4 files changed, 75 insertions, 44 deletions

diff --git a/src/common.c b/src/common.c
index 28b007b..29cc07b 100644
--- a/src/common.c
+++ b/src/common.c
@@ -1311,6 +1311,45 @@ color_index_t Com_ParseColor( const char *s, color_index_t last ) {
     return COLOR_NONE;
 }
 
+#if USE_REF == REF_GL
+/*
+================
+Com_ParseExtensionString
+
+Helper function to parse an OpenGL-style extension string.
+================
+*/
+unsigned Com_ParseExtensionString( const char *s, const char *const extnames[] ) {
+    unsigned mask;
+    const char *p;
+    size_t l1, l2;
+    int i;
+
+    if( !s ) {
+        return 0;
+    }
+
+    mask = 0;
+    while( *s ) {
+        p = Q_strchrnul( s, ' ' );
+        l1 = p - s;
+        for( i = 0; extnames[i]; i++ ) {
+            l2 = strlen( extnames[i] );
+            if( l1 == l2 && !memcmp( s, extnames[i], l1 ) ) {
+                mask |= 1 << i;
+                break;
+            }
+        }
+        if( !*p ) {
+            break;
+        }
+        s = p + 1;
+    }
+
+    return mask;
+}
+#endif
+
 /*
 ================
 Com_PlayerToEntityState
diff --git a/src/common.h b/src/common.h
index f4d03d3..db4a06b 100644
--- a/src/common.h
+++ b/src/common.h
@@ -545,6 +545,10 @@ void        Com_PageInMemory( void *buffer, size_t size );
 
 color_index_t Com_ParseColor( const char *s, color_index_t last );
 
+#if USE_REF == REF_GL
+unsigned    Com_ParseExtensionString( const char *s, const char *const extnames[] );
+#endif
+
 #ifndef _WIN32
 void        Com_FlushLogs( void );
 #endif
diff --git a/src/qgl_api.c b/src/qgl_api.c
index e9503f3..0ee81a8 100644
--- a/src/qgl_api.c
+++ b/src/qgl_api.c
@@ -1137,40 +1137,18 @@ void QGL_InitExtensions( unsigned mask ) {
 
 #undef GPA
 
-// must match defines in qgl_api.h!
-static const char *const extnames[] = {
-    "GL_EXT_compiled_vertex_array",
-    "GL_ARB_multitexture",
-    "GL_EXT_texture_filter_anisotropic",
-    "GL_ARB_fragment_program",
-    "GL_ARB_vertex_buffer_object"
-};
-
-static const int numextnames = sizeof( extnames ) / sizeof( extnames[0] );
-
 unsigned QGL_ParseExtensionString( const char *s ) {
-    unsigned mask = 0;
-    const char *p;
-    size_t l1, l2;
-    int i;
-
-    while( *s ) {
-        p = Q_strchrnul( s, ' ' );
-        l1 = p - s;
-        for( i = 0; i < numextnames; i++ ) {
-            l2 = strlen( extnames[i] );
-            if( l1 == l2 && !memcmp( s, extnames[i], l1 ) ) {
-                mask |= 1 << i;
-                break;
-            }
-        }
-        if( !*p ) {
-            break;
-        }
-        s = p + 1;
-    }
+    // must match defines in qgl_api.h!
+    static const char *const extnames[] = {
+        "GL_EXT_compiled_vertex_array",
+        "GL_ARB_multitexture",
+        "GL_EXT_texture_filter_anisotropic",
+        "GL_ARB_fragment_program",
+        "GL_ARB_vertex_buffer_object",
+        NULL
+    };
 
-    return mask;
+    return Com_ParseExtensionString( s, extnames );
 }
 
 void QGL_EnableLogging( qboolean enable )
diff --git a/src/vid_sdl.c b/src/vid_sdl.c
index ece3b11..d446b99 100644
--- a/src/vid_sdl.c
+++ b/src/vid_sdl.c
@@ -572,9 +572,19 @@ void VID_EndFrame( void ) {
 #define SHOW_SYNC() \
     Com_DDDPrintf( "%s: %u\n", __func__, sdl.sync_count )
 
+static unsigned glx_parse_extension_string( const char *s ) {
+    static const char *const extnames[] = {
+        "GLX_SGI_video_sync",
+        NULL
+    };
+
+    return Com_ParseExtensionString( s, extnames );
+}
+
 static void init_glx( void ) {
     const char *extensions;
     cvar_t *gl_video_sync;
+    unsigned mask;
 
     if( !sdl.dpy ) {
         return;
@@ -588,20 +598,20 @@ static void init_glx( void ) {
     gl_video_sync = Cvar_Get( "gl_video_sync", "1", 0 );
 
     extensions = sdl.glXQueryExtensionsString( sdl.dpy, DefaultScreen( sdl.dpy ) );
-    if( extensions && *extensions ) {
-        if( Q_stristr( extensions, "GLX_SGI_video_sync" ) ) {
-            if( gl_video_sync->integer ) {
-                Com_Printf( "...enabling GLX_SGI_video_sync\n" );
-                sdl.glXGetVideoSyncSGI = SDL_GL_GetProcAddress( "glXGetVideoSyncSGI" );
-                sdl.glXWaitVideoSyncSGI = SDL_GL_GetProcAddress( "glXWaitVideoSyncSGI" );
-                sdl.glXGetVideoSyncSGI( &sdl.sync_count );
-                sdl.flags |= QVF_VIDEOSYNC;
-            } else {
-                Com_Printf( "...ignoring GLX_SGI_video_sync\n" );
-            }
+    mask = glx_parse_extension_string( extensions );
+    if( mask & 1 ) {
+        if( gl_video_sync->integer ) {
+            Com_Printf( "...enabling GLX_SGI_video_sync\n" );
+            sdl.glXGetVideoSyncSGI = SDL_GL_GetProcAddress( "glXGetVideoSyncSGI" );
+            sdl.glXWaitVideoSyncSGI = SDL_GL_GetProcAddress( "glXWaitVideoSyncSGI" );
+            sdl.glXGetVideoSyncSGI( &sdl.sync_count );
+            sdl.flags |= QVF_VIDEOSYNC;
         } else {
-            Com_Printf( "GLX_SGI_video_sync not found\n" );
+            Com_Printf( "...ignoring GLX_SGI_video_sync\n" );
         }
+    } else if( gl_video_sync->integer ) {
+        Com_Printf( "GLX_SGI_video_sync not found\n" );
+        Cvar_Set( "gl_video_sync", "0" );
     }
 }
 #endif