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[reactos.git] / reactos / dll / opengl / mesa / 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(ARB_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(dummy_true), 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(dummy_true), GL, 1994 },
104 { "GL_ARB_multitexture", o(dummy_true), 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(dummy_true), 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(dummy_true), 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(dummy_true), 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_storage", o(ARB_texture_storage), GL, 2011 },
138 { "GL_ARB_texture_swizzle", o(EXT_texture_swizzle), GL, 2008 },
139 { "GL_ARB_transform_feedback2", o(ARB_transform_feedback2), GL, 2010 },
140 { "GL_ARB_transpose_matrix", o(ARB_transpose_matrix), GL, 1999 },
141 { "GL_ARB_uniform_buffer_object", o(ARB_uniform_buffer_object), GL, 2002 },
142 { "GL_ARB_vertex_array_bgra", o(EXT_vertex_array_bgra), GL, 2008 },
143 { "GL_ARB_vertex_array_object", o(ARB_vertex_array_object), GL, 2006 },
144 { "GL_ARB_vertex_buffer_object", o(dummy_true), GL, 2003 },
145 { "GL_ARB_vertex_program", o(ARB_vertex_program), GL, 2002 },
146 { "GL_ARB_vertex_shader", o(ARB_vertex_shader), GL, 2002 },
147 { "GL_ARB_vertex_type_2_10_10_10_rev", o(ARB_vertex_type_2_10_10_10_rev), GL, 2009 },
148 { "GL_ARB_window_pos", o(ARB_window_pos), GL, 2001 },
149 /* EXT extensions */
150 { "GL_EXT_abgr", o(dummy_true), GL, 1995 },
151 { "GL_EXT_bgra", o(dummy_true), GL, 1995 },
152 { "GL_EXT_blend_color", o(EXT_blend_color), GL, 1995 },
153 { "GL_EXT_blend_equation_separate", o(EXT_blend_equation_separate), GL, 2003 },
154 { "GL_EXT_blend_func_separate", o(EXT_blend_func_separate), GL, 1999 },
155 { "GL_EXT_blend_minmax", o(EXT_blend_minmax), GL | ES1 | ES2, 1995 },
156 { "GL_EXT_blend_subtract", o(dummy_true), GL, 1995 },
157 { "GL_EXT_clip_volume_hint", o(EXT_clip_volume_hint), GL, 1996 },
158 { "GL_EXT_compiled_vertex_array", o(EXT_compiled_vertex_array), GL, 1996 },
159 { "GL_EXT_copy_texture", o(dummy_true), GL, 1995 },
160 { "GL_EXT_depth_bounds_test", o(EXT_depth_bounds_test), GL, 2002 },
161 { "GL_EXT_draw_buffers2", o(EXT_draw_buffers2), GL, 2006 },
162 { "GL_EXT_draw_instanced", o(ARB_draw_instanced), GL, 2006 },
163 { "GL_EXT_draw_range_elements", o(EXT_draw_range_elements), GL, 1997 },
164 { "GL_EXT_fog_coord", o(EXT_fog_coord), GL, 1999 },
165 { "GL_EXT_framebuffer_blit", o(EXT_framebuffer_blit), GL, 2005 },
166 { "GL_EXT_framebuffer_multisample", o(EXT_framebuffer_multisample), GL, 2005 },
167 { "GL_EXT_framebuffer_object", o(EXT_framebuffer_object), GL, 2000 },
168 { "GL_EXT_framebuffer_sRGB", o(EXT_framebuffer_sRGB), GL, 1998 },
169 { "GL_EXT_gpu_program_parameters", o(EXT_gpu_program_parameters), GL, 2006 },
170 { "GL_EXT_gpu_shader4", o(EXT_gpu_shader4), GL, 2006 },
171 { "GL_EXT_multi_draw_arrays", o(dummy_true), GL | ES1 | ES2, 1999 },
172 { "GL_EXT_packed_depth_stencil", o(EXT_packed_depth_stencil), GL, 2005 },
173 { "GL_EXT_packed_float", o(EXT_packed_float), GL, 2004 },
174 { "GL_EXT_packed_pixels", o(EXT_packed_pixels), GL, 1997 },
175 { "GL_EXT_pixel_buffer_object", o(EXT_pixel_buffer_object), GL, 2004 },
176 { "GL_EXT_point_parameters", o(EXT_point_parameters), GL, 1997 },
177 { "GL_EXT_polygon_offset", o(dummy_true), GL, 1995 },
178 { "GL_EXT_provoking_vertex", o(EXT_provoking_vertex), GL, 2009 },
179 { "GL_EXT_rescale_normal", o(EXT_rescale_normal), GL, 1997 },
180 { "GL_EXT_secondary_color", o(EXT_secondary_color), GL, 1999 },
181 { "GL_EXT_separate_shader_objects", o(EXT_separate_shader_objects), GL, 2008 },
182 { "GL_EXT_separate_specular_color", o(EXT_separate_specular_color), GL, 1997 },
183 { "GL_EXT_shadow_funcs", o(EXT_shadow_funcs), GL, 2002 },
184 { "GL_EXT_stencil_two_side", o(EXT_stencil_two_side), GL, 2001 },
185 { "GL_EXT_stencil_wrap", o(dummy_true), GL, 2002 },
186 { "GL_EXT_subtexture", o(dummy_true), GL, 1995 },
187 { "GL_EXT_texture3D", o(EXT_texture3D), GL, 1996 },
188 { "GL_EXT_texture_array", o(EXT_texture_array), GL, 2006 },
189 { "GL_EXT_texture_compression_dxt1", o(EXT_texture_compression_s3tc), GL | ES1 | ES2, 2004 },
190 { "GL_EXT_texture_compression_latc", o(EXT_texture_compression_latc), GL, 2006 },
191 { "GL_EXT_texture_compression_rgtc", o(ARB_texture_compression_rgtc), GL, 2004 },
192 { "GL_EXT_texture_compression_s3tc", o(EXT_texture_compression_s3tc), GL, 2000 },
193 { "GL_EXT_texture_cube_map", o(ARB_texture_cube_map), GL, 2001 },
194 { "GL_EXT_texture_edge_clamp", o(dummy_true), GL, 1997 },
195 { "GL_EXT_texture_env_add", o(dummy_true), GL, 1999 },
196 { "GL_EXT_texture_env_combine", o(dummy_true), GL, 2000 },
197 { "GL_EXT_texture_env_dot3", o(EXT_texture_env_dot3), GL, 2000 },
198 { "GL_EXT_texture_filter_anisotropic", o(EXT_texture_filter_anisotropic), GL | ES1 | ES2, 1999 },
199 { "GL_EXT_texture_format_BGRA8888", o(dummy_true), ES1 | ES2, 2005 },
200 { "GL_EXT_texture_integer", o(EXT_texture_integer), GL, 2006 },
201 { "GL_EXT_texture_lod_bias", o(dummy_true), GL | ES1, 1999 },
202 { "GL_EXT_texture_mirror_clamp", o(EXT_texture_mirror_clamp), GL, 2004 },
203 { "GL_EXT_texture_object", o(dummy_true), GL, 1995 },
204 { "GL_EXT_texture", o(dummy_true), GL, 1996 },
205 { "GL_EXT_texture_rectangle", o(NV_texture_rectangle), GL, 2004 },
206 { "GL_EXT_texture_shared_exponent", o(EXT_texture_shared_exponent), GL, 2004 },
207 { "GL_EXT_texture_snorm", o(EXT_texture_snorm), GL, 2009 },
208 { "GL_EXT_texture_sRGB", o(EXT_texture_sRGB), GL, 2004 },
209 { "GL_EXT_texture_sRGB_decode", o(EXT_texture_sRGB_decode), GL, 2006 },
210 { "GL_EXT_texture_swizzle", o(EXT_texture_swizzle), GL, 2008 },
211 { "GL_EXT_texture_type_2_10_10_10_REV", o(dummy_true), ES2, 2008 },
212 { "GL_EXT_timer_query", o(EXT_timer_query), GL, 2006 },
213 { "GL_EXT_transform_feedback", o(EXT_transform_feedback), GL, 2011 },
214 { "GL_EXT_vertex_array_bgra", o(EXT_vertex_array_bgra), GL, 2008 },
215 { "GL_EXT_vertex_array", o(dummy_true), GL, 1995 },
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(dummy_true), ES1, 2009 },
221 { "GL_OES_byte_coordinates", o(dummy_true), ES1, 2002 },
222 { "GL_OES_compressed_ETC1_RGB8_texture", o(OES_compressed_ETC1_RGB8_texture), ES1 | ES2, 2005 },
223 { "GL_OES_compressed_paletted_texture", o(dummy_true), ES1, 2003 },
224 { "GL_OES_depth24", o(EXT_framebuffer_object), ES1 | ES2, 2005 },
225 { "GL_OES_depth32", o(dummy_false), DISABLE, 2005 },
226 { "GL_OES_depth_texture", o(ARB_depth_texture), ES2, 2006 },
227 #if FEATURE_OES_draw_texture
228 { "GL_OES_draw_texture", o(OES_draw_texture), ES1 | ES2, 2004 },
229 #endif
230 #if FEATURE_OES_EGL_image
231 /* FIXME: Mesa expects GL_OES_EGL_image to be available in OpenGL contexts. */
232 { "GL_OES_EGL_image", o(OES_EGL_image), GL | ES1 | ES2, 2006 },
233 { "GL_OES_EGL_image_external", o(OES_EGL_image_external), ES1 | ES2, 2010 },
234 #endif
235 { "GL_OES_element_index_uint", o(dummy_true), ES1 | ES2, 2005 },
236 { "GL_OES_fbo_render_mipmap", o(EXT_framebuffer_object), ES1 | ES2, 2005 },
237 { "GL_OES_fixed_point", o(dummy_true), ES1, 2002 },
238 { "GL_OES_framebuffer_object", o(EXT_framebuffer_object), ES1, 2005 },
239 { "GL_OES_mapbuffer", o(dummy_true), ES1 | ES2, 2005 },
240 { "GL_OES_matrix_get", o(dummy_true), ES1, 2004 },
241 { "GL_OES_packed_depth_stencil", o(EXT_packed_depth_stencil), ES1 | ES2, 2007 },
242 { "GL_OES_point_size_array", o(dummy_true), ES1, 2004 },
243 { "GL_OES_point_sprite", o(ARB_point_sprite), ES1, 2004 },
244 { "GL_OES_query_matrix", o(dummy_true), ES1, 2003 },
245 { "GL_OES_read_format", o(dummy_true), GL | ES1, 2003 },
246 { "GL_OES_rgb8_rgba8", o(EXT_framebuffer_object), ES1 | ES2, 2005 },
247 { "GL_OES_single_precision", o(dummy_true), ES1, 2003 },
248 { "GL_OES_standard_derivatives", o(OES_standard_derivatives), ES2, 2005 },
249 { "GL_OES_stencil1", o(dummy_false), DISABLE, 2005 },
250 { "GL_OES_stencil4", o(dummy_false), DISABLE, 2005 },
251 { "GL_OES_stencil8", o(EXT_framebuffer_object), ES1 | ES2, 2005 },
252 { "GL_OES_stencil_wrap", o(dummy_true), ES1, 2002 },
253 { "GL_OES_texture_3D", o(EXT_texture3D), ES2, 2005 },
254 { "GL_OES_texture_cube_map", o(ARB_texture_cube_map), ES1, 2007 },
255 { "GL_OES_texture_env_crossbar", o(ARB_texture_env_crossbar), ES1, 2005 },
256 { "GL_OES_texture_mirrored_repeat", o(dummy_true), ES1, 2005 },
257 { "GL_OES_texture_npot", o(ARB_texture_non_power_of_two), ES2, 2005 },
258
259 /* Vendor extensions */
260 { "GL_3DFX_texture_compression_FXT1", o(TDFX_texture_compression_FXT1), GL, 1999 },
261 { "GL_AMD_conservative_depth", o(ARB_conservative_depth), GL, 2009 },
262 { "GL_AMD_draw_buffers_blend", o(ARB_draw_buffers_blend), GL, 2009 },
263 { "GL_AMD_seamless_cubemap_per_texture", o(AMD_seamless_cubemap_per_texture), GL, 2009 },
264 { "GL_AMD_shader_stencil_export", o(ARB_shader_stencil_export), GL, 2009 },
265 { "GL_APPLE_object_purgeable", o(APPLE_object_purgeable), GL, 2006 },
266 { "GL_APPLE_packed_pixels", o(APPLE_packed_pixels), GL, 2002 },
267 { "GL_APPLE_vertex_array_object", o(APPLE_vertex_array_object), GL, 2002 },
268 { "GL_ATI_blend_equation_separate", o(EXT_blend_equation_separate), GL, 2003 },
269 { "GL_ATI_draw_buffers", o(dummy_true), GL, 2002 },
270 { "GL_ATI_envmap_bumpmap", o(ATI_envmap_bumpmap), GL, 2001 },
271 { "GL_ATI_fragment_shader", o(ATI_fragment_shader), GL, 2001 },
272 { "GL_ATI_separate_stencil", o(ATI_separate_stencil), GL, 2006 },
273 { "GL_ATI_texture_compression_3dc", o(ATI_texture_compression_3dc), GL, 2004 },
274 { "GL_ATI_texture_env_combine3", o(ATI_texture_env_combine3), GL, 2002 },
275 { "GL_ATI_texture_float", o(ARB_texture_float), GL, 2002 },
276 { "GL_ATI_texture_mirror_once", o(ATI_texture_mirror_once), GL, 2006 },
277 { "GL_IBM_multimode_draw_arrays", o(IBM_multimode_draw_arrays), GL, 1998 },
278 { "GL_IBM_rasterpos_clip", o(IBM_rasterpos_clip), GL, 1996 },
279 { "GL_IBM_texture_mirrored_repeat", o(dummy_true), GL, 1998 },
280 { "GL_INGR_blend_func_separate", o(EXT_blend_func_separate), GL, 1999 },
281 { "GL_MESA_pack_invert", o(MESA_pack_invert), GL, 2002 },
282 { "GL_MESA_resize_buffers", o(MESA_resize_buffers), GL, 1999 },
283 { "GL_MESA_texture_array", o(MESA_texture_array), GL, 2007 },
284 { "GL_MESA_texture_signed_rgba", o(EXT_texture_snorm), GL, 2009 },
285 { "GL_MESA_window_pos", o(ARB_window_pos), GL, 2000 },
286 { "GL_MESA_ycbcr_texture", o(MESA_ycbcr_texture), GL, 2002 },
287 { "GL_NV_blend_square", o(NV_blend_square), GL, 1999 },
288 { "GL_NV_conditional_render", o(NV_conditional_render), GL, 2008 },
289 { "GL_NV_depth_clamp", o(ARB_depth_clamp), GL, 2001 },
290 { "GL_NV_draw_buffers", o(dummy_true), ES2, 2011 },
291 { "GL_NV_fbo_color_attachments", o(EXT_framebuffer_object), ES2, 2010 },
292 { "GL_NV_fog_distance", o(NV_fog_distance), GL, 2001 },
293 { "GL_NV_fragment_program", o(NV_fragment_program), GL, 2001 },
294 { "GL_NV_fragment_program_option", o(NV_fragment_program_option), GL, 2005 },
295 { "GL_NV_light_max_exponent", o(NV_light_max_exponent), GL, 1999 },
296 { "GL_NV_packed_depth_stencil", o(EXT_packed_depth_stencil), GL, 2000 },
297 { "GL_NV_point_sprite", o(NV_point_sprite), GL, 2001 },
298 { "GL_NV_primitive_restart", o(NV_primitive_restart), GL, 2002 },
299 { "GL_NV_texgen_reflection", o(NV_texgen_reflection), GL, 1999 },
300 { "GL_NV_texture_barrier", o(NV_texture_barrier), GL, 2009 },
301 { "GL_NV_texture_env_combine4", o(NV_texture_env_combine4), GL, 1999 },
302 { "GL_NV_texture_rectangle", o(NV_texture_rectangle), GL, 2000 },
303 { "GL_NV_vertex_program1_1", o(NV_vertex_program1_1), GL, 2001 },
304 { "GL_NV_vertex_program", o(NV_vertex_program), GL, 2000 },
305 { "GL_S3_s3tc", o(S3_s3tc), GL, 1999 },
306 { "GL_SGIS_generate_mipmap", o(dummy_true), GL, 1997 },
307 { "GL_SGIS_texture_border_clamp", o(ARB_texture_border_clamp), GL, 1997 },
308 { "GL_SGIS_texture_edge_clamp", o(dummy_true), GL, 1997 },
309 { "GL_SGIS_texture_lod", o(SGIS_texture_lod), GL, 1997 },
310 { "GL_SUN_multi_draw_arrays", o(dummy_true), GL, 1999 },
311
312 { 0, 0, 0, 0 },
313 };
314
315
316 /**
317 * Given an extension name, lookup up the corresponding member of struct
318 * gl_extensions and return that member's offset (in bytes). If the name is
319 * not found in the \c extension_table, return 0.
320 *
321 * \param name Name of extension.
322 * \return Offset of member in struct gl_extensions.
323 */
324 static size_t
325 name_to_offset(const char* name)
326 {
327 const struct extension *i;
328
329 if (name == 0)
330 return 0;
331
332 for (i = extension_table; i->name != 0; ++i) {
333 if (strcmp(name, i->name) == 0)
334 return i->offset;
335 }
336
337 return 0;
338 }
339
340
341 /**
342 * \brief Extensions enabled by default.
343 *
344 * These extensions are enabled by _mesa_init_extensions().
345 *
346 * XXX: Should these defaults also apply to GLES?
347 */
348 static const size_t default_extensions[] = {
349 o(ARB_copy_buffer),
350 o(ARB_transpose_matrix),
351 o(ARB_window_pos),
352
353 o(EXT_compiled_vertex_array),
354 o(EXT_draw_range_elements),
355 o(EXT_packed_pixels),
356 o(EXT_rescale_normal),
357 o(EXT_separate_specular_color),
358 o(EXT_texture3D),
359
360 o(OES_standard_derivatives),
361
362 /* Vendor Extensions */
363 o(APPLE_packed_pixels),
364 o(IBM_multimode_draw_arrays),
365 o(IBM_rasterpos_clip),
366 o(NV_light_max_exponent),
367 o(NV_texgen_reflection),
368 o(SGIS_texture_lod),
369
370 0,
371 };
372
373
374 /**
375 * Enable all extensions suitable for a software-only renderer.
376 * This is a convenience function used by the XMesa, OSMesa, GGI drivers, etc.
377 */
378 void
379 _mesa_enable_sw_extensions(struct gl_context *ctx)
380 {
381 /*ctx->Extensions.ARB_copy_buffer = GL_TRUE;*/
382 ctx->Extensions.ARB_depth_clamp = GL_TRUE;
383 ctx->Extensions.ARB_depth_texture = GL_TRUE;
384 ctx->Extensions.ARB_draw_elements_base_vertex = GL_TRUE;
385 ctx->Extensions.ARB_draw_instanced = GL_TRUE;
386 ctx->Extensions.ARB_explicit_attrib_location = GL_TRUE;
387 ctx->Extensions.ARB_fragment_coord_conventions = GL_TRUE;
388 #if FEATURE_ARB_fragment_program
389 ctx->Extensions.ARB_fragment_program = GL_TRUE;
390 ctx->Extensions.ARB_fragment_program_shadow = GL_TRUE;
391 #endif
392 #if FEATURE_ARB_fragment_shader
393 ctx->Extensions.ARB_fragment_shader = GL_TRUE;
394 #endif
395 #if FEATURE_ARB_framebuffer_object
396 ctx->Extensions.ARB_framebuffer_object = GL_TRUE;
397 #endif
398 #if FEATURE_ARB_geometry_shader4 && 0
399 /* XXX re-enable when GLSL compiler again supports geometry shaders */
400 ctx->Extensions.ARB_geometry_shader4 = GL_TRUE;
401 #endif
402 ctx->Extensions.ARB_half_float_pixel = GL_TRUE;
403 ctx->Extensions.ARB_half_float_vertex = GL_TRUE;
404 ctx->Extensions.ARB_map_buffer_range = GL_TRUE;
405 #if FEATURE_queryobj
406 ctx->Extensions.ARB_occlusion_query = GL_TRUE;
407 ctx->Extensions.ARB_occlusion_query2 = GL_TRUE;
408 #endif
409 ctx->Extensions.ARB_point_sprite = GL_TRUE;
410 #if FEATURE_ARB_shader_objects
411 ctx->Extensions.ARB_shader_objects = GL_TRUE;
412 ctx->Extensions.EXT_separate_shader_objects = GL_TRUE;
413 #endif
414 #if FEATURE_ARB_shading_language_100
415 ctx->Extensions.ARB_shading_language_100 = GL_TRUE;
416 #endif
417 ctx->Extensions.ARB_shadow = GL_TRUE;
418 ctx->Extensions.ARB_shadow_ambient = GL_TRUE;
419 ctx->Extensions.ARB_texture_border_clamp = GL_TRUE;
420 ctx->Extensions.ARB_texture_cube_map = GL_TRUE;
421 ctx->Extensions.ARB_texture_env_combine = GL_TRUE;
422 ctx->Extensions.ARB_texture_env_crossbar = GL_TRUE;
423 ctx->Extensions.ARB_texture_env_dot3 = GL_TRUE;
424 /*ctx->Extensions.ARB_texture_float = GL_TRUE;*/
425 ctx->Extensions.ARB_texture_non_power_of_two = GL_TRUE;
426 ctx->Extensions.ARB_texture_rg = GL_TRUE;
427 ctx->Extensions.ARB_texture_compression_rgtc = GL_TRUE;
428 ctx->Extensions.ARB_texture_storage = GL_TRUE;
429 ctx->Extensions.ARB_vertex_array_object = GL_TRUE;
430 #if FEATURE_ARB_vertex_program
431 ctx->Extensions.ARB_vertex_program = GL_TRUE;
432 #endif
433 #if FEATURE_ARB_vertex_shader
434 ctx->Extensions.ARB_vertex_shader = GL_TRUE;
435 #endif
436 #if FEATURE_ARB_sync
437 ctx->Extensions.ARB_sync = GL_TRUE;
438 #endif
439 ctx->Extensions.APPLE_vertex_array_object = GL_TRUE;
440 #if FEATURE_APPLE_object_purgeable
441 ctx->Extensions.APPLE_object_purgeable = GL_TRUE;
442 #endif
443 ctx->Extensions.ATI_envmap_bumpmap = GL_TRUE;
444 #if FEATURE_ATI_fragment_shader
445 ctx->Extensions.ATI_fragment_shader = GL_TRUE;
446 #endif
447 ctx->Extensions.ATI_texture_compression_3dc = GL_TRUE;
448 ctx->Extensions.ATI_texture_env_combine3 = GL_TRUE;
449 ctx->Extensions.ATI_texture_mirror_once = GL_TRUE;
450 ctx->Extensions.ATI_separate_stencil = GL_TRUE;
451 ctx->Extensions.EXT_blend_color = GL_TRUE;
452 ctx->Extensions.EXT_blend_equation_separate = GL_TRUE;
453 ctx->Extensions.EXT_blend_func_separate = GL_TRUE;
454 ctx->Extensions.EXT_blend_minmax = GL_TRUE;
455 ctx->Extensions.EXT_depth_bounds_test = GL_TRUE;
456 ctx->Extensions.EXT_draw_buffers2 = GL_TRUE;
457 ctx->Extensions.EXT_fog_coord = GL_TRUE;
458 #if FEATURE_EXT_framebuffer_object
459 ctx->Extensions.EXT_framebuffer_object = GL_TRUE;
460 #endif
461 #if FEATURE_EXT_framebuffer_blit
462 ctx->Extensions.EXT_framebuffer_blit = GL_TRUE;
463 #endif
464 #if FEATURE_ARB_framebuffer_object
465 ctx->Extensions.EXT_framebuffer_multisample = GL_TRUE;
466 #endif
467 ctx->Extensions.EXT_packed_depth_stencil = GL_TRUE;
468 #if FEATURE_EXT_pixel_buffer_object
469 ctx->Extensions.EXT_pixel_buffer_object = GL_TRUE;
470 #endif
471 ctx->Extensions.EXT_point_parameters = GL_TRUE;
472 ctx->Extensions.EXT_provoking_vertex = GL_TRUE;
473 ctx->Extensions.EXT_shadow_funcs = GL_TRUE;
474 ctx->Extensions.EXT_secondary_color = GL_TRUE;
475 ctx->Extensions.EXT_stencil_two_side = GL_TRUE;
476 ctx->Extensions.EXT_texture_array = GL_TRUE;
477 ctx->Extensions.EXT_texture_compression_latc = GL_TRUE;
478 ctx->Extensions.EXT_texture_env_dot3 = GL_TRUE;
479 ctx->Extensions.EXT_texture_filter_anisotropic = GL_TRUE;
480 ctx->Extensions.EXT_texture_mirror_clamp = GL_TRUE;
481 ctx->Extensions.EXT_texture_shared_exponent = GL_TRUE;
482 #if FEATURE_EXT_texture_sRGB
483 ctx->Extensions.EXT_texture_sRGB = GL_TRUE;
484 ctx->Extensions.EXT_texture_sRGB_decode = GL_TRUE;
485 #endif
486 ctx->Extensions.EXT_texture_swizzle = GL_TRUE;
487 #if FEATURE_EXT_transform_feedback
488 /*ctx->Extensions.EXT_transform_feedback = GL_TRUE;*/
489 #endif
490 ctx->Extensions.EXT_vertex_array_bgra = GL_TRUE;
491 /*ctx->Extensions.IBM_multimode_draw_arrays = GL_TRUE;*/
492 ctx->Extensions.MESA_pack_invert = GL_TRUE;
493 ctx->Extensions.MESA_resize_buffers = GL_TRUE;
494 ctx->Extensions.MESA_texture_array = GL_TRUE;
495 ctx->Extensions.MESA_ycbcr_texture = GL_TRUE;
496 ctx->Extensions.NV_blend_square = GL_TRUE;
497 ctx->Extensions.NV_conditional_render = GL_TRUE;
498 /*ctx->Extensions.NV_light_max_exponent = GL_TRUE;*/
499 ctx->Extensions.NV_point_sprite = GL_TRUE;
500 ctx->Extensions.NV_texture_env_combine4 = GL_TRUE;
501 ctx->Extensions.NV_texture_rectangle = GL_TRUE;
502 /*ctx->Extensions.NV_texgen_reflection = GL_TRUE;*/
503 #if FEATURE_NV_vertex_program
504 ctx->Extensions.NV_vertex_program = GL_TRUE;
505 ctx->Extensions.NV_vertex_program1_1 = GL_TRUE;
506 #endif
507 #if FEATURE_NV_fragment_program
508 ctx->Extensions.NV_fragment_program = GL_TRUE;
509 #endif
510 #if FEATURE_NV_fragment_program && FEATURE_ARB_fragment_program
511 ctx->Extensions.NV_fragment_program_option = GL_TRUE;
512 #endif
513 #if FEATURE_ARB_vertex_program || FEATURE_ARB_fragment_program
514 ctx->Extensions.EXT_gpu_program_parameters = GL_TRUE;
515 #endif
516 #if FEATURE_texture_fxt1
517 _mesa_enable_extension(ctx, "GL_3DFX_texture_compression_FXT1");
518 #endif
519 #if FEATURE_texture_s3tc
520 if (ctx->Mesa_DXTn) {
521 _mesa_enable_extension(ctx, "GL_EXT_texture_compression_s3tc");
522 _mesa_enable_extension(ctx, "GL_S3_s3tc");
523 }
524 #endif
525 }
526
527
528 /**
529 * Enable all OpenGL 1.3 features and extensions.
530 * A convenience function to be called by drivers.
531 */
532 void
533 _mesa_enable_1_3_extensions(struct gl_context *ctx)
534 {
535 ctx->Extensions.ARB_texture_border_clamp = GL_TRUE;
536 ctx->Extensions.ARB_texture_cube_map = GL_TRUE;
537 ctx->Extensions.ARB_texture_env_combine = GL_TRUE;
538 ctx->Extensions.ARB_texture_env_dot3 = GL_TRUE;
539 /*ctx->Extensions.ARB_transpose_matrix = GL_TRUE;*/
540 }
541
542
543
544 /**
545 * Enable all OpenGL 1.4 features and extensions.
546 * A convenience function to be called by drivers.
547 */
548 void
549 _mesa_enable_1_4_extensions(struct gl_context *ctx)
550 {
551 ctx->Extensions.ARB_depth_texture = GL_TRUE;
552 ctx->Extensions.ARB_shadow = GL_TRUE;
553 ctx->Extensions.ARB_texture_env_crossbar = GL_TRUE;
554 ctx->Extensions.ARB_window_pos = GL_TRUE;
555 ctx->Extensions.EXT_blend_color = GL_TRUE;
556 ctx->Extensions.EXT_blend_func_separate = GL_TRUE;
557 ctx->Extensions.EXT_blend_minmax = GL_TRUE;
558 ctx->Extensions.EXT_fog_coord = GL_TRUE;
559 ctx->Extensions.EXT_point_parameters = GL_TRUE;
560 ctx->Extensions.EXT_secondary_color = GL_TRUE;
561 }
562
563
564 /**
565 * Enable all OpenGL 1.5 features and extensions.
566 * A convenience function to be called by drivers.
567 */
568 void
569 _mesa_enable_1_5_extensions(struct gl_context *ctx)
570 {
571 ctx->Extensions.ARB_occlusion_query = GL_TRUE;
572 ctx->Extensions.EXT_shadow_funcs = GL_TRUE;
573 }
574
575
576 /**
577 * Enable all OpenGL 2.0 features and extensions.
578 * A convenience function to be called by drivers.
579 */
580 void
581 _mesa_enable_2_0_extensions(struct gl_context *ctx)
582 {
583 #if FEATURE_ARB_fragment_shader
584 ctx->Extensions.ARB_fragment_shader = GL_TRUE;
585 #endif
586 ctx->Extensions.ARB_point_sprite = GL_TRUE;
587 ctx->Extensions.EXT_blend_equation_separate = GL_TRUE;
588 ctx->Extensions.ARB_texture_non_power_of_two = GL_TRUE;
589 #if FEATURE_ARB_shader_objects
590 ctx->Extensions.ARB_shader_objects = GL_TRUE;
591 #endif
592 #if FEATURE_ARB_shading_language_100
593 ctx->Extensions.ARB_shading_language_100 = GL_TRUE;
594 #endif
595 ctx->Extensions.EXT_stencil_two_side = GL_TRUE;
596 #if FEATURE_ARB_vertex_shader
597 ctx->Extensions.ARB_vertex_shader = GL_TRUE;
598 #endif
599 }
600
601
602 /**
603 * Enable all OpenGL 2.1 features and extensions.
604 * A convenience function to be called by drivers.
605 */
606 void
607 _mesa_enable_2_1_extensions(struct gl_context *ctx)
608 {
609 #if FEATURE_EXT_pixel_buffer_object
610 ctx->Extensions.EXT_pixel_buffer_object = GL_TRUE;
611 #endif
612 #if FEATURE_EXT_texture_sRGB
613 ctx->Extensions.EXT_texture_sRGB = GL_TRUE;
614 #endif
615 }
616
617
618 /**
619 * Either enable or disable the named extension.
620 * \return GL_TRUE for success, GL_FALSE if invalid extension name
621 */
622 static GLboolean
623 set_extension( struct gl_context *ctx, const char *name, GLboolean state )
624 {
625 size_t offset;
626
627 if (ctx->Extensions.String) {
628 /* The string was already queried - can't change it now! */
629 _mesa_problem(ctx, "Trying to enable/disable extension after glGetString(GL_EXTENSIONS): %s", name);
630 return GL_FALSE;
631 }
632
633 offset = name_to_offset(name);
634 if (offset == 0) {
635 _mesa_problem(ctx, "Trying to enable/disable unknown extension %s",
636 name);
637 return GL_FALSE;
638 } else if (offset == o(dummy_true) && state == GL_FALSE) {
639 _mesa_problem(ctx, "Trying to disable a permanently enabled extension: "
640 "%s", name);
641 return GL_FALSE;
642 } else {
643 GLboolean *base = (GLboolean *) &ctx->Extensions;
644 base[offset] = state;
645 return GL_TRUE;
646 }
647 }
648
649
650 /**
651 * Enable the named extension.
652 * Typically called by drivers.
653 */
654 void
655 _mesa_enable_extension( struct gl_context *ctx, const char *name )
656 {
657 if (!set_extension(ctx, name, GL_TRUE))
658 _mesa_problem(ctx, "Trying to enable unknown extension: %s", name);
659 }
660
661
662 /**
663 * Disable the named extension.
664 * XXX is this really needed???
665 */
666 void
667 _mesa_disable_extension( struct gl_context *ctx, const char *name )
668 {
669 if (!set_extension(ctx, name, GL_FALSE))
670 _mesa_problem(ctx, "Trying to disable unknown extension: %s", name);
671 }
672
673
674 /**
675 * Test if the named extension is enabled in this context.
676 */
677 GLboolean
678 _mesa_extension_is_enabled( struct gl_context *ctx, const char *name )
679 {
680 size_t offset;
681 GLboolean *base;
682
683 if (name == 0)
684 return GL_FALSE;
685
686 offset = name_to_offset(name);
687 if (offset == 0)
688 return GL_FALSE;
689 base = (GLboolean *) &ctx->Extensions;
690 return base[offset];
691 }
692
693
694 /**
695 * \brief Apply the \c MESA_EXTENSION_OVERRIDE environment variable.
696 *
697 * \c MESA_EXTENSION_OVERRIDE is a space-separated list of extensions to
698 * enable or disable. The list is processed thus:
699 * - Enable recognized extension names that are prefixed with '+'.
700 * - Disable recognized extension names that are prefixed with '-'.
701 * - Enable recognized extension names that are not prefixed.
702 * - Collect unrecognized extension names in a new string.
703 *
704 * \return Space-separated list of unrecognized extension names (which must
705 * be freed). Does not return \c NULL.
706 */
707 static char *
708 get_extension_override( struct gl_context *ctx )
709 {
710 const char *env_const = _mesa_getenv("MESA_EXTENSION_OVERRIDE");
711 char *env;
712 char *ext;
713 char *extra_exts;
714 int len;
715
716 if (env_const == NULL) {
717 /* Return the empty string rather than NULL. This simplifies the logic
718 * of client functions. */
719 return calloc(4, sizeof(char));
720 }
721
722 /* extra_exts: List of unrecognized extensions. */
723 extra_exts = calloc(ALIGN(strlen(env_const) + 2, 4), sizeof(char));
724
725 /* Copy env_const because strtok() is destructive. */
726 env = strdup(env_const);
727 for (ext = strtok(env, " "); ext != NULL; ext = strtok(NULL, " ")) {
728 int enable;
729 int recognized;
730 switch (ext[0]) {
731 case '+':
732 enable = 1;
733 ++ext;
734 break;
735 case '-':
736 enable = 0;
737 ++ext;
738 break;
739 default:
740 enable = 1;
741 break;
742 }
743 recognized = set_extension(ctx, ext, enable);
744 if (!recognized) {
745 strcat(extra_exts, ext);
746 strcat(extra_exts, " ");
747 }
748 }
749
750 free(env);
751
752 /* Remove trailing space. */
753 len = strlen(extra_exts);
754 if (extra_exts[len - 1] == ' ')
755 extra_exts[len - 1] = '\0';
756
757 return extra_exts;
758 }
759
760
761 /**
762 * \brief Initialize extension tables and enable default extensions.
763 *
764 * This should be called during context initialization.
765 * Note: Sets gl_extensions.dummy_true to true.
766 */
767 void
768 _mesa_init_extensions( struct gl_context *ctx )
769 {
770 GLboolean *base = (GLboolean *) &ctx->Extensions;
771 GLboolean *sentinel = base + o(extension_sentinel);
772 GLboolean *i;
773 const size_t *j;
774
775 /* First, turn all extensions off. */
776 for (i = base; i != sentinel; ++i)
777 *i = GL_FALSE;
778
779 /* Then, selectively turn default extensions on. */
780 ctx->Extensions.dummy_true = GL_TRUE;
781 for (j = default_extensions; *j != 0; ++j)
782 base[*j] = GL_TRUE;
783 }
784
785
786 typedef unsigned short extension_index;
787
788
789 /**
790 * Compare two entries of the extensions table. Sorts first by year,
791 * then by name.
792 *
793 * Arguments are indices into extension_table.
794 */
795 static int
796 extension_compare(const void *p1, const void *p2)
797 {
798 extension_index i1 = * (const extension_index *) p1;
799 extension_index i2 = * (const extension_index *) p2;
800 const struct extension *e1 = &extension_table[i1];
801 const struct extension *e2 = &extension_table[i2];
802 int res;
803
804 res = (int)e1->year - (int)e2->year;
805
806 if (res == 0) {
807 res = strcmp(e1->name, e2->name);
808 }
809
810 return res;
811 }
812
813
814 /**
815 * Construct the GL_EXTENSIONS string. Called the first time that
816 * glGetString(GL_EXTENSIONS) is called.
817 */
818 GLubyte*
819 _mesa_make_extension_string(struct gl_context *ctx)
820 {
821 /* The extension string. */
822 char *exts = 0;
823 /* Length of extension string. */
824 size_t length = 0;
825 /* Number of extensions */
826 unsigned count;
827 /* Indices of the extensions sorted by year */
828 extension_index *extension_indices;
829 /* String of extra extensions. */
830 char *extra_extensions = get_extension_override(ctx);
831 GLboolean *base = (GLboolean *) &ctx->Extensions;
832 const struct extension *i;
833 unsigned j;
834 unsigned maxYear = ~0;
835
836 /* Check if the MESA_EXTENSION_MAX_YEAR env var is set */
837 {
838 const char *env = getenv("MESA_EXTENSION_MAX_YEAR");
839 if (env) {
840 maxYear = atoi(env);
841 _mesa_debug(ctx, "Note: limiting GL extensions to %u or earlier\n",
842 maxYear);
843 }
844 }
845
846 /* Compute length of the extension string. */
847 count = 0;
848 for (i = extension_table; i->name != 0; ++i) {
849 if (base[i->offset] &&
850 i->year <= maxYear &&
851 (i->api_set & (1 << ctx->API))) {
852 length += strlen(i->name) + 1; /* +1 for space */
853 ++count;
854 }
855 }
856 if (extra_extensions != NULL)
857 length += 1 + strlen(extra_extensions); /* +1 for space */
858
859 exts = (char *) calloc(ALIGN(length + 1, 4), sizeof(char));
860 if (exts == NULL) {
861 free(extra_extensions);
862 return NULL;
863 }
864
865 extension_indices = malloc(count * sizeof(extension_index));
866 if (extension_indices == NULL) {
867 free(exts);
868 free(extra_extensions);
869 return NULL;
870 }
871
872 /* Sort extensions in chronological order because certain old applications (e.g.,
873 * Quake3 demo) store the extension list in a static size buffer so chronologically
874 * order ensure that the extensions that such applications expect will fit into
875 * that buffer.
876 */
877 j = 0;
878 for (i = extension_table; i->name != 0; ++i) {
879 if (base[i->offset] &&
880 i->year <= maxYear &&
881 (i->api_set & (1 << ctx->API))) {
882 extension_indices[j++] = i - extension_table;
883 }
884 }
885 assert(j == count);
886 qsort(extension_indices, count, sizeof *extension_indices, extension_compare);
887
888 /* Build the extension string.*/
889 for (j = 0; j < count; ++j) {
890 i = &extension_table[extension_indices[j]];
891 assert(base[i->offset] && (i->api_set & (1 << ctx->API)));
892 strcat(exts, i->name);
893 strcat(exts, " ");
894 }
895 free(extension_indices);
896 if (extra_extensions != 0) {
897 strcat(exts, extra_extensions);
898 free(extra_extensions);
899 }
900
901 return (GLubyte *) exts;
902 }
903
904 /**
905 * Return number of enabled extensions.
906 */
907 GLuint
908 _mesa_get_extension_count(struct gl_context *ctx)
909 {
910 GLboolean *base;
911 const struct extension *i;
912
913 /* only count once */
914 if (ctx->Extensions.Count != 0)
915 return ctx->Extensions.Count;
916
917 base = (GLboolean *) &ctx->Extensions;
918 for (i = extension_table; i->name != 0; ++i) {
919 if (base[i->offset]) {
920 ctx->Extensions.Count++;
921 }
922 }
923 return ctx->Extensions.Count;
924 }
925
926 /**
927 * Return name of i-th enabled extension
928 */
929 const GLubyte *
930 _mesa_get_enabled_extension(struct gl_context *ctx, GLuint index)
931 {
932 const GLboolean *base;
933 size_t n;
934 const struct extension *i;
935
936 if (index < 0)
937 return NULL;
938
939 base = (GLboolean*) &ctx->Extensions;
940 n = 0;
941 for (i = extension_table; i->name != 0; ++i) {
942 if (n == index && base[i->offset]) {
943 return (GLubyte*) i->name;
944 } else if (base[i->offset]) {
945 ++n;
946 }
947 }
948
949 return NULL;
950 }
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