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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 /* Semaphore functions using the Win32 API */
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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 <windows.h>
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33
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34 #include "SDL_error.h"
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35 #include "SDL_thread.h"
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36
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37 #if defined(_WIN32_WCE) && (_WIN32_WCE < 300)
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38
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39 /* No semaphores on Windows CE earlier than 3.0, hmm... */
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40
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41 /* Create a semaphore */
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42 SDL_sem *SDL_CreateSemaphore(Uint32 initial_value)
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43 {
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44 SDL_SetError("Semaphores not supported on WinCE");
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45 return(NULL);
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46 }
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47
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48 /* Free the semaphore */
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49 void SDL_DestroySemaphore(SDL_sem *sem)
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50 {
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51 return;
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52 }
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53
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54 int SDL_SemWaitTimeout(SDL_sem *sem, Uint32 timeout)
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55 {
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56 SDL_SetError("Semaphores not supported on WinCE");
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57 return(-1);
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58 }
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59
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60 int SDL_SemTryWait(SDL_sem *sem)
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61 {
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62 return SDL_SemWaitTimeout(sem, 0);
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63 }
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64
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65 int SDL_SemWait(SDL_sem *sem)
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66 {
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67 return SDL_SemWaitTimeout(sem, SDL_MUTEX_MAXWAIT);
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68 }
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69
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70 /* Returns the current count of the semaphore */
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71 Uint32 SDL_SemValue(SDL_sem *sem)
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72 {
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73 return(0);
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74 }
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75
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76 int SDL_SemPost(SDL_sem *sem)
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77 {
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78 SDL_SetError("Semaphores not supported on WinCE");
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79 return(-1);
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80 }
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81
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82 #else
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83
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84 struct SDL_semaphore {
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85 HANDLE id;
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86 Uint32 volatile count;
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87 };
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88
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89
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90 /* Create a semaphore */
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91 SDL_sem *SDL_CreateSemaphore(Uint32 initial_value)
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92 {
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93 SDL_sem *sem;
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94
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95 /* Allocate sem memory */
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96 sem = (SDL_sem *)malloc(sizeof(*sem));
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97 if ( sem ) {
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98 /* Create the semaphore, with max value 32K */
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99 sem->id = CreateSemaphore(NULL, initial_value, 32*1024, NULL);
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100 sem->count = initial_value;
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101 if ( ! sem->id ) {
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102 SDL_SetError("Couldn't create semaphore");
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103 free(sem);
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104 sem = NULL;
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105 }
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106 } else {
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107 SDL_OutOfMemory();
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108 }
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109 return(sem);
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110 }
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111
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112 /* Free the semaphore */
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113 void SDL_DestroySemaphore(SDL_sem *sem)
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114 {
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115 if ( sem ) {
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116 if ( sem->id ) {
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117 CloseHandle(sem->id);
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118 sem->id = 0;
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119 }
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120 free(sem);
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121 }
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122 }
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123
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124 int SDL_SemWaitTimeout(SDL_sem *sem, Uint32 timeout)
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125 {
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126 int retval;
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127 DWORD dwMilliseconds;
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128
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129 if ( ! sem ) {
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130 SDL_SetError("Passed a NULL sem");
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131 return -1;
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132 }
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133
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134 if ( timeout == SDL_MUTEX_MAXWAIT ) {
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135 dwMilliseconds = INFINITE;
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136 } else {
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137 dwMilliseconds = (DWORD)timeout;
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138 }
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139 switch (WaitForSingleObject(sem->id, dwMilliseconds)) {
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140 case WAIT_OBJECT_0:
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141 --sem->count;
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142 retval = 0;
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143 break;
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144 case WAIT_TIMEOUT:
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145 retval = SDL_MUTEX_TIMEDOUT;
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146 break;
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147 default:
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148 SDL_SetError("WaitForSingleObject() failed");
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149 retval = -1;
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150 break;
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151 }
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152 return retval;
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153 }
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154
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155 int SDL_SemTryWait(SDL_sem *sem)
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156 {
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157 return SDL_SemWaitTimeout(sem, 0);
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158 }
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159
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160 int SDL_SemWait(SDL_sem *sem)
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161 {
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162 return SDL_SemWaitTimeout(sem, SDL_MUTEX_MAXWAIT);
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163 }
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164
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165 /* Returns the current count of the semaphore */
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166 Uint32 SDL_SemValue(SDL_sem *sem)
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167 {
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168 if ( ! sem ) {
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169 SDL_SetError("Passed a NULL sem");
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170 return 0;
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171 }
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172 return sem->count;
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173 }
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174
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175 int SDL_SemPost(SDL_sem *sem)
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176 {
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177 if ( ! sem ) {
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178 SDL_SetError("Passed a NULL sem");
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179 return -1;
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180 }
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181 /* Increase the counter in the first place, because
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182 * after a successful release the semaphore may
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183 * immediately get destroyed by another thread which
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184 * is waiting for this semaphore.
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185 */
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186 ++sem->count;
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187 if ( ReleaseSemaphore(sem->id, 1, NULL) == FALSE ) {
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188 --sem->count; /* restore */
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189 SDL_SetError("ReleaseSemaphore() failed");
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190 return -1;
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191 }
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192 return 0;
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193 }
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194
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195 #endif /* _WIN32_WCE */ |
