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