sokol_gfx.h: change _SG_GL_IMAGE_CACHE_SIZE from enum to define, improve some bounds check asserts

sokol_gfx.h

@@ -4069,9 +4069,7 @@ typedef struct {
     GLuint texture;
 } _sg_gl_texture_bind_slot;
 
-enum {
-    _SG_GL_IMAGE_CACHE_SIZE = SG_MAX_SHADERSTAGE_IMAGES * SG_NUM_SHADER_STAGES,
-};
+#define _SG_GL_IMAGE_CACHE_SIZE (SG_MAX_SHADERSTAGE_IMAGES * SG_NUM_SHADER_STAGES)
 
 typedef struct {
     sg_depth_state depth;
@@ -6747,7 +6745,7 @@ _SOKOL_PRIVATE void _sg_gl_cache_bind_texture(int slot_index, GLenum target, GLu
        target=0 will unbind the previous binding, texture=0 will clear
        the new binding
     */
-    SOKOL_ASSERT(slot_index < _SG_GL_IMAGE_CACHE_SIZE);
+    SOKOL_ASSERT((slot_index >= 0) && (slot_index < _SG_GL_IMAGE_CACHE_SIZE));
     if (slot_index >= _sg.gl.max_combined_texture_image_units) {
         return;
     }
@@ -6768,12 +6766,12 @@ _SOKOL_PRIVATE void _sg_gl_cache_bind_texture(int slot_index, GLenum target, GLu
 }
 
 _SOKOL_PRIVATE void _sg_gl_cache_store_texture_binding(int slot_index) {
-    SOKOL_ASSERT(slot_index < _SG_GL_IMAGE_CACHE_SIZE);
+    SOKOL_ASSERT((slot_index >= 0) && (slot_index < _SG_GL_IMAGE_CACHE_SIZE));
     _sg.gl.cache.stored_texture = _sg.gl.cache.textures[slot_index];
 }
 
 _SOKOL_PRIVATE void _sg_gl_cache_restore_texture_binding(int slot_index) {
-    SOKOL_ASSERT(slot_index < _SG_GL_IMAGE_CACHE_SIZE);
+    SOKOL_ASSERT((slot_index >= 0) && (slot_index < _SG_GL_IMAGE_CACHE_SIZE));
     _sg_gl_texture_bind_slot* slot = &_sg.gl.cache.stored_texture;
     if (slot->texture != 0) {
         /* we only care restoring valid ids */