extensions.c revision 7ef1869d69005c523ad81b23060ed02e306073f3
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
42enum {
43   DISABLE = 0,
44   GLL = 1 << API_OPENGL,       /* GL Legacy / Compatibility */
45   GLC = 1 << API_OPENGL_CORE,  /* GL Core */
46   GL  = (1 << API_OPENGL) | (1 << API_OPENGL_CORE),
47   ES1 = 1 << API_OPENGLES,
48   ES2 = 1 << API_OPENGLES2,
49};
50
51/**
52 * \brief An element of the \c extension_table.
53 */
54struct extension {
55   /** Name of extension, such as "GL_ARB_depth_clamp". */
56   const char *name;
57
58   /** Offset (in bytes) of the corresponding member in struct gl_extensions. */
59   size_t offset;
60
61   /** Set of API's in which the extension exists, as a bitset. */
62   uint8_t api_set;
63
64   /** Year the extension was proposed or approved.  Used to sort the
65    * extension string chronologically. */
66   uint16_t year;
67};
68
69
70/**
71 * Given a member \c x of struct gl_extensions, return offset of
72 * \c x in bytes.
73 */
74#define o(x) offsetof(struct gl_extensions, x)
75
76
77/**
78 * \brief Table of supported OpenGL extensions for all API's.
79 */
80static const struct extension extension_table[] = {
81   /* ARB Extensions */
82   { "GL_ARB_ES2_compatibility",                   o(ARB_ES2_compatibility),                   GL,             2009 },
83   { "GL_ARB_base_instance",                       o(ARB_base_instance),                       GL,             2011 },
84   { "GL_ARB_blend_func_extended",                 o(ARB_blend_func_extended),                 GL,             2009 },
85   { "GL_ARB_color_buffer_float",                  o(ARB_color_buffer_float),                  GL,             2004 },
86   { "GL_ARB_copy_buffer",                         o(ARB_copy_buffer),                         GL,             2008 },
87   { "GL_ARB_conservative_depth",                  o(ARB_conservative_depth),                  GL,             2011 },
88   { "GL_ARB_debug_output",                        o(dummy_true),                              GL,             2009 },
89   { "GL_ARB_depth_buffer_float",                  o(ARB_depth_buffer_float),                  GL,             2008 },
90   { "GL_ARB_depth_clamp",                         o(ARB_depth_clamp),                         GL,             2003 },
91   { "GL_ARB_depth_texture",                       o(ARB_depth_texture),                       GL,             2001 },
92   { "GL_ARB_draw_buffers",                        o(dummy_true),                              GL,             2002 },
93   { "GL_ARB_draw_buffers_blend",                  o(ARB_draw_buffers_blend),                  GL,             2009 },
94   { "GL_ARB_draw_elements_base_vertex",           o(ARB_draw_elements_base_vertex),           GL,             2009 },
95   { "GL_ARB_draw_instanced",                      o(ARB_draw_instanced),                      GL,             2008 },
96   { "GL_ARB_explicit_attrib_location",            o(ARB_explicit_attrib_location),            GL,             2009 },
97   { "GL_ARB_fragment_coord_conventions",          o(ARB_fragment_coord_conventions),          GL,             2009 },
98   { "GL_ARB_fragment_program",                    o(ARB_fragment_program),                    GLL,            2002 },
99   { "GL_ARB_fragment_program_shadow",             o(ARB_fragment_program_shadow),             GLL,            2003 },
100   { "GL_ARB_fragment_shader",                     o(ARB_fragment_shader),                     GL,             2002 },
101   { "GL_ARB_framebuffer_object",                  o(ARB_framebuffer_object),                  GL,             2005 },
102   { "GL_ARB_framebuffer_sRGB",                    o(EXT_framebuffer_sRGB),                    GL,             1998 },
103   { "GL_ARB_half_float_pixel",                    o(ARB_half_float_pixel),                    GL,             2003 },
104   { "GL_ARB_half_float_vertex",                   o(ARB_half_float_vertex),                   GL,             2008 },
105   { "GL_ARB_instanced_arrays",                    o(ARB_instanced_arrays),                    GL,             2008 },
106   { "GL_ARB_map_buffer_range",                    o(ARB_map_buffer_range),                    GL,             2008 },
107   { "GL_ARB_multisample",                         o(dummy_true),                              GL,             1994 },
108   { "GL_ARB_multitexture",                        o(dummy_true),                              GL,             1998 },
109   { "GL_ARB_occlusion_query2",                    o(ARB_occlusion_query2),                    GL,             2003 },
110   { "GL_ARB_occlusion_query",                     o(ARB_occlusion_query),                     GL,             2001 },
111   { "GL_ARB_pixel_buffer_object",                 o(EXT_pixel_buffer_object),                 GL,             2004 },
112   { "GL_ARB_point_parameters",                    o(EXT_point_parameters),                    GL,             1997 },
113   { "GL_ARB_point_sprite",                        o(ARB_point_sprite),                        GL,             2003 },
114   { "GL_ARB_provoking_vertex",                    o(EXT_provoking_vertex),                    GL,             2009 },
115   { "GL_ARB_robustness",                          o(dummy_true),                              GL,             2010 },
116   { "GL_ARB_sampler_objects",                     o(dummy_true),                              GL,             2009 },
117   { "GL_ARB_seamless_cube_map",                   o(ARB_seamless_cube_map),                   GL,             2009 },
118   { "GL_ARB_shader_bit_encoding",                 o(ARB_shader_bit_encoding),                 GL,             2010 },
119   { "GL_ARB_shader_objects",                      o(ARB_shader_objects),                      GL,             2002 },
120   { "GL_ARB_shader_stencil_export",               o(ARB_shader_stencil_export),               GL,             2009 },
121   { "GL_ARB_shader_texture_lod",                  o(ARB_shader_texture_lod),                  GL,             2009 },
122   { "GL_ARB_shading_language_100",                o(ARB_shading_language_100),                GLL,            2003 },
123   { "GL_ARB_shadow_ambient",                      o(ARB_shadow_ambient),                      GL,             2001 },
124   { "GL_ARB_shadow",                              o(ARB_shadow),                              GL,             2001 },
125   { "GL_ARB_sync",                                o(ARB_sync),                                GL,             2003 },
126   { "GL_ARB_texture_border_clamp",                o(ARB_texture_border_clamp),                GL,             2000 },
127   { "GL_ARB_texture_buffer_object",               o(ARB_texture_buffer_object),               GL,             2008 },
128   { "GL_ARB_texture_compression",                 o(dummy_true),                              GL,             2000 },
129   { "GL_ARB_texture_compression_rgtc",            o(ARB_texture_compression_rgtc),            GL,             2004 },
130   { "GL_ARB_texture_cube_map",                    o(ARB_texture_cube_map),                    GL,             1999 },
131   { "GL_ARB_texture_env_add",                     o(dummy_true),                              GLL,            1999 },
132   { "GL_ARB_texture_env_combine",                 o(ARB_texture_env_combine),                 GLL,            2001 },
133   { "GL_ARB_texture_env_crossbar",                o(ARB_texture_env_crossbar),                GLL,            2001 },
134   { "GL_ARB_texture_env_dot3",                    o(ARB_texture_env_dot3),                    GLL,            2001 },
135   { "GL_ARB_texture_float",                       o(ARB_texture_float),                       GL,             2004 },
136   { "GL_ARB_texture_mirrored_repeat",             o(dummy_true),                              GL,             2001 },
137   { "GL_ARB_texture_multisample",                 o(ARB_texture_multisample),                 GL,             2009 },
138   { "GL_ARB_texture_non_power_of_two",            o(ARB_texture_non_power_of_two),            GL,             2003 },
139   { "GL_ARB_texture_rectangle",                   o(NV_texture_rectangle),                    GL,             2004 },
140   { "GL_ARB_texture_rgb10_a2ui",                  o(ARB_texture_rgb10_a2ui),                  GL,             2009 },
141   { "GL_ARB_texture_rg",                          o(ARB_texture_rg),                          GL,             2008 },
142   { "GL_ARB_texture_storage",                     o(ARB_texture_storage),                     GL,             2011 },
143   { "GL_ARB_texture_swizzle",                     o(EXT_texture_swizzle),                     GL,             2008 },
144   { "GL_ARB_timer_query",                         o(ARB_timer_query),                         GL,             2010 },
145   { "GL_ARB_transform_feedback2",                 o(ARB_transform_feedback2),                 GL,             2010 },
146   { "GL_ARB_transform_feedback3",                 o(ARB_transform_feedback3),                 GL,             2010 },
147   { "GL_ARB_transform_feedback_instanced",        o(ARB_transform_feedback_instanced),        GL,             2011 },
148   { "GL_ARB_transpose_matrix",                    o(ARB_transpose_matrix),                    GLL,            1999 },
149   { "GL_ARB_uniform_buffer_object",               o(ARB_uniform_buffer_object),               GL,             2009 },
150   { "GL_ARB_vertex_array_bgra",                   o(EXT_vertex_array_bgra),                   GL,             2008 },
151   { "GL_ARB_vertex_array_object",                 o(ARB_vertex_array_object),                 GL,             2006 },
152   { "GL_ARB_vertex_buffer_object",                o(dummy_true),                              GL,             2003 },
153   { "GL_ARB_vertex_program",                      o(ARB_vertex_program),                      GLL,            2002 },
154   { "GL_ARB_vertex_shader",                       o(ARB_vertex_shader),                       GL,             2002 },
155   { "GL_ARB_vertex_type_2_10_10_10_rev",          o(ARB_vertex_type_2_10_10_10_rev),          GL,             2009 },
156   { "GL_ARB_window_pos",                          o(ARB_window_pos),                          GLL,            2001 },
157   /* EXT extensions */
158   { "GL_EXT_abgr",                                o(dummy_true),                              GL,             1995 },
159   { "GL_EXT_bgra",                                o(dummy_true),                              GLL,            1995 },
160   { "GL_EXT_blend_color",                         o(EXT_blend_color),                         GLL,            1995 },
161   { "GL_EXT_blend_equation_separate",             o(EXT_blend_equation_separate),             GL,             2003 },
162   { "GL_EXT_blend_func_separate",                 o(EXT_blend_func_separate),                 GL,             1999 },
163   { "GL_EXT_blend_minmax",                        o(EXT_blend_minmax),                        GLL | ES1 | ES2, 1995 },
164   { "GL_EXT_blend_subtract",                      o(dummy_true),                              GLL,            1995 },
165   { "GL_EXT_clip_volume_hint",                    o(EXT_clip_volume_hint),                    GL,             1996 },
166   { "GL_EXT_compiled_vertex_array",               o(EXT_compiled_vertex_array),               GLL,            1996 },
167   { "GL_EXT_copy_texture",                        o(dummy_true),                              GLL,            1995 },
168   { "GL_EXT_depth_bounds_test",                   o(EXT_depth_bounds_test),                   GL,             2002 },
169   { "GL_EXT_draw_buffers2",                       o(EXT_draw_buffers2),                       GL,             2006 },
170   { "GL_EXT_draw_instanced",                      o(ARB_draw_instanced),                      GL,             2006 },
171   { "GL_EXT_draw_range_elements",                 o(EXT_draw_range_elements),                 GLL,            1997 },
172   { "GL_EXT_fog_coord",                           o(EXT_fog_coord),                           GLL,            1999 },
173   { "GL_EXT_framebuffer_blit",                    o(EXT_framebuffer_blit),                    GL,             2005 },
174   { "GL_EXT_framebuffer_multisample",             o(EXT_framebuffer_multisample),             GL,             2005 },
175   { "GL_EXT_framebuffer_object",                  o(EXT_framebuffer_object),                  GL,             2000 },
176   { "GL_EXT_framebuffer_sRGB",                    o(EXT_framebuffer_sRGB),                    GL,             1998 },
177   { "GL_EXT_gpu_program_parameters",              o(EXT_gpu_program_parameters),              GLL,            2006 },
178   { "GL_EXT_gpu_shader4",                         o(EXT_gpu_shader4),                         GL,             2006 },
179   { "GL_EXT_multi_draw_arrays",                   o(dummy_true),                              GL | ES1 | ES2, 1999 },
180   { "GL_EXT_packed_depth_stencil",                o(EXT_packed_depth_stencil),                GL,             2005 },
181   { "GL_EXT_packed_float",                        o(EXT_packed_float),                        GL,             2004 },
182   { "GL_EXT_packed_pixels",                       o(EXT_packed_pixels),                       GLL,            1997 },
183   { "GL_EXT_pixel_buffer_object",                 o(EXT_pixel_buffer_object),                 GL,             2004 },
184   { "GL_EXT_point_parameters",                    o(EXT_point_parameters),                    GL,             1997 },
185   { "GL_EXT_polygon_offset",                      o(dummy_true),                              GLL,            1995 },
186   { "GL_EXT_provoking_vertex",                    o(EXT_provoking_vertex),                    GL,             2009 },
187   { "GL_EXT_rescale_normal",                      o(EXT_rescale_normal),                      GLL,            1997 },
188   { "GL_EXT_secondary_color",                     o(EXT_secondary_color),                     GLL,            1999 },
189   { "GL_EXT_separate_shader_objects",             o(EXT_separate_shader_objects),             GLL,            2008 },
190   { "GL_EXT_separate_specular_color",             o(EXT_separate_specular_color),             GLL,            1997 },
191   { "GL_EXT_shadow_funcs",                        o(EXT_shadow_funcs),                        GL,             2002 },
192   { "GL_EXT_stencil_two_side",                    o(EXT_stencil_two_side),                    GLL,            2001 },
193   { "GL_EXT_stencil_wrap",                        o(dummy_true),                              GL,             2002 },
194   { "GL_EXT_subtexture",                          o(dummy_true),                              GLL,            1995 },
195   { "GL_EXT_texture3D",                           o(EXT_texture3D),                           GLL,            1996 },
196   { "GL_EXT_texture_array",                       o(EXT_texture_array),                       GL,             2006 },
197   { "GL_EXT_texture_compression_dxt1",            o(EXT_texture_compression_s3tc),            GL | ES1 | ES2, 2004 },
198   { "GL_EXT_texture_compression_latc",            o(EXT_texture_compression_latc),            GL,             2006 },
199   { "GL_EXT_texture_compression_rgtc",            o(ARB_texture_compression_rgtc),            GL,             2004 },
200   { "GL_EXT_texture_compression_s3tc",            o(EXT_texture_compression_s3tc),            GL,             2000 },
201   { "GL_EXT_texture_cube_map",                    o(ARB_texture_cube_map),                    GLL,            2001 },
202   { "GL_EXT_texture_edge_clamp",                  o(dummy_true),                              GLL,            1997 },
203   { "GL_EXT_texture_env_add",                     o(dummy_true),                              GLL,            1999 },
204   { "GL_EXT_texture_env_combine",                 o(dummy_true),                              GLL,            2000 },
205   { "GL_EXT_texture_env_dot3",                    o(EXT_texture_env_dot3),                    GLL,            2000 },
206   { "GL_EXT_texture_filter_anisotropic",          o(EXT_texture_filter_anisotropic),          GL | ES1 | ES2, 1999 },
207   { "GL_EXT_texture_format_BGRA8888",             o(dummy_true),                                   ES1 | ES2, 2005 },
208   { "GL_EXT_texture_rg",                          o(ARB_texture_rg),                                     ES2, 2011 },
209   { "GL_EXT_read_format_bgra",                    o(dummy_true),                                   ES1 | ES2, 2009 },
210   { "GL_EXT_texture_integer",                     o(EXT_texture_integer),                     GL,             2006 },
211   { "GL_EXT_texture_lod_bias",                    o(dummy_true),                              GL | ES1,       1999 },
212   { "GL_EXT_texture_mirror_clamp",                o(EXT_texture_mirror_clamp),                GL,             2004 },
213   { "GL_EXT_texture_object",                      o(dummy_true),                              GLL,            1995 },
214   { "GL_EXT_texture",                             o(dummy_true),                              GLL,            1996 },
215   { "GL_EXT_texture_rectangle",                   o(NV_texture_rectangle),                    GLL,            2004 },
216   { "GL_EXT_texture_shared_exponent",             o(EXT_texture_shared_exponent),             GL,             2004 },
217   { "GL_EXT_texture_snorm",                       o(EXT_texture_snorm),                       GL,             2009 },
218   { "GL_EXT_texture_sRGB",                        o(EXT_texture_sRGB),                        GL,             2004 },
219   { "GL_EXT_texture_sRGB_decode",                 o(EXT_texture_sRGB_decode),                        GL,      2006 },
220   { "GL_EXT_texture_swizzle",                     o(EXT_texture_swizzle),                     GL,             2008 },
221   { "GL_EXT_texture_type_2_10_10_10_REV",         o(dummy_true),                                         ES2, 2008 },
222   { "GL_EXT_timer_query",                         o(EXT_timer_query),                         GL,             2006 },
223   { "GL_EXT_transform_feedback",                  o(EXT_transform_feedback),                  GL,             2011 },
224   { "GL_EXT_unpack_subimage",                     o(dummy_true),                                         ES2, 2011 },
225   { "GL_EXT_vertex_array_bgra",                   o(EXT_vertex_array_bgra),                   GL,             2008 },
226   { "GL_EXT_vertex_array",                        o(dummy_true),                              GLL,            1995 },
227
228   /* OES extensions */
229   { "GL_OES_blend_equation_separate",             o(EXT_blend_equation_separate),                  ES1,       2009 },
230   { "GL_OES_blend_func_separate",                 o(EXT_blend_func_separate),                      ES1,       2009 },
231   { "GL_OES_blend_subtract",                      o(dummy_true),                                   ES1,       2009 },
232   { "GL_OES_byte_coordinates",                    o(dummy_true),                                   ES1,       2002 },
233   { "GL_OES_compressed_ETC1_RGB8_texture",        o(OES_compressed_ETC1_RGB8_texture),             ES1 | ES2, 2005 },
234   { "GL_OES_compressed_paletted_texture",         o(dummy_true),                                   ES1,       2003 },
235   { "GL_OES_depth24",                             o(EXT_framebuffer_object),                       ES1 | ES2, 2005 },
236   { "GL_OES_depth32",                             o(dummy_false),                     DISABLE,                2005 },
237   { "GL_OES_depth_texture",                       o(ARB_depth_texture),                                  ES2, 2006 },
238#if FEATURE_OES_draw_texture
239   { "GL_OES_draw_texture",                        o(OES_draw_texture),                             ES1,       2004 },
240#endif
241#if FEATURE_OES_EGL_image
242   /*  FIXME: Mesa expects GL_OES_EGL_image to be available in OpenGL contexts. */
243   { "GL_OES_EGL_image",                           o(OES_EGL_image),                           GL | ES1 | ES2, 2006 },
244   { "GL_OES_EGL_image_external",                  o(OES_EGL_image_external),                       ES1 | ES2, 2010 },
245#endif
246   { "GL_OES_element_index_uint",                  o(dummy_true),                                   ES1 | ES2, 2005 },
247   { "GL_OES_fbo_render_mipmap",                   o(EXT_framebuffer_object),                       ES1 | ES2, 2005 },
248   { "GL_OES_fixed_point",                         o(dummy_true),                                   ES1,       2002 },
249   { "GL_OES_framebuffer_object",                  o(EXT_framebuffer_object),                       ES1,       2005 },
250   { "GL_OES_mapbuffer",                           o(dummy_true),                                   ES1 | ES2, 2005 },
251   { "GL_OES_matrix_get",                          o(dummy_true),                                   ES1,       2004 },
252   { "GL_OES_packed_depth_stencil",                o(EXT_packed_depth_stencil),                     ES1 | ES2, 2007 },
253   { "GL_OES_point_size_array",                    o(dummy_true),                                   ES1,       2004 },
254   { "GL_OES_point_sprite",                        o(ARB_point_sprite),                             ES1,       2004 },
255   { "GL_OES_query_matrix",                        o(dummy_true),                                   ES1,       2003 },
256   { "GL_OES_read_format",                         o(dummy_true),                              GL | ES1,       2003 },
257   { "GL_OES_rgb8_rgba8",                          o(EXT_framebuffer_object),                       ES1 | ES2, 2005 },
258   { "GL_OES_single_precision",                    o(dummy_true),                                   ES1,       2003 },
259   { "GL_OES_standard_derivatives",                o(OES_standard_derivatives),                           ES2, 2005 },
260   { "GL_OES_stencil1",                            o(dummy_false),                     DISABLE,                2005 },
261   { "GL_OES_stencil4",                            o(dummy_false),                     DISABLE,                2005 },
262   { "GL_OES_stencil8",                            o(EXT_framebuffer_object),                       ES1 | ES2, 2005 },
263   { "GL_OES_stencil_wrap",                        o(dummy_true),                                   ES1,       2002 },
264   { "GL_OES_texture_3D",                          o(EXT_texture3D),                                      ES2, 2005 },
265   { "GL_OES_texture_cube_map",                    o(ARB_texture_cube_map),                         ES1,       2007 },
266   { "GL_OES_texture_env_crossbar",                o(ARB_texture_env_crossbar),                     ES1,       2005 },
267   { "GL_OES_texture_mirrored_repeat",             o(dummy_true),                                   ES1,       2005 },
268   { "GL_OES_texture_npot",                        o(ARB_texture_non_power_of_two),                       ES2, 2005 },
269
270   /* Vendor extensions */
271   { "GL_3DFX_texture_compression_FXT1",           o(TDFX_texture_compression_FXT1),           GL,             1999 },
272   { "GL_AMD_conservative_depth",                  o(ARB_conservative_depth),                  GL,             2009 },
273   { "GL_AMD_draw_buffers_blend",                  o(ARB_draw_buffers_blend),                  GL,             2009 },
274   { "GL_AMD_seamless_cubemap_per_texture",        o(AMD_seamless_cubemap_per_texture),        GL,             2009 },
275   { "GL_AMD_shader_stencil_export",               o(ARB_shader_stencil_export),               GL,             2009 },
276   { "GL_APPLE_object_purgeable",                  o(APPLE_object_purgeable),                  GL,             2006 },
277   { "GL_APPLE_packed_pixels",                     o(APPLE_packed_pixels),                     GLL,            2002 },
278   { "GL_APPLE_vertex_array_object",               o(APPLE_vertex_array_object),               GLL,            2002 },
279   { "GL_ATI_blend_equation_separate",             o(EXT_blend_equation_separate),             GL,             2003 },
280   { "GL_ATI_draw_buffers",                        o(dummy_true),                              GLL,            2002 },
281   { "GL_ATI_envmap_bumpmap",                      o(ATI_envmap_bumpmap),                      GLL,            2001 },
282   { "GL_ATI_fragment_shader",                     o(ATI_fragment_shader),                     GLL,            2001 },
283   { "GL_ATI_separate_stencil",                    o(ATI_separate_stencil),                    GLL,            2006 },
284   { "GL_ATI_texture_compression_3dc",             o(ATI_texture_compression_3dc),             GL,             2004 },
285   { "GL_ATI_texture_env_combine3",                o(ATI_texture_env_combine3),                GLL,            2002 },
286   { "GL_ATI_texture_float",                       o(ARB_texture_float),                       GL,             2002 },
287   { "GL_ATI_texture_mirror_once",                 o(ATI_texture_mirror_once),                 GL,             2006 },
288   { "GL_IBM_multimode_draw_arrays",               o(IBM_multimode_draw_arrays),               GL,             1998 },
289   { "GL_IBM_rasterpos_clip",                      o(IBM_rasterpos_clip),                      GL,             1996 },
290   { "GL_IBM_texture_mirrored_repeat",             o(dummy_true),                              GL,             1998 },
291   { "GL_INGR_blend_func_separate",                o(EXT_blend_func_separate),                 GLL,            1999 },
292   { "GL_MESA_pack_invert",                        o(MESA_pack_invert),                        GL,             2002 },
293   { "GL_MESA_resize_buffers",                     o(MESA_resize_buffers),                     GL,             1999 },
294   { "GL_MESA_texture_array",                      o(MESA_texture_array),                      GLL,            2007 },
295   { "GL_MESA_texture_signed_rgba",                o(EXT_texture_snorm),                       GL,             2009 },
296   { "GL_MESA_window_pos",                         o(ARB_window_pos),                          GLL,            2000 },
297   { "GL_MESA_ycbcr_texture",                      o(MESA_ycbcr_texture),                      GL,             2002 },
298   { "GL_NV_blend_square",                         o(NV_blend_square),                         GL,             1999 },
299   { "GL_NV_conditional_render",                   o(NV_conditional_render),                   GL,             2008 },
300   { "GL_NV_depth_clamp",                          o(ARB_depth_clamp),                         GL,             2001 },
301   { "GL_NV_draw_buffers",                         o(dummy_true),                                         ES2, 2011 },
302   { "GL_NV_fbo_color_attachments",                o(EXT_framebuffer_object),                             ES2, 2010 },
303   { "GL_NV_fog_distance",                         o(NV_fog_distance),                         GLL,            2001 },
304   { "GL_NV_fragment_program",                     o(NV_fragment_program),                     GLL,            2001 },
305   { "GL_NV_fragment_program_option",              o(NV_fragment_program_option),              GLL,            2005 },
306   { "GL_NV_light_max_exponent",                   o(NV_light_max_exponent),                   GLL,            1999 },
307   { "GL_NV_packed_depth_stencil",                 o(EXT_packed_depth_stencil),                GL,             2000 },
308   { "GL_NV_point_sprite",                         o(NV_point_sprite),                         GL,             2001 },
309   { "GL_NV_primitive_restart",                    o(NV_primitive_restart),                    GL,             2002 },
310   { "GL_NV_read_buffer",                          o(dummy_true),                              ES2,            2011 },
311   { "GL_NV_texgen_reflection",                    o(NV_texgen_reflection),                    GLL,            1999 },
312   { "GL_NV_texture_barrier",                      o(NV_texture_barrier),                      GL,             2009 },
313   { "GL_NV_texture_env_combine4",                 o(NV_texture_env_combine4),                 GLL,            1999 },
314   { "GL_NV_texture_rectangle",                    o(NV_texture_rectangle),                    GLL,            2000 },
315   { "GL_NV_vertex_program1_1",                    o(NV_vertex_program1_1),                    GLL,            2001 },
316   { "GL_NV_vertex_program",                       o(NV_vertex_program),                       GLL,            2000 },
317   { "GL_S3_s3tc",                                 o(S3_s3tc),                                 GL,             1999 },
318   { "GL_SGIS_generate_mipmap",                    o(dummy_true),                              GLL,            1997 },
319   { "GL_SGIS_texture_border_clamp",               o(ARB_texture_border_clamp),                GL,             1997 },
320   { "GL_SGIS_texture_edge_clamp",                 o(dummy_true),                              GLL,            1997 },
321   { "GL_SGIS_texture_lod",                        o(SGIS_texture_lod),                        GLL,            1997 },
322   { "GL_SUN_multi_draw_arrays",                   o(dummy_true),                              GL,             1999 },
323
324   { 0, 0, 0, 0 },
325};
326
327
328/**
329 * Given an extension name, lookup up the corresponding member of struct
330 * gl_extensions and return that member's offset (in bytes).  If the name is
331 * not found in the \c extension_table, return 0.
332 *
333 * \param name Name of extension.
334 * \return Offset of member in struct gl_extensions.
335 */
336static size_t
337name_to_offset(const char* name)
338{
339   const struct extension *i;
340
341   if (name == 0)
342      return 0;
343
344   for (i = extension_table; i->name != 0; ++i) {
345      if (strcmp(name, i->name) == 0)
346	 return i->offset;
347   }
348
349   return 0;
350}
351
352
353/**
354 * \brief Extensions enabled by default.
355 *
356 * These extensions are enabled by _mesa_init_extensions().
357 *
358 * XXX: Should these defaults also apply to GLES?
359 */
360static const size_t default_extensions[] = {
361   o(ARB_copy_buffer),
362   o(ARB_transpose_matrix),
363   o(ARB_window_pos),
364
365   o(EXT_compiled_vertex_array),
366   o(EXT_draw_range_elements),
367   o(EXT_packed_pixels),
368   o(EXT_rescale_normal),
369   o(EXT_separate_specular_color),
370   o(EXT_texture3D),
371
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_texture_lod),
381
382   0,
383};
384
385
386/**
387 * Enable all extensions suitable for a software-only renderer.
388 * This is a convenience function used by the XMesa, OSMesa, GGI drivers, etc.
389 */
390void
391_mesa_enable_sw_extensions(struct gl_context *ctx)
392{
393   /*ctx->Extensions.ARB_copy_buffer = GL_TRUE;*/
394   ctx->Extensions.ARB_depth_clamp = GL_TRUE;
395   ctx->Extensions.ARB_depth_texture = 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#if FEATURE_queryobj
418   ctx->Extensions.ARB_occlusion_query = GL_TRUE;
419   ctx->Extensions.ARB_occlusion_query2 = GL_TRUE;
420#endif
421   ctx->Extensions.ARB_point_sprite = GL_TRUE;
422#if FEATURE_ARB_shader_objects
423   ctx->Extensions.ARB_shader_objects = GL_TRUE;
424   ctx->Extensions.EXT_separate_shader_objects = GL_TRUE;
425#endif
426#if FEATURE_ARB_shading_language_100
427   ctx->Extensions.ARB_shading_language_100 = GL_TRUE;
428#endif
429   ctx->Extensions.ARB_shadow = GL_TRUE;
430   ctx->Extensions.ARB_shadow_ambient = GL_TRUE;
431   ctx->Extensions.ARB_texture_border_clamp = GL_TRUE;
432   ctx->Extensions.ARB_texture_cube_map = GL_TRUE;
433   ctx->Extensions.ARB_texture_env_combine = GL_TRUE;
434   ctx->Extensions.ARB_texture_env_crossbar = GL_TRUE;
435   ctx->Extensions.ARB_texture_env_dot3 = GL_TRUE;
436   /*ctx->Extensions.ARB_texture_float = GL_TRUE;*/
437   ctx->Extensions.ARB_texture_non_power_of_two = GL_TRUE;
438   ctx->Extensions.ARB_texture_rg = GL_TRUE;
439   ctx->Extensions.ARB_texture_compression_rgtc = GL_TRUE;
440   ctx->Extensions.ARB_texture_storage = GL_TRUE;
441   ctx->Extensions.ARB_vertex_array_object = GL_TRUE;
442#if FEATURE_ARB_vertex_program
443   ctx->Extensions.ARB_vertex_program = GL_TRUE;
444#endif
445#if FEATURE_ARB_vertex_shader
446   ctx->Extensions.ARB_vertex_shader = GL_TRUE;
447#endif
448#if FEATURE_ARB_sync
449   ctx->Extensions.ARB_sync = GL_TRUE;
450#endif
451   ctx->Extensions.APPLE_vertex_array_object = GL_TRUE;
452#if FEATURE_APPLE_object_purgeable
453   ctx->Extensions.APPLE_object_purgeable = GL_TRUE;
454#endif
455   ctx->Extensions.ATI_envmap_bumpmap = GL_TRUE;
456#if FEATURE_ATI_fragment_shader
457   ctx->Extensions.ATI_fragment_shader = GL_TRUE;
458#endif
459   ctx->Extensions.ATI_texture_compression_3dc = GL_TRUE;
460   ctx->Extensions.ATI_texture_env_combine3 = GL_TRUE;
461   ctx->Extensions.ATI_texture_mirror_once = GL_TRUE;
462   ctx->Extensions.ATI_separate_stencil = GL_TRUE;
463   ctx->Extensions.EXT_blend_color = GL_TRUE;
464   ctx->Extensions.EXT_blend_equation_separate = GL_TRUE;
465   ctx->Extensions.EXT_blend_func_separate = GL_TRUE;
466   ctx->Extensions.EXT_blend_minmax = GL_TRUE;
467   ctx->Extensions.EXT_depth_bounds_test = GL_TRUE;
468   ctx->Extensions.EXT_draw_buffers2 = GL_TRUE;
469   ctx->Extensions.EXT_fog_coord = GL_TRUE;
470#if FEATURE_EXT_framebuffer_object
471   ctx->Extensions.EXT_framebuffer_object = GL_TRUE;
472#endif
473#if FEATURE_EXT_framebuffer_blit
474   ctx->Extensions.EXT_framebuffer_blit = GL_TRUE;
475#endif
476#if FEATURE_ARB_framebuffer_object
477   ctx->Extensions.EXT_framebuffer_multisample = GL_TRUE;
478#endif
479   ctx->Extensions.EXT_packed_depth_stencil = GL_TRUE;
480#if FEATURE_EXT_pixel_buffer_object
481   ctx->Extensions.EXT_pixel_buffer_object = GL_TRUE;
482#endif
483   ctx->Extensions.EXT_point_parameters = GL_TRUE;
484   ctx->Extensions.EXT_provoking_vertex = GL_TRUE;
485   ctx->Extensions.EXT_shadow_funcs = GL_TRUE;
486   ctx->Extensions.EXT_secondary_color = GL_TRUE;
487   ctx->Extensions.EXT_stencil_two_side = GL_TRUE;
488   ctx->Extensions.EXT_texture_array = GL_TRUE;
489   ctx->Extensions.EXT_texture_compression_latc = GL_TRUE;
490   ctx->Extensions.EXT_texture_env_dot3 = GL_TRUE;
491   ctx->Extensions.EXT_texture_filter_anisotropic = GL_TRUE;
492   ctx->Extensions.EXT_texture_mirror_clamp = GL_TRUE;
493   ctx->Extensions.EXT_texture_shared_exponent = GL_TRUE;
494#if FEATURE_EXT_texture_sRGB
495   ctx->Extensions.EXT_texture_sRGB = GL_TRUE;
496   ctx->Extensions.EXT_texture_sRGB_decode = GL_TRUE;
497#endif
498   ctx->Extensions.EXT_texture_swizzle = GL_TRUE;
499#if FEATURE_EXT_transform_feedback
500   /*ctx->Extensions.EXT_transform_feedback = GL_TRUE;*/
501#endif
502   ctx->Extensions.EXT_vertex_array_bgra = GL_TRUE;
503   /*ctx->Extensions.IBM_multimode_draw_arrays = GL_TRUE;*/
504   ctx->Extensions.MESA_pack_invert = GL_TRUE;
505   ctx->Extensions.MESA_resize_buffers = GL_TRUE;
506   ctx->Extensions.MESA_texture_array = GL_TRUE;
507   ctx->Extensions.MESA_ycbcr_texture = GL_TRUE;
508   ctx->Extensions.NV_blend_square = GL_TRUE;
509   ctx->Extensions.NV_conditional_render = GL_TRUE;
510   /*ctx->Extensions.NV_light_max_exponent = GL_TRUE;*/
511   ctx->Extensions.NV_point_sprite = GL_TRUE;
512   ctx->Extensions.NV_texture_env_combine4 = GL_TRUE;
513   ctx->Extensions.NV_texture_rectangle = GL_TRUE;
514   /*ctx->Extensions.NV_texgen_reflection = GL_TRUE;*/
515#if FEATURE_NV_vertex_program
516   ctx->Extensions.NV_vertex_program = GL_TRUE;
517   ctx->Extensions.NV_vertex_program1_1 = GL_TRUE;
518#endif
519#if FEATURE_NV_fragment_program
520   ctx->Extensions.NV_fragment_program = GL_TRUE;
521#endif
522#if FEATURE_NV_fragment_program && FEATURE_ARB_fragment_program
523   ctx->Extensions.NV_fragment_program_option = GL_TRUE;
524#endif
525#if FEATURE_ARB_vertex_program || FEATURE_ARB_fragment_program
526   ctx->Extensions.EXT_gpu_program_parameters = GL_TRUE;
527#endif
528#if FEATURE_texture_fxt1
529   _mesa_enable_extension(ctx, "GL_3DFX_texture_compression_FXT1");
530#endif
531#if FEATURE_texture_s3tc
532   if (ctx->Mesa_DXTn) {
533      _mesa_enable_extension(ctx, "GL_EXT_texture_compression_s3tc");
534      _mesa_enable_extension(ctx, "GL_S3_s3tc");
535   }
536#endif
537}
538
539
540/**
541 * Enable all OpenGL 1.3 features and extensions.
542 * A convenience function to be called by drivers.
543 */
544void
545_mesa_enable_1_3_extensions(struct gl_context *ctx)
546{
547   ctx->Extensions.ARB_texture_border_clamp = GL_TRUE;
548   ctx->Extensions.ARB_texture_cube_map = GL_TRUE;
549   ctx->Extensions.ARB_texture_env_combine = GL_TRUE;
550   ctx->Extensions.ARB_texture_env_dot3 = GL_TRUE;
551   /*ctx->Extensions.ARB_transpose_matrix = GL_TRUE;*/
552}
553
554
555
556/**
557 * Enable all OpenGL 1.4 features and extensions.
558 * A convenience function to be called by drivers.
559 */
560void
561_mesa_enable_1_4_extensions(struct gl_context *ctx)
562{
563   ctx->Extensions.ARB_depth_texture = GL_TRUE;
564   ctx->Extensions.ARB_shadow = GL_TRUE;
565   ctx->Extensions.ARB_texture_env_crossbar = GL_TRUE;
566   ctx->Extensions.ARB_window_pos = GL_TRUE;
567   ctx->Extensions.EXT_blend_color = GL_TRUE;
568   ctx->Extensions.EXT_blend_func_separate = GL_TRUE;
569   ctx->Extensions.EXT_blend_minmax = GL_TRUE;
570   ctx->Extensions.EXT_fog_coord = GL_TRUE;
571   ctx->Extensions.EXT_point_parameters = GL_TRUE;
572   ctx->Extensions.EXT_secondary_color = GL_TRUE;
573}
574
575
576/**
577 * Enable all OpenGL 1.5 features and extensions.
578 * A convenience function to be called by drivers.
579 */
580void
581_mesa_enable_1_5_extensions(struct gl_context *ctx)
582{
583   ctx->Extensions.ARB_occlusion_query = GL_TRUE;
584   ctx->Extensions.EXT_shadow_funcs = GL_TRUE;
585}
586
587
588/**
589 * Enable all OpenGL 2.0 features and extensions.
590 * A convenience function to be called by drivers.
591 */
592void
593_mesa_enable_2_0_extensions(struct gl_context *ctx)
594{
595#if FEATURE_ARB_fragment_shader
596   ctx->Extensions.ARB_fragment_shader = GL_TRUE;
597#endif
598   ctx->Extensions.ARB_point_sprite = GL_TRUE;
599   ctx->Extensions.EXT_blend_equation_separate = GL_TRUE;
600   ctx->Extensions.ARB_texture_non_power_of_two = GL_TRUE;
601#if FEATURE_ARB_shader_objects
602   ctx->Extensions.ARB_shader_objects = GL_TRUE;
603#endif
604#if FEATURE_ARB_shading_language_100
605   ctx->Extensions.ARB_shading_language_100 = GL_TRUE;
606#endif
607   ctx->Extensions.EXT_stencil_two_side = GL_TRUE;
608#if FEATURE_ARB_vertex_shader
609   ctx->Extensions.ARB_vertex_shader = GL_TRUE;
610#endif
611}
612
613
614/**
615 * Enable all OpenGL 2.1 features and extensions.
616 * A convenience function to be called by drivers.
617 */
618void
619_mesa_enable_2_1_extensions(struct gl_context *ctx)
620{
621#if FEATURE_EXT_pixel_buffer_object
622   ctx->Extensions.EXT_pixel_buffer_object = GL_TRUE;
623#endif
624#if FEATURE_EXT_texture_sRGB
625   ctx->Extensions.EXT_texture_sRGB = GL_TRUE;
626#endif
627}
628
629
630/**
631 * Either enable or disable the named extension.
632 * \return GL_TRUE for success, GL_FALSE if invalid extension name
633 */
634static GLboolean
635set_extension( struct gl_context *ctx, const char *name, GLboolean state )
636{
637   size_t offset;
638
639   if (ctx->Extensions.String) {
640      /* The string was already queried - can't change it now! */
641      _mesa_problem(ctx, "Trying to enable/disable extension after glGetString(GL_EXTENSIONS): %s", name);
642      return GL_FALSE;
643   }
644
645   offset = name_to_offset(name);
646   if (offset == 0) {
647      _mesa_problem(ctx, "Trying to enable/disable unknown extension %s",
648	            name);
649      return GL_FALSE;
650   } else if (offset == o(dummy_true) && state == GL_FALSE) {
651      _mesa_problem(ctx, "Trying to disable a permanently enabled extension: "
652	                  "%s", name);
653      return GL_FALSE;
654   } else {
655      GLboolean *base = (GLboolean *) &ctx->Extensions;
656      base[offset] = state;
657      return GL_TRUE;
658   }
659}
660
661
662/**
663 * Enable the named extension.
664 * Typically called by drivers.
665 */
666void
667_mesa_enable_extension( struct gl_context *ctx, const char *name )
668{
669   if (!set_extension(ctx, name, GL_TRUE))
670      _mesa_problem(ctx, "Trying to enable unknown extension: %s", name);
671}
672
673
674/**
675 * Disable the named extension.
676 * XXX is this really needed???
677 */
678void
679_mesa_disable_extension( struct gl_context *ctx, const char *name )
680{
681   if (!set_extension(ctx, name, GL_FALSE))
682      _mesa_problem(ctx, "Trying to disable unknown extension: %s", name);
683}
684
685
686/**
687 * Test if the named extension is enabled in this context.
688 */
689GLboolean
690_mesa_extension_is_enabled( struct gl_context *ctx, const char *name )
691{
692   size_t offset;
693   GLboolean *base;
694
695   if (name == 0)
696      return GL_FALSE;
697
698   offset = name_to_offset(name);
699   if (offset == 0)
700      return GL_FALSE;
701   base = (GLboolean *) &ctx->Extensions;
702   return base[offset];
703}
704
705
706/**
707 * \brief Apply the \c MESA_EXTENSION_OVERRIDE environment variable.
708 *
709 * \c MESA_EXTENSION_OVERRIDE is a space-separated list of extensions to
710 * enable or disable. The list is processed thus:
711 *    - Enable recognized extension names that are prefixed with '+'.
712 *    - Disable recognized extension names that are prefixed with '-'.
713 *    - Enable recognized extension names that are not prefixed.
714 *    - Collect unrecognized extension names in a new string.
715 *
716 * \return Space-separated list of unrecognized extension names (which must
717 *    be freed). Does not return \c NULL.
718 */
719static char *
720get_extension_override( struct gl_context *ctx )
721{
722   const char *env_const = _mesa_getenv("MESA_EXTENSION_OVERRIDE");
723   char *env;
724   char *ext;
725   char *extra_exts;
726   int len;
727
728   if (env_const == NULL) {
729      /* Return the empty string rather than NULL. This simplifies the logic
730       * of client functions. */
731      return calloc(4, sizeof(char));
732   }
733
734   /* extra_exts: List of unrecognized extensions. */
735   extra_exts = calloc(ALIGN(strlen(env_const) + 2, 4), sizeof(char));
736
737   /* Copy env_const because strtok() is destructive. */
738   env = strdup(env_const);
739   for (ext = strtok(env, " "); ext != NULL; ext = strtok(NULL, " ")) {
740      int enable;
741      int recognized;
742      switch (ext[0]) {
743      case '+':
744         enable = 1;
745         ++ext;
746         break;
747      case '-':
748         enable = 0;
749         ++ext;
750         break;
751      default:
752         enable = 1;
753         break;
754      }
755      recognized = set_extension(ctx, ext, enable);
756      if (!recognized) {
757         strcat(extra_exts, ext);
758         strcat(extra_exts, " ");
759      }
760   }
761
762   free(env);
763
764   /* Remove trailing space. */
765   len = strlen(extra_exts);
766   if (len > 0 && extra_exts[len - 1] == ' ')
767      extra_exts[len - 1] = '\0';
768
769   return extra_exts;
770}
771
772
773/**
774 * \brief Initialize extension tables and enable default extensions.
775 *
776 * This should be called during context initialization.
777 * Note: Sets gl_extensions.dummy_true to true.
778 */
779void
780_mesa_init_extensions( struct gl_context *ctx )
781{
782   GLboolean *base = (GLboolean *) &ctx->Extensions;
783   GLboolean *sentinel = base + o(extension_sentinel);
784   GLboolean *i;
785   const size_t *j;
786
787   /* First, turn all extensions off. */
788   for (i = base; i != sentinel; ++i)
789      *i = GL_FALSE;
790
791   /* Then, selectively turn default extensions on. */
792   ctx->Extensions.dummy_true = GL_TRUE;
793   for (j = default_extensions; *j != 0; ++j)
794      base[*j] = GL_TRUE;
795}
796
797
798typedef unsigned short extension_index;
799
800
801/**
802 * Compare two entries of the extensions table.  Sorts first by year,
803 * then by name.
804 *
805 * Arguments are indices into extension_table.
806 */
807static int
808extension_compare(const void *p1, const void *p2)
809{
810   extension_index i1 = * (const extension_index *) p1;
811   extension_index i2 = * (const extension_index *) p2;
812   const struct extension *e1 = &extension_table[i1];
813   const struct extension *e2 = &extension_table[i2];
814   int res;
815
816   res = (int)e1->year - (int)e2->year;
817
818   if (res == 0) {
819      res = strcmp(e1->name, e2->name);
820   }
821
822   return res;
823}
824
825
826/**
827 * Construct the GL_EXTENSIONS string.  Called the first time that
828 * glGetString(GL_EXTENSIONS) is called.
829 */
830GLubyte*
831_mesa_make_extension_string(struct gl_context *ctx)
832{
833   /* The extension string. */
834   char *exts = 0;
835   /* Length of extension string. */
836   size_t length = 0;
837   /* Number of extensions */
838   unsigned count;
839   /* Indices of the extensions sorted by year */
840   extension_index *extension_indices;
841   /* String of extra extensions. */
842   char *extra_extensions = get_extension_override(ctx);
843   GLboolean *base = (GLboolean *) &ctx->Extensions;
844   const struct extension *i;
845   unsigned j;
846   unsigned maxYear = ~0;
847
848   /* Check if the MESA_EXTENSION_MAX_YEAR env var is set */
849   {
850      const char *env = getenv("MESA_EXTENSION_MAX_YEAR");
851      if (env) {
852         maxYear = atoi(env);
853         _mesa_debug(ctx, "Note: limiting GL extensions to %u or earlier\n",
854                     maxYear);
855      }
856   }
857
858   /* Compute length of the extension string. */
859   count = 0;
860   for (i = extension_table; i->name != 0; ++i) {
861      if (base[i->offset] &&
862          i->year <= maxYear &&
863          (i->api_set & (1 << ctx->API))) {
864	 length += strlen(i->name) + 1; /* +1 for space */
865	 ++count;
866      }
867   }
868   if (extra_extensions != NULL)
869      length += 1 + strlen(extra_extensions); /* +1 for space */
870
871   exts = (char *) calloc(ALIGN(length + 1, 4), sizeof(char));
872   if (exts == NULL) {
873      free(extra_extensions);
874      return NULL;
875   }
876
877   extension_indices = malloc(count * sizeof(extension_index));
878   if (extension_indices == NULL) {
879      free(exts);
880      free(extra_extensions);
881      return NULL;
882   }
883
884   /* Sort extensions in chronological order because certain old applications (e.g.,
885    * Quake3 demo) store the extension list in a static size buffer so chronologically
886    * order ensure that the extensions that such applications expect will fit into
887    * that buffer.
888    */
889   j = 0;
890   for (i = extension_table; i->name != 0; ++i) {
891      if (base[i->offset] &&
892          i->year <= maxYear &&
893          (i->api_set & (1 << ctx->API))) {
894         extension_indices[j++] = i - extension_table;
895      }
896   }
897   assert(j == count);
898   qsort(extension_indices, count, sizeof *extension_indices, extension_compare);
899
900   /* Build the extension string.*/
901   for (j = 0; j < count; ++j) {
902      i = &extension_table[extension_indices[j]];
903      assert(base[i->offset] && (i->api_set & (1 << ctx->API)));
904      strcat(exts, i->name);
905      strcat(exts, " ");
906   }
907   free(extension_indices);
908   if (extra_extensions != 0) {
909      strcat(exts, extra_extensions);
910      free(extra_extensions);
911   }
912
913   return (GLubyte *) exts;
914}
915
916/**
917 * Return number of enabled extensions.
918 */
919GLuint
920_mesa_get_extension_count(struct gl_context *ctx)
921{
922   GLboolean *base;
923   const struct extension *i;
924
925   /* only count once */
926   if (ctx->Extensions.Count != 0)
927      return ctx->Extensions.Count;
928
929   base = (GLboolean *) &ctx->Extensions;
930   for (i = extension_table; i->name != 0; ++i) {
931      if (base[i->offset]) {
932	 ctx->Extensions.Count++;
933      }
934   }
935   return ctx->Extensions.Count;
936}
937
938/**
939 * Return name of i-th enabled extension
940 */
941const GLubyte *
942_mesa_get_enabled_extension(struct gl_context *ctx, GLuint index)
943{
944   const GLboolean *base;
945   size_t n;
946   const struct extension *i;
947
948   base = (GLboolean*) &ctx->Extensions;
949   n = 0;
950   for (i = extension_table; i->name != 0; ++i) {
951      if (n == index && base[i->offset]) {
952	 return (const GLubyte*) i->name;
953      } else if (base[i->offset]) {
954	 ++n;
955      }
956   }
957
958   return NULL;
959}
960