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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 /* Semaphores in the BeOS environment */
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29
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30 #include <be/kernel/OS.h>
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31
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32 #include "SDL_error.h"
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33 #include "SDL_thread.h"
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34
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35
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36 struct SDL_semaphore {
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37 sem_id id;
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38 };
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39
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40 /* Create a counting semaphore */
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41 SDL_sem *SDL_CreateSemaphore(Uint32 initial_value)
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42 {
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43 SDL_sem *sem;
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44
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45 sem = (SDL_sem *)malloc(sizeof(*sem));
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46 if ( sem ) {
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47 sem->id = create_sem(initial_value, "SDL semaphore");
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48 if ( sem->id < B_NO_ERROR ) {
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49 SDL_SetError("create_sem() failed");
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50 free(sem);
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51 sem = NULL;
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52 }
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53 } else {
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54 SDL_OutOfMemory();
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55 }
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56 return(sem);
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57 }
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58
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59 /* Free the semaphore */
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60 void SDL_DestroySemaphore(SDL_sem *sem)
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61 {
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62 if ( sem ) {
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63 if ( sem->id >= B_NO_ERROR ) {
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64 delete_sem(sem->id);
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65 }
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66 free(sem);
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67 }
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68 }
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69
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70 int SDL_SemWaitTimeout(SDL_sem *sem, Uint32 timeout)
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71 {
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72 int32 val;
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73 int retval;
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74
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75 if ( ! sem ) {
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76 SDL_SetError("Passed a NULL semaphore");
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77 return -1;
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78 }
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79
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80 tryagain:
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81 if ( timeout == SDL_MUTEX_MAXWAIT ) {
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82 val = acquire_sem(sem->id);
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83 } else {
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84 timeout *= 1000; /* BeOS uses a timeout in microseconds */
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85 val = acquire_sem_etc(sem->id, 1, B_RELATIVE_TIMEOUT, timeout);
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86 }
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87 switch (val) {
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88 case B_INTERRUPTED:
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89 goto tryagain;
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90 case B_NO_ERROR:
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91 retval = 0;
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92 break;
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93 default:
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94 SDL_SetError("acquire_sem() failed");
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95 retval = -1;
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96 break;
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97 }
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98
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99 return retval;
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100 }
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101
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102 int SDL_SemTryWait(SDL_sem *sem)
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103 {
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104 return SDL_SemWaitTimeout(sem, 0);
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105 }
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106
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107 int SDL_SemWait(SDL_sem *sem)
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108 {
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109 return SDL_SemWaitTimeout(sem, SDL_MUTEX_MAXWAIT);
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110 }
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111
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112 /* Returns the current count of the semaphore */
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113 Uint32 SDL_SemValue(SDL_sem *sem)
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114 {
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115 int32 count;
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116 Uint32 value;
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117
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118 value = 0;
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119 if ( sem ) {
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120 get_sem_count(sem->id, &count);
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121 if ( count > 0 ) {
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122 value = (Uint32)count;
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123 }
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124 }
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125 return value;
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126 }
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127
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128 /* Atomically increases the semaphore's count (not blocking) */
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129 int SDL_SemPost(SDL_sem *sem)
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130 {
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131 if ( ! sem ) {
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132 SDL_SetError("Passed a NULL semaphore");
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133 return -1;
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134 }
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135
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136 if ( release_sem(sem->id) != B_NO_ERROR ) {
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137 SDL_SetError("release_sem() failed");
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138 return -1;
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139 }
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140 return 0;
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141 }
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