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1 /* |
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2 SDL - Simple DirectMedia Layer |
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3 Copyright (C) 1997-2006 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 Lesser General Public |
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7 License as published by the Free Software Foundation; either |
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8 version 2.1 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 Lesser 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 Lesser General Public |
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16 License along with this library; if not, write to the Free Software |
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17 Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA |
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18 |
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19 Sam Lantinga |
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20 slouken@libsdl.org |
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21 */ |
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22 #include "SDL_config.h" |
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23 |
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24 #include <pthread.h> |
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25 #include <semaphore.h> |
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26 #include <errno.h> |
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27 |
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28 #include "SDL_thread.h" |
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29 #include "SDL_timer.h" |
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30 |
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31 /* Wrapper around POSIX 1003.1b semaphores */ |
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32 |
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33 #ifdef __MACOSX__ |
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34 /* Mac OS X doesn't support sem_getvalue() as of version 10.4 */ |
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35 #include "../generic/SDL_syssem.c" |
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36 #else |
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37 |
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38 struct SDL_semaphore { |
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39 sem_t sem; |
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40 }; |
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41 |
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42 /* Create a semaphore, initialized with value */ |
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43 SDL_sem *SDL_CreateSemaphore(Uint32 initial_value) |
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44 { |
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45 SDL_sem *sem = (SDL_sem *) SDL_malloc(sizeof(SDL_sem)); |
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46 if ( sem ) { |
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47 if ( sem_init(&sem->sem, 0, initial_value) < 0 ) { |
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48 SDL_SetError("sem_init() failed"); |
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49 SDL_free(sem); |
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50 sem = NULL; |
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51 } |
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52 } else { |
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53 SDL_OutOfMemory(); |
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54 } |
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55 return sem; |
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56 } |
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57 |
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58 void SDL_DestroySemaphore(SDL_sem *sem) |
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59 { |
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60 if ( sem ) { |
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61 sem_destroy(&sem->sem); |
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62 SDL_free(sem); |
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63 } |
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64 } |
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65 |
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66 int SDL_SemTryWait(SDL_sem *sem) |
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67 { |
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68 int retval; |
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69 |
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70 if ( ! sem ) { |
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71 SDL_SetError("Passed a NULL semaphore"); |
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72 return -1; |
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73 } |
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74 retval = SDL_MUTEX_TIMEDOUT; |
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75 if ( sem_trywait(&sem->sem) == 0 ) { |
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76 retval = 0; |
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77 } |
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78 return retval; |
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79 } |
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80 |
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81 int SDL_SemWait(SDL_sem *sem) |
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82 { |
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83 int retval; |
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84 |
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85 if ( ! sem ) { |
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86 SDL_SetError("Passed a NULL semaphore"); |
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87 return -1; |
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88 } |
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89 |
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90 while ( ((retval = sem_wait(&sem->sem)) == -1) && (errno == EINTR) ) {} |
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91 if ( retval < 0 ) { |
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92 SDL_SetError("sem_wait() failed"); |
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93 } |
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94 return retval; |
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95 } |
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96 |
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97 int SDL_SemWaitTimeout(SDL_sem *sem, Uint32 timeout) |
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98 { |
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99 int retval; |
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100 |
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101 if ( ! sem ) { |
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102 SDL_SetError("Passed a NULL semaphore"); |
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103 return -1; |
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104 } |
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105 |
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106 /* Try the easy cases first */ |
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107 if ( timeout == 0 ) { |
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108 return SDL_SemTryWait(sem); |
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109 } |
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110 if ( timeout == SDL_MUTEX_MAXWAIT ) { |
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111 return SDL_SemWait(sem); |
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112 } |
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113 |
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114 /* Ack! We have to busy wait... */ |
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115 /* FIXME: Use sem_timedwait()? */ |
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116 timeout += SDL_GetTicks(); |
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117 do { |
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118 retval = SDL_SemTryWait(sem); |
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119 if ( retval == 0 ) { |
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120 break; |
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121 } |
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122 SDL_Delay(1); |
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123 } while ( SDL_GetTicks() < timeout ); |
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124 |
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125 return retval; |
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126 } |
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127 |
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128 Uint32 SDL_SemValue(SDL_sem *sem) |
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129 { |
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130 int ret = 0; |
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131 if ( sem ) { |
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132 sem_getvalue(&sem->sem, &ret); |
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133 if ( ret < 0 ) { |
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134 ret = 0; |
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135 } |
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136 } |
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137 return (Uint32)ret; |
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138 } |
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139 |
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140 int SDL_SemPost(SDL_sem *sem) |
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141 { |
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142 int retval; |
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143 |
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144 if ( ! sem ) { |
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145 SDL_SetError("Passed a NULL semaphore"); |
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146 return -1; |
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147 } |
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148 |
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149 retval = sem_post(&sem->sem); |
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150 if ( retval < 0 ) { |
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151 SDL_SetError("sem_post() failed"); |
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152 } |
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153 return retval; |
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154 } |
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155 |
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156 #endif /* __MACOSX__ */ |