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/* ------------------------------------------------------------------------- */
static int _glewExtensionCompare(const char *s1, const char *s2)
{
/* http://www.chanduthedev.com/2012/07/strcmp-implementation-in-c.html */
while (*s1 || *s2)
{
if (*s1 > *s2)
return 1;
if (*s1 < *s2)
return -1;
s1++;
s2++;
}
return 0;
}
static ptrdiff_t _glewBsearchExtension(const char* name)
{
ptrdiff_t lo = 0, hi = sizeof(_glewExtensionLookup) / sizeof(char*) - 2;
while (lo <= hi)
{
ptrdiff_t mid = (lo + hi) / 2;
const int cmp = _glewExtensionCompare(name, _glewExtensionLookup[mid]);
if (cmp < 0) hi = mid - 1;
else if (cmp > 0) lo = mid + 1;
else return mid;
}
return -1;
}
static GLboolean *_glewGetExtensionString(const char *name)
{
ptrdiff_t n = _glewBsearchExtension(name);
if (n >= 0) return &_glewExtensionString[n];
return NULL;
}
static GLboolean *_glewGetExtensionEnable(const char *name)
{
ptrdiff_t n = _glewBsearchExtension(name);
if (n >= 0) return _glewExtensionEnabled[n];
return NULL;
}
static const char *_glewNextSpace(const char *i)
{
const char *j = i;
if (j)
while (*j!=' ' && *j) ++j;
return j;
}
static const char *_glewNextNonSpace(const char *i)
{
const char *j = i;
if (j)
while (*j==' ') ++j;
return j;
}
GLboolean GLEWAPIENTRY glewGetExtension (const char* name)
{
GLboolean *enable = _glewGetExtensionString(name);
if (enable)
return *enable;
return GL_FALSE;
}
/* ------------------------------------------------------------------------- */
typedef const GLubyte* (GLAPIENTRY * PFNGLGETSTRINGPROC) (GLenum name);
typedef void (GLAPIENTRY * PFNGLGETINTEGERVPROC) (GLenum pname, GLint *params);
static GLenum GLEWAPIENTRY glewContextInit ()
{
PFNGLGETSTRINGPROC getString;
const GLubyte* s;
GLuint dot;
GLint major, minor;
size_t n;
#ifdef _WIN32
getString = glGetString;
#else
getString = (PFNGLGETSTRINGPROC) glewGetProcAddress((const GLubyte*)"glGetString");
if (!getString)
return GLEW_ERROR_NO_GL_VERSION;
#endif
/* query opengl version */
s = getString(GL_VERSION);
dot = _glewStrCLen(s, '.');
if (dot == 0)
return GLEW_ERROR_NO_GL_VERSION;
major = s[dot-1]-'0';
minor = s[dot+1]-'0';
if (minor < 0 || minor > 9)
minor = 0;
if (major<0 || major>9)
return GLEW_ERROR_NO_GL_VERSION;
if (major == 1 && minor == 0)
{
return GLEW_ERROR_GL_VERSION_10_ONLY;
}
else
{
GLEW_VERSION_4_5 = ( major > 4 ) || ( major == 4 && minor >= 5 ) ? GL_TRUE : GL_FALSE;
GLEW_VERSION_4_4 = GLEW_VERSION_4_5 == GL_TRUE || ( major == 4 && minor >= 4 ) ? GL_TRUE : GL_FALSE;
GLEW_VERSION_4_3 = GLEW_VERSION_4_4 == GL_TRUE || ( major == 4 && minor >= 3 ) ? GL_TRUE : GL_FALSE;
GLEW_VERSION_4_2 = GLEW_VERSION_4_3 == GL_TRUE || ( major == 4 && minor >= 2 ) ? GL_TRUE : GL_FALSE;
GLEW_VERSION_4_1 = GLEW_VERSION_4_2 == GL_TRUE || ( major == 4 && minor >= 1 ) ? GL_TRUE : GL_FALSE;
GLEW_VERSION_4_0 = GLEW_VERSION_4_1 == GL_TRUE || ( major == 4 ) ? GL_TRUE : GL_FALSE;
GLEW_VERSION_3_3 = GLEW_VERSION_4_0 == GL_TRUE || ( major == 3 && minor >= 3 ) ? GL_TRUE : GL_FALSE;
GLEW_VERSION_3_2 = GLEW_VERSION_3_3 == GL_TRUE || ( major == 3 && minor >= 2 ) ? GL_TRUE : GL_FALSE;
GLEW_VERSION_3_1 = GLEW_VERSION_3_2 == GL_TRUE || ( major == 3 && minor >= 1 ) ? GL_TRUE : GL_FALSE;
GLEW_VERSION_3_0 = GLEW_VERSION_3_1 == GL_TRUE || ( major == 3 ) ? GL_TRUE : GL_FALSE;
GLEW_VERSION_2_1 = GLEW_VERSION_3_0 == GL_TRUE || ( major == 2 && minor >= 1 ) ? GL_TRUE : GL_FALSE;
GLEW_VERSION_2_0 = GLEW_VERSION_2_1 == GL_TRUE || ( major == 2 ) ? GL_TRUE : GL_FALSE;
GLEW_VERSION_1_5 = GLEW_VERSION_2_0 == GL_TRUE || ( major == 1 && minor >= 5 ) ? GL_TRUE : GL_FALSE;
GLEW_VERSION_1_4 = GLEW_VERSION_1_5 == GL_TRUE || ( major == 1 && minor >= 4 ) ? GL_TRUE : GL_FALSE;
GLEW_VERSION_1_3 = GLEW_VERSION_1_4 == GL_TRUE || ( major == 1 && minor >= 3 ) ? GL_TRUE : GL_FALSE;
GLEW_VERSION_1_2_1 = GLEW_VERSION_1_3 == GL_TRUE ? GL_TRUE : GL_FALSE;
GLEW_VERSION_1_2 = GLEW_VERSION_1_2_1 == GL_TRUE || ( major == 1 && minor >= 2 ) ? GL_TRUE : GL_FALSE;
GLEW_VERSION_1_1 = GLEW_VERSION_1_2 == GL_TRUE || ( major == 1 && minor >= 1 ) ? GL_TRUE : GL_FALSE;
}
for (n = 0; n < sizeof(_glewExtensionString) / sizeof(_glewExtensionString[0]); ++n)
_glewExtensionString[n] = GL_FALSE;
if (GLEW_VERSION_3_0)
{
GLint n = 0;
GLint i;
PFNGLGETINTEGERVPROC getIntegerv;
PFNGLGETSTRINGIPROC getStringi;
const char *ext;
GLboolean *enable;
#ifdef _WIN32
getIntegerv = glGetIntegerv;
#else
getIntegerv = (PFNGLGETINTEGERVPROC) glewGetProcAddress((const GLubyte*)"glGetIntegerv");
#endif
if (getIntegerv)
getIntegerv(GL_NUM_EXTENSIONS, &n);
/* glGetStringi is OpenGL 3.0 */
getStringi = (PFNGLGETSTRINGIPROC) glewGetProcAddress((const GLubyte*)"glGetStringi");
if (getStringi)
for (i = 0; i<n; ++i)
{
ext = (const char *) getStringi(GL_EXTENSIONS, i);
/* Based on extension string(s), glewGetExtension purposes */
enable = _glewGetExtensionString(ext);
if (enable)
*enable = GL_TRUE;
/* Based on extension string(s), experimental mode, glewIsSupported purposes */
enable = _glewGetExtensionEnable(ext);
if (enable)
*enable = GL_TRUE;
}
}
else
{
const char *extensions;
const char *end;
const char *i;
const char *j;
char ext[128];
GLboolean *enable;
extensions = (const char *) getString(GL_EXTENSIONS);
if (extensions)
{
end = extensions + _glewStrLen((const GLubyte *) extensions);
for (i=extensions; i<end; i = j + 1)
{
i = _glewNextNonSpace(i);
j = _glewNextSpace(i);
/* Copy extension into NUL terminated string */
if (j-i >= (ptrdiff_t) sizeof(ext))
continue;
_glewStrCopy(ext, i, ' ');
/* Based on extension string(s), glewGetExtension purposes */
enable = _glewGetExtensionString(ext);
if (enable)
*enable = GL_TRUE;
/* Based on extension string(s), experimental mode, glewIsSupported purposes */
enable = _glewGetExtensionEnable(ext);
if (enable)
*enable = GL_TRUE;
}
}
}
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