src/mesa/main/extensions.c

   1 /*
   2  * Mesa 3-D graphics library
   3  * Version:  7.6
   4  *
   5  * Copyright (C) 1999-2008  Brian Paul   All Rights Reserved.
   6  * Copyright (C) 2009  VMware, Inc.  All Rights Reserved.
   7  *
   8  * Permission is hereby granted, free of charge, to any person obtaining a
   9  * copy of this software and associated documentation files (the "Software"),
  10  * to deal in the Software without restriction, including without limitation
  11  * the rights to use, copy, modify, merge, publish, distribute, sublicense,
  12  * and/or sell copies of the Software, and to permit persons to whom the
  13  * Software is furnished to do so, subject to the following conditions:
  14  *
  15  * The above copyright notice and this permission notice shall be included
  16  * in all copies or substantial portions of the Software.
  17  *
  18  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
  19  * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  20  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
  21  * BRIAN PAUL BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN
  22  * AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
  23  * CONNECTION WITH THE SOFTWARE OR THE USE OR 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 "mfeatures.h"
  38 #include "mtypes.h"
  39
  40 enum {
  41    DISABLE = 0,
  42    GL  = 1 << API_OPENGL,
  43    ES1 = 1 << API_OPENGLES,
  44    ES2 = 1 << API_OPENGLES2,
  45 };
  46
  47 /**
  48  * \brief An element of the \c extension_table.
  49  */
  50 struct extension {
  51    /** Name of extension, such as "GL_ARB_depth_clamp". */
  52    const char *name;
  53
  54    /** Offset (in bytes) of the corresponding member in struct gl_extensions. */
  55    size_t offset;
  56
  57    /** Set of API's in which the extension exists, as a bitset. */
  58    uint8_t api_set;
  59
  60    /** Year the extension was proposed or approved.  Used to sort the
  61     * extension string chronologically. */
  62    uint16_t year;
  63 };
  64
  65
  66 /**
  67  * Given a member \c x of struct gl_extensions, return offset of
  68  * \c x in bytes.
  69  */
  70 #define o(x) offsetof(struct gl_extensions, x)
  71
  72
  73 /**
  74  * \brief Table of supported OpenGL extensions for all API's.
  75  *
  76  * Note: The GL_MESAX_* extensions are placeholders for future ARB extensions.
  77  */
  78 static const struct extension extension_table[] = {
  79    /* ARB Extensions */
  80    { "GL_ARB_ES2_compatibility",                   o(ARB_ES2_compatibility),                   GL,             2009 },
  81    { "GL_ARB_blend_func_extended",                 o(ARB_blend_func_extended),                 GL,             2009 },
  82    { "GL_ARB_color_buffer_float",                  o(ARB_color_buffer_float),                  GL,             2004 },
  83    { "GL_ARB_copy_buffer",                         o(ARB_copy_buffer),                         GL,             2008 },
  84    { "GL_ARB_depth_buffer_float",                  o(ARB_depth_buffer_float),                  GL,             2008 },
  85    { "GL_ARB_depth_clamp",                         o(ARB_depth_clamp),                         GL,             2003 },
  86    { "GL_ARB_depth_texture",                       o(ARB_depth_texture),                       GL,             2001 },
  87    { "GL_ARB_draw_buffers",                        o(ARB_draw_buffers),                        GL,             2002 },
  88    { "GL_ARB_draw_buffers_blend",                  o(ARB_draw_buffers_blend),                  GL,             2009 },
  89    { "GL_ARB_draw_elements_base_vertex",           o(ARB_draw_elements_base_vertex),           GL,             2009 },
  90    { "GL_ARB_draw_instanced",                      o(ARB_draw_instanced),                      GL,             2008 },
  91    { "GL_ARB_explicit_attrib_location",            o(ARB_explicit_attrib_location),            GL,             2009 },
  92    { "GL_ARB_fragment_coord_conventions",          o(ARB_fragment_coord_conventions),          GL,             2009 },
  93    { "GL_ARB_fragment_program",                    o(ARB_fragment_program),                    GL,             2002 },
  94    { "GL_ARB_fragment_program_shadow",             o(ARB_fragment_program_shadow),             GL,             2003 },
  95    { "GL_ARB_fragment_shader",                     o(ARB_fragment_shader),                     GL,             2002 },
  96    { "GL_ARB_framebuffer_object",                  o(ARB_framebuffer_object),                  GL,             2005 },
  97    { "GL_ARB_framebuffer_sRGB",                    o(EXT_framebuffer_sRGB),                    GL,             1998 },
  98    { "GL_ARB_half_float_pixel",                    o(ARB_half_float_pixel),                    GL,             2003 },
  99    { "GL_ARB_half_float_vertex",                   o(ARB_half_float_vertex),                   GL,             2008 },
 100    { "GL_ARB_instanced_arrays",                    o(ARB_instanced_arrays),                    GL,             2008 },
 101    { "GL_ARB_map_buffer_range",                    o(ARB_map_buffer_range),                    GL,             2008 },
 102    { "GL_ARB_multisample",                         o(ARB_multisample),                         GL,             1994 },
 103    { "GL_ARB_multitexture",                        o(ARB_multitexture),                        GL,             1998 },
 104    { "GL_ARB_occlusion_query2",                    o(ARB_occlusion_query2),                    GL,             2003 },
 105    { "GL_ARB_occlusion_query",                     o(ARB_occlusion_query),                     GL,             2001 },
 106    { "GL_ARB_pixel_buffer_object",                 o(EXT_pixel_buffer_object),                 GL,             2004 },
 107    { "GL_ARB_point_parameters",                    o(EXT_point_parameters),                    GL,             1997 },
 108    { "GL_ARB_point_sprite",                        o(ARB_point_sprite),                        GL,             2003 },
 109    { "GL_ARB_provoking_vertex",                    o(EXT_provoking_vertex),                    GL,             2009 },
 110    { "GL_ARB_robustness",                          o(dummy_true),                              GL,             2010 },
 111    { "GL_ARB_sampler_objects",                     o(ARB_sampler_objects),                     GL,             2009 },
 112    { "GL_ARB_seamless_cube_map",                   o(ARB_seamless_cube_map),                   GL,             2009 },
 113    { "GL_ARB_shader_objects",                      o(ARB_shader_objects),                      GL,             2002 },
 114    { "GL_ARB_shader_stencil_export",               o(ARB_shader_stencil_export),               GL,             2009 },
 115    { "GL_ARB_shader_texture_lod",                  o(ARB_shader_texture_lod),                  GL,             2009 },
 116    { "GL_ARB_shading_language_100",                o(ARB_shading_language_100),                GL,             2003 },
 117    { "GL_ARB_shadow_ambient",                      o(ARB_shadow_ambient),                      GL,             2001 },
 118    { "GL_ARB_shadow",                              o(ARB_shadow),                              GL,             2001 },
 119    { "GL_ARB_sync",                                o(ARB_sync),                                GL,             2003 },
 120    { "GL_ARB_texture_border_clamp",                o(ARB_texture_border_clamp),                GL,             2000 },
 121    { "GL_ARB_texture_buffer_object",               o(ARB_texture_buffer_object),               GL,             2008 },
 122    { "GL_ARB_texture_compression",                 o(ARB_texture_compression),                 GL,             2000 },
 123    { "GL_ARB_texture_compression_rgtc",            o(ARB_texture_compression_rgtc),            GL,             2004 },
 124    { "GL_ARB_texture_cube_map",                    o(ARB_texture_cube_map),                    GL,             1999 },
 125    { "GL_ARB_texture_env_add",                     o(EXT_texture_env_add),                     GL,             1999 },
 126    { "GL_ARB_texture_env_combine",                 o(ARB_texture_env_combine),                 GL,             2001 },
 127    { "GL_ARB_texture_env_crossbar",                o(ARB_texture_env_crossbar),                GL,             2001 },
 128    { "GL_ARB_texture_env_dot3",                    o(ARB_texture_env_dot3),                    GL,             2001 },
 129    { "GL_ARB_texture_float",                       o(ARB_texture_float),                       GL,             2004 },
 130    { "GL_ARB_texture_mirrored_repeat",             o(ARB_texture_mirrored_repeat),             GL,             2001 },
 131    { "GL_ARB_texture_multisample",                 o(ARB_texture_multisample),                 GL,             2009 },
 132    { "GL_ARB_texture_non_power_of_two",            o(ARB_texture_non_power_of_two),            GL,             2003 },
 133    { "GL_ARB_texture_rectangle",                   o(NV_texture_rectangle),                    GL,             2004 },
 134    { "GL_ARB_texture_rgb10_a2ui",                  o(ARB_texture_rgb10_a2ui),                  GL,             2009 },
 135    { "GL_ARB_texture_rg",                          o(ARB_texture_rg),                          GL,             2008 },
 136    { "GL_ARB_texture_swizzle",                     o(EXT_texture_swizzle),                     GL,             2008 },
 137    { "GL_ARB_transform_feedback2",                 o(ARB_transform_feedback2),                 GL,             2010 },
 138    { "GL_ARB_transpose_matrix",                    o(ARB_transpose_matrix),                    GL,             1999 },
 139    { "GL_ARB_uniform_buffer_object",               o(ARB_uniform_buffer_object),               GL,             2002 },
 140    { "GL_ARB_vertex_array_bgra",                   o(EXT_vertex_array_bgra),                   GL,             2008 },
 141    { "GL_ARB_vertex_array_object",                 o(ARB_vertex_array_object),                 GL,             2006 },
 142    { "GL_ARB_vertex_buffer_object",                o(ARB_vertex_buffer_object),                GL,             2003 },
 143    { "GL_ARB_vertex_program",                      o(ARB_vertex_program),                      GL,             2002 },
 144    { "GL_ARB_vertex_shader",                       o(ARB_vertex_shader),                       GL,             2002 },
 145    { "GL_ARB_vertex_type_2_10_10_10_rev",          o(ARB_vertex_type_2_10_10_10_rev),          GL,             2009 },
 146    { "GL_ARB_window_pos",                          o(ARB_window_pos),                          GL,             2001 },
 147    /* EXT extensions */
 148    { "GL_EXT_abgr",                                o(EXT_abgr),                                GL,             1995 },
 149    { "GL_EXT_bgra",                                o(EXT_bgra),                                GL,             1995 },
 150    { "GL_EXT_blend_color",                         o(EXT_blend_color),                         GL,             1995 },
 151    { "GL_EXT_blend_equation_separate",             o(EXT_blend_equation_separate),             GL,             2003 },
 152    { "GL_EXT_blend_func_separate",                 o(EXT_blend_func_separate),                 GL,             1999 },
 153    { "GL_EXT_blend_logic_op",                      o(EXT_blend_logic_op),                      GL,             1995 },
 154    { "GL_EXT_blend_minmax",                        o(EXT_blend_minmax),                        GL | ES1 | ES2, 1995 },
 155    { "GL_EXT_blend_subtract",                      o(EXT_blend_subtract),                      GL,             1995 },
 156    { "GL_EXT_clip_volume_hint",                    o(EXT_clip_volume_hint),                    GL,             1996 },
 157    { "GL_EXT_compiled_vertex_array",               o(EXT_compiled_vertex_array),               GL,             1996 },
 158    { "GL_EXT_copy_texture",                        o(EXT_copy_texture),                        GL,             1995 },
 159    { "GL_EXT_depth_bounds_test",                   o(EXT_depth_bounds_test),                   GL,             2002 },
 160    { "GL_EXT_draw_buffers2",                       o(EXT_draw_buffers2),                       GL,             2006 },
 161    { "GL_EXT_draw_instanced",                      o(ARB_draw_instanced),                      GL,             2006 },
 162    { "GL_EXT_draw_range_elements",                 o(EXT_draw_range_elements),                 GL,             1997 },
 163    { "GL_EXT_fog_coord",                           o(EXT_fog_coord),                           GL,             1999 },
 164    { "GL_EXT_framebuffer_blit",                    o(EXT_framebuffer_blit),                    GL,             2005 },
 165    { "GL_EXT_framebuffer_multisample",             o(EXT_framebuffer_multisample),             GL,             2005 },
 166    { "GL_EXT_framebuffer_object",                  o(EXT_framebuffer_object),                  GL,             2000 },
 167    { "GL_EXT_framebuffer_sRGB",                    o(EXT_framebuffer_sRGB),                    GL,             1998 },
 168    { "GL_EXT_gpu_program_parameters",              o(EXT_gpu_program_parameters),              GL,             2006 },
 169    { "GL_EXT_gpu_shader4",                         o(EXT_gpu_shader4),                         GL,             2006 },
 170    { "GL_EXT_multi_draw_arrays",                   o(EXT_multi_draw_arrays),                   GL | ES1 | ES2, 1999 },
 171    { "GL_EXT_packed_depth_stencil",                o(EXT_packed_depth_stencil),                GL,             2005 },
 172    { "GL_EXT_packed_float",                        o(EXT_packed_float),                        GL,             2004 },
 173    { "GL_EXT_packed_pixels",                       o(EXT_packed_pixels),                       GL,             1997 },
 174    { "GL_EXT_paletted_texture",                    o(EXT_paletted_texture),                    GL,             1995 },
 175    { "GL_EXT_pixel_buffer_object",                 o(EXT_pixel_buffer_object),                 GL,             2004 },
 176    { "GL_EXT_point_parameters",                    o(EXT_point_parameters),                    GL,             1997 },
 177    { "GL_EXT_polygon_offset",                      o(EXT_polygon_offset),                      GL,             1995 },
 178    { "GL_EXT_provoking_vertex",                    o(EXT_provoking_vertex),                    GL,             2009 },
 179    { "GL_EXT_rescale_normal",                      o(EXT_rescale_normal),                      GL,             1997 },
 180    { "GL_EXT_secondary_color",                     o(EXT_secondary_color),                     GL,             1999 },
 181    { "GL_EXT_separate_shader_objects",             o(EXT_separate_shader_objects),             GL,             2008 },
 182    { "GL_EXT_separate_specular_color",             o(EXT_separate_specular_color),             GL,             1997 },
 183    { "GL_EXT_shadow_funcs",                        o(EXT_shadow_funcs),                        GL,             2002 },
 184    { "GL_EXT_shared_texture_palette",              o(EXT_shared_texture_palette),              GL,             2000 },
 185    { "GL_EXT_stencil_two_side",                    o(EXT_stencil_two_side),                    GL,             2001 },
 186    { "GL_EXT_stencil_wrap",                        o(EXT_stencil_wrap),                        GL,             2002 },
 187    { "GL_EXT_subtexture",                          o(EXT_subtexture),                          GL,             1995 },
 188    { "GL_EXT_texture3D",                           o(EXT_texture3D),                           GL,             1996 },
 189    { "GL_EXT_texture_array",                       o(EXT_texture_array),                       GL,             2006 },
 190    { "GL_EXT_texture_compression_dxt1",            o(EXT_texture_compression_s3tc),            GL | ES1 | ES2, 2004 },
 191    { "GL_EXT_texture_compression_latc",            o(EXT_texture_compression_latc),            GL,             2006 },
 192    { "GL_EXT_texture_compression_rgtc",            o(ARB_texture_compression_rgtc),            GL,             2004 },
 193    { "GL_EXT_texture_compression_s3tc",            o(EXT_texture_compression_s3tc),            GL,             2000 },
 194    { "GL_EXT_texture_cube_map",                    o(ARB_texture_cube_map),                    GL,             2001 },
 195    { "GL_EXT_texture_edge_clamp",                  o(SGIS_texture_edge_clamp),                 GL,             1997 },
 196    { "GL_EXT_texture_env_add",                     o(EXT_texture_env_add),                     GL,             1999 },
 197    { "GL_EXT_texture_env_combine",                 o(EXT_texture_env_combine),                 GL,             2006 },
 198    { "GL_EXT_texture_env_dot3",                    o(EXT_texture_env_dot3),                    GL,             2000 },
 199    { "GL_EXT_texture_filter_anisotropic",          o(EXT_texture_filter_anisotropic),          GL | ES1 | ES2, 1999 },
 200    { "GL_EXT_texture_format_BGRA8888",             o(EXT_texture_format_BGRA8888),                  ES1 | ES2, 2009 },
 201    { "GL_EXT_texture_integer",                     o(EXT_texture_integer),                     GL,             2006 },
 202    { "GL_EXT_texture_lod_bias",                    o(EXT_texture_lod_bias),                    GL | ES1,       1999 },
 203    { "GL_EXT_texture_mirror_clamp",                o(EXT_texture_mirror_clamp),                GL,             2004 },
 204    { "GL_EXT_texture_object",                      o(EXT_texture_object),                      GL,             1995 },
 205    { "GL_EXT_texture",                             o(EXT_texture),                             GL,             1996 },
 206    { "GL_EXT_texture_rectangle",                   o(NV_texture_rectangle),                    GL,             2004 },
 207    { "GL_EXT_texture_shared_exponent",             o(EXT_texture_shared_exponent),             GL,             2004 },
 208    { "GL_EXT_texture_snorm",                       o(EXT_texture_snorm),                       GL,             2009 },
 209    { "GL_EXT_texture_sRGB",                        o(EXT_texture_sRGB),                        GL,             2004 },
 210    { "GL_EXT_texture_sRGB_decode",                 o(EXT_texture_sRGB_decode),                        GL,      2006 },
 211    { "GL_EXT_texture_swizzle",                     o(EXT_texture_swizzle),                     GL,             2008 },
 212    { "GL_EXT_texture_type_2_10_10_10_REV",         o(dummy_true),                                         ES2, 2008 },
 213    { "GL_EXT_timer_query",                         o(EXT_timer_query),                         GL,             2006 },
 214    { "GL_EXT_transform_feedback",                  o(EXT_transform_feedback),                  GL,             2011 },
 215    { "GL_EXT_vertex_array_bgra",                   o(EXT_vertex_array_bgra),                   GL,             2008 },
 216    { "GL_EXT_vertex_array",                        o(EXT_vertex_array),                        GL,             1995 },
 217    { "GL_EXT_vertex_array_set",                    o(EXT_vertex_array_set),                    GL,             1997 },
 218
 219    /* OES extensions */
 220    { "GL_OES_blend_equation_separate",             o(EXT_blend_equation_separate),                  ES1,       2009 },
 221    { "GL_OES_blend_func_separate",                 o(EXT_blend_func_separate),                      ES1,       2009 },
 222    { "GL_OES_blend_subtract",                      o(EXT_blend_subtract),                           ES1,       2009 },
 223    { "GL_OES_byte_coordinates",                    o(dummy_true),                                   ES1,       2002 },
 224    { "GL_OES_compressed_paletted_texture",         o(dummy_true),                                   ES1,       2003 },
 225    { "GL_OES_depth24",                             o(EXT_framebuffer_object),                       ES1 | ES2, 2005 },
 226    { "GL_OES_depth32",                             o(dummy_false),                     DISABLE,                2005 },
 227    { "GL_OES_depth_texture",                       o(ARB_depth_texture),                                  ES2, 2006 },
 228 #if FEATURE_OES_draw_texture
 229    { "GL_OES_draw_texture",                        o(OES_draw_texture),                             ES1 | ES2, 2004 },
 230 #endif
 231 #if FEATURE_OES_EGL_image
 232    /*  FIXME: Mesa expects GL_OES_EGL_image to be available in OpenGL contexts. */
 233    { "GL_OES_EGL_image",                           o(OES_EGL_image),                           GL | ES1 | ES2, 2006 },
 234 #endif
 235    { "GL_OES_element_index_uint",                  o(EXT_vertex_array),                             ES1 | ES2, 2005 },
 236    { "GL_OES_fbo_render_mipmap",                   o(EXT_framebuffer_object),                       ES1 | ES2, 2005 },
 237    { "GL_OES_fixed_point",                         o(dummy_true),                                   ES1,       2002 },
 238    { "GL_OES_framebuffer_object",                  o(EXT_framebuffer_object),                       ES1,       2005 },
 239    { "GL_OES_mapbuffer",                           o(ARB_vertex_buffer_object),                     ES1 | ES2, 2005 },
 240    { "GL_OES_matrix_get",                          o(dummy_true),                                   ES1,       2004 },
 241    { "GL_OES_packed_depth_stencil",                o(EXT_packed_depth_stencil),                     ES1 | ES2, 2007 },
 242    { "GL_OES_point_size_array",                    o(dummy_true),                                   ES1,       2004 },
 243    { "GL_OES_point_sprite",                        o(ARB_point_sprite),                             ES1,       2004 },
 244    { "GL_OES_query_matrix",                        o(dummy_true),                                   ES1,       2003 },
 245    { "GL_OES_read_format",                         o(OES_read_format),                         GL | ES1,       2003 },
 246    { "GL_OES_rgb8_rgba8",                          o(EXT_framebuffer_object),                       ES1 | ES2, 2005 },
 247    { "GL_OES_single_precision",                    o(dummy_true),                                   ES1,       2003 },
 248    { "GL_OES_standard_derivatives",                o(OES_standard_derivatives),                           ES2, 2005 },
 249    { "GL_OES_stencil1",                            o(dummy_false),                     DISABLE,                2005 },
 250    { "GL_OES_stencil4",                            o(dummy_false),                     DISABLE,                2005 },
 251    { "GL_OES_stencil8",                            o(EXT_framebuffer_object),                       ES1 | ES2, 2005 },
 252    { "GL_OES_stencil_wrap",                        o(EXT_stencil_wrap),                             ES1,       2002 },
 253    { "GL_OES_texture_3D",                          o(EXT_texture3D),                                      ES2, 2005 },
 254    { "GL_OES_texture_cube_map",                    o(ARB_texture_cube_map),                         ES1,       2007 },
 255    { "GL_OES_texture_env_crossbar",                o(ARB_texture_env_crossbar),                     ES1,       2005 },
 256    { "GL_OES_texture_mirrored_repeat",             o(ARB_texture_mirrored_repeat),                  ES1,       2005 },
 257    { "GL_OES_texture_npot",                        o(ARB_texture_non_power_of_two),                       ES2, 2005 },
 258
 259    /* Vendor extensions */
 260    { "GL_3DFX_texture_compression_FXT1",           o(TDFX_texture_compression_FXT1),           GL,             1999 },
 261    { "GL_AMD_conservative_depth",                  o(AMD_conservative_depth),                  GL,             2009 },
 262    { "GL_AMD_draw_buffers_blend",                  o(ARB_draw_buffers_blend),                  GL,             2009 },
 263    { "GL_AMD_seamless_cubemap_per_texture",        o(AMD_seamless_cubemap_per_texture),        GL,             2009 },
 264    { "GL_AMD_shader_stencil_export",               o(ARB_shader_stencil_export),               GL,             2009 },
 265    { "GL_APPLE_client_storage",                    o(APPLE_client_storage),                    GL,             2002 },
 266    { "GL_APPLE_object_purgeable",                  o(APPLE_object_purgeable),                  GL,             2006 },
 267    { "GL_APPLE_packed_pixels",                     o(APPLE_packed_pixels),                     GL,             2002 },
 268    { "GL_APPLE_vertex_array_object",               o(APPLE_vertex_array_object),               GL,             2002 },
 269    { "GL_ATI_blend_equation_separate",             o(EXT_blend_equation_separate),             GL,             2003 },
 270    { "GL_ATI_draw_buffers",                        o(ARB_draw_buffers),                        GL,             2002 },
 271    { "GL_ATI_envmap_bumpmap",                      o(ATI_envmap_bumpmap),                      GL,             2001 },
 272    { "GL_ATI_fragment_shader",                     o(ATI_fragment_shader),                     GL,             2001 },
 273    { "GL_ATI_separate_stencil",                    o(ATI_separate_stencil),                    GL,             2006 },
 274    { "GL_ATI_texture_compression_3dc",             o(ATI_texture_compression_3dc),             GL,             2004 },
 275    { "GL_ATI_texture_env_combine3",                o(ATI_texture_env_combine3),                GL,             2002 },
 276    { "GL_ATI_texture_float",                       o(ARB_texture_float),                       GL,             2002 },
 277    { "GL_ATI_texture_mirror_once",                 o(ATI_texture_mirror_once),                 GL,             2006 },
 278    { "GL_IBM_multimode_draw_arrays",               o(IBM_multimode_draw_arrays),               GL,             1998 },
 279    { "GL_IBM_rasterpos_clip",                      o(IBM_rasterpos_clip),                      GL,             1996 },
 280    { "GL_IBM_texture_mirrored_repeat",             o(ARB_texture_mirrored_repeat),             GL,             1998 },
 281    { "GL_INGR_blend_func_separate",                o(EXT_blend_func_separate),                 GL,             1999 },
 282    { "GL_MESA_pack_invert",                        o(MESA_pack_invert),                        GL,             2002 },
 283    { "GL_MESA_resize_buffers",                     o(MESA_resize_buffers),                     GL,             1999 },
 284    { "GL_MESA_texture_array",                      o(MESA_texture_array),                      GL,             2007 },
 285    { "GL_MESA_texture_signed_rgba",                o(EXT_texture_snorm),                       GL,             2009 },
 286    { "GL_MESA_window_pos",                         o(ARB_window_pos),                          GL,             2000 },
 287    { "GL_MESA_ycbcr_texture",                      o(MESA_ycbcr_texture),                      GL,             2002 },
 288    { "GL_NV_blend_square",                         o(NV_blend_square),                         GL,             1999 },
 289    { "GL_NV_conditional_render",                   o(NV_conditional_render),                   GL,             2008 },
 290    { "GL_NV_depth_clamp",                          o(ARB_depth_clamp),                         GL,             2001 },
 291    { "GL_NV_fragment_program",                     o(NV_fragment_program),                     GL,             2001 },
 292    { "GL_NV_fragment_program_option",              o(NV_fragment_program_option),              GL,             2005 },
 293    { "GL_NV_light_max_exponent",                   o(NV_light_max_exponent),                   GL,             1999 },
 294    { "GL_NV_packed_depth_stencil",                 o(EXT_packed_depth_stencil),                GL,             2000 },
 295    { "GL_NV_point_sprite",                         o(NV_point_sprite),                         GL,             2001 },
 296    { "GL_NV_primitive_restart",                    o(NV_primitive_restart),                    GL,             2002 },
 297    { "GL_NV_texgen_reflection",                    o(NV_texgen_reflection),                    GL,             1999 },
 298    { "GL_NV_texture_barrier",                      o(NV_texture_barrier),                      GL,             2009 },
 299    { "GL_NV_texture_env_combine4",                 o(NV_texture_env_combine4),                 GL,             1999 },
 300    { "GL_NV_texture_rectangle",                    o(NV_texture_rectangle),                    GL,             2000 },
 301    { "GL_NV_vertex_program1_1",                    o(NV_vertex_program1_1),                    GL,             2001 },
 302    { "GL_NV_vertex_program",                       o(NV_vertex_program),                       GL,             2000 },
 303    { "GL_S3_s3tc",                                 o(S3_s3tc),                                 GL,             1999 },
 304    { "GL_SGIS_generate_mipmap",                    o(SGIS_generate_mipmap),                    GL,             1997 },
 305    { "GL_SGIS_texture_border_clamp",               o(ARB_texture_border_clamp),                GL,             1997 },
 306    { "GL_SGIS_texture_edge_clamp",                 o(SGIS_texture_edge_clamp),                 GL,             1997 },
 307    { "GL_SGIS_texture_lod",                        o(SGIS_texture_lod),                        GL,             1997 },
 308    { "GL_SUN_multi_draw_arrays",                   o(EXT_multi_draw_arrays),                   GL,             1999 },
 309
 310    { 0, 0, 0, 0 },
 311 };
 312
 313
 314 /**
 315  * Given an extension name, lookup up the corresponding member of struct
 316  * gl_extensions and return that member's offset (in bytes).  If the name is
 317  * not found in the \c extension_table, return 0.
 318  *
 319  * \param name Name of extension.
 320  * \return Offset of member in struct gl_extensions.
 321  */
 322 static size_t
 323 name_to_offset(const char* name)
 324 {
 325    const struct extension *i;
 326
 327    if (name == 0)
 328       return 0;
 329
 330    for (i = extension_table; i->name != 0; ++i) {
 331       if (strcmp(name, i->name) == 0)
 332          return i->offset;
 333    }
 334
 335    return 0;
 336 }
 337
 338
 339 /**
 340  * \brief Extensions enabled by default.
 341  *
 342  * These extensions are enabled by _mesa_init_extensions().
 343  *
 344  * XXX: Should these defaults also apply to GLES?
 345  */
 346 static const size_t default_extensions[] = {
 347    o(ARB_copy_buffer),
 348    o(ARB_draw_buffers),
 349    o(ARB_multisample),
 350    o(ARB_texture_compression),
 351    o(ARB_transpose_matrix),
 352    o(ARB_vertex_buffer_object),
 353    o(ARB_window_pos),
 354
 355    o(EXT_abgr),
 356    o(EXT_bgra),
 357    o(EXT_compiled_vertex_array),
 358    o(EXT_copy_texture),
 359    o(EXT_draw_range_elements),
 360    o(EXT_multi_draw_arrays),
 361    o(EXT_packed_pixels),
 362    o(EXT_polygon_offset),
 363    o(EXT_rescale_normal),
 364    o(EXT_separate_specular_color),
 365    o(EXT_subtexture),
 366    o(EXT_texture),
 367    o(EXT_texture3D),
 368    o(EXT_texture_object),
 369    o(EXT_vertex_array),
 370
 371    o(OES_read_format),
 372    o(OES_standard_derivatives),
 373
 374    /* Vendor Extensions */
 375    o(APPLE_packed_pixels),
 376    o(IBM_multimode_draw_arrays),
 377    o(IBM_rasterpos_clip),
 378    o(NV_light_max_exponent),
 379    o(NV_texgen_reflection),
 380    o(SGIS_generate_mipmap),
 381    o(SGIS_texture_edge_clamp),
 382    o(SGIS_texture_lod),
 383
 384    0,
 385 };
 386
 387
 388 /**
 389  * Enable all extensions suitable for a software-only renderer.
 390  * This is a convenience function used by the XMesa, OSMesa, GGI drivers, etc.
 391  */
 392 void
 393 _mesa_enable_sw_extensions(struct gl_context *ctx)
 394 {
 395    /*ctx->Extensions.ARB_copy_buffer = GL_TRUE;*/
 396    ctx->Extensions.ARB_depth_clamp = GL_TRUE;
 397    ctx->Extensions.ARB_depth_texture = GL_TRUE;
 398    /*ctx->Extensions.ARB_draw_buffers = GL_TRUE;*/
 399    ctx->Extensions.ARB_draw_elements_base_vertex = GL_TRUE;
 400    ctx->Extensions.ARB_draw_instanced = GL_TRUE;
 401    ctx->Extensions.ARB_explicit_attrib_location = GL_TRUE;
 402    ctx->Extensions.ARB_fragment_coord_conventions = GL_TRUE;
 403 #if FEATURE_ARB_fragment_program
 404    ctx->Extensions.ARB_fragment_program = GL_TRUE;
 405    ctx->Extensions.ARB_fragment_program_shadow = GL_TRUE;
 406 #endif
 407 #if FEATURE_ARB_fragment_shader
 408    ctx->Extensions.ARB_fragment_shader = GL_TRUE;
 409 #endif
 410 #if FEATURE_ARB_framebuffer_object
 411    ctx->Extensions.ARB_framebuffer_object = GL_TRUE;
 412 #endif
 413 #if FEATURE_ARB_geometry_shader4 && 0
 414    /* XXX re-enable when GLSL compiler again supports geometry shaders */
 415    ctx->Extensions.ARB_geometry_shader4 = GL_TRUE;
 416 #endif
 417    ctx->Extensions.ARB_half_float_pixel = GL_TRUE;
 418    ctx->Extensions.ARB_half_float_vertex = GL_TRUE;
 419    ctx->Extensions.ARB_map_buffer_range = GL_TRUE;
 420    ctx->Extensions.ARB_multitexture = GL_TRUE;
 421 #if FEATURE_queryobj
 422    ctx->Extensions.ARB_occlusion_query = GL_TRUE;
 423    ctx->Extensions.ARB_occlusion_query2 = GL_TRUE;
 424 #endif
 425    ctx->Extensions.ARB_point_sprite = GL_TRUE;
 426 #if FEATURE_ARB_shader_objects
 427    ctx->Extensions.ARB_shader_objects = GL_TRUE;
 428    ctx->Extensions.EXT_separate_shader_objects = GL_TRUE;
 429 #endif
 430 #if FEATURE_ARB_shading_language_100
 431    ctx->Extensions.ARB_shading_language_100 = GL_TRUE;
 432 #endif
 433    ctx->Extensions.ARB_shadow = GL_TRUE;
 434    ctx->Extensions.ARB_shadow_ambient = GL_TRUE;
 435    ctx->Extensions.ARB_texture_border_clamp = GL_TRUE;
 436    ctx->Extensions.ARB_texture_cube_map = GL_TRUE;
 437    ctx->Extensions.ARB_texture_env_combine = GL_TRUE;
 438    ctx->Extensions.ARB_texture_env_crossbar = GL_TRUE;
 439    ctx->Extensions.ARB_texture_env_dot3 = GL_TRUE;
 440    /*ctx->Extensions.ARB_texture_float = GL_TRUE;*/
 441    ctx->Extensions.ARB_texture_mirrored_repeat = GL_TRUE;
 442    ctx->Extensions.ARB_texture_non_power_of_two = GL_TRUE;
 443    ctx->Extensions.ARB_texture_rg = GL_TRUE;
 444    ctx->Extensions.ARB_texture_compression_rgtc = GL_TRUE;
 445    ctx->Extensions.ARB_vertex_array_object = GL_TRUE;
 446 #if FEATURE_ARB_vertex_program
 447    ctx->Extensions.ARB_vertex_program = GL_TRUE;
 448 #endif
 449 #if FEATURE_ARB_vertex_shader
 450    ctx->Extensions.ARB_vertex_shader = GL_TRUE;
 451 #endif
 452 #if FEATURE_ARB_vertex_buffer_object
 453    /*ctx->Extensions.ARB_vertex_buffer_object = GL_TRUE;*/
 454 #endif
 455 #if FEATURE_ARB_sync
 456    ctx->Extensions.ARB_sync = GL_TRUE;
 457 #endif
 458    ctx->Extensions.APPLE_vertex_array_object = GL_TRUE;
 459 #if FEATURE_APPLE_object_purgeable
 460    ctx->Extensions.APPLE_object_purgeable = GL_TRUE;
 461 #endif
 462    ctx->Extensions.ATI_envmap_bumpmap = GL_TRUE;
 463 #if FEATURE_ATI_fragment_shader
 464    ctx->Extensions.ATI_fragment_shader = GL_TRUE;
 465 #endif
 466    ctx->Extensions.ATI_texture_compression_3dc = GL_TRUE;
 467    ctx->Extensions.ATI_texture_env_combine3 = GL_TRUE;
 468    ctx->Extensions.ATI_texture_mirror_once = GL_TRUE;
 469    ctx->Extensions.ATI_separate_stencil = GL_TRUE;
 470    ctx->Extensions.EXT_blend_color = GL_TRUE;
 471    ctx->Extensions.EXT_blend_equation_separate = GL_TRUE;
 472    ctx->Extensions.EXT_blend_func_separate = GL_TRUE;
 473    ctx->Extensions.EXT_blend_logic_op = GL_TRUE;
 474    ctx->Extensions.EXT_blend_minmax = GL_TRUE;
 475    ctx->Extensions.EXT_blend_subtract = GL_TRUE;
 476    ctx->Extensions.EXT_depth_bounds_test = GL_TRUE;
 477    ctx->Extensions.EXT_draw_buffers2 = GL_TRUE;
 478    ctx->Extensions.EXT_fog_coord = GL_TRUE;
 479 #if FEATURE_EXT_framebuffer_object
 480    ctx->Extensions.EXT_framebuffer_object = GL_TRUE;
 481 #endif
 482 #if FEATURE_EXT_framebuffer_blit
 483    ctx->Extensions.EXT_framebuffer_blit = GL_TRUE;
 484 #endif
 485 #if FEATURE_ARB_framebuffer_object
 486    ctx->Extensions.EXT_framebuffer_multisample = GL_TRUE;
 487 #endif
 488    /*ctx->Extensions.EXT_multi_draw_arrays = GL_TRUE;*/
 489    ctx->Extensions.EXT_packed_depth_stencil = GL_TRUE;
 490    ctx->Extensions.EXT_paletted_texture = GL_TRUE;
 491 #if FEATURE_EXT_pixel_buffer_object
 492    ctx->Extensions.EXT_pixel_buffer_object = GL_TRUE;
 493 #endif
 494    ctx->Extensions.EXT_point_parameters = GL_TRUE;
 495    ctx->Extensions.EXT_provoking_vertex = GL_TRUE;
 496    ctx->Extensions.EXT_shadow_funcs = GL_TRUE;
 497    ctx->Extensions.EXT_secondary_color = GL_TRUE;
 498    ctx->Extensions.EXT_shared_texture_palette = GL_TRUE;
 499    ctx->Extensions.EXT_stencil_wrap = GL_TRUE;
 500    ctx->Extensions.EXT_stencil_two_side = GL_TRUE;
 501    ctx->Extensions.EXT_texture_array = GL_TRUE;
 502    ctx->Extensions.EXT_texture_compression_latc = GL_TRUE;
 503    ctx->Extensions.EXT_texture_env_add = GL_TRUE;
 504    ctx->Extensions.EXT_texture_env_combine = GL_TRUE;
 505    ctx->Extensions.EXT_texture_env_dot3 = GL_TRUE;
 506    ctx->Extensions.EXT_texture_filter_anisotropic = GL_TRUE;
 507    ctx->Extensions.EXT_texture_mirror_clamp = GL_TRUE;
 508    ctx->Extensions.EXT_texture_lod_bias = GL_TRUE;
 509    ctx->Extensions.EXT_texture_shared_exponent = GL_TRUE;
 510 #if FEATURE_EXT_texture_sRGB
 511    ctx->Extensions.EXT_texture_sRGB = GL_TRUE;
 512    ctx->Extensions.EXT_texture_sRGB_decode = GL_TRUE;
 513 #endif
 514    ctx->Extensions.EXT_texture_swizzle = GL_TRUE;
 515 #if FEATURE_EXT_transform_feedback
 516    /*ctx->Extensions.EXT_transform_feedback = GL_TRUE;*/
 517 #endif
 518    ctx->Extensions.EXT_vertex_array_bgra = GL_TRUE;
 519    /*ctx->Extensions.IBM_multimode_draw_arrays = GL_TRUE;*/
 520    ctx->Extensions.MESA_pack_invert = GL_TRUE;
 521    ctx->Extensions.MESA_resize_buffers = GL_TRUE;
 522    ctx->Extensions.MESA_texture_array = GL_TRUE;
 523    ctx->Extensions.MESA_ycbcr_texture = GL_TRUE;
 524    ctx->Extensions.NV_blend_square = GL_TRUE;
 525    ctx->Extensions.NV_conditional_render = GL_TRUE;
 526    /*ctx->Extensions.NV_light_max_exponent = GL_TRUE;*/
 527    ctx->Extensions.NV_point_sprite = GL_TRUE;
 528    ctx->Extensions.NV_texture_env_combine4 = GL_TRUE;
 529    ctx->Extensions.NV_texture_rectangle = GL_TRUE;
 530    /*ctx->Extensions.NV_texgen_reflection = GL_TRUE;*/
 531 #if FEATURE_NV_vertex_program
 532    ctx->Extensions.NV_vertex_program = GL_TRUE;
 533    ctx->Extensions.NV_vertex_program1_1 = GL_TRUE;
 534 #endif
 535 #if FEATURE_NV_fragment_program
 536    ctx->Extensions.NV_fragment_program = GL_TRUE;
 537 #endif
 538 #if FEATURE_NV_fragment_program && FEATURE_ARB_fragment_program
 539    ctx->Extensions.NV_fragment_program_option = GL_TRUE;
 540 #endif
 541    /*ctx->Extensions.SGIS_generate_mipmap = GL_TRUE;*/
 542    ctx->Extensions.SGIS_texture_edge_clamp = GL_TRUE;
 543 #if FEATURE_ARB_vertex_program || FEATURE_ARB_fragment_program
 544    ctx->Extensions.EXT_gpu_program_parameters = GL_TRUE;
 545 #endif
 546 #if FEATURE_texture_fxt1
 547    _mesa_enable_extension(ctx, "GL_3DFX_texture_compression_FXT1");
 548 #endif
 549 #if FEATURE_texture_s3tc
 550    if (ctx->Mesa_DXTn) {
 551       _mesa_enable_extension(ctx, "GL_EXT_texture_compression_s3tc");
 552       _mesa_enable_extension(ctx, "GL_S3_s3tc");
 553    }
 554 #endif
 555 }
 556
 557
 558 /**
 559  * Enable common EXT extensions in the ARB_imaging subset.
 560  */
 561 void
 562 _mesa_enable_imaging_extensions(struct gl_context *ctx)
 563 {
 564    ctx->Extensions.EXT_blend_color = GL_TRUE;
 565    ctx->Extensions.EXT_blend_logic_op = GL_TRUE;
 566    ctx->Extensions.EXT_blend_minmax = GL_TRUE;
 567    ctx->Extensions.EXT_blend_subtract = GL_TRUE;
 568 }
 569
 570
 571
 572 /**
 573  * Enable all OpenGL 1.3 features and extensions.
 574  * A convenience function to be called by drivers.
 575  */
 576 void
 577 _mesa_enable_1_3_extensions(struct gl_context *ctx)
 578 {
 579    /*ctx->Extensions.ARB_multisample = GL_TRUE;*/
 580    ctx->Extensions.ARB_multitexture = GL_TRUE;
 581    ctx->Extensions.ARB_texture_border_clamp = GL_TRUE;
 582    /*ctx->Extensions.ARB_texture_compression = GL_TRUE;*/
 583    ctx->Extensions.ARB_texture_cube_map = GL_TRUE;
 584    ctx->Extensions.ARB_texture_env_combine = GL_TRUE;
 585    ctx->Extensions.ARB_texture_env_dot3 = GL_TRUE;
 586    ctx->Extensions.EXT_texture_env_add = GL_TRUE;
 587    /*ctx->Extensions.ARB_transpose_matrix = GL_TRUE;*/
 588 }
 589
 590
 591
 592 /**
 593  * Enable all OpenGL 1.4 features and extensions.
 594  * A convenience function to be called by drivers.
 595  */
 596 void
 597 _mesa_enable_1_4_extensions(struct gl_context *ctx)
 598 {
 599    ctx->Extensions.ARB_depth_texture = GL_TRUE;
 600    ctx->Extensions.ARB_shadow = GL_TRUE;
 601    ctx->Extensions.ARB_texture_env_crossbar = GL_TRUE;
 602    ctx->Extensions.ARB_texture_mirrored_repeat = GL_TRUE;
 603    ctx->Extensions.ARB_window_pos = GL_TRUE;
 604    ctx->Extensions.EXT_blend_color = GL_TRUE;
 605    ctx->Extensions.EXT_blend_func_separate = GL_TRUE;
 606    ctx->Extensions.EXT_blend_minmax = GL_TRUE;
 607    ctx->Extensions.EXT_blend_subtract = GL_TRUE;
 608    ctx->Extensions.EXT_fog_coord = GL_TRUE;
 609    /*ctx->Extensions.EXT_multi_draw_arrays = GL_TRUE;*/
 610    ctx->Extensions.EXT_point_parameters = GL_TRUE;
 611    ctx->Extensions.EXT_secondary_color = GL_TRUE;
 612    ctx->Extensions.EXT_stencil_wrap = GL_TRUE;
 613    ctx->Extensions.EXT_texture_lod_bias = GL_TRUE;
 614    /*ctx->Extensions.SGIS_generate_mipmap = GL_TRUE;*/
 615 }
 616
 617
 618 /**
 619  * Enable all OpenGL 1.5 features and extensions.
 620  * A convenience function to be called by drivers.
 621  */
 622 void
 623 _mesa_enable_1_5_extensions(struct gl_context *ctx)
 624 {
 625    ctx->Extensions.ARB_occlusion_query = GL_TRUE;
 626    /*ctx->Extensions.ARB_vertex_buffer_object = GL_TRUE;*/
 627    ctx->Extensions.EXT_shadow_funcs = GL_TRUE;
 628 }
 629
 630
 631 /**
 632  * Enable all OpenGL 2.0 features and extensions.
 633  * A convenience function to be called by drivers.
 634  */
 635 void
 636 _mesa_enable_2_0_extensions(struct gl_context *ctx)
 637 {
 638    /*ctx->Extensions.ARB_draw_buffers = GL_TRUE;*/
 639 #if FEATURE_ARB_fragment_shader
 640    ctx->Extensions.ARB_fragment_shader = GL_TRUE;
 641 #endif
 642    ctx->Extensions.ARB_point_sprite = GL_TRUE;
 643    ctx->Extensions.EXT_blend_equation_separate = GL_TRUE;
 644    ctx->Extensions.ARB_texture_non_power_of_two = GL_TRUE;
 645 #if FEATURE_ARB_shader_objects
 646    ctx->Extensions.ARB_shader_objects = GL_TRUE;
 647 #endif
 648 #if FEATURE_ARB_shading_language_100
 649    ctx->Extensions.ARB_shading_language_100 = GL_TRUE;
 650 #endif
 651    ctx->Extensions.EXT_stencil_two_side = GL_TRUE;
 652 #if FEATURE_ARB_vertex_shader
 653    ctx->Extensions.ARB_vertex_shader = GL_TRUE;
 654 #endif
 655 }
 656
 657
 658 /**
 659  * Enable all OpenGL 2.1 features and extensions.
 660  * A convenience function to be called by drivers.
 661  */
 662 void
 663 _mesa_enable_2_1_extensions(struct gl_context *ctx)
 664 {
 665 #if FEATURE_EXT_pixel_buffer_object
 666    ctx->Extensions.EXT_pixel_buffer_object = GL_TRUE;
 667 #endif
 668 #if FEATURE_EXT_texture_sRGB
 669    ctx->Extensions.EXT_texture_sRGB = GL_TRUE;
 670 #endif
 671 }
 672
 673
 674 /**
 675  * Either enable or disable the named extension.
 676  * \return GL_TRUE for success, GL_FALSE if invalid extension name
 677  */
 678 static GLboolean
 679 set_extension( struct gl_context *ctx, const char *name, GLboolean state )
 680 {
 681    size_t offset;
 682
 683    if (ctx->Extensions.String) {
 684       /* The string was already queried - can't change it now! */
 685       _mesa_problem(ctx, "Trying to enable/disable extension after glGetString(GL_EXTENSIONS): %s", name);
 686       return GL_FALSE;
 687    }
 688
 689    offset = name_to_offset(name);
 690    if (offset == 0) {
 691       _mesa_problem(ctx, "Trying to enable/disable unknown extension %s",
 692                     name);
 693       return GL_FALSE;
 694    } else if (offset == o(dummy_true) && state == GL_FALSE) {
 695       _mesa_problem(ctx, "Trying to disable a permanently enabled extension: "
 696                           "%s", name);
 697       return GL_FALSE;
 698    } else {
 699       GLboolean *base = (GLboolean *) &ctx->Extensions;
 700       base[offset] = state;
 701       return GL_TRUE;
 702    }
 703 }
 704
 705
 706 /**
 707  * Enable the named extension.
 708  * Typically called by drivers.
 709  */
 710 void
 711 _mesa_enable_extension( struct gl_context *ctx, const char *name )
 712 {
 713    if (!set_extension(ctx, name, GL_TRUE))
 714       _mesa_problem(ctx, "Trying to enable unknown extension: %s", name);
 715 }
 716
 717
 718 /**
 719  * Disable the named extension.
 720  * XXX is this really needed???
 721  */
 722 void
 723 _mesa_disable_extension( struct gl_context *ctx, const char *name )
 724 {
 725    if (!set_extension(ctx, name, GL_FALSE))
 726       _mesa_problem(ctx, "Trying to disable unknown extension: %s", name);
 727 }
 728
 729
 730 /**
 731  * Test if the named extension is enabled in this context.
 732  */
 733 GLboolean
 734 _mesa_extension_is_enabled( struct gl_context *ctx, const char *name )
 735 {
 736    size_t offset;
 737    GLboolean *base;
 738
 739    if (name == 0)
 740       return GL_FALSE;
 741
 742    offset = name_to_offset(name);
 743    if (offset == 0)
 744       return GL_FALSE;
 745    base = (GLboolean *) &ctx->Extensions;
 746    return base[offset];
 747 }
 748
 749
 750 /**
 751  * \brief Apply the \c MESA_EXTENSION_OVERRIDE environment variable.
 752  *
 753  * \c MESA_EXTENSION_OVERRIDE is a space-separated list of extensions to
 754  * enable or disable. The list is processed thus:
 755  *    - Enable recognized extension names that are prefixed with '+'.
 756  *    - Disable recognized extension names that are prefixed with '-'.
 757  *    - Enable recognized extension names that are not prefixed.
 758  *    - Collect unrecognized extension names in a new string.
 759  *
 760  * \return Space-separated list of unrecognized extension names (which must
 761  *    be freed). Does not return \c NULL.
 762  */
 763 static char *
 764 get_extension_override( struct gl_context *ctx )
 765 {
 766    const char *env_const = _mesa_getenv("MESA_EXTENSION_OVERRIDE");
 767    char *env;
 768    char *ext;
 769    char *extra_exts;
 770    int len;
 771
 772    if (env_const == NULL) {
 773       /* Return the empty string rather than NULL. This simplifies the logic
 774        * of client functions. */
 775       return calloc(1, sizeof(char));
 776    }
 777
 778    /* extra_exts: List of unrecognized extensions. */
 779    extra_exts = calloc(strlen(env_const), sizeof(char));
 780
 781    /* Copy env_const because strtok() is destructive. */
 782    env = strdup(env_const);
 783    for (ext = strtok(env, " "); ext != NULL; ext = strtok(NULL, " ")) {
 784       int enable;
 785       int recognized;
 786       switch (ext[0]) {
 787       case '+':
 788          enable = 1;
 789          ++ext;
 790          break;
 791       case '-':
 792          enable = 0;
 793          ++ext;
 794          break;
 795       default:
 796          enable = 1;
 797          break;
 798       }
 799       recognized = set_extension(ctx, ext, enable);
 800       if (!recognized) {
 801          strcat(extra_exts, ext);
 802          strcat(extra_exts, " ");
 803       }
 804    }
 805
 806    /* Remove trailing space. */
 807    len = strlen(extra_exts);
 808    if (extra_exts[len - 1] == ' ')
 809       extra_exts[len - 1] = '\0';
 810
 811    return extra_exts;
 812 }
 813
 814
 815 /**
 816  * \brief Initialize extension tables and enable default extensions.
 817  *
 818  * This should be called during context initialization.
 819  * Note: Sets gl_extensions.dummy_true to true.
 820  */
 821 void
 822 _mesa_init_extensions( struct gl_context *ctx )
 823 {
 824    GLboolean *base = (GLboolean *) &ctx->Extensions;
 825    GLboolean *sentinel = base + o(extension_sentinel);
 826    GLboolean *i;
 827    const size_t *j;
 828
 829    /* First, turn all extensions off. */
 830    for (i = base; i != sentinel; ++i)
 831       *i = GL_FALSE;
 832
 833    /* Then, selectively turn default extensions on. */
 834    ctx->Extensions.dummy_true = GL_TRUE;
 835    for (j = default_extensions; *j != 0; ++j)
 836       base[*j] = GL_TRUE;
 837 }
 838
 839
 840 typedef unsigned short extension_index;
 841
 842
 843 /**
 844  * Compare two entries of the extensions table.  Sorts first by year,
 845  * then by name.
 846  *
 847  * Arguments are indices into extension_table.
 848  */
 849 static int
 850 extension_compare(const void *p1, const void *p2)
 851 {
 852    extension_index i1 = * (const extension_index *) p1;
 853    extension_index i2 = * (const extension_index *) p2;
 854    const struct extension *e1 = &extension_table[i1];
 855    const struct extension *e2 = &extension_table[i2];
 856    int res;
 857
 858    res = (int)e1->year - (int)e2->year;
 859
 860    if (res == 0) {
 861       res = strcmp(e1->name, e2->name);
 862    }
 863
 864    return res;
 865 }
 866
 867
 868 /**
 869  * Construct the GL_EXTENSIONS string.  Called the first time that
 870  * glGetString(GL_EXTENSIONS) is called.
 871  */
 872 GLubyte*
 873 _mesa_make_extension_string(struct gl_context *ctx)
 874 {
 875    /* The extension string. */
 876    char *exts = 0;
 877    /* Length of extension string. */
 878    size_t length = 0;
 879    /* Number of extensions */
 880    unsigned count;
 881    /* Indices of the extensions sorted by year */
 882    extension_index *extension_indices;
 883    /* String of extra extensions. */
 884    char *extra_extensions = get_extension_override(ctx);
 885    GLboolean *base = (GLboolean *) &ctx->Extensions;
 886    const struct extension *i;
 887    unsigned j;
 888    unsigned maxYear = ~0;
 889
 890    /* Check if the MESA_EXTENSION_MAX_YEAR env var is set */
 891    {
 892       const char *env = getenv("MESA_EXTENSION_MAX_YEAR");
 893       if (env) {
 894          maxYear = atoi(env);
 895          _mesa_debug(ctx, "Note: limiting GL extensions to %u or earlier\n",
 896                      maxYear);
 897       }
 898    }
 899
 900    /* Compute length of the extension string. */
 901    count = 0;
 902    for (i = extension_table; i->name != 0; ++i) {
 903       if (base[i->offset] &&
 904           i->year <= maxYear &&
 905           (i->api_set & (1 << ctx->API))) {
 906          length += strlen(i->name) + 1; /* +1 for space */
 907          ++count;
 908       }
 909    }
 910    if (extra_extensions != NULL)
 911       length += 1 + strlen(extra_extensions); /* +1 for space */
 912
 913    exts = (char *) calloc(length + 1, sizeof(char));
 914    if (exts == NULL) {
 915       free(extra_extensions);
 916       return NULL;
 917    }
 918
 919    extension_indices = malloc(count * sizeof(extension_index));
 920    if (extension_indices == NULL) {
 921       free(exts);
 922       free(extra_extensions);
 923       return NULL;
 924    }
 925
 926    /* Sort extensions in chronological order because certain old applications (e.g.,
 927     * Quake3 demo) store the extension list in a static size buffer so chronologically
 928     * order ensure that the extensions that such applications expect will fit into
 929     * that buffer.
 930     */
 931    j = 0;
 932    for (i = extension_table; i->name != 0; ++i) {
 933       if (base[i->offset] &&
 934           i->year <= maxYear &&
 935           (i->api_set & (1 << ctx->API))) {
 936          extension_indices[j++] = i - extension_table;
 937       }
 938    }
 939    assert(j == count);
 940    qsort(extension_indices, count, sizeof *extension_indices, extension_compare);
 941
 942    /* Build the extension string.*/
 943    for (j = 0; j < count; ++j) {
 944       i = &extension_table[extension_indices[j]];
 945       assert(base[i->offset] && (i->api_set & (1 << ctx->API)));
 946       strcat(exts, i->name);
 947       strcat(exts, " ");
 948    }
 949    free(extension_indices);
 950    if (extra_extensions != 0) {
 951       strcat(exts, extra_extensions);
 952       free(extra_extensions);
 953    }
 954
 955    return (GLubyte *) exts;
 956 }
 957
 958 /**
 959  * Return number of enabled extensions.
 960  */
 961 GLuint
 962 _mesa_get_extension_count(struct gl_context *ctx)
 963 {
 964    GLboolean *base;
 965    const struct extension *i;
 966
 967    /* only count once */
 968    if (ctx->Extensions.Count != 0)
 969       return ctx->Extensions.Count;
 970
 971    base = (GLboolean *) &ctx->Extensions;
 972    for (i = extension_table; i->name != 0; ++i) {
 973       if (base[i->offset]) {
 974          ctx->Extensions.Count++;
 975       }
 976    }
 977    return ctx->Extensions.Count;
 978 }
 979
 980 /**
 981  * Return name of i-th enabled extension
 982  */
 983 const GLubyte *
 984 _mesa_get_enabled_extension(struct gl_context *ctx, GLuint index)
 985 {
 986    const GLboolean *base;
 987    size_t n;
 988    const struct extension *i;
 989
 990    if (index < 0)
 991       return NULL;
 992
 993    base = (GLboolean*) &ctx->Extensions;
 994    n = 0;
 995    for (i = extension_table; i->name != 0; ++i) {
 996       if (n == index && base[i->offset]) {
 997          return (GLubyte*) i->name;
 998       } else if (base[i->offset]) {
 999          ++n;
1000       }
1001    }
1002
1003    return NULL;
1004 }