chew.c

#if defined( WIN32 ) || defined( WINDOWS ) || defined( WIN64 )
#include <windows.h>
#else
#include <dlfcn.h>
#endif

#include <stdio.h>
#include "chew.h"

#define TABLEONLY
#undef CHEWTYPEDEF
#undef CHEWTYPEDEF2
#define CHEWTYPEDEF( ret, name, retcmd, parameters, ... ) name##_t name##fnptr;
#define CHEWTYPEDEF2( ret, name, usename, retcmd, parameters, ... ) usename##_t usename##fnptr;
#include "chew.h"

#define TABLEONLY
#undef CHEWTYPEDEF
#undef CHEWTYPEDEF2
#define CHEWTYPEDEF( ret, name, retcmd, parameters, ... ) ret name( __VA_ARGS__ ) { retcmd name##fnptr parameters; }
#define CHEWTYPEDEF2( ret, name, usename, retcmd, parameters, ... ) ret usename( __VA_ARGS__ ) { retcmd usename##fnptr parameters ; }
#include "chew.h"

#define TABLEONLY
#undef CHEWTYPEDEF
#undef CHEWTYPEDEF2
#define CHEWTYPEDEF( ret, name, retcmd, parameters, ... ) #name, 
#define CHEWTYPEDEF2( ret, name, usename, retcmd, parameters, ... ) #name, 
const char * symnames[] = {
	#include "chew.h"
};

#define TABLEONLY
#undef CHEWTYPEDEF
#undef CHEWTYPEDEF2
#define CHEWTYPEDEF( ret, name, retcmd, parameters, ... ) (void**)&name##fnptr, 
#define CHEWTYPEDEF2( ret, name, usename, retcmd, parameters, ... ) (void**)&usename##fnptr, 
void ** syms[] = {
	#include "chew.h"
};

#if defined( WIN32 ) || defined( WINDOWS ) || defined( WIN64 )

//From https://www.khronos.org/opengl/wiki/Load_OpenGL_Functions
void * chewGetProcAddress(const char *name)
{
	void *p = (void *)wglGetProcAddress(name);
	if(p == 0 ||
		(p == (void*)0x1) || (p == (void*)0x2) || (p == (void*)0x3) ||
		(p == (void*)-1) )
	{
		static HMODULE module;
		if( !module ) module = LoadLibraryA("opengl32.dll");
		p = (void *)GetProcAddress(module, name);
	}
	return p;
}

#else

void * chewGetProcAddress(const char *name)
{
	//Tricky use RTLD_NEXT first so we don't accidentally link against ourselves.
	void * v1 = dlsym( (void*)((intptr_t)-1) /*RTLD_NEXT = -1*/ /*RTLD_DEFAULT = 0*/, name );
	//printf( "%s = %p\n", name, v1 );
	if( !v1 ) v1 = dlsym( 0, name );
	return v1;
}

#endif



void chewInit() {
	int i;
	for( i = 0; i < sizeof(symnames) / sizeof(symnames[0]); i++ )
	{
		void * v = *syms[i] = (void*)chewGetProcAddress( symnames[i] );
		if( !v ) fprintf( stderr, "Warning: Can't find \"gl%s\"\n", symnames[i] );
		//else printf( "%p = %s\n", v, symnames[i] );
	}
}