source: trunk/sys/libpthread/include/semaphore.h @ 1

Last change on this file since 1 was 1, checked in by alain, 5 years ago

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