add barebones SDL1.2 backends

for that sweet Win9x support

Makefile

@@ -58,9 +58,9 @@ NO_LDIV ?= 0
 
 # Renderers: GL, GL_LEGACY, D3D11, D3D12
 RENDER_API ?= GL
-# Window managers: SDL2, DXGI (forced if D3D11 or D3D12 in RENDER_API)
+# Window managers: SDL1, SDL2, DXGI (forced if D3D11 or D3D12 in RENDER_API)
 WINDOW_API ?= SDL2
-# Audio backends: SDL2
+# Audio backends: SDL1, SDL2
 AUDIO_API ?= SDL2
 # Controller backends (can have multiple, space separated): SDL2
 CONTROLLER_API ?= SDL2
@@ -481,7 +481,9 @@ SDLCONFIG := $(CROSS)sdl2-config
 BACKEND_CFLAGS := -DRAPI_$(RENDER_API)=1 -DWAPI_$(WINDOW_API)=1 -DAAPI_$(AUDIO_API)=1
 # can have multiple controller APIs
 BACKEND_CFLAGS += $(foreach capi,$(CONTROLLER_API),-DCAPI_$(capi)=1)
-BACKEND_LDFLAGS :=
+BACKEND_LDFLAG0S :=
+
+SDL1_USED := 0
 SDL2_USED := 0
 
 # for now, it's either SDL+GL or DXGI+DirectX, so choose based on WAPI
@@ -492,7 +494,7 @@ ifeq ($(WINDOW_API),DXGI)
   endif
   BACKEND_LDFLAGS += -ld3dcompiler -ldxgi -ldxguid
   BACKEND_LDFLAGS += -lsetupapi -ldinput8 -luser32 -lgdi32 -limm32 -lole32 -loleaut32 -lshell32 -lwinmm -lversion -luuid -static
-else ifeq ($(WINDOW_API),SDL2)
+else ifeq ($(findstring SDL,$(WINDOW_API)),SDL)
   ifeq ($(WINDOWS_BUILD),1)
     BACKEND_LDFLAGS += -lglew32 -lglu32 -lopengl32
   else ifeq ($(TARGET_RPI),1)
@@ -502,20 +504,32 @@ else ifeq ($(WINDOW_API),SDL2)
   else
     BACKEND_LDFLAGS += -lGL
   endif
-  SDL_USED := 2
 endif
 
-ifeq ($(AUDIO_API),SDL2)
+ifneq (,$(findstring SDL2,$(AUDIO_API)$(WINDOW_API)$(CONTROLLER_API)))
-  SDL_USED := 2
+  SDL2_USED := 1
 endif
 
-ifneq (,$(findstring SDL,$(CONTROLLER_API)))
+ifneq (,$(findstring SDL1,$(AUDIO_API)$(WINDOW_API)$(CONTROLLER_API)))
-  SDL_USED := 2
+  SDL1_USED := 1
+endif
+
+ifeq ($(SDL1_USED)$(SDL2_USED),11)
+  $(error Cannot link both SDL1 and SDL2 at the same time)
 endif
 
 # SDL can be used by different systems, so we consolidate all of that shit into this
-ifeq ($(SDL_USED),2)
+
-  BACKEND_CFLAGS += -DHAVE_SDL2=1 `$(SDLCONFIG) --cflags`
+ifeq ($(SDL2_USED),1)
+  SDLCONFIG := $(CROSS)sdl2-config
+  BACKEND_CFLAGS += -DHAVE_SDL2=1
+else ifeq ($(SDL1_USED),1)
+  SDLCONFIG := $(CROSS)sdl-config
+  BACKEND_CFLAGS += -DHAVE_SDL1=1
+endif
+
+ifneq ($(SDL1_USED)$(SDL2_USED),00)
+  BACKEND_CFLAGS += `$(SDLCONFIG) --cflags`
   ifeq ($(WINDOWS_BUILD),1)
     BACKEND_LDFLAGS += `$(SDLCONFIG) --static-libs` -lsetupapi -luser32 -limm32 -lole32 -loleaut32 -lshell32 -lwinmm -lversion
   else

src/pc/audio/audio_sdl1.c

@@ -0,0 +1,190 @@
+#ifdef AAPI_SDL1
+
+#include <stdlib.h>
+#include <stdio.h>
+#include <string.h>
+#include <SDL/SDL.h>
+
+#include "audio_api.h"
+
+#define SNDPACKETLEN (8 * 1024)
+
+// this is basically SDL_dataqueue but slightly less generic
+
+typedef struct sndpacket {
+    size_t datalen;         /* bytes currently in use in this packet. */
+    size_t startpos;        /* bytes currently consumed in this packet. */
+    struct sndpacket *next; /* next item in linked list. */
+    Uint8 data[];           /* packet data */
+} sndpacket_t;
+
+static sndpacket_t *qhead;
+static sndpacket_t *qtail;
+static sndpacket_t *qpool;
+static size_t queued;
+
+static SDL_AudioSpec aspec;
+static int was_init = 0;
+
+static void sndqueue_init(const size_t bufsize) {
+    const size_t wantpackets = (bufsize + (SNDPACKETLEN - 1)) / SNDPACKETLEN;
+    for (size_t i = 0; i < wantpackets; ++i) {
+        sndpacket_t *packet = malloc(sizeof(sndpacket_t) + SNDPACKETLEN);
+        if (packet) {
+            packet->datalen = 0;
+            packet->startpos = 0;
+            packet->next = qpool;
+            qpool = packet;
+        }
+    }
+}
+
+static size_t sndqueue_read(void *buf, size_t len) {
+    sndpacket_t *packet;
+    Uint8 *ptr = buf;
+
+    while ((len > 0) && ((packet = qhead) != NULL)) {
+        const size_t avail = packet->datalen - packet->startpos;
+        const size_t tx = (len < avail) ? len : avail;
+
+        memcpy(ptr, packet->data + packet->startpos, tx);
+        packet->startpos += tx;
+        ptr += tx;
+        queued -= tx;
+        len -= tx;
+
+        if (packet->startpos == packet->datalen) {
+            qhead = packet->next;
+            packet->next = qpool;
+            qpool = packet;
+        }
+    }
+
+    if (qhead == NULL)
+        qtail = NULL;
+
+    return (size_t)(ptr - (Uint8*)buf);
+}
+
+static inline sndpacket_t *alloc_sndpacket(void) {
+    sndpacket_t *packet = qpool;
+
+    if (packet) {
+        qpool = packet->next;
+    } else {
+        packet = malloc(sizeof(sndpacket_t) + SNDPACKETLEN);
+        if (!packet) return NULL;
+    }
+
+    packet->datalen = 0;
+    packet->startpos = 0;
+    packet->next = NULL;
+
+    if (qtail == NULL)
+        qhead = packet;
+    else
+        qtail->next = packet;
+    qtail = packet;
+
+    return packet;
+}
+
+static int sndqueue_push(const void *data, size_t len) {
+    sndpacket_t *orighead = qhead;
+    sndpacket_t *origtail = qtail;
+    size_t origlen = origtail ? origtail->datalen : 0;
+    Uint8 *ptr = data;
+
+    while (len > 0) {
+        sndpacket_t *packet = qtail;
+        if (!packet || (packet->datalen >= SNDPACKETLEN)) {
+            packet = alloc_sndpacket();
+            if (!packet) {
+                // out of memory, fuck everything
+                return -1;
+            }
+        }
+
+        const size_t room = SNDPACKETLEN - packet->datalen;
+        const size_t datalen = (len < room) ? len : room;
+        memcpy(packet->data + packet->datalen, ptr, datalen);
+        ptr += datalen;
+        len -= datalen;
+        packet->datalen += datalen;
+        queued += datalen;
+    }
+
+    return 0;
+}
+
+static void audio_drain(void *user, Uint8 *buf, int len) {
+    const size_t tx = sndqueue_read(buf, len);
+    buf += tx;
+    len -= (int)tx;
+    if (len > 0) memset(buf, aspec.silence, len);
+}
+
+static bool audio_sdl_init(void) {
+    if (SDL_InitSubSystem(SDL_INIT_AUDIO) != 0) {
+        fprintf(stderr, "SDL init error: %s\n", SDL_GetError());
+        return false;
+    }
+
+    SDL_AudioSpec want, have;
+    memset(&want, 0, sizeof(want));
+    want.freq = 32000;
+    want.format = AUDIO_S16SYS;
+    want.channels = 2;
+    want.samples = 512;
+    want.callback = audio_drain;
+    if (SDL_OpenAudio(&want, &have) == -1) {
+        fprintf(stderr, "SDL_OpenAudio error: %s\n", SDL_GetError());
+        return false;
+    }
+
+    aspec = have;
+
+    was_init = 1;
+    SDL_PauseAudio(0);
+
+    return true;
+}
+
+static int audio_sdl_buffered(void) {
+    SDL_LockAudio();
+    int len = queued / 4;
+    SDL_UnlockAudio();
+    return len;
+}
+
+static int audio_sdl_get_desired_buffered(void) {
+    return 1100;
+}
+
+static void audio_sdl_play(const uint8_t *buf, size_t len) {
+    SDL_LockAudio();
+    // Don't fill the audio buffer too much in case this happens
+    if (queued / 4 < 6000)
+        sndqueue_push(buf, len);
+    SDL_UnlockAudio();
+}
+
+static void audio_sdl_shutdown(void)  {
+    if (SDL_WasInit(SDL_INIT_AUDIO)) {
+        if (was_init) {
+            SDL_CloseAudio();
+            was_init = 0;
+        }
+        SDL_QuitSubSystem(SDL_INIT_AUDIO);
+    }
+}
+
+struct AudioAPI audio_sdl = {
+    audio_sdl_init,
+    audio_sdl_buffered,
+    audio_sdl_get_desired_buffered,
+    audio_sdl_play,
+    audio_sdl_shutdown
+};
+
+#endif

src/pc/audio/audio_sdl2.c

@@ -11,10 +11,11 @@ static bool audio_sdl_init(void) {
         fprintf(stderr, "SDL init error: %s\n", SDL_GetError());
         return false;
     }
+
     SDL_AudioSpec want, have;
     SDL_zero(want);
     want.freq = 32000;
-    want.format = AUDIO_S16;
+    want.format = AUDIO_S16SYS;
     want.channels = 2;
     want.samples = 512;
     want.callback = NULL;

src/pc/controller/controller_entry_point.c

@@ -13,7 +13,9 @@
 
 static struct ControllerAPI *controller_implementations[] = {
     &controller_recorded_tas,
+    #ifdef CAPI_SDL2
     &controller_sdl,
+    #endif
     &controller_keyboard,
 };
 

src/pc/controller/controller_sdl2.c

@@ -13,7 +13,7 @@
 #include <ultra64.h>
 
 #include "controller_api.h"
-#include "controller_sdl.h"
+#include "controller_sdl2.h"
 #include "../configfile.h"
 #include "../platform.h"
 #include "../fs/fs.h"

src/pc/gfx/gfx_opengl.c

@@ -19,14 +19,21 @@
 # include <GL/glew.h>
 #endif
 
-#include <SDL2/SDL.h>
-
 #define GL_GLEXT_PROTOTYPES 1
+
+#ifdef WAPI_SDL2
+# include <SDL2/SDL.h>
 # ifdef USE_GLES
 #  include <SDL2/SDL_opengles2.h>
 # else
 #  include <SDL2/SDL_opengl.h>
 # endif
+#elif defined(WAPI_SDL1)
+# include <SDL/SDL.h>
+# ifndef GLEW_STATIC
+#  include <SDL/SDL_opengl.h>
+# endif
+#endif
 
 #include "../platform.h"
 #include "../configfile.h"

src/pc/gfx/gfx_opengl_legacy.c

@@ -15,15 +15,22 @@
 # define FOR_WINDOWS 0
 #endif
 
-#include <SDL2/SDL.h>
-
 #if FOR_WINDOWS || defined(OSX_BUILD)
 # define GLEW_STATIC
 # include <GL/glew.h>
 #endif
 
 #define GL_GLEXT_PROTOTYPES 1
+
+#ifdef WAPI_SDL2
+# include <SDL2/SDL.h>
 # include <SDL2/SDL_opengl.h>
+#elif defined(WAPI_SDL1)
+# include <SDL/SDL.h>
+# ifndef GLEW_STATIC
+#  include <SDL/SDL_opengl.h>
+# endif
+#endif
 
 // redefine this if using a different GL loader
 #define mglGetProcAddress(name) SDL_GL_GetProcAddress(name)

src/pc/gfx/gfx_sdl1.c

@@ -0,0 +1,280 @@
+#ifdef WAPI_SDL1
+
+#ifdef __MINGW32__
+#define FOR_WINDOWS 1
+#else
+#define FOR_WINDOWS 0
+#endif
+
+#include <SDL/SDL.h>
+
+#include <stdio.h>
+#include <unistd.h>
+
+#include "gfx_window_manager_api.h"
+#include "gfx_screen_config.h"
+#include "../pc_main.h"
+#include "../configfile.h"
+#include "../cliopts.h"
+#include "../platform.h"
+
+#include "src/pc/controller/controller_keyboard.h"
+
+// TODO: figure out if this shit even works
+#ifdef VERSION_EU
+# define FRAMERATE 25
+#else
+# define FRAMERATE 30
+#endif
+
+static int inverted_scancode_table[512];
+
+static kb_callback_t kb_key_down = NULL;
+static kb_callback_t kb_key_up = NULL;
+static void (*kb_all_keys_up)(void) = NULL;
+
+// time between consequtive game frames
+static const int frame_time = 1000 / FRAMERATE;
+
+static int desktop_w = 640;
+static int desktop_h = 480;
+static int desktop_bpp = 24;
+
+static int window_w = 0;
+static int window_h = 0;
+
+const SDLKey windows_scancode_table[] = {
+    /*  0            1               2                 3                  4             5                  6                    7                     */
+    /*  8            9               A                 B                  C             D                  E                    F                     */
+    SDLK_UNKNOWN,    SDLK_ESCAPE,    SDLK_1,           SDLK_2,            SDLK_3,       SDLK_4,            SDLK_5,              SDLK_6,          /* 0 */
+    SDLK_7,          SDLK_8,         SDLK_9,           SDLK_0,            SDLK_MINUS,   SDLK_EQUALS,       SDLK_BACKSPACE,      SDLK_TAB,        /* 0 */
+
+    SDLK_q,          SDLK_w,         SDLK_e,           SDLK_r,            SDLK_t,       SDLK_y,            SDLK_u,              SDLK_i,          /* 1 */
+    SDLK_o,          SDLK_p,         SDLK_LEFTBRACKET, SDLK_RIGHTBRACKET, SDLK_RETURN,  SDLK_LCTRL,        SDLK_a,              SDLK_s,          /* 1 */
+
+    SDLK_d,          SDLK_f,         SDLK_g,           SDLK_h,            SDLK_j,       SDLK_k,            SDLK_l,              SDLK_SEMICOLON,  /* 2 */
+    SDLK_UNKNOWN,    SDLK_BACKQUOTE, SDLK_LSHIFT,      SDLK_BACKSLASH,    SDLK_z,       SDLK_x,            SDLK_c,              SDLK_v,          /* 2 */
+
+    SDLK_b,          SDLK_n,         SDLK_m,           SDLK_COMMA,        SDLK_PERIOD,  SDLK_SLASH,        SDLK_RSHIFT,         SDLK_PRINT,      /* 3 */
+    SDLK_LALT,       SDLK_SPACE,     SDLK_CAPSLOCK,    SDLK_F1,           SDLK_F2,      SDLK_F3,           SDLK_F4,             SDLK_F5,         /* 3 */
+
+    SDLK_F6,         SDLK_F7,        SDLK_F8,          SDLK_F9,           SDLK_F10,     SDLK_NUMLOCK,      SDLK_SCROLLOCK,      SDLK_HOME,       /* 4 */
+    SDLK_UP,         SDLK_PAGEUP,    SDLK_KP_MINUS,    SDLK_LEFT,         SDLK_KP5,     SDLK_RIGHT,        SDLK_KP_PLUS,        SDLK_END,        /* 4 */
+
+    SDLK_DOWN,       SDLK_PAGEDOWN,  SDLK_INSERT,      SDLK_DELETE,       SDLK_UNKNOWN, SDLK_UNKNOWN,      SDLK_UNKNOWN,        SDLK_F11,        /* 5 */
+    SDLK_F12,        SDLK_PAUSE,     SDLK_UNKNOWN,     SDLK_LSUPER,       SDLK_RSUPER,  SDLK_MODE,         SDLK_UNKNOWN,        SDLK_UNKNOWN,    /* 5 */
+
+    SDLK_UNKNOWN,    SDLK_UNKNOWN,   SDLK_UNKNOWN,     SDLK_UNKNOWN,      SDLK_F13,     SDLK_F14,          SDLK_F15,            SDLK_UNKNOWN,    /* 6 */
+    SDLK_UNKNOWN,    SDLK_UNKNOWN,   SDLK_UNKNOWN,     SDLK_UNKNOWN,      SDLK_UNKNOWN, SDLK_UNKNOWN,      SDLK_UNKNOWN,        SDLK_UNKNOWN,    /* 6 */
+
+    SDLK_WORLD_2,    SDLK_UNKNOWN,   SDLK_UNKNOWN,     SDLK_WORLD_1,      SDLK_UNKNOWN, SDLK_UNKNOWN,      SDLK_UNKNOWN,        SDLK_UNKNOWN,    /* 7 */
+    SDLK_UNKNOWN,    SDLK_WORLD_4,   SDLK_UNKNOWN,     SDLK_WORLD_5,      SDLK_UNKNOWN, SDLK_WORLD_3,      SDLK_UNKNOWN,        SDLK_UNKNOWN     /* 7 */
+};
+
+const SDLKey scancode_rmapping_extended[][2] = {
+    { SDLK_KP_ENTER,  SDLK_RETURN },
+    { SDLK_RALT,      SDLK_LALT },
+    { SDLK_RCTRL,     SDLK_LCTRL },
+    { SDLK_KP_DIVIDE, SDLK_SLASH },
+    //{ SDLK_KPPLUS,    SDLK_CAPSLOCK }
+};
+
+const SDLKey scancode_rmapping_nonextended[][2] = {
+    { SDLK_KP7,         SDLK_HOME },
+    { SDLK_KP8,         SDLK_UP },
+    { SDLK_KP9,         SDLK_PAGEUP },
+    { SDLK_KP4,         SDLK_LEFT },
+    { SDLK_KP6,         SDLK_RIGHT },
+    { SDLK_KP1,         SDLK_END },
+    { SDLK_KP2,         SDLK_DOWN },
+    { SDLK_KP3,         SDLK_PAGEDOWN },
+    { SDLK_KP0,         SDLK_INSERT },
+    { SDLK_KP_PERIOD,   SDLK_DELETE },
+    { SDLK_KP_MULTIPLY, SDLK_PRINT }
+};
+
+static void gfx_sdl_set_mode(void) {
+    if (configWindow.exiting_fullscreen)
+        configWindow.exiting_fullscreen = false;
+
+    if (configWindow.reset) {
+        configWindow.fullscreen = false;
+        configWindow.x = WAPI_WIN_CENTERPOS;
+        configWindow.y = WAPI_WIN_CENTERPOS;
+        configWindow.w = DESIRED_SCREEN_WIDTH;
+        configWindow.h = DESIRED_SCREEN_HEIGHT;
+        configWindow.reset = false;
+    }
+
+    SDL_GL_SetAttribute(SDL_GL_DEPTH_SIZE, 16);
+    SDL_GL_SetAttribute(SDL_GL_DOUBLEBUFFER, 1);
+    SDL_GL_SetAttribute(SDL_GL_RED_SIZE, 8);
+    SDL_GL_SetAttribute(SDL_GL_GREEN_SIZE, 8);
+    SDL_GL_SetAttribute(SDL_GL_BLUE_SIZE, 8);
+    SDL_GL_SetAttribute(SDL_GL_ALPHA_SIZE, 8);
+
+    uint32_t flags = SDL_OPENGL;
+    if (configWindow.fullscreen)
+        flags |= SDL_FULLSCREEN;
+    else
+        flags |= SDL_RESIZABLE;
+
+    if (!SDL_VideoModeOK(configWindow.w, configWindow.h, desktop_bpp, flags)) {
+        printf(
+            "video mode [%dx%d fullscreen %d] not available, falling back to default\n",
+            configWindow.w, configWindow.h, configWindow.fullscreen
+        );
+        configWindow.w = DESIRED_SCREEN_WIDTH;
+        configWindow.h = DESIRED_SCREEN_HEIGHT;
+        configWindow.fullscreen = false;
+        flags = SDL_OPENGL | SDL_RESIZABLE;
+    }
+
+    if (!SDL_SetVideoMode(configWindow.w, configWindow.h, desktop_bpp, flags)) {
+        sys_fatal(
+            "could not set video mode [%dx%d fullscreen %d]: %s\n",
+            configWindow.w, configWindow.h, configWindow.fullscreen, SDL_GetError()
+        );
+    }
+
+    window_w = configWindow.w;
+    window_h = configWindow.h;
+}
+
+static void gfx_sdl_init(const char *window_title) {
+    if (SDL_Init(SDL_INIT_VIDEO | SDL_INIT_TIMER) != 0)
+        sys_fatal("Could not init SDL1 video: %s\n", SDL_GetError());
+
+    const SDL_VideoInfo *vinfo = SDL_GetVideoInfo();
+    desktop_w = vinfo->current_w;
+    desktop_h = vinfo->current_h;
+    desktop_bpp = vinfo->vfmt->BitsPerPixel;
+
+    SDL_WM_SetCaption(window_title, NULL);
+
+    // set actual desired video mode
+
+    gfx_sdl_set_mode();
+
+    SDL_ShowCursor(0);
+
+    for (size_t i = 0; i < sizeof(windows_scancode_table) / sizeof(SDLKey); i++) {
+        inverted_scancode_table[windows_scancode_table[i]] = i;
+    }
+
+    for (size_t i = 0; i < sizeof(scancode_rmapping_extended) / sizeof(scancode_rmapping_extended[0]); i++) {
+        inverted_scancode_table[scancode_rmapping_extended[i][0]] = inverted_scancode_table[scancode_rmapping_extended[i][1]] + 0x100;
+    }
+
+    for (size_t i = 0; i < sizeof(scancode_rmapping_nonextended) / sizeof(scancode_rmapping_nonextended[0]); i++) {
+        inverted_scancode_table[scancode_rmapping_nonextended[i][0]] = inverted_scancode_table[scancode_rmapping_nonextended[i][1]];
+        inverted_scancode_table[scancode_rmapping_nonextended[i][1]] += 0x100;
+    }
+}
+
+static void gfx_sdl_main_loop(void (*run_one_game_iter)(void)) {
+    run_one_game_iter();
+}
+
+static void gfx_sdl_get_dimensions(uint32_t *width, uint32_t *height) {
+    if (width) *width = window_w;
+    if (height) *height = window_h;
+}
+
+static int translate_scancode(int scancode) {
+    if (scancode < 512) {
+        return inverted_scancode_table[scancode];
+    } else {
+        return 0;
+    }
+}
+
+static void gfx_sdl_onkeydown(int scancode) {
+    if (kb_key_down)
+        kb_key_down(translate_scancode(scancode));
+}
+
+static void gfx_sdl_onkeyup(int scancode) {
+    if (kb_key_up)
+        kb_key_up(translate_scancode(scancode));
+}
+
+static void gfx_sdl_handle_events(void) {
+    SDL_Event event;
+    while (SDL_PollEvent(&event)) {
+        switch (event.type) {
+#ifndef TARGET_WEB
+            // Scancodes are broken in Emscripten SDL2: https://bugzilla.libsdl.org/show_bug.cgi?id=3259
+            case SDL_KEYDOWN:
+                gfx_sdl_onkeydown(event.key.keysym.sym);
+                // ALT+F4 in case the OS doesn't do it (SDL1 doesn't seem to do it on my machine)
+                if (event.key.keysym.sym == SDLK_F4 && (event.key.keysym.mod & (KMOD_LALT | KMOD_RALT)))
+                    game_exit();
+                break;
+            case SDL_KEYUP:
+                gfx_sdl_onkeyup(event.key.keysym.sym);
+                break;
+#endif
+            case SDL_VIDEORESIZE:
+                window_w = configWindow.w = event.resize.w;
+                window_h = configWindow.h = event.resize.h;
+                break;
+            case SDL_QUIT:
+                game_exit();
+                break;
+        }
+    }
+}
+
+static void gfx_sdl_set_keyboard_callbacks(kb_callback_t on_key_down, kb_callback_t on_key_up, void (*on_all_keys_up)(void)) {
+    kb_key_down = on_key_down;
+    kb_key_up = on_key_up;
+    kb_all_keys_up = on_all_keys_up;
+}
+
+static bool gfx_sdl_start_frame(void) {
+    return true;
+}
+
+static inline void sync_framerate_with_timer(void) {
+    static Uint32 last_time = 0;
+    // get base timestamp on the first frame (might be different from 0)
+    if (last_time == 0) last_time = SDL_GetTicks();
+    const int elapsed = SDL_GetTicks() - last_time;
+    if (elapsed < frame_time)
+        SDL_Delay(frame_time - elapsed);
+    last_time += frame_time;
+}
+
+static void gfx_sdl_swap_buffers_begin(void) {
+    sync_framerate_with_timer();
+    SDL_GL_SwapBuffers();
+}
+
+static void gfx_sdl_swap_buffers_end(void) {
+}
+
+static double gfx_sdl_get_time(void) {
+    return 0.0;
+}
+
+
+static void gfx_sdl_shutdown(void) {
+    if (SDL_WasInit(0))
+        SDL_Quit();
+}
+
+struct GfxWindowManagerAPI gfx_sdl = {
+    gfx_sdl_init,
+    gfx_sdl_set_keyboard_callbacks,
+    gfx_sdl_main_loop,
+    gfx_sdl_get_dimensions,
+    gfx_sdl_handle_events,
+    gfx_sdl_start_frame,
+    gfx_sdl_swap_buffers_begin,
+    gfx_sdl_swap_buffers_end,
+    gfx_sdl_get_time,
+    gfx_sdl_shutdown
+};
+
+#endif // BACKEND_WM

src/pc/pc_main.c

@@ -222,8 +222,10 @@ void main_func(void) {
     gfx_init(wm_api, rendering_api, window_title);
     wm_api->set_keyboard_callbacks(keyboard_on_key_down, keyboard_on_key_up, keyboard_on_all_keys_up);
 
+    #if defined(AAPI_SDL1) || defined(AAPI_SDL2)
     if (audio_api == NULL && audio_sdl.init()) 
         audio_api = &audio_sdl;
+    #endif
 
     if (audio_api == NULL) {
         audio_api = &audio_null;