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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 /* An native implementation of semaphores on AmigaOS */
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29
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30 #include "SDL_error.h"
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31 #include "SDL_thread.h"
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32 #include "SDL_systhread_c.h"
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33
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34
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35 struct SDL_semaphore
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36 {
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37 struct SignalSemaphore Sem;
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38 };
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39
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40 #undef D(x)
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41
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42 #define D(x)
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43
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44 SDL_sem *SDL_CreateSemaphore(Uint32 initial_value)
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45 {
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46 SDL_sem *sem;
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47
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48 sem = (SDL_sem *)malloc(sizeof(*sem));
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49 if ( ! sem ) {
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50 SDL_OutOfMemory();
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51 return(0);
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52 }
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53 memset(sem, 0, sizeof(*sem));
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54
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55 D(bug("Creating semaphore %lx...\n",sem));
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56
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57 InitSemaphore(&sem->Sem);
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58 #if 1 // Allow multiple obtainings of the semaphore
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59 while ( initial_value-- ) {
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60 ReleaseSemaphore(&sem->Sem);
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61 }
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62 #endif
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63 return(sem);
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64 }
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65
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66 void SDL_DestroySemaphore(SDL_sem *sem)
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67 {
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68 D(bug("Destroying semaphore %lx...\n",sem));
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69
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70 if ( sem ) {
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71 // Condizioni per liberare i task in attesa?
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72 free(sem);
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73 }
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74 }
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75
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76 int SDL_SemTryWait(SDL_sem *sem)
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77 {
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78 int retval;
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79
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80 if ( ! sem ) {
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81 SDL_SetError("Passed a NULL semaphore");
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82 return -1;
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83 }
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84
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85 D(bug("TryWait semaphore...%lx\n",sem));
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86
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87 retval = SDL_MUTEX_TIMEDOUT;
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88 if ( AttemptSemaphore(&sem->Sem) ) {
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89 retval = 0;
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90 }
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91 return retval;
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92 }
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93
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94 int SDL_SemWaitTimeout(SDL_sem *sem, Uint32 timeout)
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95 {
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96 int retval;
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97
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98 if ( ! sem ) {
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99 SDL_SetError("Passed a NULL semaphore");
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100 return -1;
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101 }
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102
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103 D(bug("WaitTimeout (%ld) semaphore...%lx\n",timeout,sem));
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104
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105 #if 1 // We need to keep trying the semaphore until the timeout expires
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106 retval = SDL_MUTEX_TIMEDOUT;
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107 then = SDL_GetTicks();
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108 do {
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109 if ( AttemptSemaphore(&sem->Sem) ) {
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110 retval = 0;
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111 }
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112 now = SDL_GetTicks();
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113 } while ( (retval == SDL_MUTEX_TIMEDOUT) && ((now-then) < timeout) );
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114 #else
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115 if(!(retval=AttemptSemaphore(&sem->Sem)))
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116 {
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117 SDL_Delay(timeout);
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118 retval=AttemptSemaphore(&sem->Sem);
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119 }
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120
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121 if(retval==TRUE)
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122 {
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123 // ReleaseSemaphore(&sem->Sem);
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124 retval=1;
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125 }
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126 #endif
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127 return retval;
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128 }
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129
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130 int SDL_SemWait(SDL_sem *sem)
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131 {
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132 if ( ! sem ) {
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133 SDL_SetError("Passed a NULL semaphore");
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134 return -1;
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135 }
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136 #if 1 // This should be an infinite wait - FIXME, what is the return value?
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137 ObtainSemaphore(&sem->Sem);
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138 return 0;
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139 #else
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140 return SDL_SemWaitTimeout(sem, SDL_MUTEX_MAXWAIT);
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141 #endif
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142 }
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143
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144 Uint32 SDL_SemValue(SDL_sem *sem)
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145 {
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146 Uint32 value;
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147
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148 value = 0;
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149 if ( sem ) {
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150 value = sem->Sem.ss_NestCount;
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151 }
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152 return value;
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153 }
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154
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155 int SDL_SemPost(SDL_sem *sem)
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156 {
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157 if ( ! sem ) {
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158 SDL_SetError("Passed a NULL semaphore");
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159 return -1;
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160 }
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161 D(bug("SemPost semaphore...%lx\n",sem));
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162
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163 ReleaseSemaphore(&sem->Sem);
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164 return 0;
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165 }
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166
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