src/mesa/main/extensions.c

   1 /*
   2  * Mesa 3-D graphics library
   3  *
   4  * Copyright (C) 1999-2008  Brian Paul   All Rights Reserved.
   5  * Copyright (C) 2009  VMware, Inc.  All Rights Reserved.
   6  *
   7  * Permission is hereby granted, free of charge, to any person obtaining a
   8  * copy of this software and associated documentation files (the "Software"),
   9  * to deal in the Software without restriction, including without limitation
  10  * the rights to use, copy, modify, merge, publish, distribute, sublicense,
  11  * and/or sell copies of the Software, and to permit persons to whom the
  12  * Software is furnished to do so, subject to the following conditions:
  13  *
  14  * The above copyright notice and this permission notice shall be included
  15  * in all copies or substantial portions of the Software.
  16  *
  17  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
  18  * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  19  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
  20  * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR
  21  * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
  22  * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
  23  * OTHER DEALINGS IN THE SOFTWARE.
  24  */
  25
  26
  27 /**
  28  * \file
  29  * \brief Extension handling
  30  */
  31
  32
  33 #include "glheader.h"
  34 #include "imports.h"
  35 #include "context.h"
  36 #include "extensions.h"
  37 #include "macros.h"
  38 #include "mtypes.h"
  39
  40 enum {
  41    DISABLE = 0,
  42    GLL = 1 << API_OPENGL_COMPAT,       /* GL Legacy / Compatibility */
  43    GLC = 1 << API_OPENGL_CORE,  /* GL Core */
  44    GL  = (1 << API_OPENGL_COMPAT) | (1 << API_OPENGL_CORE),
  45    ES1 = 1 << API_OPENGLES,
  46    ES2 = 1 << API_OPENGLES2,
  47    ES3 = 1 << (API_OPENGL_LAST + 1),
  48 };
  49
  50 /**
  51  * \brief An element of the \c extension_table.
  52  */
  53 struct extension {
  54    /** Name of extension, such as "GL_ARB_depth_clamp". */
  55    const char *name;
  56
  57    /** Offset (in bytes) of the corresponding member in struct gl_extensions. */
  58    size_t offset;
  59
  60    /** Set of API's in which the extension exists, as a bitset. */
  61    uint8_t api_set;
  62
  63    /** Year the extension was proposed or approved.  Used to sort the
  64     * extension string chronologically. */
  65    uint16_t year;
  66 };
  67
  68
  69 /**
  70  * Given a member \c x of struct gl_extensions, return offset of
  71  * \c x in bytes.
  72  */
  73 #define o(x) offsetof(struct gl_extensions, x)
  74
  75
  76 /**
  77  * \brief Table of supported OpenGL extensions for all API's.
  78  */
  79 static const struct extension extension_table[] = {
  80    /* ARB Extensions */
  81    { "GL_ARB_ES2_compatibility",                   o(ARB_ES2_compatibility),                   GL,             2009 },
  82    { "GL_ARB_ES3_compatibility",                   o(ARB_ES3_compatibility),                   GL,             2012 },
  83    { "GL_ARB_base_instance",                       o(ARB_base_instance),                       GL,             2011 },
  84    { "GL_ARB_blend_func_extended",                 o(ARB_blend_func_extended),                 GL,             2009 },
  85    { "GL_ARB_color_buffer_float",                  o(ARB_color_buffer_float),                  GL,             2004 },
  86    { "GL_ARB_copy_buffer",                         o(dummy_true),                              GL,             2008 },
  87    { "GL_ARB_conservative_depth",                  o(ARB_conservative_depth),                  GL,             2011 },
  88    { "GL_ARB_debug_output",                        o(dummy_true),                              GL,             2009 },
  89    { "GL_ARB_depth_buffer_float",                  o(ARB_depth_buffer_float),                  GL,             2008 },
  90    { "GL_ARB_depth_clamp",                         o(ARB_depth_clamp),                         GL,             2003 },
  91    { "GL_ARB_depth_texture",                       o(ARB_depth_texture),                       GLL,            2001 },
  92    { "GL_ARB_draw_buffers",                        o(dummy_true),                              GL,             2002 },
  93    { "GL_ARB_draw_buffers_blend",                  o(ARB_draw_buffers_blend),                  GL,             2009 },
  94    { "GL_ARB_draw_elements_base_vertex",           o(ARB_draw_elements_base_vertex),           GL,             2009 },
  95    { "GL_ARB_draw_indirect",                       o(ARB_draw_indirect),                       GLC,            2010 },
  96    { "GL_ARB_draw_instanced",                      o(ARB_draw_instanced),                      GL,             2008 },
  97    { "GL_ARB_explicit_attrib_location",            o(ARB_explicit_attrib_location),            GL,             2009 },
  98    { "GL_ARB_fragment_coord_conventions",          o(ARB_fragment_coord_conventions),          GL,             2009 },
  99    { "GL_ARB_fragment_program",                    o(ARB_fragment_program),                    GLL,            2002 },
 100    { "GL_ARB_fragment_program_shadow",             o(ARB_fragment_program_shadow),             GLL,            2003 },
 101    { "GL_ARB_fragment_shader",                     o(ARB_fragment_shader),                     GL,             2002 },
 102    { "GL_ARB_framebuffer_object",                  o(ARB_framebuffer_object),                  GL,             2005 },
 103    { "GL_ARB_framebuffer_sRGB",                    o(EXT_framebuffer_sRGB),                    GL,             1998 },
 104    { "GL_ARB_get_program_binary",                  o(dummy_true),                              GL,             2010 },
 105    { "GL_ARB_gpu_shader5",                         o(ARB_gpu_shader5),                         GL,             2010 },
 106    { "GL_ARB_half_float_pixel",                    o(ARB_half_float_pixel),                    GL,             2003 },
 107    { "GL_ARB_half_float_vertex",                   o(ARB_half_float_vertex),                   GL,             2008 },
 108    { "GL_ARB_instanced_arrays",                    o(ARB_instanced_arrays),                    GL,             2008 },
 109    { "GL_ARB_internalformat_query",                o(ARB_internalformat_query),                GL,             2011 },
 110    { "GL_ARB_invalidate_subdata",                  o(dummy_true),                              GL,             2012 },
 111    { "GL_ARB_map_buffer_alignment",                o(ARB_map_buffer_alignment),                GL,             2011 },
 112    { "GL_ARB_map_buffer_range",                    o(ARB_map_buffer_range),                    GL,             2008 },
 113    { "GL_ARB_multi_draw_indirect",                 o(ARB_draw_indirect),                       GLC,            2012 },
 114    { "GL_ARB_multisample",                         o(dummy_true),                              GLL,            1994 },
 115    { "GL_ARB_multitexture",                        o(dummy_true),                              GLL,            1998 },
 116    { "GL_ARB_occlusion_query2",                    o(ARB_occlusion_query2),                    GL,             2003 },
 117    { "GL_ARB_occlusion_query",                     o(ARB_occlusion_query),                     GLL,            2001 },
 118    { "GL_ARB_pixel_buffer_object",                 o(EXT_pixel_buffer_object),                 GL,             2004 },
 119    { "GL_ARB_point_parameters",                    o(EXT_point_parameters),                    GLL,            1997 },
 120    { "GL_ARB_point_sprite",                        o(ARB_point_sprite),                        GL,             2003 },
 121    { "GL_ARB_provoking_vertex",                    o(EXT_provoking_vertex),                    GL,             2009 },
 122    { "GL_ARB_robustness",                          o(dummy_true),                              GL,             2010 },
 123    { "GL_ARB_sample_shading",                      o(ARB_sample_shading),                      GL,             2009 },
 124    { "GL_ARB_sampler_objects",                     o(dummy_true),                              GL,             2009 },
 125    { "GL_ARB_seamless_cube_map",                   o(ARB_seamless_cube_map),                   GL,             2009 },
 126    { "GL_ARB_shader_atomic_counters",              o(ARB_shader_atomic_counters),              GL,             2011 },
 127    { "GL_ARB_shader_bit_encoding",                 o(ARB_shader_bit_encoding),                 GL,             2010 },
 128    { "GL_ARB_shader_objects",                      o(dummy_true),                              GL,             2002 },
 129    { "GL_ARB_shader_stencil_export",               o(ARB_shader_stencil_export),               GL,             2009 },
 130    { "GL_ARB_shader_texture_lod",                  o(ARB_shader_texture_lod),                  GL,             2009 },
 131    { "GL_ARB_shading_language_100",                o(dummy_true),                              GLL,            2003 },
 132    { "GL_ARB_shading_language_packing",            o(ARB_shading_language_packing),            GL,             2011 },
 133    { "GL_ARB_shading_language_420pack",            o(ARB_shading_language_420pack),            GL,             2011 },
 134    { "GL_ARB_shadow",                              o(ARB_shadow),                              GLL,            2001 },
 135    { "GL_ARB_sync",                                o(ARB_sync),                                GL,             2003 },
 136    { "GL_ARB_texture_border_clamp",                o(ARB_texture_border_clamp),                GLL,            2000 },
 137    { "GL_ARB_texture_buffer_object",               o(ARB_texture_buffer_object),               GLC,            2008 },
 138    { "GL_ARB_texture_buffer_object_rgb32",         o(ARB_texture_buffer_object_rgb32),         GLC,            2009 },
 139    { "GL_ARB_texture_buffer_range",                o(ARB_texture_buffer_range),                GLC,            2012 },
 140    { "GL_ARB_texture_compression",                 o(dummy_true),                              GLL,            2000 },
 141    { "GL_ARB_texture_compression_rgtc",            o(ARB_texture_compression_rgtc),            GL,             2004 },
 142    { "GL_ARB_texture_cube_map",                    o(ARB_texture_cube_map),                    GLL,            1999 },
 143    { "GL_ARB_texture_cube_map_array",              o(ARB_texture_cube_map_array),              GL,             2009 },
 144    { "GL_ARB_texture_env_add",                     o(dummy_true),                              GLL,            1999 },
 145    { "GL_ARB_texture_env_combine",                 o(ARB_texture_env_combine),                 GLL,            2001 },
 146    { "GL_ARB_texture_env_crossbar",                o(ARB_texture_env_crossbar),                GLL,            2001 },
 147    { "GL_ARB_texture_env_dot3",                    o(ARB_texture_env_dot3),                    GLL,            2001 },
 148    { "GL_ARB_texture_float",                       o(ARB_texture_float),                       GL,             2004 },
 149    { "GL_ARB_texture_gather",                      o(ARB_texture_gather),                      GL,             2009 },
 150    { "GL_ARB_texture_mirrored_repeat",             o(dummy_true),                              GLL,            2001 },
 151    { "GL_ARB_texture_mirror_clamp_to_edge",        o(ARB_texture_mirror_clamp_to_edge),        GL,             2013 },
 152    { "GL_ARB_texture_multisample",                 o(ARB_texture_multisample),                 GL,             2009 },
 153    { "GL_ARB_texture_non_power_of_two",            o(ARB_texture_non_power_of_two),            GL,             2003 },
 154    { "GL_ARB_texture_query_levels",                o(ARB_texture_query_levels),                GL,             2012 },
 155    { "GL_ARB_texture_query_lod",                   o(ARB_texture_query_lod),                   GL,             2009 },
 156    { "GL_ARB_texture_rectangle",                   o(NV_texture_rectangle),                    GL,             2004 },
 157    { "GL_ARB_texture_rgb10_a2ui",                  o(ARB_texture_rgb10_a2ui),                  GL,             2009 },
 158    { "GL_ARB_texture_rg",                          o(ARB_texture_rg),                          GL,             2008 },
 159    { "GL_ARB_texture_storage",                     o(dummy_true),                              GL,             2011 },
 160    { "GL_ARB_texture_storage_multisample",         o(ARB_texture_multisample),                 GL,             2012 },
 161    { "GL_ARB_texture_swizzle",                     o(EXT_texture_swizzle),                     GL,             2008 },
 162    { "GL_ARB_timer_query",                         o(ARB_timer_query),                         GL,             2010 },
 163    { "GL_ARB_transform_feedback2",                 o(ARB_transform_feedback2),                 GL,             2010 },
 164    { "GL_ARB_transform_feedback3",                 o(ARB_transform_feedback3),                 GL,             2010 },
 165    { "GL_ARB_transform_feedback_instanced",        o(ARB_transform_feedback_instanced),        GL,             2011 },
 166    { "GL_ARB_transpose_matrix",                    o(dummy_true),                              GLL,            1999 },
 167    { "GL_ARB_uniform_buffer_object",               o(ARB_uniform_buffer_object),               GL,             2009 },
 168    { "GL_ARB_vertex_array_bgra",                   o(EXT_vertex_array_bgra),                   GL,             2008 },
 169    { "GL_ARB_vertex_array_object",                 o(dummy_true),                              GL,             2006 },
 170    { "GL_ARB_vertex_attrib_binding",               o(dummy_true),                              GL,             2012 },
 171    { "GL_ARB_vertex_buffer_object",                o(dummy_true),                              GLL,            2003 },
 172    { "GL_ARB_vertex_program",                      o(ARB_vertex_program),                      GLL,            2002 },
 173    { "GL_ARB_vertex_shader",                       o(ARB_vertex_shader),                       GL,             2002 },
 174    { "GL_ARB_vertex_type_10f_11f_11f_rev",         o(ARB_vertex_type_10f_11f_11f_rev),         GL,             2013 },
 175    { "GL_ARB_vertex_type_2_10_10_10_rev",          o(ARB_vertex_type_2_10_10_10_rev),          GL,             2009 },
 176    { "GL_ARB_window_pos",                          o(dummy_true),                              GLL,            2001 },
 177    /* EXT extensions */
 178    { "GL_EXT_abgr",                                o(dummy_true),                              GL,             1995 },
 179    { "GL_EXT_bgra",                                o(dummy_true),                              GLL,            1995 },
 180    { "GL_EXT_blend_color",                         o(EXT_blend_color),                         GLL,            1995 },
 181    { "GL_EXT_blend_equation_separate",             o(EXT_blend_equation_separate),             GL,             2003 },
 182    { "GL_EXT_blend_func_separate",                 o(EXT_blend_func_separate),                 GLL,            1999 },
 183    { "GL_EXT_discard_framebuffer",                 o(dummy_true),                                    ES1 | ES2, 2009 },
 184    { "GL_EXT_blend_minmax",                        o(EXT_blend_minmax),                        GLL | ES1 | ES2, 1995 },
 185    { "GL_EXT_blend_subtract",                      o(dummy_true),                              GLL,            1995 },
 186    { "GL_EXT_compiled_vertex_array",               o(dummy_true),                              GLL,            1996 },
 187    { "GL_EXT_copy_texture",                        o(dummy_true),                              GLL,            1995 },
 188    { "GL_EXT_depth_bounds_test",                   o(EXT_depth_bounds_test),                   GL,             2002 },
 189    { "GL_EXT_draw_buffers2",                       o(EXT_draw_buffers2),                       GL,             2006 },
 190    { "GL_EXT_draw_instanced",                      o(ARB_draw_instanced),                      GL,             2006 },
 191    { "GL_EXT_draw_range_elements",                 o(dummy_true),                              GLL,            1997 },
 192    { "GL_EXT_fog_coord",                           o(dummy_true),                              GLL,            1999 },
 193    { "GL_EXT_framebuffer_blit",                    o(EXT_framebuffer_blit),                    GL,             2005 },
 194    { "GL_EXT_framebuffer_multisample",             o(EXT_framebuffer_multisample),             GL,             2005 },
 195    { "GL_EXT_framebuffer_multisample_blit_scaled", o(EXT_framebuffer_multisample_blit_scaled), GL,             2011 },
 196    { "GL_EXT_framebuffer_object",                  o(dummy_true),                              GLL,            2000 },
 197    { "GL_EXT_framebuffer_sRGB",                    o(EXT_framebuffer_sRGB),                    GL,             1998 },
 198    { "GL_EXT_gpu_program_parameters",              o(EXT_gpu_program_parameters),              GLL,            2006 },
 199    { "GL_EXT_gpu_shader4",                         o(EXT_gpu_shader4),                         GL,             2006 },
 200    { "GL_EXT_map_buffer_range",                    o(ARB_map_buffer_range),                          ES1 | ES2, 2012 },
 201    { "GL_EXT_multi_draw_arrays",                   o(dummy_true),                              GLL | ES1 | ES2, 1999 },
 202    { "GL_EXT_packed_depth_stencil",                o(EXT_packed_depth_stencil),                GL,             2005 },
 203    { "GL_EXT_packed_float",                        o(EXT_packed_float),                        GL,             2004 },
 204    { "GL_EXT_packed_pixels",                       o(dummy_true),                              GLL,            1997 },
 205    { "GL_EXT_pixel_buffer_object",                 o(EXT_pixel_buffer_object),                 GL,             2004 },
 206    { "GL_EXT_point_parameters",                    o(EXT_point_parameters),                    GLL,            1997 },
 207    { "GL_EXT_polygon_offset",                      o(dummy_true),                              GLL,            1995 },
 208    { "GL_EXT_provoking_vertex",                    o(EXT_provoking_vertex),                    GL,             2009 },
 209    { "GL_EXT_rescale_normal",                      o(dummy_true),                              GLL,            1997 },
 210    { "GL_EXT_secondary_color",                     o(dummy_true),                              GLL,            1999 },
 211    { "GL_EXT_separate_shader_objects",             o(EXT_separate_shader_objects),             GLL,            2008 },
 212    { "GL_EXT_separate_specular_color",             o(dummy_true),                              GLL,            1997 },
 213    { "GL_EXT_shader_integer_mix",                  o(EXT_shader_integer_mix),                  GL       | ES3, 2013 },
 214    { "GL_EXT_shadow_funcs",                        o(ARB_shadow),                              GLL,            2002 },
 215    { "GL_EXT_stencil_two_side",                    o(EXT_stencil_two_side),                    GLL,            2001 },
 216    { "GL_EXT_stencil_wrap",                        o(dummy_true),                              GLL,            2002 },
 217    { "GL_EXT_subtexture",                          o(dummy_true),                              GLL,            1995 },
 218    { "GL_EXT_texture3D",                           o(EXT_texture3D),                           GLL,            1996 },
 219    { "GL_EXT_texture_array",                       o(EXT_texture_array),                       GL,             2006 },
 220    { "GL_EXT_texture_compression_dxt1",            o(ANGLE_texture_compression_dxt),           GL | ES1 | ES2, 2004 },
 221    { "GL_ANGLE_texture_compression_dxt3",          o(ANGLE_texture_compression_dxt),           GL | ES1 | ES2, 2011 },
 222    { "GL_ANGLE_texture_compression_dxt5",          o(ANGLE_texture_compression_dxt),           GL | ES1 | ES2, 2011 },
 223    { "GL_EXT_texture_compression_latc",            o(EXT_texture_compression_latc),            GL,             2006 },
 224    { "GL_EXT_texture_compression_rgtc",            o(ARB_texture_compression_rgtc),            GL,             2004 },
 225    { "GL_EXT_texture_compression_s3tc",            o(EXT_texture_compression_s3tc),            GL,             2000 },
 226    { "GL_EXT_texture_cube_map",                    o(ARB_texture_cube_map),                    GLL,            2001 },
 227    { "GL_EXT_texture_edge_clamp",                  o(dummy_true),                              GLL,            1997 },
 228    { "GL_EXT_texture_env_add",                     o(dummy_true),                              GLL,            1999 },
 229    { "GL_EXT_texture_env_combine",                 o(dummy_true),                              GLL,            2000 },
 230    { "GL_EXT_texture_env_dot3",                    o(EXT_texture_env_dot3),                    GLL,            2000 },
 231    { "GL_EXT_texture_filter_anisotropic",          o(EXT_texture_filter_anisotropic),          GL | ES1 | ES2, 1999 },
 232    { "GL_EXT_texture_format_BGRA8888",             o(dummy_true),                                   ES1 | ES2, 2005 },
 233    { "GL_EXT_texture_rg",                          o(ARB_texture_rg),                                     ES2, 2011 },
 234    { "GL_EXT_read_format_bgra",                    o(dummy_true),                                   ES1 | ES2, 2009 },
 235    { "GL_EXT_texture_integer",                     o(EXT_texture_integer),                     GL,             2006 },
 236    { "GL_EXT_texture_lod_bias",                    o(dummy_true),                              GLL | ES1,      1999 },
 237    { "GL_EXT_texture_mirror_clamp",                o(EXT_texture_mirror_clamp),                GL,             2004 },
 238    { "GL_EXT_texture_object",                      o(dummy_true),                              GLL,            1995 },
 239    { "GL_EXT_texture",                             o(dummy_true),                              GLL,            1996 },
 240    { "GL_EXT_texture_rectangle",                   o(NV_texture_rectangle),                    GLL,            2004 },
 241    { "GL_EXT_texture_shared_exponent",             o(EXT_texture_shared_exponent),             GL,             2004 },
 242    { "GL_EXT_texture_snorm",                       o(EXT_texture_snorm),                       GL,             2009 },
 243    { "GL_EXT_texture_sRGB",                        o(EXT_texture_sRGB),                        GL,             2004 },
 244    { "GL_EXT_texture_sRGB_decode",                 o(EXT_texture_sRGB_decode),                        GL,      2006 },
 245    { "GL_EXT_texture_swizzle",                     o(EXT_texture_swizzle),                     GL,             2008 },
 246    { "GL_EXT_texture_type_2_10_10_10_REV",         o(dummy_true),                                         ES2, 2008 },
 247    { "GL_EXT_timer_query",                         o(EXT_timer_query),                         GL,             2006 },
 248    { "GL_EXT_transform_feedback",                  o(EXT_transform_feedback),                  GL,             2011 },
 249    { "GL_EXT_unpack_subimage",                     o(dummy_true),                                         ES2, 2011 },
 250    { "GL_EXT_vertex_array_bgra",                   o(EXT_vertex_array_bgra),                   GL,             2008 },
 251    { "GL_EXT_vertex_array",                        o(dummy_true),                              GLL,            1995 },
 252    { "GL_EXT_color_buffer_float",                  o(dummy_true),                                         ES3, 2013 },
 253
 254    /* OES extensions */
 255    { "GL_OES_blend_equation_separate",             o(EXT_blend_equation_separate),                  ES1,       2009 },
 256    { "GL_OES_blend_func_separate",                 o(EXT_blend_func_separate),                      ES1,       2009 },
 257    { "GL_OES_blend_subtract",                      o(dummy_true),                                   ES1,       2009 },
 258    { "GL_OES_byte_coordinates",                    o(dummy_true),                                   ES1,       2002 },
 259    { "GL_OES_compressed_ETC1_RGB8_texture",        o(OES_compressed_ETC1_RGB8_texture),             ES1 | ES2, 2005 },
 260    { "GL_OES_compressed_paletted_texture",         o(dummy_true),                                   ES1,       2003 },
 261    { "GL_OES_depth24",                             o(dummy_true),                                   ES1 | ES2, 2005 },
 262    { "GL_OES_depth32",                             o(dummy_false),                     DISABLE,                2005 },
 263    { "GL_OES_depth_texture",                       o(ARB_depth_texture),                                  ES2, 2006 },
 264    { "GL_OES_depth_texture_cube_map",              o(OES_depth_texture_cube_map),                         ES2, 2012 },
 265    { "GL_OES_draw_texture",                        o(OES_draw_texture),                             ES1,       2004 },
 266    /*  FIXME: Mesa expects GL_OES_EGL_image to be available in OpenGL contexts. */
 267    { "GL_OES_EGL_image",                           o(OES_EGL_image),                           GL | ES1 | ES2, 2006 },
 268    { "GL_OES_EGL_image_external",                  o(OES_EGL_image_external),                       ES1 | ES2, 2010 },
 269    { "GL_OES_element_index_uint",                  o(dummy_true),                                   ES1 | ES2, 2005 },
 270    { "GL_OES_fbo_render_mipmap",                   o(dummy_true),                                   ES1 | ES2, 2005 },
 271    { "GL_OES_fixed_point",                         o(dummy_true),                                   ES1,       2002 },
 272    { "GL_OES_framebuffer_object",                  o(dummy_true),                                   ES1,       2005 },
 273    { "GL_OES_get_program_binary",                  o(dummy_true),                                         ES2, 2008 },
 274    { "GL_OES_mapbuffer",                           o(dummy_true),                                   ES1 | ES2, 2005 },
 275    { "GL_OES_packed_depth_stencil",                o(EXT_packed_depth_stencil),                     ES1 | ES2, 2007 },
 276    { "GL_OES_point_size_array",                    o(dummy_true),                                   ES1,       2004 },
 277    { "GL_OES_point_sprite",                        o(ARB_point_sprite),                             ES1,       2004 },
 278    { "GL_OES_query_matrix",                        o(dummy_true),                                   ES1,       2003 },
 279    { "GL_OES_read_format",                         o(dummy_true),                              GL | ES1,       2003 },
 280    { "GL_OES_rgb8_rgba8",                          o(dummy_true),                                   ES1 | ES2, 2005 },
 281    { "GL_OES_single_precision",                    o(dummy_true),                                   ES1,       2003 },
 282    { "GL_OES_standard_derivatives",                o(OES_standard_derivatives),                           ES2, 2005 },
 283    { "GL_OES_stencil1",                            o(dummy_false),                     DISABLE,                2005 },
 284    { "GL_OES_stencil4",                            o(dummy_false),                     DISABLE,                2005 },
 285    { "GL_OES_stencil8",                            o(dummy_true),                                   ES1 | ES2, 2005 },
 286    { "GL_OES_stencil_wrap",                        o(dummy_true),                                   ES1,       2002 },
 287    { "GL_OES_surfaceless_context",                 o(dummy_true),                                   ES1 | ES2, 2012 },
 288    { "GL_OES_texture_3D",                          o(EXT_texture3D),                                      ES2, 2005 },
 289    { "GL_OES_texture_cube_map",                    o(ARB_texture_cube_map),                         ES1,       2007 },
 290    { "GL_OES_texture_env_crossbar",                o(ARB_texture_env_crossbar),                     ES1,       2005 },
 291    { "GL_OES_texture_mirrored_repeat",             o(dummy_true),                                   ES1,       2005 },
 292    { "GL_OES_texture_npot",                        o(ARB_texture_non_power_of_two),                 ES1 | ES2, 2005 },
 293    { "GL_OES_vertex_array_object",                 o(dummy_true),                                   ES1 | ES2, 2010 },
 294
 295    /* KHR extensions */
 296    { "GL_KHR_debug",                               o(dummy_true),                              GL,             2012 },
 297
 298    /* Vendor extensions */
 299    { "GL_3DFX_texture_compression_FXT1",           o(TDFX_texture_compression_FXT1),           GL,             1999 },
 300    { "GL_AMD_conservative_depth",                  o(ARB_conservative_depth),                  GL,             2009 },
 301    { "GL_AMD_draw_buffers_blend",                  o(ARB_draw_buffers_blend),                  GL,             2009 },
 302    { "GL_AMD_performance_monitor",                 o(AMD_performance_monitor),                 GL,             2007 },
 303    { "GL_AMD_seamless_cubemap_per_texture",        o(AMD_seamless_cubemap_per_texture),        GL,             2009 },
 304    { "GL_AMD_shader_stencil_export",               o(ARB_shader_stencil_export),               GL,             2009 },
 305    { "GL_AMD_vertex_shader_layer",                 o(AMD_vertex_shader_layer),                 GLC,            2012 },
 306    { "GL_APPLE_object_purgeable",                  o(APPLE_object_purgeable),                  GL,             2006 },
 307    { "GL_APPLE_packed_pixels",                     o(dummy_true),                              GLL,            2002 },
 308    { "GL_APPLE_texture_max_level",                 o(dummy_true),                                   ES1 | ES2, 2009 },
 309    { "GL_APPLE_vertex_array_object",               o(dummy_true),                              GLL,            2002 },
 310    { "GL_ATI_blend_equation_separate",             o(EXT_blend_equation_separate),             GL,             2003 },
 311    { "GL_ATI_draw_buffers",                        o(dummy_true),                              GLL,            2002 },
 312    { "GL_ATI_envmap_bumpmap",                      o(ATI_envmap_bumpmap),                      GLL,            2001 },
 313    { "GL_ATI_fragment_shader",                     o(ATI_fragment_shader),                     GLL,            2001 },
 314    { "GL_ATI_separate_stencil",                    o(ATI_separate_stencil),                    GLL,            2006 },
 315    { "GL_ATI_texture_compression_3dc",             o(ATI_texture_compression_3dc),             GL,             2004 },
 316    { "GL_ATI_texture_env_combine3",                o(ATI_texture_env_combine3),                GLL,            2002 },
 317    { "GL_ATI_texture_float",                       o(ARB_texture_float),                       GL,             2002 },
 318    { "GL_ATI_texture_mirror_once",                 o(ATI_texture_mirror_once),                 GL,             2006 },
 319    { "GL_IBM_multimode_draw_arrays",               o(dummy_true),                              GL,             1998 },
 320    { "GL_IBM_rasterpos_clip",                      o(dummy_true),                              GLL,            1996 },
 321    { "GL_IBM_texture_mirrored_repeat",             o(dummy_true),                              GLL,            1998 },
 322    { "GL_INGR_blend_func_separate",                o(EXT_blend_func_separate),                 GLL,            1999 },
 323    { "GL_MESA_pack_invert",                        o(MESA_pack_invert),                        GL,             2002 },
 324    { "GL_MESA_texture_signed_rgba",                o(EXT_texture_snorm),                       GL,             2009 },
 325    { "GL_MESA_window_pos",                         o(dummy_true),                              GLL,            2000 },
 326    { "GL_MESA_ycbcr_texture",                      o(MESA_ycbcr_texture),                      GL,             2002 },
 327    { "GL_NV_blend_square",                         o(dummy_true),                              GLL,            1999 },
 328    { "GL_NV_conditional_render",                   o(NV_conditional_render),                   GL,             2008 },
 329    { "GL_NV_depth_clamp",                          o(ARB_depth_clamp),                         GL,             2001 },
 330    { "GL_NV_draw_buffers",                         o(dummy_true),                                         ES2, 2011 },
 331    { "GL_NV_fbo_color_attachments",                o(dummy_true),                                         ES2, 2010 },
 332    { "GL_NV_fog_distance",                         o(NV_fog_distance),                         GLL,            2001 },
 333    { "GL_NV_fragment_program_option",              o(NV_fragment_program_option),              GLL,            2005 },
 334    { "GL_NV_light_max_exponent",                   o(dummy_true),                              GLL,            1999 },
 335    { "GL_NV_packed_depth_stencil",                 o(EXT_packed_depth_stencil),                GL,             2000 },
 336    { "GL_NV_point_sprite",                         o(NV_point_sprite),                         GL,             2001 },
 337    { "GL_NV_primitive_restart",                    o(NV_primitive_restart),                    GLL,            2002 },
 338    { "GL_NV_read_buffer",                          o(dummy_true),                              ES2,            2011 },
 339    { "GL_NV_texgen_reflection",                    o(dummy_true),                              GLL,            1999 },
 340    { "GL_NV_texture_barrier",                      o(NV_texture_barrier),                      GL,             2009 },
 341    { "GL_NV_texture_env_combine4",                 o(NV_texture_env_combine4),                 GLL,            1999 },
 342    { "GL_NV_texture_rectangle",                    o(NV_texture_rectangle),                    GLL,            2000 },
 343    { "GL_NV_vdpau_interop",                        o(NV_vdpau_interop),                        GL,             2010 },
 344    { "GL_S3_s3tc",                                 o(ANGLE_texture_compression_dxt),           GL,             1999 },
 345    { "GL_SGIS_generate_mipmap",                    o(dummy_true),                              GLL,            1997 },
 346    { "GL_SGIS_texture_border_clamp",               o(ARB_texture_border_clamp),                GLL,            1997 },
 347    { "GL_SGIS_texture_edge_clamp",                 o(dummy_true),                              GLL,            1997 },
 348    { "GL_SGIS_texture_lod",                        o(dummy_true),                              GLL,            1997 },
 349    { "GL_SUN_multi_draw_arrays",                   o(dummy_true),                              GLL,            1999 },
 350
 351    { 0, 0, 0, 0 },
 352 };
 353
 354
 355 /**
 356  * Given an extension name, lookup up the corresponding member of struct
 357  * gl_extensions and return that member's offset (in bytes).  If the name is
 358  * not found in the \c extension_table, return 0.
 359  *
 360  * \param name Name of extension.
 361  * \return Offset of member in struct gl_extensions.
 362  */
 363 static size_t
 364 name_to_offset(const char* name)
 365 {
 366    const struct extension *i;
 367
 368    if (name == 0)
 369       return 0;
 370
 371    for (i = extension_table; i->name != 0; ++i) {
 372       if (strcmp(name, i->name) == 0)
 373          return i->offset;
 374    }
 375
 376    return 0;
 377 }
 378
 379
 380 /**
 381  * Enable all extensions suitable for a software-only renderer.
 382  * This is a convenience function used by the XMesa, OSMesa, GGI drivers, etc.
 383  */
 384 void
 385 _mesa_enable_sw_extensions(struct gl_context *ctx)
 386 {
 387    ctx->Extensions.ARB_depth_clamp = GL_TRUE;
 388    ctx->Extensions.ARB_depth_texture = GL_TRUE;
 389    ctx->Extensions.ARB_draw_elements_base_vertex = GL_TRUE;
 390    ctx->Extensions.ARB_draw_instanced = GL_TRUE;
 391    ctx->Extensions.ARB_explicit_attrib_location = GL_TRUE;
 392    ctx->Extensions.ARB_fragment_coord_conventions = GL_TRUE;
 393    ctx->Extensions.ARB_fragment_program = GL_TRUE;
 394    ctx->Extensions.ARB_fragment_program_shadow = GL_TRUE;
 395    ctx->Extensions.ARB_fragment_shader = GL_TRUE;
 396    ctx->Extensions.ARB_framebuffer_object = GL_TRUE;
 397    /* XXX re-enable when GLSL compiler again supports geometry shaders */
 398 #if 0
 399    ctx->Extensions.ARB_geometry_shader4 = GL_TRUE;
 400 #endif
 401    ctx->Extensions.ARB_half_float_pixel = GL_TRUE;
 402    ctx->Extensions.ARB_half_float_vertex = GL_TRUE;
 403    ctx->Extensions.ARB_map_buffer_range = GL_TRUE;
 404    ctx->Extensions.ARB_occlusion_query = GL_TRUE;
 405    ctx->Extensions.ARB_occlusion_query2 = GL_TRUE;
 406    ctx->Extensions.ARB_point_sprite = GL_TRUE;
 407    ctx->Extensions.EXT_separate_shader_objects = GL_TRUE;
 408    ctx->Extensions.ARB_shadow = GL_TRUE;
 409    ctx->Extensions.ARB_texture_border_clamp = GL_TRUE;
 410    ctx->Extensions.ARB_texture_cube_map = GL_TRUE;
 411    ctx->Extensions.ARB_texture_env_combine = GL_TRUE;
 412    ctx->Extensions.ARB_texture_env_crossbar = GL_TRUE;
 413    ctx->Extensions.ARB_texture_env_dot3 = GL_TRUE;
 414 #ifdef TEXTURE_FLOAT_ENABLED
 415    ctx->Extensions.ARB_texture_float = GL_TRUE;
 416 #endif
 417    ctx->Extensions.ARB_texture_mirror_clamp_to_edge = GL_TRUE;
 418    ctx->Extensions.ARB_texture_non_power_of_two = GL_TRUE;
 419    ctx->Extensions.ARB_texture_rg = GL_TRUE;
 420    ctx->Extensions.ARB_texture_compression_rgtc = GL_TRUE;
 421    ctx->Extensions.ARB_vertex_program = GL_TRUE;
 422    ctx->Extensions.ARB_vertex_shader = GL_TRUE;
 423    ctx->Extensions.ARB_sync = GL_TRUE;
 424    ctx->Extensions.APPLE_object_purgeable = GL_TRUE;
 425    ctx->Extensions.ATI_envmap_bumpmap = GL_TRUE;
 426    ctx->Extensions.ATI_fragment_shader = GL_TRUE;
 427    ctx->Extensions.ATI_texture_compression_3dc = GL_TRUE;
 428    ctx->Extensions.ATI_texture_env_combine3 = GL_TRUE;
 429    ctx->Extensions.ATI_texture_mirror_once = GL_TRUE;
 430    ctx->Extensions.ATI_separate_stencil = GL_TRUE;
 431    ctx->Extensions.EXT_blend_color = GL_TRUE;
 432    ctx->Extensions.EXT_blend_equation_separate = GL_TRUE;
 433    ctx->Extensions.EXT_blend_func_separate = GL_TRUE;
 434    ctx->Extensions.EXT_blend_minmax = GL_TRUE;
 435    ctx->Extensions.EXT_depth_bounds_test = GL_TRUE;
 436    ctx->Extensions.EXT_draw_buffers2 = GL_TRUE;
 437    ctx->Extensions.EXT_framebuffer_blit = GL_TRUE;
 438    ctx->Extensions.EXT_packed_depth_stencil = GL_TRUE;
 439    ctx->Extensions.EXT_pixel_buffer_object = GL_TRUE;
 440    ctx->Extensions.EXT_point_parameters = GL_TRUE;
 441    ctx->Extensions.EXT_provoking_vertex = GL_TRUE;
 442    ctx->Extensions.EXT_stencil_two_side = GL_TRUE;
 443    ctx->Extensions.EXT_texture_array = GL_TRUE;
 444    ctx->Extensions.EXT_texture_compression_latc = GL_TRUE;
 445    ctx->Extensions.EXT_texture_env_dot3 = GL_TRUE;
 446    ctx->Extensions.EXT_texture_filter_anisotropic = GL_TRUE;
 447    ctx->Extensions.EXT_texture_mirror_clamp = GL_TRUE;
 448    ctx->Extensions.EXT_texture_shared_exponent = GL_TRUE;
 449    ctx->Extensions.EXT_texture_sRGB = GL_TRUE;
 450    ctx->Extensions.EXT_texture_sRGB_decode = GL_TRUE;
 451    ctx->Extensions.EXT_texture_swizzle = GL_TRUE;
 452    /*ctx->Extensions.EXT_transform_feedback = GL_TRUE;*/
 453    ctx->Extensions.EXT_vertex_array_bgra = GL_TRUE;
 454    ctx->Extensions.MESA_pack_invert = GL_TRUE;
 455    ctx->Extensions.MESA_ycbcr_texture = GL_TRUE;
 456    ctx->Extensions.NV_conditional_render = GL_TRUE;
 457    ctx->Extensions.NV_point_sprite = GL_TRUE;
 458    ctx->Extensions.NV_texture_env_combine4 = GL_TRUE;
 459    ctx->Extensions.NV_texture_rectangle = GL_TRUE;
 460    ctx->Extensions.NV_fragment_program_option = GL_TRUE;
 461    ctx->Extensions.EXT_gpu_program_parameters = GL_TRUE;
 462    ctx->Extensions.OES_standard_derivatives = GL_TRUE;
 463    ctx->Extensions.TDFX_texture_compression_FXT1 = GL_TRUE;
 464    if (ctx->Mesa_DXTn) {
 465       ctx->Extensions.ANGLE_texture_compression_dxt = GL_TRUE;
 466       ctx->Extensions.EXT_texture_compression_s3tc = GL_TRUE;
 467    }
 468 }
 469
 470 /**
 471  * Either enable or disable the named extension.
 472  * \return GL_TRUE for success, GL_FALSE if invalid extension name
 473  */
 474 static GLboolean
 475 set_extension( struct gl_context *ctx, const char *name, GLboolean state )
 476 {
 477    size_t offset;
 478
 479    if (ctx->Extensions.String) {
 480       /* The string was already queried - can't change it now! */
 481       _mesa_problem(ctx, "Trying to enable/disable extension after glGetString(GL_EXTENSIONS): %s", name);
 482       return GL_FALSE;
 483    }
 484
 485    offset = name_to_offset(name);
 486    if (offset == 0) {
 487       _mesa_problem(ctx, "Trying to enable/disable unknown extension %s",
 488                     name);
 489       return GL_FALSE;
 490    } else if (offset == o(dummy_true) && state == GL_FALSE) {
 491       _mesa_problem(ctx, "Trying to disable a permanently enabled extension: "
 492                           "%s", name);
 493       return GL_FALSE;
 494    } else {
 495       GLboolean *base = (GLboolean *) &ctx->Extensions;
 496       base[offset] = state;
 497       return GL_TRUE;
 498    }
 499 }
 500
 501 /**
 502  * \brief Apply the \c MESA_EXTENSION_OVERRIDE environment variable.
 503  *
 504  * \c MESA_EXTENSION_OVERRIDE is a space-separated list of extensions to
 505  * enable or disable. The list is processed thus:
 506  *    - Enable recognized extension names that are prefixed with '+'.
 507  *    - Disable recognized extension names that are prefixed with '-'.
 508  *    - Enable recognized extension names that are not prefixed.
 509  *    - Collect unrecognized extension names in a new string.
 510  *
 511  * \return Space-separated list of unrecognized extension names (which must
 512  *    be freed). Does not return \c NULL.
 513  */
 514 static char *
 515 get_extension_override( struct gl_context *ctx )
 516 {
 517    const char *env_const = _mesa_getenv("MESA_EXTENSION_OVERRIDE");
 518    char *env;
 519    char *ext;
 520    char *extra_exts;
 521    int len;
 522
 523    if (env_const == NULL) {
 524       /* Return the empty string rather than NULL. This simplifies the logic
 525        * of client functions. */
 526       return calloc(4, sizeof(char));
 527    }
 528
 529    /* extra_exts: List of unrecognized extensions. */
 530    extra_exts = calloc(ALIGN(strlen(env_const) + 2, 4), sizeof(char));
 531
 532    /* Copy env_const because strtok() is destructive. */
 533    env = strdup(env_const);
 534    for (ext = strtok(env, " "); ext != NULL; ext = strtok(NULL, " ")) {
 535       int enable;
 536       int recognized;
 537       switch (ext[0]) {
 538       case '+':
 539          enable = 1;
 540          ++ext;
 541          break;
 542       case '-':
 543          enable = 0;
 544          ++ext;
 545          break;
 546       default:
 547          enable = 1;
 548          break;
 549       }
 550       recognized = set_extension(ctx, ext, enable);
 551       if (!recognized) {
 552          strcat(extra_exts, ext);
 553          strcat(extra_exts, " ");
 554       }
 555    }
 556
 557    free(env);
 558
 559    /* Remove trailing space. */
 560    len = strlen(extra_exts);
 561    if (len > 0 && extra_exts[len - 1] == ' ')
 562       extra_exts[len - 1] = '\0';
 563
 564    return extra_exts;
 565 }
 566
 567
 568 /**
 569  * \brief Initialize extension tables and enable default extensions.
 570  *
 571  * This should be called during context initialization.
 572  * Note: Sets gl_extensions.dummy_true to true.
 573  */
 574 void
 575 _mesa_init_extensions( struct gl_context *ctx )
 576 {
 577    GLboolean *base = (GLboolean *) &ctx->Extensions;
 578    GLboolean *sentinel = base + o(extension_sentinel);
 579    GLboolean *i;
 580
 581    /* First, turn all extensions off. */
 582    for (i = base; i != sentinel; ++i)
 583       *i = GL_FALSE;
 584
 585    /* Then, selectively turn default extensions on. */
 586    ctx->Extensions.dummy_true = GL_TRUE;
 587    ctx->Extensions.EXT_texture3D = GL_TRUE;
 588 }
 589
 590
 591 typedef unsigned short extension_index;
 592
 593
 594 /**
 595  * Compare two entries of the extensions table.  Sorts first by year,
 596  * then by name.
 597  *
 598  * Arguments are indices into extension_table.
 599  */
 600 static int
 601 extension_compare(const void *p1, const void *p2)
 602 {
 603    extension_index i1 = * (const extension_index *) p1;
 604    extension_index i2 = * (const extension_index *) p2;
 605    const struct extension *e1 = &extension_table[i1];
 606    const struct extension *e2 = &extension_table[i2];
 607    int res;
 608
 609    res = (int)e1->year - (int)e2->year;
 610
 611    if (res == 0) {
 612       res = strcmp(e1->name, e2->name);
 613    }
 614
 615    return res;
 616 }
 617
 618
 619 /**
 620  * Construct the GL_EXTENSIONS string.  Called the first time that
 621  * glGetString(GL_EXTENSIONS) is called.
 622  */
 623 GLubyte*
 624 _mesa_make_extension_string(struct gl_context *ctx)
 625 {
 626    /* The extension string. */
 627    char *exts = 0;
 628    /* Length of extension string. */
 629    size_t length = 0;
 630    /* Number of extensions */
 631    unsigned count;
 632    /* Indices of the extensions sorted by year */
 633    extension_index *extension_indices;
 634    /* String of extra extensions. */
 635    char *extra_extensions = get_extension_override(ctx);
 636    GLboolean *base = (GLboolean *) &ctx->Extensions;
 637    const struct extension *i;
 638    unsigned j;
 639    unsigned maxYear = ~0;
 640    unsigned api_set = (1 << ctx->API);
 641    if (_mesa_is_gles3(ctx))
 642       api_set |= ES3;
 643
 644    /* Check if the MESA_EXTENSION_MAX_YEAR env var is set */
 645    {
 646       const char *env = getenv("MESA_EXTENSION_MAX_YEAR");
 647       if (env) {
 648          maxYear = atoi(env);
 649          _mesa_debug(ctx, "Note: limiting GL extensions to %u or earlier\n",
 650                      maxYear);
 651       }
 652    }
 653
 654    /* Compute length of the extension string. */
 655    count = 0;
 656    for (i = extension_table; i->name != 0; ++i) {
 657       if (base[i->offset] &&
 658           i->year <= maxYear &&
 659           (i->api_set & api_set)) {
 660          length += strlen(i->name) + 1; /* +1 for space */
 661          ++count;
 662       }
 663    }
 664    if (extra_extensions != NULL)
 665       length += 1 + strlen(extra_extensions); /* +1 for space */
 666
 667    exts = calloc(ALIGN(length + 1, 4), sizeof(char));
 668    if (exts == NULL) {
 669       free(extra_extensions);
 670       return NULL;
 671    }
 672
 673    extension_indices = malloc(count * sizeof(extension_index));
 674    if (extension_indices == NULL) {
 675       free(exts);
 676       free(extra_extensions);
 677       return NULL;
 678    }
 679
 680    /* Sort extensions in chronological order because certain old applications (e.g.,
 681     * Quake3 demo) store the extension list in a static size buffer so chronologically
 682     * order ensure that the extensions that such applications expect will fit into
 683     * that buffer.
 684     */
 685    j = 0;
 686    for (i = extension_table; i->name != 0; ++i) {
 687       if (base[i->offset] &&
 688           i->year <= maxYear &&
 689           (i->api_set & api_set)) {
 690          extension_indices[j++] = i - extension_table;
 691       }
 692    }
 693    assert(j == count);
 694    qsort(extension_indices, count, sizeof *extension_indices, extension_compare);
 695
 696    /* Build the extension string.*/
 697    for (j = 0; j < count; ++j) {
 698       i = &extension_table[extension_indices[j]];
 699       assert(base[i->offset] && (i->api_set & api_set));
 700       strcat(exts, i->name);
 701       strcat(exts, " ");
 702    }
 703    free(extension_indices);
 704    if (extra_extensions != 0) {
 705       strcat(exts, extra_extensions);
 706       free(extra_extensions);
 707    }
 708
 709    return (GLubyte *) exts;
 710 }
 711
 712 /**
 713  * Return number of enabled extensions.
 714  */
 715 GLuint
 716 _mesa_get_extension_count(struct gl_context *ctx)
 717 {
 718    GLboolean *base;
 719    const struct extension *i;
 720    unsigned api_set = (1 << ctx->API);
 721    if (_mesa_is_gles3(ctx))
 722       api_set |= ES3;
 723
 724    /* only count once */
 725    if (ctx->Extensions.Count != 0)
 726       return ctx->Extensions.Count;
 727
 728    base = (GLboolean *) &ctx->Extensions;
 729    for (i = extension_table; i->name != 0; ++i) {
 730       if (base[i->offset] && (i->api_set & api_set)) {
 731          ctx->Extensions.Count++;
 732       }
 733    }
 734    return ctx->Extensions.Count;
 735 }
 736
 737 /**
 738  * Return name of i-th enabled extension
 739  */
 740 const GLubyte *
 741 _mesa_get_enabled_extension(struct gl_context *ctx, GLuint index)
 742 {
 743    const GLboolean *base;
 744    size_t n;
 745    const struct extension *i;
 746    unsigned api_set = (1 << ctx->API);
 747    if (_mesa_is_gles3(ctx))
 748       api_set |= ES3;
 749
 750    base = (GLboolean*) &ctx->Extensions;
 751    n = 0;
 752    for (i = extension_table; i->name != 0; ++i) {
 753       if (base[i->offset] && (i->api_set & api_set)) {
 754          if (n == index)
 755             return (const GLubyte*) i->name;
 756          else
 757             ++n;
 758       }
 759    }
 760
 761    return NULL;
 762 }