1 semaphore.h |
1 /* |
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2 * Copyright (c) 2005-2009 Nokia Corporation and/or its subsidiary(-ies). |
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3 * All rights reserved. |
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4 * This component and the accompanying materials are made available |
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5 * under the terms of the License "Symbian Foundation License v1.0" to Symbian Foundation members and "Symbian Foundation End User License Agreement v1.0" to non-members |
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6 * which accompanies this distribution, and is available |
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7 * at the URL "http://www.symbianfoundation.org/legal/licencesv10.html". |
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8 * |
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9 * Initial Contributors: |
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10 * Nokia Corporation - initial contribution. |
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11 * |
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12 * Contributors: |
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13 * |
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14 * Description: |
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15 * Name : semaphore.h |
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16 * Part of : semaphore |
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17 * Interface : POSIX, semaphores |
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18 * POSIX implementation of semaphores on Symbian |
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19 * Version : |
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20 * All rights reserved. |
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21 * Redistribution and use in source and binary forms, with or without |
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22 * modification, are permitted provided that the following conditions are met: |
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23 * Redistributions of source code must retain the above copyright notice, this |
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24 * list of conditions and the following disclaimer. |
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25 * Redistributions in binary form must reproduce the above copyright notice, |
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26 * this list of conditions and the following disclaimer in the documentation |
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27 * and/or other materials provided with the distribution. |
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28 * Neither the name of the <ORGANIZATION> nor the names of its contributors |
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29 * may be used to endorse or promote products derived from this software |
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30 * without specific prior written permission. |
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31 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" |
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32 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE |
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33 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE |
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34 * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE |
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35 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL |
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36 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR |
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37 * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER |
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38 * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, |
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39 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE |
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40 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
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41 * |
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42 */ |
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43 |
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44 |
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45 |
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46 #ifndef __SEMAPHORE_H__ |
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47 #define __SEMAPHORE_H__ |
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48 |
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49 #include <sys/types.h> |
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50 |
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51 #ifdef __cplusplus |
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52 extern "C" |
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53 { |
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54 #endif /* __cplusplus */ |
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55 |
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56 /*Semaphores supported */ |
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57 |
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58 #define SEM_FAILED -1 |
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59 typedef struct _sem_t* sem_t; |
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60 |
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61 /* |
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62 This function initializes the semaphore object. |
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63 The semaphore count is set to the initial count value. |
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64 */ |
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65 IMPORT_C extern int sem_init (sem_t * sem, int pshared, unsigned int value); |
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66 |
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67 /* |
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68 This function destroys the semaphore object. |
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69 */ |
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70 IMPORT_C extern int sem_destroy (sem_t* sem); |
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71 |
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72 /* |
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73 This function atomically decrements sem's count if it is greater than 0 and returns immediately, |
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74 or it returns immediately with a return code of -1 after having set errno to EAGAIN. |
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75 sem_trywait never blocks. |
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76 */ |
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77 IMPORT_C extern int sem_trywait (sem_t* sem); |
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78 |
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79 /* |
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80 This function atomically decrements sem's count if it is greater than 0 and returns immediately |
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81 or it suspends the calling thread until it can resume following a call to sem_post or sem_post_multiple |
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82 */ |
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83 IMPORT_C extern int sem_wait (sem_t* sem); |
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84 |
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85 /* |
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86 This function atomically decrements sem's count if it is greater than 0 and returns immediately, or it |
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87 suspends the calling thread. If timeout time lapses before the thread can be resumed because of a sem_post, |
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88 case, then sem_timedwait returns with a return code of -1 after having set errno to ETIMEDOUT. If the |
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89 thread can return without suspending then abstime parameter is not checked. |
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90 */ |
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91 IMPORT_C extern int sem_timedwait (sem_t* sem, const struct timespec* abstime); |
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92 |
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93 /* |
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94 The function increments (unlocks) the semaphore pointed to by sem . |
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95 If there are threads blocked on the semaphore when sem_post is called, the highest priority thread that has been blocked the longest on |
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96 the semaphore will be allowed to return from sem_wait . |
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97 If successful, the function returns zero; otherwise, it returns -1 and set errno to indicate the error. |
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98 */ |
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99 IMPORT_C extern int sem_post (sem_t* sem); |
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100 |
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101 /* |
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102 This function establish a connection between a named semaphore and a process |
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103 */ |
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104 /* IMPORT_C extern sem_t* sem_open (const char* name,int oflag,mode_t mode, unsigned int value); */ |
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105 |
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106 /* |
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107 This function indicate that the calling process is finished using the named semaphore indicated by sem*/ |
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108 /* IMPORT_C extern int sem_close (sem_t* sem); */ |
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109 |
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110 /* |
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111 This function cleans up resources associated with a system-wide semaphore. |
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112 */ |
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113 /* IMPORT_C extern int sem_unlink (const char* name); */ |
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114 |
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115 /* |
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116 This function updates the location referenced by the sval argument with the value of the semaphore |
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117 referenced by sem without affecting the state of the semaphore. |
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118 The updated value represents an actual semaphore value that occurred at some unspecified time |
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119 during the call, but it need not be the actual value of the semaphore when it is returned to |
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120 the calling process. If sem is locked, then the object to which sval points shall either be set |
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121 to zero or to a negative number whose absolute value represents the number of processes waiting |
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122 for the semaphore at some unspecified time during the call. |
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123 */ |
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124 IMPORT_C extern int sem_getvalue (sem_t* sem, int* sval); |
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125 |
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126 |
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127 #ifdef __cplusplus |
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128 } /* End of extern "C" */ |
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129 #endif /* __cplusplus */ |
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130 |
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131 #endif /* __SEMAPHORE_H__ */ |