uint32_t gui_palette_native[4];
+
+SDL_Window *window = NULL;
+SDL_Renderer *renderer = NULL;
+SDL_Texture *texture = NULL;
+SDL_PixelFormat *pixel_format = NULL;
+enum pending_command pending_command;
+unsigned command_parameter;
+
+#ifdef __APPLE__
+#define MODIFIER_NAME " " CMD_STRING
+#else
+#define MODIFIER_NAME CTRL_STRING
+#endif
+
+shader_t shader;
+SDL_Rect rect;
+
+void render_texture(void *pixels,  void *previous)
+{
+    if (renderer) {
+        if (pixels) {
+            SDL_UpdateTexture(texture, NULL, pixels, 160 * sizeof (uint32_t));
+        }
+        SDL_RenderClear(renderer);
+        SDL_RenderCopy(renderer, texture, NULL, NULL);
+        SDL_RenderPresent(renderer);
+    }
+    else {
+        static void *_pixels = NULL;
+        if (pixels) {
+            _pixels = pixels;
+        }
+        glClearColor(0, 0, 0, 1);
+        glClear(GL_COLOR_BUFFER_BIT);
+        render_bitmap_with_shader(&shader, _pixels, previous, rect.x, rect.y, rect.w, rect.h);
+        SDL_GL_SwapWindow(window);
+    }
+}
+
+configuration_t configuration =
+{
+    .keys = {   SDL_SCANCODE_RIGHT,
+        SDL_SCANCODE_LEFT,
+        SDL_SCANCODE_UP,
+        SDL_SCANCODE_DOWN,
+        SDL_SCANCODE_X,
+        SDL_SCANCODE_Z,
+        SDL_SCANCODE_BACKSPACE,
+        SDL_SCANCODE_RETURN,
+        SDL_SCANCODE_SPACE
+    },
+    .color_correction_mode = GB_COLOR_CORRECTION_EMULATE_HARDWARE,
+    .highpass_mode = GB_HIGHPASS_ACCURATE,
+    .scaling_mode = GB_SDL_SCALING_INTEGER_FACTOR,
+    .blend_frames = true
+};
+
+
+static const char *help[] ={
+"Drop a GB or GBC ROM\n"
+"file to play.\n"
+"\n"
+"Keyboard Shortcuts:\n"
+" Open Menu:        Escape\n"
+" Reset:             " MODIFIER_NAME "+R\n"
+" Pause:             " MODIFIER_NAME "+P\n"
+" Toggle DMG/CGB:    " MODIFIER_NAME "+T\n"
+" Save state:    " MODIFIER_NAME "+(0-9)\n"
+" Load state:  " MODIFIER_NAME "+" SHIFT_STRING "+(0-9)\n"
+#ifdef __APPLE__
+" Mute/Unmute:     " MODIFIER_NAME "+" SHIFT_STRING "+M\n"
+#else
+" Mute/Unmute:       " MODIFIER_NAME "+M\n"
+#endif
+" Break Debugger:    " CTRL_STRING "+C"
+};
+
+void update_viewport(void)
+{
+    int win_width, win_height;
+    SDL_GL_GetDrawableSize(window, &win_width, &win_height);
+    double x_factor = win_width / 160.0;
+    double y_factor = win_height / 144.0;
+    
+    if (configuration.scaling_mode == GB_SDL_SCALING_INTEGER_FACTOR) {
+        x_factor = (int)(x_factor);
+        y_factor = (int)(y_factor);
+    }
+    
+    if (configuration.scaling_mode != GB_SDL_SCALING_ENTIRE_WINDOW) {
+        if (x_factor > y_factor) {
+            x_factor = y_factor;
+        }
+        else {
+            y_factor = x_factor;
+        }
+    }
+    
+    unsigned new_width = x_factor * 160;
+    unsigned new_height = y_factor * 144;
+    
+    rect = (SDL_Rect){(win_width  - new_width) / 2, (win_height - new_height) /2,
+        new_width, new_height};
+    
+    if (renderer) {
+        SDL_RenderSetViewport(renderer, &rect);
+    }
+    else {
+        glViewport(rect.x, rect.y, rect.w, rect.h);
+    }
+}
+
+/* Does NOT check for bounds! */
+static void draw_char(uint32_t *buffer, unsigned char ch, uint32_t color)
+{
+    if (ch < ' ' || ch > font_max) {
+        ch = '?';
+    }
+    
+    uint8_t *data = &font[(ch - ' ') * GLYPH_WIDTH * GLYPH_HEIGHT];
+    
+    for (unsigned y = GLYPH_HEIGHT; y--;) {
+        for (unsigned x = GLYPH_WIDTH; x--;) {
+            if (*(data++)) {
+                (*buffer) = color;
+            }
+            buffer++;
+        }
+        buffer += 160 - GLYPH_WIDTH;
+    }
+}
+
+static void draw_unbordered_text(uint32_t *buffer, unsigned x, unsigned y, const char *string, uint32_t color)
+{
+    unsigned orig_x = x;
+    while (*string) {
+        if (*string == '\n') {
+            x = orig_x;
+            y += GLYPH_HEIGHT + 4;
+            string++;
+            continue;
+        }
+        
+        if (x > 160 - GLYPH_WIDTH || y == 0 || y > 144 - GLYPH_HEIGHT) {
+            break;
+        }
+        
+        draw_char(&buffer[x + 160 * y], *string, color);
+        x += GLYPH_WIDTH;
+        string++;
+    }
+}
+
+static void draw_text(uint32_t *buffer, unsigned x, unsigned y, const char *string, uint32_t color, uint32_t border)
+{
+    draw_unbordered_text(buffer, x - 1, y, string, border);
+    draw_unbordered_text(buffer, x + 1, y, string, border);
+    draw_unbordered_text(buffer, x, y - 1, string, border);
+    draw_unbordered_text(buffer, x, y + 1, string, border);
+    draw_unbordered_text(buffer, x, y, string, color);
+}
+
+enum decoration {
+    DECORATION_NONE,
+    DECORATION_SELECTION,
+    DECORATION_ARROWS,
+};
+
+static void draw_text_centered(uint32_t *buffer, unsigned y, const char *string, uint32_t color, uint32_t border, enum decoration decoration)
+{
+    unsigned x = 160 / 2 - (unsigned) strlen(string) * GLYPH_WIDTH / 2;
+    draw_text(buffer, x, y, string, color, border);
+    switch (decoration) {
+        case DECORATION_SELECTION:
+            draw_text(buffer, x - GLYPH_WIDTH, y, SELECTION_STRING, color, border);
+            break;
+        case DECORATION_ARROWS:
+            draw_text(buffer, x - GLYPH_WIDTH, y, LEFT_ARROW_STRING, color, border);
+            draw_text(buffer, 160 - x, y, RIGHT_ARROW_STRING, color, border);
+            break;
+            
+        case DECORATION_NONE:
+            break;
+    }
+}
+
+struct menu_item {
+    const char *string;
+    void (*handler)(unsigned);
+    const char *(*value_getter)(unsigned);
+    void (*backwards_handler)(unsigned);
+};
+static const struct menu_item *current_menu = NULL;
+static const struct menu_item *root_menu = NULL;
+static unsigned current_selection = 0;
+
+static enum {
+    SHOWING_DROP_MESSAGE,
+    SHOWING_MENU,
+    SHOWING_HELP,
+    WAITING_FOR_KEY,
+    WAITING_FOR_JBUTTON,
+} gui_state;
+
+unsigned auto_detect_progress = 0;
+unsigned auto_detect_inputs[3];
+
+static void item_exit(unsigned index)
+{
+    pending_command = GB_SDL_QUIT_COMMAND;
+}
+
+static unsigned current_help_page = 0;
+static void item_help(unsigned index)
+{
+    current_help_page = 0;
+    gui_state = SHOWING_HELP;
+}
+
+static void enter_graphics_menu(unsigned index);
+static void enter_controls_menu(unsigned index);
+static void enter_joypad_menu(unsigned index);
+static void enter_audio_menu(unsigned index);
+
+static const struct menu_item paused_menu[] = {
+    {"Resume", NULL},
+    {"Graphic Options", enter_graphics_menu},
+    {"Audio Options", enter_audio_menu},
+    {"Keyboard", enter_controls_menu},
+    {"Joypad", enter_joypad_menu},
+    {"Help", item_help},
+    {"Exit", item_exit},
+    {NULL,}
+};
+
+static const struct menu_item *const nonpaused_menu = &paused_menu[1];
+
+const char *current_scaling_mode(unsigned index)
+{
+    return (const char *[]){"Fill Entire Window", "Retain Aspect Ratio", "Retain Integer Factor"}
+        [configuration.scaling_mode];
+}
+
+const char *current_color_correction_mode(unsigned index)
+{
+    return (const char *[]){"Disabled", "Correct Color Curves", "Emulate Hardware", "Preserve Brightness"}
+        [configuration.color_correction_mode];
+}
+
+void cycle_scaling(unsigned index)
+{
+    configuration.scaling_mode++;
+    if (configuration.scaling_mode == GB_SDL_SCALING_MAX) {
+        configuration.scaling_mode = 0;
+    }
+    update_viewport();
+    render_texture(NULL, NULL);
+}
+
+void cycle_scaling_backwards(unsigned index)
+{
+    if (configuration.scaling_mode == 0) {
+        configuration.scaling_mode = GB_SDL_SCALING_MAX - 1;
+    }
+    else {
+        configuration.scaling_mode--;
+    }
+    update_viewport();
+    render_texture(NULL, NULL);
+}
+
+static void cycle_color_correction(unsigned index)
+{
+    if (configuration.color_correction_mode == GB_COLOR_CORRECTION_PRESERVE_BRIGHTNESS) {
+        configuration.color_correction_mode = GB_COLOR_CORRECTION_DISABLED;
+    }
+    else {
+        configuration.color_correction_mode++;
+    }
+}
+
+static void cycle_color_correction_backwards(unsigned index)
+{
+    if (configuration.color_correction_mode == GB_COLOR_CORRECTION_DISABLED) {
+        configuration.color_correction_mode = GB_COLOR_CORRECTION_PRESERVE_BRIGHTNESS;
+    }
+    else {
+        configuration.color_correction_mode--;
+    }
+}
+
+struct shader_name {
+    const char *file_name;
+    const char *display_name;
+} shaders[] =
+{
+    {"NearestNeighbor", "Nearest Neighbor"},
+    {"Bilinear", "Bilinear"},
+    {"SmoothBilinear", "Smooth Bilinear"},
+    {"Scale2x", "Scale2x"},
+    {"Scale4x", "Scale4x"},
+    {"AAScale2x", "Anti-aliased Scale2x"},
+    {"AAScale4x", "Anti-aliased Scale4x"},
+    {"HQ2x", "HQ2x"},
+    {"OmniScale", "OmniScale"},
+    {"OmniScaleLegacy", "OmniScale Legacy"},
+    {"AAOmniScaleLegacy", "AA OmniScale Legacy"},
+};
+
+static void cycle_filter(unsigned index)
+{
+    unsigned i = 0;
+    for (; i < sizeof(shaders) / sizeof(shaders[0]); i++) {
+        if (strcmp(shaders[i].file_name, configuration.filter) == 0) {
+            break;
+        }
+    }
+    
+
+    i += 1;
+    if (i >= sizeof(shaders) / sizeof(shaders[0])) {
+        i -= sizeof(shaders) / sizeof(shaders[0]);
+    }
+    
+    strcpy(configuration.filter, shaders[i].file_name);
+    free_shader(&shader);
+    if (!init_shader_with_name(&shader, configuration.filter)) {
+        init_shader_with_name(&shader, "NearestNeighbor");
+    }
+}
+
+static void cycle_filter_backwards(unsigned index)
+{
+    unsigned i = 0;
+    for (; i < sizeof(shaders) / sizeof(shaders[0]); i++) {
+        if (strcmp(shaders[i].file_name, configuration.filter) == 0) {
+            break;
+        }
+    }
+    
+    i -= 1;
+    if (i >= sizeof(shaders) / sizeof(shaders[0])) {
+        i = sizeof(shaders) / sizeof(shaders[0]) - 1;
+    }
+    
+    strcpy(configuration.filter, shaders[i].file_name);
+    free_shader(&shader);
+    if (!init_shader_with_name(&shader, configuration.filter)) {
+        init_shader_with_name(&shader, "NearestNeighbor");
+    }
+
+}
+const char *current_filter_name(unsigned index)
+{
+    unsigned i = 0;
+    for (; i < sizeof(shaders) / sizeof(shaders[0]); i++) {
+        if (strcmp(shaders[i].file_name, configuration.filter) == 0) {
+            break;
+        }
+    }
+    
+    if (i == sizeof(shaders) / sizeof(shaders[0])) {
+        i = 0;
+    }
+    
+    return shaders[i].display_name;
+}
+
+static void return_to_root_menu(unsigned index)
+{
+    current_menu = root_menu;
+    current_selection = 0;
+}
+
+static void toggle_blend_frames(unsigned index)
+{
+    configuration.blend_frames ^= true;
+}
+
+const char *blend_frames_string(unsigned index)
+{
+    return configuration.blend_frames? "Enabled" : "Disabled";
+}
+
+static const struct menu_item graphics_menu[] = {
+    {"Scaling Mode:", cycle_scaling, current_scaling_mode, cycle_scaling_backwards},
+    {"Scaling Filter:", cycle_filter, current_filter_name, cycle_filter_backwards},
+    {"Color Correction:", cycle_color_correction, current_color_correction_mode, cycle_color_correction_backwards},
+    {"Blend Frames:", toggle_blend_frames, blend_frames_string, toggle_blend_frames},
+    {"Back", return_to_root_menu},
+    {NULL,}
+};
+
+static void enter_graphics_menu(unsigned index)
+{
+    current_menu = graphics_menu;
+    current_selection = 0;
+}
+
+const char *highpass_filter_string(unsigned index)
+{
+    return (const char *[]){"None (Keep DC Offset)", "Accurate", "Preserve Waveform"}
+        [configuration.highpass_mode];
+}
+
+void cycle_highpass_filter(unsigned index)
+{
+    configuration.highpass_mode++;
+    if (configuration.highpass_mode == GB_HIGHPASS_MAX) {
+        configuration.highpass_mode = 0;
+    }
+}
+
+void cycle_highpass_filter_backwards(unsigned index)
+{
+    if (configuration.highpass_mode == 0) {
+        configuration.highpass_mode = GB_HIGHPASS_MAX - 1;
+    }
+    else {
+        configuration.highpass_mode--;
+    }
+}
+
+static const struct menu_item audio_menu[] = {
+    {"Highpass Filter:", cycle_highpass_filter, highpass_filter_string, cycle_highpass_filter_backwards},
+    {"Back", return_to_root_menu},
+    {NULL,}
+};
+
+static void enter_audio_menu(unsigned index)
+{
+    current_menu = audio_menu;
+    current_selection = 0;
+}
+static const char *key_name(unsigned index)
+{
+    return SDL_GetScancodeName(configuration.keys[index]);
+}
+
+static void modify_key(unsigned index)
+{
+    gui_state = WAITING_FOR_KEY;
+}
+
+static const struct menu_item controls_menu[] = {
+    {"Right:", modify_key, key_name,},
+    {"Left:", modify_key, key_name,},
+    {"Up:", modify_key, key_name,},
+    {"Down:", modify_key, key_name,},
+    {"A:", modify_key, key_name,},
+    {"B:", modify_key, key_name,},
+    {"Select:", modify_key, key_name,},
+    {"Start:", modify_key, key_name,},
+    {"Turbo:", modify_key, key_name,},
+    {"Back", return_to_root_menu},
+    {NULL,}
+};
+
+static void enter_controls_menu(unsigned index)
+{
+    current_menu = controls_menu;
+    current_selection = 0;
+}
+
+static unsigned joypad_index = 0;
+SDL_Joystick *joystick = NULL;
+SDL_GameController *controller = NULL;
+const char *current_joypad_name(unsigned index)
+{
+    static char name[23] = {0,};
+    const char *orig_name = joystick? SDL_JoystickName(joystick) : NULL;
+    if (!orig_name) return "Not Found";
+    unsigned i = 0;
+    
+    // SDL returns a name with repeated and trailing spaces
+    while (*orig_name && i < sizeof(name) - 2) {
+        if (orig_name[0] != ' ' || orig_name[1] != ' ') {
+            name[i++] = *orig_name;
+        }
+        orig_name++;
+    }
+    if (i && name[i - 1] == ' ') {
+        i--;
+    }
+    name[i] = 0;
+    
+    return name;
+}
+
+static void cycle_joypads(unsigned index)
+{
+    joypad_index++;
+    if (joypad_index >= SDL_NumJoysticks()) {
+        joypad_index = 0;
+    }
+    if (controller) {
+        SDL_GameControllerClose(controller);
+        controller = NULL;
+    }
+    else if (joystick) {
+        SDL_JoystickClose(joystick);
+        joystick = NULL;
+    }
+    if ((controller = SDL_GameControllerOpen(joypad_index))){
+        joystick = SDL_GameControllerGetJoystick(controller);
+    }
+    else {
+        joystick = SDL_JoystickOpen(joypad_index);
+    }
+}
+
+static void cycle_joypads_backwards(unsigned index)
+{
+    joypad_index++;
+    if (joypad_index >= SDL_NumJoysticks()) {
+        joypad_index = SDL_NumJoysticks() - 1;
+    }
+    if (controller) {
+        SDL_GameControllerClose(controller);
+        controller = NULL;
+    }
+    else if (joystick) {
+        SDL_JoystickClose(joystick);
+        joystick = NULL;
+    }
+    if ((controller = SDL_GameControllerOpen(joypad_index))){
+        joystick = SDL_GameControllerGetJoystick(controller);
+    }
+    else {
+        joystick = SDL_JoystickOpen(joypad_index);
+    }
+}
+
+unsigned fix_joypad_axis(unsigned axis)
+{
+    if (controller) {
+        /* Convert to the mapping used by generic Xbox-style controllers */
+        for (SDL_GameControllerAxis i = 0; i < SDL_CONTROLLER_AXIS_MAX; i++) {
+            if (SDL_GameControllerGetBindForAxis(controller, i).value.axis == axis) {
+                if (i == SDL_CONTROLLER_AXIS_LEFTX || i == SDL_CONTROLLER_AXIS_RIGHTX) return 0;
+                if (i == SDL_CONTROLLER_AXIS_LEFTY || i == SDL_CONTROLLER_AXIS_RIGHTY) return 1;
+                return i;
+            }
+        }
+        return -1;
+    }
+    
+    
+    if (configuration.div_joystick) {
+        axis >>= 1;
+    }
+    
+    return axis & 1;
+}
+
+unsigned fix_joypad_button(unsigned button)
+{
+    if (controller) {
+        /* Convert to the mapping used by generic Xbox-style controllers */
+        for (SDL_GameControllerButton i = 0; i < SDL_CONTROLLER_BUTTON_MAX; i++) {
+            if (SDL_GameControllerGetBindForButton(controller, i).value.button == button) {
+                if (i == SDL_CONTROLLER_BUTTON_START) {
+                    return 9;
+                }
+                if (i == 9) {
+                    return SDL_CONTROLLER_BUTTON_START;
+                }
+                
+                if (i == SDL_CONTROLLER_BUTTON_BACK) {
+                    return 8;
+                }
+                if (i == 8) {
+                    return SDL_CONTROLLER_BUTTON_BACK;
+                }
+                return i;
+            }
+        }
+        return -1;
+    }
+    
+    
+    if (configuration.div_joystick) {
+        button >>= 1;
+    }
+    
+    if (button < 4) {
+        if (configuration.swap_joysticks_bits_1_and_2) {
+            button = (int[]){0, 2, 1, 3}[button];
+        }
+        
+        if (configuration.flip_joystick_bit_1) {
+            button ^= 1;
+        }
+    }
+    
+    return button;
+}
+
+static void detect_joypad_layout(unsigned index)
+{
+    gui_state = WAITING_FOR_JBUTTON;
+    auto_detect_progress = 0;
+}
+
+static const struct menu_item joypad_menu[] = {
+    {"Joypad:", cycle_joypads, current_joypad_name, cycle_joypads_backwards},
+    {"Detect layout", detect_joypad_layout},
+    {"Back", return_to_root_menu},
+    {NULL,}
+};
+
+static void enter_joypad_menu(unsigned index)
+{
+    current_menu = joypad_menu;
+    current_selection = 0;
+}
+
+extern void set_filename(const char *new_filename, bool new_should_free);
+void run_gui(bool is_running)
+{
+    if (joystick && !SDL_NumJoysticks()) {
+        if (controller) {
+            SDL_GameControllerClose(controller);
+            controller = NULL;
+            joystick = NULL;
+        }
+        else {
+            SDL_JoystickClose(joystick);
+            joystick = NULL;
+        }
+    }
+    else if (!joystick && SDL_NumJoysticks()) {
+        if ((controller = SDL_GameControllerOpen(0))){
+            joystick = SDL_GameControllerGetJoystick(controller);
+        }
+        else {
+            joystick = SDL_JoystickOpen(0);
+        }
+    }
+    /* Draw the background screen */
+    static SDL_Surface *converted_background = NULL;
+    if (!converted_background) {
+        SDL_Surface *background = SDL_LoadBMP(executable_relative_path("background.bmp"));
+        SDL_SetPaletteColors(background->format->palette, gui_palette, 0, 4);
+        converted_background = SDL_ConvertSurface(background, pixel_format, 0);
+        SDL_LockSurface(converted_background);
+        SDL_FreeSurface(background);
+        
+        for (unsigned i = 4; i--; ) {
+            gui_palette_native[i] = SDL_MapRGB(pixel_format, gui_palette[i].r, gui_palette[i].g, gui_palette[i].b);
+        }
+    }
+
+    uint32_t pixels[160 * 144];
+    SDL_Event event = {0,};
+    gui_state = is_running? SHOWING_MENU : SHOWING_DROP_MESSAGE;
+    bool should_render = true;
+    current_menu = root_menu = is_running? paused_menu : nonpaused_menu;
+    current_selection = 0;
+    do {
+        /* Convert Joypad events (We only generate down events) */
+        if (gui_state != WAITING_FOR_KEY && gui_state != WAITING_FOR_JBUTTON) {
+            switch (event.type) {
+                case SDL_JOYBUTTONDOWN:
+                    event.type = SDL_KEYDOWN;
+                    event.jbutton.button = fix_joypad_button(event.jbutton.button);
+                    if (event.jbutton.button < 4) {
+                        event.key.keysym.scancode = (event.jbutton.button & 1) ? SDL_SCANCODE_RETURN : SDL_SCANCODE_ESCAPE;
+                    }
+                    else if (event.jbutton.button == 8 || event.jbutton.button == 9) {
+                        event.key.keysym.scancode = SDL_SCANCODE_ESCAPE;
+                    }
+                    else if (event.jbutton.button == SDL_CONTROLLER_BUTTON_DPAD_UP) event.key.keysym.scancode = SDL_SCANCODE_UP;
+                    else if (event.jbutton.button == SDL_CONTROLLER_BUTTON_DPAD_DOWN) event.key.keysym.scancode = SDL_SCANCODE_DOWN;
+                    else if (event.jbutton.button == SDL_CONTROLLER_BUTTON_DPAD_LEFT) event.key.keysym.scancode = SDL_SCANCODE_LEFT;
+                    else if (event.jbutton.button == SDL_CONTROLLER_BUTTON_DPAD_RIGHT) event.key.keysym.scancode = SDL_SCANCODE_RIGHT;
+                    break;
+                    
+                case SDL_JOYAXISMOTION: {
+                    static bool axis_active[2] = {false, false};
+                    event.jaxis.axis = fix_joypad_axis(event.jaxis.axis);
+                    if (event.jaxis.axis == 1) {
+                        if (event.jaxis.value > 0x4000) {
+                            if (!axis_active[1]) {
+                                event.type = SDL_KEYDOWN;
+                                event.key.keysym.scancode = SDL_SCANCODE_DOWN;
+                            }
+                            axis_active[1] = true;
+                        }
+                        else if (event.jaxis.value < -0x4000) {
+                            if (!axis_active[0]) {
+                                event.type = SDL_KEYDOWN;
+                                event.key.keysym.scancode = SDL_SCANCODE_UP;
+                            }
+                            axis_active[1] = true;
+                        }
+                        else {
+                            axis_active[1] = false;
+                        }
+                    }
+                    else if (event.jaxis.axis == 0) {
+                        if (event.jaxis.value > 0x4000) {
+                            if (!axis_active[0]) {
+                                event.type = SDL_KEYDOWN;
+                                event.key.keysym.scancode = SDL_SCANCODE_RIGHT;
+                            }
+                            axis_active[0] = true;
+                        }
+                        else if (event.jaxis.value < -0x4000) {
+                            if (!axis_active[0]) {
+                                event.type = SDL_KEYDOWN;
+                                event.key.keysym.scancode = SDL_SCANCODE_LEFT;
+                            }
+                            axis_active[0] = true;
+                        }
+                        else {
+                            axis_active[0] = false;
+                        }
+                    }
+                }
+            }
+        }
+        switch (event.type) {
+            case SDL_QUIT: {
+                if (!is_running) {
+                    exit(0);
+                }
+                else {
+                    pending_command = GB_SDL_QUIT_COMMAND;
+                    return;
+                }
+                
+            }
+            case SDL_WINDOWEVENT: {
+                if (event.window.event == SDL_WINDOWEVENT_RESIZED) {
+                    update_viewport();
+                    render_texture(NULL, NULL);
+                }
+                break;
+            }
+            case SDL_DROPFILE: {
+                set_filename(event.drop.file, true);
+                pending_command = GB_SDL_NEW_FILE_COMMAND;
+                return;
+            }
+            case SDL_JOYBUTTONDOWN:
+            {
+                if (gui_state == WAITING_FOR_JBUTTON) {
+                    should_render = true;
+                    auto_detect_inputs[auto_detect_progress++] = event.jbutton.button;
+                    if (auto_detect_progress == 3) {
+                        gui_state = SHOWING_MENU;
+                        
+                        configuration.div_joystick =
+                            ((auto_detect_inputs[0] | auto_detect_inputs[1] | auto_detect_inputs[2]) & 1) == 0 &&
+                            auto_detect_inputs[0] > 9;
+                        
+                        if (configuration.div_joystick) {
+                            auto_detect_inputs[0] >>= 1;
+                            auto_detect_inputs[1] >>= 1;
+                            auto_detect_inputs[2] >>= 1;
+                        }
+                        
+                        configuration.swap_joysticks_bits_1_and_2 =
+                            (auto_detect_inputs[1] & 1) == (auto_detect_inputs[2] & 1);
+                        
+                        if (configuration.swap_joysticks_bits_1_and_2) {
+                            auto_detect_inputs[1] = (int[]){0, 2, 1, 3}[auto_detect_inputs[1]];
+                            auto_detect_inputs[2] = (int[]){0, 2, 1, 3}[auto_detect_inputs[2]];
+                        }
+                        
+                        configuration.flip_joystick_bit_1 = auto_detect_inputs[2] & 1;
+                    }
+                }
+            }
+            case SDL_KEYDOWN:
+                if (event.key.keysym.scancode == SDL_SCANCODE_ESCAPE) {
+                    if (is_running) {
+                        return;
+                    }
+                    else {
+                        if (gui_state == SHOWING_DROP_MESSAGE) {
+                            gui_state = SHOWING_MENU;
+                        }
+                        else if (gui_state == SHOWING_MENU) {
+                            gui_state = SHOWING_DROP_MESSAGE;
+                        }
+                        current_selection = 0;
+                        current_menu = root_menu;
+                        should_render = true;
+                    }
+                }
+                
+                if (gui_state == SHOWING_MENU) {
+                    if (event.key.keysym.scancode == SDL_SCANCODE_DOWN && current_menu[current_selection + 1].string) {
+                        current_selection++;
+                        should_render = true;
+                    }
+                    else if (event.key.keysym.scancode == SDL_SCANCODE_UP && current_selection) {
+                        current_selection--;
+                        should_render = true;
+                    }
+                    else if (event.key.keysym.scancode == SDL_SCANCODE_RETURN) {
+                        if (current_menu[current_selection].handler) {
+                            current_menu[current_selection].handler(current_selection);
+                            if (pending_command) {
+                                if (!is_running && pending_command == GB_SDL_QUIT_COMMAND) {
+                                    exit(0);
+                                }
+                                return;
+                            }
+                            should_render = true;
+                        }
+                        else {
+                            return;
+                        }
+                    }
+                    else if (event.key.keysym.scancode == SDL_SCANCODE_RIGHT && current_menu[current_selection].backwards_handler) {
+                        current_menu[current_selection].handler(current_selection);
+                        should_render = true;
+                    }
+                    else if (event.key.keysym.scancode == SDL_SCANCODE_LEFT && current_menu[current_selection].backwards_handler) {
+                        current_menu[current_selection].backwards_handler(current_selection);
+                        should_render = true;
+                    }
+                }
+                else if (gui_state == SHOWING_HELP) {
+                    current_help_page++;
+                    if (current_help_page == sizeof(help) / sizeof(help[0])) {
+                        gui_state = SHOWING_MENU;
+                    }
+                    should_render = true;
+                }
+                else if (gui_state == WAITING_FOR_KEY) {
+                    configuration.keys[current_selection] = event.key.keysym.scancode;
+                    gui_state = SHOWING_MENU;
+                    should_render = true;
+                }
+                break;
+        }
+        
+        if (should_render) {
+            should_render = false;
+            memcpy(pixels, converted_background->pixels, sizeof(pixels));
+            
+            switch (gui_state) {
+                case SHOWING_DROP_MESSAGE:
+                    draw_text_centered(pixels, 116, "Drop a GB or GBC", gui_palette_native[3], gui_palette_native[0], false);
+                    draw_text_centered(pixels, 128, "file to play", gui_palette_native[3], gui_palette_native[0], false);
+                    break;
+                case SHOWING_MENU:
+                    draw_text_centered(pixels, 8, "SameBoy", gui_palette_native[3], gui_palette_native[0], false);
+                    unsigned i = 0, y = 24;
+                    for (const struct menu_item *item = current_menu; item->string; item++, i++) {
+                        if (item->value_getter && !item->backwards_handler) {
+                            char line[25];
+                            snprintf(line, sizeof(line), "%s%*s", item->string, 24 - (int)strlen(item->string), item->value_getter(i));
+                            draw_text_centered(pixels, y, line, gui_palette_native[3], gui_palette_native[0],
+                                               i == current_selection ? DECORATION_SELECTION : DECORATION_NONE);
+                            y += 12;
+                            
+                        }
+                        else {
+                            draw_text_centered(pixels, y, item->string, gui_palette_native[3], gui_palette_native[0],
+                                               i == current_selection && !item->value_getter ? DECORATION_SELECTION : DECORATION_NONE);
+                            y += 12;
+                            if (item->value_getter) {
+                                draw_text_centered(pixels, y, item->value_getter(i), gui_palette_native[3], gui_palette_native[0],
+                                                   i == current_selection ? DECORATION_ARROWS : DECORATION_NONE);
+                                y += 12;
+                            }
+                        }
+                    }
+                    break;
+                case SHOWING_HELP:
+                    draw_text(pixels, 2, 2, help[current_help_page], gui_palette_native[3], gui_palette_native[0]);
+                    break;
+                case WAITING_FOR_KEY:
+                    draw_text_centered(pixels, 68, "Press a Key", gui_palette_native[3], gui_palette_native[0], DECORATION_NONE);
+                    break;
+                case WAITING_FOR_JBUTTON:
+                    draw_text_centered(pixels, 68, (const char *[])
+                                       {
+                                           "Press button for Start",
+                                           "Press button for A",
+                                           "Press button for B",
+                                       } [auto_detect_progress],
+                                       gui_palette_native[3], gui_palette_native[0], DECORATION_NONE);
+                    break;
+            }
+            
+            render_texture(pixels, NULL);
+        }
+    } while (SDL_WaitEvent(&event));
+}

SDL/gui.h

@@ -0,0 +1,57 @@
+#ifndef gui_h
+#define gui_h
+
+#include <SDL2/SDL.h>
+#include <Core/gb.h>
+#include "shader.h"
+
+extern SDL_Window *window;
+extern SDL_Renderer *renderer;
+extern SDL_Texture *texture;
+extern SDL_PixelFormat *pixel_format;
+extern shader_t shader;
+
+enum scaling_mode {
+    GB_SDL_SCALING_ENTIRE_WINDOW,
+    GB_SDL_SCALING_KEEP_RATIO,
+    GB_SDL_SCALING_INTEGER_FACTOR,
+    GB_SDL_SCALING_MAX,
+};
+
+
+enum pending_command {
+    GB_SDL_NO_COMMAND,
+    GB_SDL_SAVE_STATE_COMMAND,
+    GB_SDL_LOAD_STATE_COMMAND,
+    GB_SDL_RESET_COMMAND,
+    GB_SDL_NEW_FILE_COMMAND,
+    GB_SDL_TOGGLE_MODEL_COMMAND,
+    GB_SDL_QUIT_COMMAND,
+};
+
+extern enum pending_command pending_command;
+extern unsigned command_parameter;
+typedef struct {
+    SDL_Scancode keys[9];
+    GB_color_correction_mode_t color_correction_mode;
+    enum scaling_mode scaling_mode;
+    bool blend_frames;
+    
+    GB_highpass_mode_t highpass_mode;
+    
+    bool div_joystick;
+    bool flip_joystick_bit_1;
+    bool swap_joysticks_bits_1_and_2;
+    
+    char filter[32];
+} configuration_t;
+
+extern configuration_t configuration;
+
+void update_viewport(void);
+void run_gui(bool is_running);
+unsigned fix_joypad_button(unsigned button);
+unsigned fix_joypad_axis(unsigned axis);
+void render_texture(void *pixels, void *previous);
+
+#endif

SDL/main.c

@@ -2,8 +2,9 @@
 #include <signal.h>
 #include <SDL2/SDL.h>
 #include <Core/gb.h>
-
 #include "utils.h"
+#include "gui.h"
+#include "shader.h"
 
 #ifndef _WIN32
 #define AUDIO_FREQUENCY 96000
@@ -12,50 +13,26 @@
 #define AUDIO_FREQUENCY 44100
 #endif
 
-#ifdef __APPLE__
-#define MODIFIER_NAME "Cmd"
-#else
-#define MODIFIER_NAME "Ctrl"
-#endif
-
-static const char help[] =
-"Drop a GB or GBC ROM file to play.\n"
-"\n"
-"Controls:\n"
-"    D-Pad: Arrow Keys\n"
-"    A: X\n"
-"    B: Z\n"
-"    Start: Enter\n"
-"    Select: Backspace\n"
-"\n"
-"Keyboard Shortcuts: \n"
-"    Restart: " MODIFIER_NAME "+R\n"
-"    Pause: " MODIFIER_NAME "+P\n"
-"    Turbo: Space\n"
-#ifdef __APPLE__
-"    Mute/Unmute: " MODIFIER_NAME "+Shift+M\n"
-#else
-"    Mute/Unmute: " MODIFIER_NAME "+M\n"
-#endif
-"    Save state: " MODIFIER_NAME "+Number (0-9)\n"
-"    Load state: " MODIFIER_NAME "+Shift+Number (0-9)\n"
-"    Cycle between DMG/CGB emulation: " MODIFIER_NAME "+T\n"
-"    Cycle scaling modes: Tab"
-;
-
 GB_gameboy_t gb;
 static bool dmg = false;
 static bool paused = false;
-static uint32_t pixels[160*144];
+static uint32_t pixel_buffer_1[160*144], pixel_buffer_2[160*144];
+static uint32_t *active_pixel_buffer = pixel_buffer_1, *previous_pixel_buffer = pixel_buffer_2;
+
 
 static char *filename = NULL;
 static bool should_free_filename = false;
 static char *battery_save_path_ptr;
 
-static SDL_Window *window = NULL;
+void set_filename(const char *new_filename, bool new_should_free)
-static SDL_Renderer *renderer = NULL;
+{
-static SDL_Texture *texture = NULL;
+    if (filename && should_free_filename) {
-static SDL_PixelFormat *pixel_format = NULL;
+        SDL_free(filename);
+    }
+    filename = (char *) new_filename;
+    should_free_filename = new_should_free;
+}
+
 static SDL_AudioSpec want_aspec, have_aspec;
 
 static char *captured_log = NULL;
@@ -97,62 +74,6 @@ static const char *end_capturing_logs(bool show_popup, bool should_exit)
     return captured_log;
 }
 
-static enum {
-    GB_SDL_NO_COMMAND,
-    GB_SDL_SAVE_STATE_COMMAND,
-    GB_SDL_LOAD_STATE_COMMAND,
-    GB_SDL_RESET_COMMAND,
-    GB_SDL_NEW_FILE_COMMAND,
-    GB_SDL_TOGGLE_MODEL_COMMAND,
-} pending_command;
-
-static enum {
-    GB_SDL_SCALING_ENTIRE_WINDOW,
-    GB_SDL_SCALING_KEEP_RATIO,
-    GB_SDL_SCALING_INTEGER_FACTOR,
-    GB_SDL_SCALING_MAX,
-} scaling_mode = GB_SDL_SCALING_INTEGER_FACTOR;
-static unsigned command_parameter;
-
-static void update_viewport(void)
-{
-    int win_width, win_height;
-    SDL_GetWindowSize(window, &win_width, &win_height);
-    double x_factor = win_width / 160.0;
-    double y_factor = win_height / 144.0;
-    
-    if (scaling_mode == GB_SDL_SCALING_INTEGER_FACTOR) {
-        x_factor = (int)(x_factor);
-        y_factor = (int)(y_factor);
-    }
-
-    if (scaling_mode != GB_SDL_SCALING_ENTIRE_WINDOW) {
-        if (x_factor > y_factor) {
-            x_factor = y_factor;
-        }
-        else {
-            y_factor = x_factor;
-        }
-    }
-    
-    unsigned new_width = x_factor * 160;
-    unsigned new_height = y_factor * 144;
-    
-    SDL_Rect rect = (SDL_Rect){(win_width  - new_width) / 2, (win_height - new_height) /2,
-        new_width, new_height};
-    SDL_RenderSetViewport(renderer, &rect);
-}
-
-static void cycle_scaling(void)
-{
-    scaling_mode++;
-    scaling_mode %= GB_SDL_SCALING_MAX;
-    update_viewport();
-    SDL_RenderClear(renderer);
-    SDL_RenderCopy(renderer, texture, NULL, NULL);
-    SDL_RenderPresent(renderer);
-}
-
 static void handle_events(GB_gameboy_t *gb)
 {
 #ifdef __APPLE__
@@ -165,15 +86,11 @@ static void handle_events(GB_gameboy_t *gb)
     {
         switch (event.type) {
             case SDL_QUIT:
-                GB_save_battery(gb, battery_save_path_ptr);
+                pending_command = GB_SDL_QUIT_COMMAND;
-                exit(0);
+                break;
                 
             case SDL_DROPFILE: {
-                if (should_free_filename) {
+                set_filename(event.drop.file, true);
-                    SDL_free(filename);
-                }
-                filename = event.drop.file;
-                should_free_filename = true;
                 pending_command = GB_SDL_NEW_FILE_COMMAND;
                 break;
             }
@@ -182,36 +99,105 @@ static void handle_events(GB_gameboy_t *gb)
                 if (event.window.event == SDL_WINDOWEVENT_RESIZED) {
                     update_viewport();
                 }
+                break;
             }
                 
+            case SDL_JOYBUTTONUP:
+            case SDL_JOYBUTTONDOWN:
+                event.jbutton.button = fix_joypad_button(event.jbutton.button);
+                if (event.jbutton.button < 4) {
+                    GB_set_key_state(gb, (event.jbutton.button & 1) ? GB_KEY_A : GB_KEY_B,
+                                     event.type == SDL_JOYBUTTONDOWN);
+                }
+                else if (event.jbutton.button == 8) {
+                    GB_set_key_state(gb, GB_KEY_SELECT, event.type == SDL_JOYBUTTONDOWN);
+                }
+                else if (event.jbutton.button == 9) {
+                    GB_set_key_state(gb, GB_KEY_START, event.type == SDL_JOYBUTTONDOWN);
+                }
+                else if (event.jbutton.button == SDL_CONTROLLER_BUTTON_DPAD_UP) {
+                    GB_set_key_state(gb, GB_KEY_UP, event.type == SDL_JOYBUTTONDOWN);
+                }
+                else if (event.jbutton.button == SDL_CONTROLLER_BUTTON_DPAD_DOWN) {
+                    GB_set_key_state(gb, GB_KEY_DOWN, event.type == SDL_JOYBUTTONDOWN);
+                }
+                else if (event.jbutton.button == SDL_CONTROLLER_BUTTON_DPAD_LEFT) {
+                    GB_set_key_state(gb, GB_KEY_LEFT, event.type == SDL_JOYBUTTONDOWN);
+                }
+                else if (event.jbutton.button == SDL_CONTROLLER_BUTTON_DPAD_RIGHT) {
+                    GB_set_key_state(gb, GB_KEY_RIGHT, event.type == SDL_JOYBUTTONDOWN);
+                }
+                else if (event.jbutton.button & 1) {
+                    GB_set_turbo_mode(gb, event.type == SDL_JOYBUTTONDOWN, false);
+                }
+                
+                else {
+                    bool audio_playing = SDL_GetAudioStatus() == SDL_AUDIO_PLAYING;
+                    if (audio_playing) {
+                        SDL_PauseAudio(true);
+                    }
+                    run_gui(true);
+                    if (audio_playing) {
+                        SDL_PauseAudio(false);
+                    }
+                    GB_set_color_correction_mode(gb, configuration.color_correction_mode);
+                    GB_set_highpass_filter_mode(gb, configuration.highpass_mode);
+                }
+            break;
+                
+            case SDL_JOYAXISMOTION:
+                event.jaxis.axis = fix_joypad_axis(event.jaxis.axis);
+                if (event.jaxis.axis == 1) {
+                    GB_set_key_state(gb, GB_KEY_DOWN, event.jaxis.value > 0x4000);
+                    GB_set_key_state(gb, GB_KEY_UP, event.jaxis.value < -0x4000);
+                }
+                else if (event.jaxis.axis == 0) {
+                    GB_set_key_state(gb, GB_KEY_RIGHT, event.jaxis.value > 0x4000);
+                    GB_set_key_state(gb, GB_KEY_LEFT, event.jaxis.value < -0x4000);
+                }
+            break;
+                
             case SDL_KEYDOWN:
-                switch (event.key.keysym.sym) {
+                switch (event.key.keysym.scancode) {
-                    case SDLK_c:
+                    case SDL_SCANCODE_ESCAPE: {
+                        bool audio_playing = SDL_GetAudioStatus() == SDL_AUDIO_PLAYING;
+                        if (audio_playing) {
+                            SDL_PauseAudio(true);
+                        }
+                        run_gui(true);
+                        if (audio_playing) {
+                            SDL_PauseAudio(false);
+                        }
+                        GB_set_color_correction_mode(gb, configuration.color_correction_mode);
+                        GB_set_highpass_filter_mode(gb, configuration.highpass_mode);
+                        break;
+                    }
+                    case SDL_SCANCODE_C:
                         if (event.type == SDL_KEYDOWN && (event.key.keysym.mod & KMOD_CTRL)) {
                             GB_debugger_break(gb);
                             
                         }
                         break;
                         
-                    case SDLK_r:
+                    case SDL_SCANCODE_R:
                         if (event.key.keysym.mod & MODIFIER) {
                             pending_command = GB_SDL_RESET_COMMAND;
                         }
                         break;
                         
-                    case SDLK_t:
+                    case SDL_SCANCODE_T:
                         if (event.key.keysym.mod & MODIFIER) {
                             pending_command = GB_SDL_TOGGLE_MODEL_COMMAND;
                         }
                         break;
                     
-                    case SDLK_p:
+                    case SDL_SCANCODE_P:
                         if (event.key.keysym.mod & MODIFIER) {
                             paused = !paused;
                         }
                         break;
                         
-                    case SDLK_m:
+                    case SDL_SCANCODE_M:
                         if (event.key.keysym.mod & MODIFIER) {
 #ifdef __APPLE__
                             // Can't override CMD+M (Minimize) in SDL
@@ -223,27 +209,11 @@ static void handle_events(GB_gameboy_t *gb)
                         }
                         break;
                         
-                    case SDLK_TAB:
-                        cycle_scaling();
-                        break;
-#ifndef __APPLE__
-                    case SDLK_F1:
-                        SDL_ShowSimpleMessageBox(SDL_MESSAGEBOX_INFORMATION, "Help", help, window);
-                        break;
-#else
-                    case SDLK_SLASH:
-                        if (!(event.key.keysym.sym && (event.key.keysym.mod & KMOD_SHIFT))) {
-                            break;
-                        }
-                    case SDLK_QUESTION:
-                            SDL_ShowSimpleMessageBox(SDL_MESSAGEBOX_INFORMATION, "Help", help, window);
-#endif
-                        
                     default:
                         /* Save states */
-                        if (event.key.keysym.sym >= SDLK_0 && event.key.keysym.sym <= SDLK_9) {
+                        if (event.key.keysym.scancode >= SDL_SCANCODE_0 && event.key.keysym.scancode <= SDL_SCANCODE_9) {
                             if (event.key.keysym.mod & MODIFIER) {
-                                command_parameter = event.key.keysym.sym - SDLK_0;
+                                command_parameter = event.key.keysym.scancode - SDL_SCANCODE_0;
                                 
                                 if (event.key.keysym.mod & KMOD_SHIFT) {
                                     pending_command = GB_SDL_LOAD_STATE_COMMAND;
@@ -256,34 +226,15 @@ static void handle_events(GB_gameboy_t *gb)
                         break;
                 }
             case SDL_KEYUP: // Fallthrough
-                switch (event.key.keysym.sym) {
+                if (event.key.keysym.scancode == configuration.keys[8]) {
-                    case SDLK_RIGHT:
-                        GB_set_key_state(gb, GB_KEY_RIGHT, event.type == SDL_KEYDOWN);
-                        break;
-                    case SDLK_LEFT:
-                        GB_set_key_state(gb, GB_KEY_LEFT, event.type == SDL_KEYDOWN);
-                        break;
-                    case SDLK_UP:
-                        GB_set_key_state(gb, GB_KEY_UP, event.type == SDL_KEYDOWN);
-                        break;
-                    case SDLK_DOWN:
-                        GB_set_key_state(gb, GB_KEY_DOWN, event.type == SDL_KEYDOWN);
-                        break;
-                    case SDLK_x:
-                        GB_set_key_state(gb, GB_KEY_A, event.type == SDL_KEYDOWN);
-                        break;
-                    case SDLK_z:
-                        GB_set_key_state(gb, GB_KEY_B, event.type == SDL_KEYDOWN);
-                        break;
-                    case SDLK_BACKSPACE:
-                        GB_set_key_state(gb, GB_KEY_SELECT, event.type == SDL_KEYDOWN);
-                        break;
-                    case SDLK_RETURN:
-                        GB_set_key_state(gb, GB_KEY_START, event.type == SDL_KEYDOWN);
-                        break;
-                    case SDLK_SPACE:
                     GB_set_turbo_mode(gb, event.type == SDL_KEYDOWN, false);
-                        break;
+                }
+                else {
+                    for (unsigned i = 0; i < GB_KEY_MAX; i++) {
+                        if (event.key.keysym.scancode == configuration.keys[i]) {
+                            GB_set_key_state(gb, i, event.type == SDL_KEYDOWN);
+                        }
+                    }
                 }
                 break;
             default:
@@ -294,10 +245,16 @@ static void handle_events(GB_gameboy_t *gb)
 
 static void vblank(GB_gameboy_t *gb)
 {
-    SDL_UpdateTexture(texture, NULL, pixels, 160 * sizeof (uint32_t));
+    if (configuration.blend_frames) {
-    SDL_RenderClear(renderer);
+        render_texture(active_pixel_buffer, previous_pixel_buffer);
-    SDL_RenderCopy(renderer, texture, NULL, NULL);
+        uint32_t *temp = active_pixel_buffer;
-    SDL_RenderPresent(renderer);
+        active_pixel_buffer = previous_pixel_buffer;
+        previous_pixel_buffer = temp;
+        GB_set_pixels_output(gb, active_pixel_buffer);
+    }
+    else {
+        render_texture(active_pixel_buffer, NULL);
+    }
     handle_events(gb);
 }
 
@@ -309,8 +266,10 @@ static uint32_t rgb_encode(GB_gameboy_t *gb, uint8_t r, uint8_t g, uint8_t b)
 
 static void debugger_interrupt(int ignore)
 {
+    if (!GB_is_inited(&gb)) return;
     /* ^C twice to exit */
     if (GB_debugger_is_stopped(&gb)) {
+        GB_save_battery(&gb, battery_save_path_ptr);
         exit(0);
     }
     GB_debugger_break(&gb);
@@ -361,12 +320,17 @@ static bool handle_pending_command(void)
         case GB_SDL_TOGGLE_MODEL_COMMAND:
             dmg = !dmg;
             return true;
+            
+        case GB_SDL_QUIT_COMMAND:
+            GB_save_battery(&gb, battery_save_path_ptr);
+            exit(0);
     }
     return false;
 }
 
 static void run(void)
 {
+    pending_command = GB_SDL_NO_COMMAND;
 restart:
     if (GB_is_inited(&gb)) {
         GB_switch_model_and_reset(&gb, !dmg);
@@ -380,9 +344,11 @@ restart:
         }
         
         GB_set_vblank_callback(&gb, (GB_vblank_callback_t) vblank);
-        GB_set_pixels_output(&gb, pixels);
+        GB_set_pixels_output(&gb, active_pixel_buffer);
         GB_set_rgb_encode_callback(&gb, rgb_encode);
         GB_set_sample_rate(&gb, have_aspec.freq);
+        GB_set_color_correction_mode(&gb, configuration.color_correction_mode);
+        GB_set_highpass_filter_mode(&gb, configuration.highpass_mode);
     }
     
     bool error = false;
@@ -433,6 +399,17 @@ restart:
     }
 }
 
+static char prefs_path[1024] = {0, };
+
+static void save_configuration(void)
+{
+    FILE *prefs_file = fopen(prefs_path, "wb");
+    if (prefs_file) {
+        fwrite(&configuration, 1, sizeof(configuration), prefs_file);
+        fclose(prefs_file);
+    }
+}
+
 int main(int argc, char **argv)
 {
 #define str(x) #x
@@ -464,14 +441,34 @@ usage:
 
     SDL_Init( SDL_INIT_EVERYTHING );
     
+    SDL_GL_SetAttribute(SDL_GL_CONTEXT_MAJOR_VERSION, 3);
+    SDL_GL_SetAttribute(SDL_GL_CONTEXT_MINOR_VERSION, 2);
+    SDL_GL_SetAttribute(SDL_GL_CONTEXT_PROFILE_MASK, SDL_GL_CONTEXT_PROFILE_CORE);
+
     window = SDL_CreateWindow("SameBoy v" xstr(VERSION), SDL_WINDOWPOS_UNDEFINED, SDL_WINDOWPOS_UNDEFINED,
-                              160 * 2, 144 * 2, SDL_WINDOW_OPENGL | SDL_WINDOW_RESIZABLE);
+                              160 * 2, 144 * 2, SDL_WINDOW_OPENGL | SDL_WINDOW_RESIZABLE | SDL_WINDOW_ALLOW_HIGHDPI);
     SDL_SetWindowMinimumSize(window, 160, 144);
+    
+    SDL_GLContext gl_context = SDL_GL_CreateContext(window);
+    
+    GLint major, minor;
+    glGetIntegerv(GL_MAJOR_VERSION, &major);
+    glGetIntegerv(GL_MINOR_VERSION, &minor);
+    
+    if (major * 0x100 + minor < 0x302) {
+        SDL_GL_DeleteContext(gl_context);
+        gl_context = NULL;
+    }
+    
+    if (gl_context == NULL) {
         renderer = SDL_CreateRenderer(window, -1, 0);
-    
         texture = SDL_CreateTexture(renderer, SDL_GetWindowPixelFormat(window), SDL_TEXTUREACCESS_STREAMING, 160, 144);
-    
         pixel_format = SDL_AllocFormat(SDL_GetWindowPixelFormat(window));
+    }
+    else {
+        pixel_format = SDL_AllocFormat(SDL_PIXELFORMAT_ABGR8888);
+    }
+    
     
     /* Configure Audio */
     memset(&want_aspec, 0, sizeof(want_aspec));
@@ -490,60 +487,30 @@ usage:
     SDL_OpenAudio(&want_aspec, &have_aspec);
     
     /* Start Audio */
-    SDL_PauseAudio(false);
 
     SDL_EventState(SDL_DROPFILE, SDL_ENABLE);
     
-    if (filename == NULL) {
+    char *prefs_dir = SDL_GetPrefPath("", "SameBoy");
-        /* Draw the "Drop file" screen */
+    snprintf(prefs_path, sizeof(prefs_path) - 1, "%sprefs.bin", prefs_dir);
-        SDL_Surface *drop_backround = SDL_LoadBMP(executable_relative_path("drop.bmp"));
+    SDL_free(prefs_dir);
-        SDL_Surface *drop_converted = SDL_ConvertSurface(drop_backround, pixel_format, 0);
+    
-        SDL_LockSurface(drop_converted);
+    FILE *prefs_file = fopen(prefs_path, "rb");
-        SDL_UpdateTexture(texture, NULL, drop_converted->pixels, drop_converted->pitch);
+    if (prefs_file) {
-        SDL_RenderClear(renderer);
+        fread(&configuration, 1, sizeof(configuration), prefs_file);
-        SDL_RenderCopy(renderer, texture, NULL, NULL);
+        fclose(prefs_file);
-        SDL_RenderPresent(renderer);
+    }
-        SDL_FreeSurface(drop_converted);
+    
-        SDL_FreeSurface(drop_backround);
+    atexit(save_configuration);
-        SDL_Event event;
+    
-        while (SDL_WaitEvent(&event))
+    if (!init_shader_with_name(&shader, configuration.filter)) {
-        {
+        init_shader_with_name(&shader, "NearestNeighbor");
-            switch (event.type) {
-                case SDL_QUIT: {
-                    exit(0);
     }
-                case SDL_WINDOWEVENT: {
-                    if (event.window.event == SDL_WINDOWEVENT_RESIZED) {
     update_viewport();
-                        SDL_RenderClear(renderer);
+    
-                        SDL_RenderCopy(renderer, texture, NULL, NULL);
+    if (filename == NULL) {
-                        SDL_RenderPresent(renderer);
+        run_gui(false);
     }
-                    break;
+    SDL_PauseAudio(false);
-                }
-                case SDL_DROPFILE: {
-                    filename = event.drop.file;
-                    should_free_filename = true;
-                    goto start;
-                }
-                case SDL_KEYDOWN:
-                    if (event.key.keysym.sym == SDLK_TAB) {
-                        cycle_scaling();
-                    }
-#ifndef __APPLE__
-                    else if (event.key.keysym.sym == SDLK_F1) {
-                        SDL_ShowSimpleMessageBox(SDL_MESSAGEBOX_INFORMATION, "Help", help, window);
-                    }
-#else
-                    else if (event.key.keysym.sym == SDLK_QUESTION || (event.key.keysym.sym && (event.key.keysym.mod & KMOD_SHIFT))) {
-                        SDL_ShowSimpleMessageBox(SDL_MESSAGEBOX_INFORMATION, "Help", help, window);
-                    }
-#endif
-                    break;
-            }
-        }
-    }
-start:
     run(); // Never returns
     return 0;
 }

SDL/opengl_compat.c

@@ -0,0 +1,34 @@
+#define GL_GLEXT_PROTOTYPES
+#include <SDL2/SDL_opengl.h>
+
+#ifndef __APPLE__
+#define GL_COMPAT_NAME(func) gl_compat_##func
+#define GL_COMPAT_VAR(func) typeof(func) *GL_COMPAT_NAME(func)
+
+GL_COMPAT_VAR(glCreateShader);
+GL_COMPAT_VAR(glGetAttribLocation);
+GL_COMPAT_VAR(glGetUniformLocation);
+GL_COMPAT_VAR(glUseProgram);
+GL_COMPAT_VAR(glGenVertexArrays);
+GL_COMPAT_VAR(glBindVertexArray);
+GL_COMPAT_VAR(glGenBuffers);
+GL_COMPAT_VAR(glBindBuffer);
+GL_COMPAT_VAR(glBufferData);
+GL_COMPAT_VAR(glEnableVertexAttribArray);
+GL_COMPAT_VAR(glVertexAttribPointer);
+GL_COMPAT_VAR(glCreateProgram);
+GL_COMPAT_VAR(glAttachShader);
+GL_COMPAT_VAR(glLinkProgram);
+GL_COMPAT_VAR(glGetProgramiv);
+GL_COMPAT_VAR(glGetProgramInfoLog);
+GL_COMPAT_VAR(glDeleteShader);
+GL_COMPAT_VAR(glUniform2f);
+GL_COMPAT_VAR(glActiveTexture);
+GL_COMPAT_VAR(glUniform1i);
+GL_COMPAT_VAR(glBindFragDataLocation);
+GL_COMPAT_VAR(glDeleteProgram);
+GL_COMPAT_VAR(glShaderSource);
+GL_COMPAT_VAR(glCompileShader);
+GL_COMPAT_VAR(glGetShaderiv);
+GL_COMPAT_VAR(glGetShaderInfoLog);
+#endif

SDL/opengl_compat.h

@@ -0,0 +1,45 @@
+#ifndef opengl_compat_h
+#define opengl_compat_h
+
+#define GL_GLEXT_PROTOTYPES
+#include <SDL2/SDL_opengl.h>
+#include <SDL2/SDL_video.h>
+
+#ifndef __APPLE__
+#define GL_COMPAT_NAME(func) gl_compat_##func
+
+#define GL_COMPAT_WRAPPER(func) \
+({  extern typeof(func) *GL_COMPAT_NAME(func); \
+if(!GL_COMPAT_NAME(func)) GL_COMPAT_NAME(func) = SDL_GL_GetProcAddress(#func); \
+    GL_COMPAT_NAME(func); \
+})
+
+#define glCreateShader GL_COMPAT_WRAPPER(glCreateShader)
+#define glGetAttribLocation GL_COMPAT_WRAPPER(glGetAttribLocation)
+#define glGetUniformLocation GL_COMPAT_WRAPPER(glGetUniformLocation)
+#define glUseProgram GL_COMPAT_WRAPPER(glUseProgram)
+#define glGenVertexArrays GL_COMPAT_WRAPPER(glGenVertexArrays)
+#define glBindVertexArray GL_COMPAT_WRAPPER(glBindVertexArray)
+#define glGenBuffers GL_COMPAT_WRAPPER(glGenBuffers)
+#define glBindBuffer GL_COMPAT_WRAPPER(glBindBuffer)
+#define glBufferData GL_COMPAT_WRAPPER(glBufferData)
+#define glEnableVertexAttribArray GL_COMPAT_WRAPPER(glEnableVertexAttribArray)
+#define glVertexAttribPointer GL_COMPAT_WRAPPER(glVertexAttribPointer)
+#define glCreateProgram GL_COMPAT_WRAPPER(glCreateProgram)
+#define glAttachShader GL_COMPAT_WRAPPER(glAttachShader)
+#define glLinkProgram GL_COMPAT_WRAPPER(glLinkProgram)
+#define glGetProgramiv GL_COMPAT_WRAPPER(glGetProgramiv)
+#define glGetProgramInfoLog GL_COMPAT_WRAPPER(glGetProgramInfoLog)
+#define glDeleteShader GL_COMPAT_WRAPPER(glDeleteShader)
+#define glUniform2f GL_COMPAT_WRAPPER(glUniform2f)
+#define glActiveTexture GL_COMPAT_WRAPPER(glActiveTexture)
+#define glUniform1i GL_COMPAT_WRAPPER(glUniform1i)
+#define glBindFragDataLocation GL_COMPAT_WRAPPER(glBindFragDataLocation)
+#define glDeleteProgram GL_COMPAT_WRAPPER(glDeleteProgram)
+#define glShaderSource GL_COMPAT_WRAPPER(glShaderSource)
+#define glCompileShader GL_COMPAT_WRAPPER(glCompileShader)
+#define glGetShaderiv GL_COMPAT_WRAPPER(glGetShaderiv)
+#define glGetShaderInfoLog GL_COMPAT_WRAPPER(glGetShaderInfoLog)
+#endif
+
+#endif /* opengl_compat_h */

SDL/shader.c

@@ -0,0 +1,191 @@
+#include <stdio.h>
+#include <string.h>
+#include "shader.h"
+#include "utils.h"
+
+static const char *vertex_shader = "\n\
+#version 150 \n\
+in vec4 aPosition;\n\
+void main(void) {\n\
+gl_Position = aPosition;\n\
+}\n\
+";
+
+static GLuint create_shader(const char *source, GLenum type)
+{
+    // Create the shader object
+    GLuint shader = glCreateShader(type);
+    // Load the shader source
+    glShaderSource(shader, 1, &source, 0);
+    // Compile the shader
+    glCompileShader(shader);
+    // Check for errors
+    GLint status = 0;
+    glGetShaderiv(shader, GL_COMPILE_STATUS, &status);
+    if (status == GL_FALSE) {
+        GLchar messages[1024];
+        glGetShaderInfoLog(shader, sizeof(messages), 0, &messages[0]);
+        fprintf(stderr, "GLSL Shader Error: %s", messages);
+    }
+    return shader;
+}
+
+static GLuint create_program(const char *vsh, const char *fsh)
+{
+    // Build shaders
+    GLuint vertex_shader = create_shader(vsh, GL_VERTEX_SHADER);
+    GLuint fragment_shader = create_shader(fsh, GL_FRAGMENT_SHADER);
+    
+    // Create program
+    GLuint program = glCreateProgram();
+    
+    // Attach shaders
+    glAttachShader(program, vertex_shader);
+    glAttachShader(program, fragment_shader);
+    
+    // Link program
+    glLinkProgram(program);
+    // Check for errors
+    GLint status;
+    glGetProgramiv(program, GL_LINK_STATUS, &status);
+    
+    if (status == GL_FALSE) {
+        GLchar messages[1024];
+        glGetProgramInfoLog(program, sizeof(messages), 0, &messages[0]);
+        fprintf(stderr, "GLSL Program Error: %s", messages);
+    }
+    
+    // Delete shaders
+    glDeleteShader(vertex_shader);
+    glDeleteShader(fragment_shader);
+    
+    return program;
+}
+
+bool init_shader_with_name(shader_t *shader, const char *name)
+{
+    GLint major, minor;
+    glGetIntegerv(GL_MAJOR_VERSION, &major);
+    glGetIntegerv(GL_MINOR_VERSION, &minor);
+    
+    if (major * 0x100 + minor < 0x302) {
+        return false;
+    }
+    
+    static char master_shader_code[0x801] = {0,};
+    static char shader_code[0x10001] = {0,};
+    static char final_shader_code[0x10801] = {0,};
+    static signed long filter_token_location = 0;
+    
+    if (!master_shader_code[0]) {
+        FILE *master_shader_f = fopen(executable_relative_path("Shaders/MasterShader.fsh"), "r");
+        if (!master_shader_f) return false;
+        fread(master_shader_code, 1, sizeof(master_shader_code) - 1, master_shader_f);
+        fclose(master_shader_f);
+        filter_token_location = strstr(master_shader_code, "{filter}") - master_shader_code;
+        if (filter_token_location < 0) {
+            master_shader_code[0] = 0;
+            return false;
+        }
+    }
+    
+    char shader_path[1024];
+    sprintf(shader_path, "Shaders/%s.fsh", name);
+    
+    FILE *shader_f = fopen(executable_relative_path(shader_path), "r");
+    if (!shader_f) return false;
+    memset(shader_code, 0, sizeof(shader_code));
+    fread(shader_code, 1, sizeof(shader_code) - 1, shader_f);
+    fclose(shader_f);
+    
+    memset(final_shader_code, 0, sizeof(final_shader_code));
+    memcpy(final_shader_code, master_shader_code, filter_token_location);
+    strcpy(final_shader_code + filter_token_location, shader_code);
+    strcat(final_shader_code + filter_token_location,
+           master_shader_code + filter_token_location + sizeof("{filter}") - 1);
+    
+    shader->program = create_program(vertex_shader, final_shader_code);
+    
+    // Attributes
+    shader->position_attribute = glGetAttribLocation(shader->program, "aPosition");
+    // Uniforms
+    shader->resolution_uniform = glGetUniformLocation(shader->program, "uResolution");
+    shader->origin_uniform = glGetUniformLocation(shader->program, "uOrigin");
+
+    glGenTextures(1, &shader->texture);
+    glBindTexture(GL_TEXTURE_2D, shader->texture);
+    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
+    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
+    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
+    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
+    glBindTexture(GL_TEXTURE_2D, 0);
+    shader->texture_uniform = glGetUniformLocation(shader->program, "image");
+    
+    glGenTextures(1, &shader->previous_texture);
+    glBindTexture(GL_TEXTURE_2D, shader->previous_texture);
+    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
+    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
+    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
+    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
+    glBindTexture(GL_TEXTURE_2D, 0);
+    shader->previous_texture_uniform = glGetUniformLocation(shader->program, "previousImage");
+    
+    shader->mix_previous_uniform = glGetUniformLocation(shader->program, "uMixPrevious");
+    
+    // Program
+    
+    glUseProgram(shader->program);
+    
+    GLuint vao;
+    glGenVertexArrays(1, &vao);
+    glBindVertexArray(vao);
+    
+    GLuint vbo;
+    glGenBuffers(1, &vbo);
+    
+    // Attributes
+    
+    
+    static GLfloat const quad[16] = {
+        -1.f, -1.f, 0, 1,
+        -1.f, +1.f, 0, 1,
+        +1.f, -1.f, 0, 1,
+        +1.f, +1.f, 0, 1,
+    };
+    
+    
+    glBindBuffer(GL_ARRAY_BUFFER, vbo);
+    glBufferData(GL_ARRAY_BUFFER, sizeof(quad), quad, GL_STATIC_DRAW);
+    glEnableVertexAttribArray(shader->position_attribute);
+    glVertexAttribPointer(shader->position_attribute, 4, GL_FLOAT, GL_FALSE, 0, 0);
+    
+    return true;
+}
+
+void render_bitmap_with_shader(shader_t *shader, void *bitmap, void *previous,unsigned x, unsigned y, unsigned w, unsigned h)
+{
+    glUseProgram(shader->program);
+    glUniform2f(shader->origin_uniform, x, y);
+    glUniform2f(shader->resolution_uniform, w, h);
+    glActiveTexture(GL_TEXTURE0);
+    glBindTexture(GL_TEXTURE_2D, shader->texture);
+    glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, 160, 144, 0, GL_RGBA, GL_UNSIGNED_BYTE, bitmap);
+    glUniform1i(shader->texture_uniform, 0);
+    glUniform1i(shader->mix_previous_uniform, previous != NULL);
+    if (previous) {
+        glActiveTexture(GL_TEXTURE1);
+        glBindTexture(GL_TEXTURE_2D, shader->previous_texture);
+        glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, 160, 144, 0, GL_RGBA, GL_UNSIGNED_BYTE, previous);
+        glUniform1i(shader->previous_texture_uniform, 1);
+    }
+    glBindFragDataLocation(shader->program, 0, "frag_color");
+    glDrawArrays(GL_TRIANGLE_STRIP, 0, 4);
+}
+
+void free_shader(shader_t *shader)
+{
+    glDeleteProgram(shader->program);
+    glDeleteTextures(1, &shader->texture);
+    glDeleteTextures(1, &shader->previous_texture);
+
+}

SDL/shader.h

@@ -0,0 +1,23 @@
+#ifndef shader_h
+#define shader_h
+#include "opengl_compat.h"
+#include <stdbool.h>
+
+typedef struct shader_s {
+    GLuint resolution_uniform;
+    GLuint origin_uniform;
+    GLuint texture_uniform;
+    GLuint previous_texture_uniform;
+    GLuint mix_previous_uniform;
+    
+    GLuint position_attribute;
+    GLuint texture;
+    GLuint previous_texture;
+    GLuint program;
+} shader_t;
+
+bool init_shader_with_name(shader_t *shader, const char *name);
+void render_bitmap_with_shader(shader_t *shader, void *bitmap, void *previous,unsigned x, unsigned y, unsigned w, unsigned h);
+void free_shader(struct shader_s *shader);
+
+#endif /* shader_h */

SDL/utils.c

@@ -1,62 +1,24 @@
+#include <SDL2/SDL.h>
 #include <stdio.h>
 #include <string.h>
-#ifdef __APPLE__
-#include <mach-o/dyld.h>
-#endif
-#ifdef _WIN32
-#include <direct.h>
-#include <windows.h>
-#endif
-#ifdef __linux__
-#include <assert.h>
-#include <unistd.h>
-#endif
 #include "utils.h"
 
 const char *executable_folder(void)
 {
-    static char path[1024] = {0,};
+    static const char *ret = NULL;
-    if (path[0]) {
+    if (!ret) {
-        return path;
+        ret = SDL_GetBasePath();
-    }
+        if (!ret) {
-    /* Ugly unportable code! :( */
+            ret = "./";
-#ifdef __APPLE__
-    unsigned int length = sizeof(path) - 1;
-    _NSGetExecutablePath(&path[0], &length);
-#else
-#ifdef __linux__
-    ssize_t __attribute__((unused)) length = readlink("/proc/self/exe", &path[0], sizeof(path) - 1);
-    assert (length != -1);
-#else
-#ifdef _WIN32
-    HMODULE hModule = GetModuleHandle(NULL);
-    GetModuleFileName(hModule, path, sizeof(path) - 1);
-#else
-    /* No OS-specific way, assume running from CWD */
-    getcwd(&path[0], sizeof(path) - 1);
-    return path;
-#endif
-#endif
-#endif
-    size_t pos = strlen(path);
-    while (pos) {
-        pos--;
-#ifdef _WIN32
-        if (path[pos] == '\\') {
-#else
-        if (path[pos] == '/') {
-#endif
-            path[pos] = 0;
-            break;
         }
     }
-    return path;
+    return ret;
 }
 
 char *executable_relative_path(const char *filename)
 {
     static char path[1024];
-    snprintf(path, sizeof(path), "%s/%s", executable_folder(), filename);
+    snprintf(path, sizeof(path), "%s%s", executable_folder(), filename);
     return path;
 }
 

Shaders/MasterShader.fsh

@@ -4,14 +4,20 @@ uniform sampler2D previousImage;
 uniform bool uMixPrevious;
 
 uniform vec2 uResolution;
+uniform vec2 uOrigin;
 const vec2 textureDimensions = vec2(160, 144);
 
 out vec4 frag_color;
 
+vec4 modified_frag_cord;
+#define gl_FragCoord modified_frag_cord
 #line 1
 {filter}
+#undef gl_FragCoord
 
 void main() {
+    modified_frag_cord = gl_FragCoord - vec4(uOrigin.x, uOrigin.y, 0, 0);
+    
     if (uMixPrevious) {
         frag_color = mix(scale(image), scale(previousImage), 0.5);
     }

Windows/inttypes.h

@@ -0,0 +1 @@
+#include <stdint.h>