| 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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