| 1 | /* |
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| 2 | * semaphore.h - POSIX semaphore related system calls definition. |
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| 3 | * |
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| 4 | * Author Ghassan Almaless (2008,2009,2010,2011,2012) |
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| 5 | * Alain Greiner (2016) |
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| 6 | * |
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| 7 | * Copyright (c) UPMC Sorbonne Universites |
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| 8 | * |
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| 9 | * This file is part of ALMOS-MKH. |
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| 10 | * |
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| 11 | * ALMOS-MKH is free software; you can redistribute it and/or modify it |
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| 12 | * under the terms of the GNU General Public License as published by |
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| 13 | * the Free Software Foundation; version 2.0 of the License. |
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| 14 | * |
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| 15 | * ALMOS-MKH is distributed in the hope that it will be useful, but |
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| 16 | * WITHOUT ANY WARRANTY; without even the implied warranty of |
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| 17 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
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| 18 | * General Public License for more details. |
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| 19 | * |
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| 20 | * You should have received a copy of the GNU General Public License |
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| 21 | * along with ALMOS-MKH; if not, write to the Free Software Foundation, |
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| 22 | * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA |
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| 23 | */ |
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| 24 | |
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| 25 | #ifndef _SEMAPHORE_H_ |
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| 26 | #define _SEMAPHORE_H_ |
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| 27 | |
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| 28 | /********************************************************************************************* |
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| 29 | * This defines the user sem_t structure |
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| 30 | ********************************************************************************************/ |
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| 31 | |
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| 32 | typedef unsigned long sem_t; |
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| 33 | |
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| 34 | /********************************************************************************************* |
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| 35 | * This function initializes a semaphore, defined as a global variable in user process. |
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| 36 | ********************************************************************************************* |
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| 37 | * @ sem : pointer on semaphore in user space. |
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| 38 | * @ pshared : inter-process semaphore if non-zero. Not supported => must be zero. |
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| 39 | * @ value : semaphore initial value. |
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| 40 | * @ returns 0 if success / returns -1 if failure. |
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| 41 | ********************************************************************************************/ |
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| 42 | int sem_init( sem_t * sem, |
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| 43 | int pshared, |
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| 44 | unsigned int value ); |
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| 45 | |
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| 46 | /********************************************************************************************* |
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| 47 | * This function destroy a semaphore defined as a global variable in user process. |
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| 48 | ********************************************************************************************* |
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| 49 | * @ sem : pointer on semaphore in user space. |
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| 50 | * @ returns 0 if success / returns -1 if failure. |
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| 51 | ********************************************************************************************/ |
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| 52 | int sem_destroy( sem_t * sem ); |
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| 53 | |
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| 54 | /********************************************************************************************* |
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| 55 | * This function returns in the value buffer the current semaphore current value. |
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| 56 | ********************************************************************************************* |
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| 57 | * @ sem : pointer on semaphore in user space. |
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| 58 | * @ value : pointer on buffer for returned value in user space. |
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| 59 | * @ returns 0 if success / returns -1 if failure. |
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| 60 | ********************************************************************************************/ |
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| 61 | int sem_getvalue(sem_t *sem, int *value); |
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| 62 | |
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| 63 | /********************************************************************************************* |
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| 64 | * This blocking function returns only when the semaphore has been obtained (or if error). |
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| 65 | ********************************************************************************************* |
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| 66 | * @ sem : pointer on semaphore in user space. |
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| 67 | * @ returns 0 if success / returns -1 if failure. |
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| 68 | ********************************************************************************************/ |
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| 69 | int sem_wait(sem_t *sem); |
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| 70 | |
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| 71 | /********************************************************************************************* |
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| 72 | * This function releases a semaphore obtained by a previous sem_wait(). |
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| 73 | ********************************************************************************************* |
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| 74 | * @ sem : pointer on semaphore in user space. |
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| 75 | * @ returns 0 if success / returns -1 if failure. |
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| 76 | ********************************************************************************************/ |
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| 77 | int sem_post(sem_t *sem); |
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| 78 | |
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| 79 | #endif /* _SEMAPHORE_H_ */ |
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