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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 /* Semaphores in the BeOS environment */ |
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25 |
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26 #include <be/kernel/OS.h> |
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27 |
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28 #include "SDL_thread.h" |
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29 |
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30 |
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31 struct SDL_semaphore { |
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32 sem_id id; |
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33 }; |
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34 |
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35 /* Create a counting semaphore */ |
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36 SDL_sem *SDL_CreateSemaphore(Uint32 initial_value) |
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37 { |
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38 SDL_sem *sem; |
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39 |
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40 sem = (SDL_sem *)SDL_malloc(sizeof(*sem)); |
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41 if ( sem ) { |
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42 sem->id = create_sem(initial_value, "SDL semaphore"); |
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43 if ( sem->id < B_NO_ERROR ) { |
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44 SDL_SetError("create_sem() failed"); |
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45 SDL_free(sem); |
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46 sem = NULL; |
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47 } |
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48 } else { |
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49 SDL_OutOfMemory(); |
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50 } |
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51 return(sem); |
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52 } |
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53 |
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54 /* Free the semaphore */ |
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55 void SDL_DestroySemaphore(SDL_sem *sem) |
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56 { |
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57 if ( sem ) { |
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58 if ( sem->id >= B_NO_ERROR ) { |
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59 delete_sem(sem->id); |
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60 } |
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61 SDL_free(sem); |
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62 } |
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63 } |
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64 |
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65 int SDL_SemWaitTimeout(SDL_sem *sem, Uint32 timeout) |
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66 { |
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67 int32 val; |
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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 |
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75 tryagain: |
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76 if ( timeout == SDL_MUTEX_MAXWAIT ) { |
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77 val = acquire_sem(sem->id); |
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78 } else { |
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79 timeout *= 1000; /* BeOS uses a timeout in microseconds */ |
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80 val = acquire_sem_etc(sem->id, 1, B_RELATIVE_TIMEOUT, timeout); |
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81 } |
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82 switch (val) { |
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83 case B_INTERRUPTED: |
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84 goto tryagain; |
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85 case B_NO_ERROR: |
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86 retval = 0; |
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87 break; |
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88 case B_TIMED_OUT: |
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89 retval = SDL_MUTEX_TIMEDOUT; |
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90 break; |
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91 case B_WOULD_BLOCK: |
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92 retval = SDL_MUTEX_TIMEDOUT; |
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93 break; |
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94 default: |
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95 SDL_SetError("acquire_sem() failed"); |
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96 retval = -1; |
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97 break; |
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98 } |
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99 |
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100 return retval; |
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101 } |
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102 |
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103 int SDL_SemTryWait(SDL_sem *sem) |
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104 { |
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105 return SDL_SemWaitTimeout(sem, 0); |
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106 } |
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107 |
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108 int SDL_SemWait(SDL_sem *sem) |
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109 { |
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110 return SDL_SemWaitTimeout(sem, SDL_MUTEX_MAXWAIT); |
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111 } |
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112 |
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113 /* Returns the current count of the semaphore */ |
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114 Uint32 SDL_SemValue(SDL_sem *sem) |
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115 { |
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116 int32 count; |
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117 Uint32 value; |
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118 |
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119 value = 0; |
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120 if ( sem ) { |
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121 get_sem_count(sem->id, &count); |
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122 if ( count > 0 ) { |
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123 value = (Uint32)count; |
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124 } |
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125 } |
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126 return value; |
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127 } |
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128 |
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129 /* Atomically increases the semaphore's count (not blocking) */ |
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130 int SDL_SemPost(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 |
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137 if ( release_sem(sem->id) != B_NO_ERROR ) { |
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138 SDL_SetError("release_sem() failed"); |
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139 return -1; |
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140 } |
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141 return 0; |
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142 } |