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1 /*
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2 SDL - Simple DirectMedia Layer
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3 Copyright (C) 1997, 1998, 1999, 2000, 2001 Sam Lantinga
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4
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5 This library is free software; you can redistribute it and/or
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6 modify it under the terms of the GNU Library General Public
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7 License as published by the Free Software Foundation; either
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8 version 2 of the License, or (at your option) any later version.
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9
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10 This library is distributed in the hope that it will be useful,
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11 but WITHOUT ANY WARRANTY; without even the implied warranty of
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12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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13 Library General Public License for more details.
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14
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15 You should have received a copy of the GNU Library General Public
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16 License along with this library; if not, write to the Free
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17 Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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18
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19 Sam Lantinga
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20 slouken@devolution.com
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21 */
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22
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23 #ifdef SAVE_RCSID
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24 static char rcsid =
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25 "@(#) $Id$";
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26 #endif
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27
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28 /* System independent thread management routines for SDL */
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29
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30 #include <stdio.h>
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31 #include <stdlib.h>
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32 #include <string.h>
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33
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34 #include "SDL_error.h"
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35 #include "SDL_mutex.h"
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36 #include "SDL_thread.h"
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37 #include "SDL_thread_c.h"
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38 #include "SDL_systhread.h"
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39
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40 #define ARRAY_CHUNKSIZE 32
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41 /* The array of threads currently active in the application
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42 (except the main thread)
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43 The manipulation of an array here is safer than using a linked list.
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44 */
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45 static int SDL_maxthreads = 0;
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46 static int SDL_numthreads = 0;
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47 static SDL_Thread **SDL_Threads = NULL;
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48 static SDL_mutex *thread_lock = NULL;
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49 int _creating_thread_lock = 0;
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50
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51 int SDL_ThreadsInit(void)
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52 {
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53 int retval;
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54
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55 retval = 0;
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56 /* Set the thread lock creation flag so that we can reuse an
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57 existing lock on the system - since this mutex never gets
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58 destroyed (see SDL_ThreadsQuit()), we want to reuse it.
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59 */
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60 _creating_thread_lock = 1;
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61 thread_lock = SDL_CreateMutex();
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62 _creating_thread_lock = 0;
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63 if ( thread_lock == NULL ) {
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64 retval = -1;
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65 }
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66 return(retval);
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67 }
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68
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69 /* This should never be called...
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70 If this is called by SDL_Quit(), we don't know whether or not we should
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71 clean up threads here. If any threads are still running after this call,
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72 they will no longer have access to any per-thread data.
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73 */
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74 void SDL_ThreadsQuit()
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75 {
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76 SDL_mutex *mutex;
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77
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78 mutex = thread_lock;
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79 thread_lock = NULL;
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80 if ( mutex != NULL ) {
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81 SDL_DestroyMutex(mutex);
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82 }
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83 }
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84
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85 /* Routines for manipulating the thread list */
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86 static void SDL_AddThread(SDL_Thread *thread)
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87 {
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88 SDL_Thread **threads;
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89
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90 /* WARNING:
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91 If the very first threads are created simultaneously, then
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92 there could be a race condition causing memory corruption.
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93 In practice, this isn't a problem because by definition there
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94 is only one thread running the first time this is called.
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95 */
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96 if ( thread_lock == NULL ) {
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97 if ( SDL_ThreadsInit() < 0 ) {
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98 return;
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99 }
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100 }
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101 SDL_mutexP(thread_lock);
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102
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103 /* Expand the list of threads, if necessary */
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104 #ifdef DEBUG_THREADS
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105 printf("Adding thread (%d already - %d max)\n",
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106 SDL_numthreads, SDL_maxthreads);
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107 #endif
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108 if ( SDL_numthreads == SDL_maxthreads ) {
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109 threads=(SDL_Thread **)malloc((SDL_maxthreads+ARRAY_CHUNKSIZE)*
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110 (sizeof *threads));
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111 if ( threads == NULL ) {
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112 SDL_OutOfMemory();
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113 goto done;
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114 }
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115 memcpy(threads, SDL_Threads, SDL_numthreads*(sizeof *threads));
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116 SDL_maxthreads += ARRAY_CHUNKSIZE;
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117 if ( SDL_Threads ) {
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118 free(SDL_Threads);
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119 }
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120 SDL_Threads = threads;
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121 }
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122 SDL_Threads[SDL_numthreads++] = thread;
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123 done:
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124 SDL_mutexV(thread_lock);
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125 }
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126
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127 static void SDL_DelThread(SDL_Thread *thread)
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128 {
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129 int i;
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130
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131 if ( thread_lock ) {
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132 SDL_mutexP(thread_lock);
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133 for ( i=0; i<SDL_numthreads; ++i ) {
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134 if ( thread == SDL_Threads[i] ) {
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135 break;
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136 }
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137 }
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138 if ( i < SDL_numthreads ) {
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139 --SDL_numthreads;
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140 while ( i < SDL_numthreads ) {
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141 SDL_Threads[i] = SDL_Threads[i+1];
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142 ++i;
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143 }
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144 #ifdef DEBUG_THREADS
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145 printf("Deleting thread (%d left - %d max)\n",
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146 SDL_numthreads, SDL_maxthreads);
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147 #endif
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148 }
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149 SDL_mutexV(thread_lock);
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150 }
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151 }
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152
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153 /* The default (non-thread-safe) global error variable */
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154 static SDL_error SDL_global_error;
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155
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156 /* Routine to get the thread-specific error variable */
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157 SDL_error *SDL_GetErrBuf(void)
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158 {
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159 SDL_error *errbuf;
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160
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161 errbuf = &SDL_global_error;
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162 if ( SDL_Threads ) {
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163 int i;
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164 Uint32 this_thread;
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165
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166 this_thread = SDL_ThreadID();
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167 SDL_mutexP(thread_lock);
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168 for ( i=0; i<SDL_numthreads; ++i ) {
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169 if ( this_thread == SDL_Threads[i]->threadid ) {
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170 errbuf = &SDL_Threads[i]->errbuf;
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171 break;
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172 }
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173 }
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174 SDL_mutexV(thread_lock);
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175 }
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176 return(errbuf);
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177 }
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178
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179
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180 /* Arguments and callback to setup and run the user thread function */
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181 typedef struct {
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182 int (*func)(void *);
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183 void *data;
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184 SDL_Thread *info;
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185 SDL_sem *wait;
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186 } thread_args;
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187
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188 void SDL_RunThread(void *data)
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189 {
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190 thread_args *args;
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191 int (*userfunc)(void *);
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192 void *userdata;
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193 int *statusloc;
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194
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195 /* Perform any system-dependent setup
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196 - this function cannot fail, and cannot use SDL_SetError()
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197 */
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198 SDL_SYS_SetupThread();
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199
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200 /* Get the thread id */
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201 args = (thread_args *)data;
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202 args->info->threadid = SDL_ThreadID();
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203
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204 /* Figure out what function to run */
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205 userfunc = args->func;
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206 userdata = args->data;
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207 statusloc = &args->info->status;
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208
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209 /* Wake up the parent thread */
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210 SDL_SemPost(args->wait);
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211
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212 /* Run the function */
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213 *statusloc = userfunc(userdata);
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214 }
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215
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216 SDL_Thread *SDL_CreateThread(int (*fn)(void *), void *data)
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217 {
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218 SDL_Thread *thread;
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219 thread_args *args;
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220 int ret;
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221
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222 /* Allocate memory for the thread info structure */
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223 thread = (SDL_Thread *)malloc(sizeof(*thread));
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224 if ( thread == NULL ) {
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225 SDL_OutOfMemory();
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226 return(NULL);
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227 }
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228 memset(thread, 0, (sizeof *thread));
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229 thread->status = -1;
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230
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231 /* Set up the arguments for the thread */
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232 args = (thread_args *)malloc(sizeof(*args));
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233 if ( args == NULL ) {
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234 SDL_OutOfMemory();
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235 free(thread);
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236 return(NULL);
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237 }
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238 args->func = fn;
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239 args->data = data;
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240 args->info = thread;
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241 args->wait = SDL_CreateSemaphore(0);
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242 if ( args->wait == NULL ) {
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243 free(thread);
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244 free(args);
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245 return(NULL);
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246 }
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247
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248 /* Add the thread to the list of available threads */
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249 SDL_AddThread(thread);
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250
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251 /* Create the thread and go! */
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252 ret = SDL_SYS_CreateThread(thread, args);
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253 if ( ret >= 0 ) {
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254 /* Wait for the thread function to use arguments */
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255 SDL_SemWait(args->wait);
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256 } else {
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257 /* Oops, failed. Gotta free everything */
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258 SDL_DelThread(thread);
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259 free(thread);
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260 thread = NULL;
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261 }
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262 SDL_DestroySemaphore(args->wait);
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263 free(args);
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264
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265 /* Everything is running now */
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266 return(thread);
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267 }
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268
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269 void SDL_WaitThread(SDL_Thread *thread, int *status)
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270 {
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271 if ( thread ) {
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272 SDL_SYS_WaitThread(thread);
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273 if ( status ) {
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274 *status = thread->status;
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275 }
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276 SDL_DelThread(thread);
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277 free(thread);
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278 }
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279 }
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280
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281 Uint32 SDL_GetThreadID(SDL_Thread *thread)
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282 {
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283 Uint32 id;
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284
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285 if ( thread ) {
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286 id = thread->threadid;
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287 } else {
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288 id = SDL_ThreadID();
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289 }
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290 return(id);
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291 }
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292
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293 void SDL_KillThread(SDL_Thread *thread)
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294 {
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295 if ( thread ) {
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296 SDL_SYS_KillThread(thread);
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297 SDL_WaitThread(thread, NULL);
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298 }
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299 }
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300
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