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1901 | serge | 1 | /* |
2 | * Mesa 3-D graphics library |
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3 | * Version: 7.1 |
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4 | * |
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5 | * Copyright (C) 1999-2008 Brian Paul All Rights Reserved. |
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6 | * |
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7 | * Permission is hereby granted, free of charge, to any person obtaining a |
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8 | * copy of this software and associated documentation files (the "Software"), |
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9 | * to deal in the Software without restriction, including without limitation |
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10 | * the rights to use, copy, modify, merge, publish, distribute, sublicense, |
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11 | * and/or sell copies of the Software, and to permit persons to whom the |
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12 | * Software is furnished to do so, subject to the following conditions: |
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13 | * |
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14 | * The above copyright notice and this permission notice shall be included |
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15 | * in all copies or substantial portions of the Software. |
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16 | * |
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17 | * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS |
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18 | * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, |
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19 | * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL |
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20 | * BRIAN PAUL BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN |
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21 | * AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN |
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22 | * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. |
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23 | */ |
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24 | |||
25 | |||
26 | /* |
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27 | * This file manages the OpenGL API dispatch layer. |
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28 | * The dispatch table (struct _glapi_table) is basically just a list |
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29 | * of function pointers. |
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30 | * There are functions to set/get the current dispatch table for the |
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31 | * current thread and to manage registration/dispatch of dynamically |
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32 | * added extension functions. |
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33 | * |
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34 | * It's intended that this file and the other glapi*.[ch] files are |
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35 | * flexible enough to be reused in several places: XFree86, DRI- |
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36 | * based libGL.so, and perhaps the SGI SI. |
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37 | * |
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38 | * NOTE: There are no dependencies on Mesa in this code. |
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39 | * |
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40 | * Versions (API changes): |
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41 | * 2000/02/23 - original version for Mesa 3.3 and XFree86 4.0 |
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42 | * 2001/01/16 - added dispatch override feature for Mesa 3.5 |
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43 | * 2002/06/28 - added _glapi_set_warning_func(), Mesa 4.1. |
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44 | * 2002/10/01 - _glapi_get_proc_address() will now generate new entrypoints |
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45 | * itself (using offset ~0). _glapi_add_entrypoint() can be |
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46 | * called afterward and it'll fill in the correct dispatch |
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47 | * offset. This allows DRI libGL to avoid probing for DRI |
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48 | * drivers! No changes to the public glapi interface. |
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49 | */ |
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50 | |||
51 | #include "u_current.h" |
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52 | #include "u_thread.h" |
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53 | |||
54 | #ifndef MAPI_GLAPI_CURRENT |
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55 | |||
56 | #include "table.h" |
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57 | #include "stub.h" |
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58 | |||
59 | #else |
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60 | |||
61 | extern void init_glapi_relocs_once(void); |
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62 | extern void (*__glapi_noop_table[])(void); |
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63 | |||
64 | #define table_noop_array __glapi_noop_table |
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65 | #define stub_init_once() init_glapi_relocs_once() |
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66 | |||
67 | #endif |
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68 | |||
69 | /** |
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70 | * \name Current dispatch and current context control variables |
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71 | * |
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72 | * Depending on whether or not multithreading is support, and the type of |
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73 | * support available, several variables are used to store the current context |
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74 | * pointer and the current dispatch table pointer. In the non-threaded case, |
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75 | * the variables \c _glapi_Dispatch and \c _glapi_Context are used for this |
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76 | * purpose. |
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77 | * |
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78 | * In the "normal" threaded case, the variables \c _glapi_Dispatch and |
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79 | * \c _glapi_Context will be \c NULL if an application is detected as being |
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80 | * multithreaded. Single-threaded applications will use \c _glapi_Dispatch |
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81 | * and \c _glapi_Context just like the case without any threading support. |
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82 | * When \c _glapi_Dispatch and \c _glapi_Context are \c NULL, the thread state |
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83 | * data \c _gl_DispatchTSD and \c ContextTSD are used. Drivers and the |
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84 | * static dispatch functions access these variables via \c _glapi_get_dispatch |
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85 | * and \c _glapi_get_context. |
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86 | * |
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87 | * There is a race condition in setting \c _glapi_Dispatch to \c NULL. It is |
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88 | * possible for the original thread to be setting it at the same instant a new |
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89 | * thread, perhaps running on a different processor, is clearing it. Because |
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90 | * of that, \c ThreadSafe, which can only ever be changed to \c GL_TRUE, is |
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91 | * used to determine whether or not the application is multithreaded. |
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92 | * |
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93 | * In the TLS case, the variables \c _glapi_Dispatch and \c _glapi_Context are |
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94 | * hardcoded to \c NULL. Instead the TLS variables \c _glapi_tls_Dispatch and |
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95 | * \c _glapi_tls_Context are used. Having \c _glapi_Dispatch and |
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96 | * \c _glapi_Context be hardcoded to \c NULL maintains binary compatability |
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97 | * between TLS enabled loaders and non-TLS DRI drivers. |
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98 | */ |
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99 | /*@{*/ |
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100 | #if defined(GLX_USE_TLS) |
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101 | |||
102 | __thread struct mapi_table *u_current_table_tls |
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103 | __attribute__((tls_model("initial-exec"))) |
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104 | = (struct mapi_table *) table_noop_array; |
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105 | |||
106 | __thread void *u_current_user_tls |
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107 | __attribute__((tls_model("initial-exec"))); |
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108 | |||
109 | const struct mapi_table *u_current_table; |
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110 | const void *u_current_user; |
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111 | |||
112 | #else |
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113 | |||
114 | struct mapi_table *u_current_table = |
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115 | (struct mapi_table *) table_noop_array; |
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116 | void *u_current_user; |
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117 | |||
118 | #ifdef THREADS |
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119 | struct u_tsd u_current_table_tsd; |
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120 | static struct u_tsd u_current_user_tsd; |
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121 | static int ThreadSafe; |
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122 | #endif /* THREADS */ |
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123 | |||
124 | #endif /* defined(GLX_USE_TLS) */ |
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125 | /*@}*/ |
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126 | |||
127 | |||
128 | void |
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129 | u_current_destroy(void) |
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130 | { |
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131 | #if defined(THREADS) && defined(WIN32) |
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132 | u_tsd_destroy(&u_current_table_tsd); |
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133 | u_tsd_destroy(&u_current_user_tsd); |
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134 | #endif |
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135 | } |
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136 | |||
137 | |||
138 | #if defined(THREADS) && !defined(GLX_USE_TLS) |
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139 | |||
140 | static void |
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141 | u_current_init_tsd(void) |
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142 | { |
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143 | u_tsd_init(&u_current_table_tsd); |
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144 | u_tsd_init(&u_current_user_tsd); |
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145 | } |
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146 | |||
147 | /** |
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148 | * Mutex for multithread check. |
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149 | */ |
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150 | #ifdef WIN32 |
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151 | /* _glthread_DECLARE_STATIC_MUTEX is broken on windows. There will be race! */ |
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152 | #define CHECK_MULTITHREAD_LOCK() |
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153 | #define CHECK_MULTITHREAD_UNLOCK() |
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154 | #else |
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155 | u_mutex_declare_static(ThreadCheckMutex); |
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156 | #define CHECK_MULTITHREAD_LOCK() u_mutex_lock(ThreadCheckMutex) |
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157 | #define CHECK_MULTITHREAD_UNLOCK() u_mutex_unlock(ThreadCheckMutex) |
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158 | #endif |
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159 | |||
160 | /** |
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161 | * We should call this periodically from a function such as glXMakeCurrent |
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162 | * in order to test if multiple threads are being used. |
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163 | */ |
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164 | void |
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165 | u_current_init(void) |
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166 | { |
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167 | static unsigned long knownID; |
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168 | static int firstCall = 1; |
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169 | |||
170 | if (ThreadSafe) |
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171 | return; |
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172 | |||
173 | CHECK_MULTITHREAD_LOCK(); |
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174 | if (firstCall) { |
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175 | u_current_init_tsd(); |
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176 | |||
177 | knownID = u_thread_self(); |
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178 | firstCall = 0; |
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179 | } |
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180 | else if (knownID != u_thread_self()) { |
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181 | ThreadSafe = 1; |
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182 | u_current_set_internal(NULL); |
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183 | u_current_set_user_internal(NULL); |
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184 | } |
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185 | CHECK_MULTITHREAD_UNLOCK(); |
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186 | } |
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187 | |||
188 | #else |
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189 | |||
190 | void |
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191 | u_current_init(void) |
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192 | { |
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193 | } |
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194 | |||
195 | #endif |
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196 | |||
197 | |||
198 | |||
199 | /** |
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200 | * Set the current context pointer for this thread. |
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201 | * The context pointer is an opaque type which should be cast to |
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202 | * void from the real context pointer type. |
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203 | */ |
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204 | void |
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205 | u_current_set_user_internal(void *ptr) |
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206 | { |
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207 | u_current_init(); |
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208 | |||
209 | #if defined(GLX_USE_TLS) |
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210 | u_current_user_tls = ptr; |
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211 | #elif defined(THREADS) |
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212 | u_tsd_set(&u_current_user_tsd, ptr); |
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213 | u_current_user = (ThreadSafe) ? NULL : ptr; |
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214 | #else |
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215 | u_current_user = ptr; |
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216 | #endif |
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217 | } |
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218 | |||
219 | /** |
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220 | * Get the current context pointer for this thread. |
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221 | * The context pointer is an opaque type which should be cast from |
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222 | * void to the real context pointer type. |
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223 | */ |
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224 | void * |
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225 | u_current_get_user_internal(void) |
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226 | { |
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227 | #if defined(GLX_USE_TLS) |
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228 | return u_current_user_tls; |
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229 | #elif defined(THREADS) |
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230 | return (ThreadSafe) |
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231 | ? u_tsd_get(&u_current_user_tsd) |
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232 | : u_current_user; |
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233 | #else |
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234 | return u_current_user; |
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235 | #endif |
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236 | } |
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237 | |||
238 | /** |
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239 | * Set the global or per-thread dispatch table pointer. |
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240 | * If the dispatch parameter is NULL we'll plug in the no-op dispatch |
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241 | * table (__glapi_noop_table). |
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242 | */ |
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243 | void |
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244 | u_current_set_internal(struct mapi_table *tbl) |
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245 | { |
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246 | u_current_init(); |
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247 | |||
248 | stub_init_once(); |
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249 | |||
250 | if (!tbl) |
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251 | tbl = (struct mapi_table *) table_noop_array; |
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252 | |||
253 | #if defined(GLX_USE_TLS) |
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254 | u_current_table_tls = tbl; |
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255 | #elif defined(THREADS) |
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256 | u_tsd_set(&u_current_table_tsd, (void *) tbl); |
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257 | u_current_table = (ThreadSafe) ? NULL : tbl; |
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258 | #else |
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259 | u_current_table = tbl; |
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260 | #endif |
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261 | } |
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262 | |||
263 | /** |
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264 | * Return pointer to current dispatch table for calling thread. |
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265 | */ |
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266 | struct mapi_table * |
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267 | u_current_get_internal(void) |
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268 | { |
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269 | #if defined(GLX_USE_TLS) |
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270 | return u_current_table_tls; |
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271 | #elif defined(THREADS) |
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272 | return (struct mapi_table *) ((ThreadSafe) ? |
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273 | u_tsd_get(&u_current_table_tsd) : (void *) u_current_table); |
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274 | #else |
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275 | return u_current_table; |
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276 | #endif |
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277 | } |