Loading SDL with dlopen

Loading the library at runtime, instead of utilizing the static
linker/ld-linux.so is way smaller.

Makefile

@@ -4,7 +4,7 @@ NASM = nasm
 STRIP = sstrip -z
 SHADER_MINIFIER = shader_minifier.exe
 CFLAGS = -m32 -std=c99 -Wall -Werror -ggdb -Oz -ffast-math -fomit-frame-pointer -march=i686 $(shell pkg-config --cflags sdl) $(shell pkg-config --cflags gl)
-LDFLAGS = -melf_i386 -dynamic-linker /lib/ld-linux.so.2 $(shell pkg-config --libs sdl)
+LDFLAGS = -melf_i386 -dynamic-linker /lib/ld-linux.so.2 -ldl
 NASMFLAGS = -f elf
 
 SOURCES = $(wildcard *.c)

gl_functions.h

@@ -3,46 +3,99 @@
 
 #include <GL/gl.h>
 #include <SDL.h>
+#include "sdl_functions.h"
 
-static GLAPI void GLAPIENTRY (*glMatrixMode_)(GLenum);
-static GLAPI void GLAPIENTRY (*glOrtho_)(GLdouble, GLdouble, GLdouble, GLdouble, GLdouble, GLdouble);
+#define gl_call(name, type) ((type)gl_functions[name ## _i])
 
-static GLAPI void GLAPIENTRY (*glBegin_)(GLenum);
-static GLAPI void GLAPIENTRY (*glEnd_)();
-static GLAPI void GLAPIENTRY (*glVertex3f_)(GLfloat, GLfloat, GLfloat);
+#define glMatrixMode_fn \
+    gl_call(glMatrixMode, void GLAPIENTRY (*)(GLenum))
 
-static GLAPI GLuint GLAPIENTRY (*glCreateShader_)(GLenum);
-static GLAPI void GLAPIENTRY (*glShaderSource_)(GLuint, GLsizei count, const GLchar**, const GLint*);
-static GLAPI void GLAPIENTRY (*glCompileShader_)(GLuint);
-static GLAPI void GLAPIENTRY (*glAttachShader_)(GLuint, GLuint);
-static GLAPI GLuint GLAPIENTRY (*glCreateProgram_)();
-static GLAPI void GLAPIENTRY (*glLinkProgram_)(GLuint);
-static GLAPI void GLAPIENTRY (*glUseProgram_)(GLuint);
+#define glOrtho_fn \
+    gl_call(glOrtho, void GLAPIENTRY (*)(GLdouble, GLdouble, GLdouble, GLdouble, GLdouble, GLdouble))
 
-static GLAPI GLint GLAPIENTRY (*glGetUniformLocation_)(GLuint, const GLchar*);
-static GLAPI void GLAPIENTRY (*glUniform3fv_)(GLint, GLsizei, const GLfloat*);
-static GLAPI void GLAPIENTRY (*glUniformMatrix3fv_)(GLint, GLsizei, GLboolean, const GLfloat*);
+#define glBegin_fn \
+    gl_call(glBegin, void GLAPIENTRY (*)(GLenum))
+
+#define glEnd_fn \
+    gl_call(glEnd, void GLAPIENTRY (*)())
+
+#define glVertex3f_fn \
+    gl_call(glVertex3f, void GLAPIENTRY (*)(GLfloat, GLfloat, GLfloat))
+
+#define glCreateShader_fn \
+    gl_call(glCreateShader, GLuint GLAPIENTRY (*)(GLenum))
+
+#define glShaderSource_fn \
+    gl_call(glShaderSource, void GLAPIENTRY (*)(GLuint, GLsizei count, const GLchar**, const GLint*))
+
+#define glCompileShader_fn \
+    gl_call(glCompileShader, void GLAPIENTRY (*)(GLuint))
+
+#define glAttachShader_fn \
+    gl_call(glAttachShader, void GLAPIENTRY (*)(GLuint, GLuint))
+
+#define glCreateProgram_fn \
+    gl_call(glCreateProgram, GLuint GLAPIENTRY (*)())
+
+#define glLinkProgram_fn \
+    gl_call(glLinkProgram, void GLAPIENTRY (*)(GLuint))
+
+#define glUseProgram_fn \
+    gl_call(glUseProgram, void GLAPIENTRY (*)(GLuint))
+
+#define glGetUniformLocation_fn \
+    gl_call(glGetUniformLocation, GLint GLAPIENTRY (*)(GLuint, const GLchar*))
+
+#define glUniform3fv_fn \
+    gl_call(glUniform3fv, void GLAPIENTRY (*)(GLint, GLsizei, const GLfloat*))
+
+#define glUniformMatrix3fv_fn \
+    gl_call(glUniformMatrix3fv, void GLAPIENTRY (*)(GLint, GLsizei, GLboolean, const GLfloat*))
+
+enum {
+    glMatrixMode_i,
+    glOrtho_i,
+    glBegin_i,
+    glEnd_i,
+    glVertex3f_i,
+    glCreateShader_i,
+    glShaderSource_i,
+    glCompileShader_i,
+    glAttachShader_i,
+    glCreateProgram_i,
+    glLinkProgram_i,
+    glUseProgram_i,
+    glGetUniformLocation_i,
+    glUniform3fv_i,
+    glUniformMatrix3fv_i
+};
+
+static const char* gl_symbols[] = {
+    "glMatrixMode",
+    "glOrtho",
+    "glBegin",
+    "glEnd",
+    "glVertex3f",
+    "glCreateShader",
+    "glShaderSource",
+    "glCompileShader",
+    "glAttachShader",
+    "glCreateProgram",
+    "glLinkProgram",
+    "glUseProgram",
+    "glGetUniformLocation",
+    "glUniform3fv",
+    "glUniformMatrix3fv"
+};
+
+static const void* gl_functions[sizeof(gl_symbols) / sizeof(const char*)];
 
 static stdcall void initialize_gl_functions()
 {
-    glMatrixMode_ = SDL_GL_GetProcAddress("glMatrixMode");
-    glOrtho_ = SDL_GL_GetProcAddress("glOrtho");
-
-    glBegin_ = SDL_GL_GetProcAddress("glBegin");
-    glEnd_ = SDL_GL_GetProcAddress("glEnd");
-    glVertex3f_ = SDL_GL_GetProcAddress("glVertex3f");
-
-    glCreateShader_ = SDL_GL_GetProcAddress("glCreateShader");
-    glShaderSource_ = SDL_GL_GetProcAddress("glShaderSource");
-    glCompileShader_ = SDL_GL_GetProcAddress("glCompileShader");
-    glAttachShader_ = SDL_GL_GetProcAddress("glAttachShader");
-    glCreateProgram_ = SDL_GL_GetProcAddress("glCreateProgram");
-    glLinkProgram_ = SDL_GL_GetProcAddress("glLinkProgram");
-    glUseProgram_ = SDL_GL_GetProcAddress("glUseProgram");
-
-    glGetUniformLocation_ = SDL_GL_GetProcAddress("glGetUniformLocation");
-    glUniform3fv_ = SDL_GL_GetProcAddress("glUniform3fv");
-    glUniformMatrix3fv_ = SDL_GL_GetProcAddress("glUniformMatrix3fv");
+    for (int i = 0; i < sizeof(gl_symbols) / sizeof(const char*); i++)
+    {
+        gl_functions[i] = SDL_GL_GetProcAddress_fn(gl_symbols[i]);
+    }
 }
 
 #endif

main.c

@@ -2,6 +2,7 @@
 #include <SDL.h>
 #include <GL/gl.h>
 #include "clib.h"
+#include "sdl_functions.h"
 #include "gl_functions.h"
 #include "vector.h"
 #include "shader.h"
@@ -24,29 +25,29 @@ static float sphere_radius;
 
 static stdcall void initialize_sdl()
 {
-    SDL_SetVideoMode(resolution_x, resolution_y, 0,
+    SDL_SetVideoMode_fn(resolution_x, resolution_y, 0,
             SDL_OPENGL | (fullscreen ? SDL_FULLSCREEN : 0));
-    SDL_WM_SetCaption(window_caption, NULL);
-    SDL_ShowCursor(SDL_DISABLE);
+    SDL_WM_SetCaption_fn(window_caption, NULL);
+    SDL_ShowCursor_fn(SDL_DISABLE);
 }
 
 static stdcall void cleanup_sdl()
 {
     // SDL_Quit crashes since main() is removed, but we need this call to reset
     // the screen resolution when running fullscreen
-    SDL_QuitSubSystem(SDL_INIT_VIDEO);
+    SDL_QuitSubSystem_fn(SDL_INIT_VIDEO);
 }
 
 static stdcall void setup_viewport()
 {
-    glMatrixMode_(GL_PROJECTION);
-    glOrtho_(-window_ratio, window_ratio, -1.0, 1.0, -1.0, 1.0);
+    glMatrixMode_fn(GL_PROJECTION);
+    glOrtho_fn(-window_ratio, window_ratio, -1.0, 1.0, -1.0, 1.0);
 }
 
 static stdcall bool exit_requested()
 {
     SDL_Event event;
-    SDL_PollEvent(&event);
+    SDL_PollEvent_fn(&event);
 
     if (event.type == SDL_QUIT)
     {
@@ -68,7 +69,7 @@ static stdcall float linear_step(float start, float end, float position, float d
 
 static stdcall bool update_scene()
 {
-    Uint32 time = SDL_GetTicks();
+    Uint32 time = SDL_GetTicks_fn();
 
     if (time > keypoints[sizeof(keypoints) / sizeof(struct keypoint) - 1].time)
     {
@@ -116,27 +117,28 @@ static stdcall bool update_scene()
 static stdcall void mainloop()
 {
     GLuint program = compile_program(vertex_glsl, fragment_glsl);
-    glUseProgram_(program);
+    glUseProgram_fn(program);
 
     while (exit_requested() && update_scene())
     {
         uniform_vector3(program, "x", position);
         uniform_matrix3(program, "o", orientation);
         uniform_vector3(program, "f", (vector3){box_scale, box_radius, sphere_radius});
 
-        glBegin_(GL_QUADS);
-        glVertex3f_(-window_ratio, -1.0, 0.0);
-        glVertex3f_( window_ratio, -1.0, 0.0);
-        glVertex3f_( window_ratio,  1.0, 0.0);
-        glVertex3f_(-window_ratio,  1.0, 0.0);
-        glEnd_();
+        glBegin_fn(GL_QUADS);
+        glVertex3f_fn(-window_ratio, -1.0, 0.0);
+        glVertex3f_fn( window_ratio, -1.0, 0.0);
+        glVertex3f_fn( window_ratio,  1.0, 0.0);
+        glVertex3f_fn(-window_ratio,  1.0, 0.0);
+        glEnd_fn();
 
-        SDL_GL_SwapBuffers();
+        SDL_GL_SwapBuffers_fn();
     }
 }
 
 void _start()
 {
+    initialize_sdl_functions();
     initialize_sdl();
     initialize_gl_functions();
     initialize_sound();

sdl_functions.h

@@ -0,0 +1,78 @@
+#ifndef SDL_FUNCTIONS_H
+#define SDL_FUNCTIONS_H
+
+#include <dlfcn.h>
+#include <SDL.h>
+
+#define sdl_call(name, type) ((type)sdl_functions[name ## _i])
+
+#define SDL_GL_GetProcAddress_fn \
+    sdl_call(SDL_GL_GetProcAddress, void* SDLCALL (*)(const char*))
+
+#define SDL_SetVideoMode_fn \
+    sdl_call(SDL_SetVideoMode, SDL_Surface* SDLCALL (*)(int, int, int, Uint32))
+
+#define SDL_WM_SetCaption_fn \
+    sdl_call(SDL_WM_SetCaption, void SDLCALL (*)(const char*, const char*))
+
+#define SDL_ShowCursor_fn \
+    sdl_call(SDL_ShowCursor, int SDLCALL (*)(int))
+
+#define SDL_QuitSubSystem_fn \
+    sdl_call(SDL_QuitSubSystem, void SDLCALL (*)(Uint32))
+
+#define SDL_PollEvent_fn \
+    sdl_call(SDL_PollEvent, int SDLCALL (*)(SDL_Event*))
+
+#define SDL_GetTicks_fn \
+    sdl_call(SDL_GetTicks, Uint32 SDLCALL (*)())
+
+#define SDL_GL_SwapBuffers_fn \
+    sdl_call(SDL_GL_SwapBuffers, void SDLCALL (*)())
+
+#define SDL_OpenAudio_fn \
+    sdl_call(SDL_OpenAudio, int SDLCALL (*)(SDL_AudioSpec*, SDL_AudioSpec*))
+
+#define SDL_PauseAudio_fn \
+    sdl_call(SDL_PauseAudio, void SDLCALL (*)(int))
+
+enum {
+    SDL_GL_GetProcAddress_i,
+    SDL_SetVideoMode_i,
+    SDL_WM_SetCaption_i,
+    SDL_ShowCursor_i,
+    SDL_QuitSubSystem_i,
+    SDL_PollEvent_i,
+    SDL_GetTicks_i,
+    SDL_GL_SwapBuffers_i,
+    SDL_OpenAudio_i,
+    SDL_PauseAudio_i
+};
+
+static const char* sdl_symbols[] = {
+    "SDL_GL_GetProcAddress",
+    "SDL_SetVideoMode",
+    "SDL_WM_SetCaption",
+    "SDL_ShowCursor",
+    "SDL_QuitSubSystem",
+    "SDL_PollEvent",
+    "SDL_GetTicks",
+    "SDL_GL_SwapBuffers",
+    "SDL_OpenAudio",
+    "SDL_PauseAudio"
+};
+
+static const void* sdl_functions[sizeof(sdl_symbols) / sizeof(const char*)];
+
+static stdcall void initialize_sdl_functions()
+{
+    void* libsdl = dlopen("libSDL-1.2.so", RTLD_NOW);
+
+    for (int i = 0; i < sizeof(sdl_symbols) / sizeof(const char*); i++)
+    {
+        sdl_functions[i] = dlsym(libsdl, sdl_symbols[i]);
+    }
+}
+
+#endif
+

shader.h

@@ -9,31 +9,31 @@
 
 static stdcall void add_shader(GLuint program, GLenum type, const GLchar* source)
 {
-    GLuint shader = glCreateShader_(type);
-    glShaderSource_(shader, 1, &source, NULL);
-    glCompileShader_(shader);
-    glAttachShader_(program, shader);
+    GLuint shader = glCreateShader_fn(type);
+    glShaderSource_fn(shader, 1, &source, NULL);
+    glCompileShader_fn(shader);
+    glAttachShader_fn(program, shader);
 }
 
 static stdcall GLuint compile_program(const char* vertex_source, const char* fragment_source)
 {
-    GLuint program = glCreateProgram_();
+    GLuint program = glCreateProgram_fn();
     add_shader(program, GL_VERTEX_SHADER, vertex_source);
     add_shader(program, GL_FRAGMENT_SHADER, fragment_source);
-    glLinkProgram_(program);
+    glLinkProgram_fn(program);
     return program;
 }
 
 static stdcall void uniform_vector3(GLuint program, const char* identifier, const vector3 value)
 {
-    GLint location = glGetUniformLocation_(program, identifier);
-    glUniform3fv_(location, 1, value);
+    GLint location = glGetUniformLocation_fn(program, identifier);
+    glUniform3fv_fn(location, 1, value);
 }
 
 static stdcall void uniform_matrix3(GLuint program, const char* identifier, const matrix3 value)
 {
-    GLint location = glGetUniformLocation_(program, identifier);
-    glUniformMatrix3fv_(location, 1, GL_TRUE, (const GLfloat*)value);
+    GLint location = glGetUniformLocation_fn(program, identifier);
+    glUniformMatrix3fv_fn(location, 1, GL_TRUE, (const GLfloat*)value);
 }
 
 #endif

sound.h

@@ -3,6 +3,7 @@
 
 #include <SDL.h>
 #include "clib.h"
+#include "sdl_functions.h"
 #include "4klang.inh"
 
 static const int sound_channels = 2;
@@ -29,7 +30,7 @@ static SDL_AudioSpec sound_spec = {
 
 static stdcall void initialize_sound()
 {
-    SDL_OpenAudio(&sound_spec, NULL);
+    SDL_OpenAudio_fn(&sound_spec, NULL);
 }
 
 static stdcall void play_sound()
@@ -38,7 +39,7 @@ static stdcall void play_sound()
             sound_thread_stack + sizeof(sound_thread_stack),
             CLONE_VM | CLONE_FS | CLONE_FILES | CLONE_SIGHAND | CLONE_SYSVSEM,
             sound_buffer);
-    SDL_PauseAudio(0);
+    SDL_PauseAudio_fn(0);
 }
 
 #endif