1/*
2Copyright (c) 2012, Broadcom Europe Ltd
3All rights reserved.
4
5Redistribution and use in source and binary forms, with or without
6modification, are permitted provided that the following conditions are met:
7 * Redistributions of source code must retain the above copyright
8 notice, this list of conditions and the following disclaimer.
9 * Redistributions in binary form must reproduce the above copyright
10 notice, this list of conditions and the following disclaimer in the
11 documentation and/or other materials provided with the distribution.
12 * Neither the name of the copyright holder nor the
13 names of its contributors may be used to endorse or promote products
14 derived from this software without specific prior written permission.
15
16THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
17ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
18WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
19DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY
20DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
21(INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
22LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
23ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
24(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
25SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
26*/
27
28/*=============================================================================
29VideoCore OS Abstraction Layer - named semaphores
30=============================================================================*/
31
32#ifndef VCOS_NAMED_SEMAPHORE_H
33#define VCOS_NAMED_SEMAPHORE_H
34
35#ifdef __cplusplus
36extern "C" {
37#endif
38
39#include "interface/vcos/vcos_types.h"
40#include "vcos.h"
41
42/**
43 * \file
44 *
45 * Create a named semaphore, or open an existing one by name.
46 *
47 */
48
49/**
50 * \brief Create a named semaphore.
51 *
52 * Semaphores are not re-entrant.
53 *
54 * @param sem Pointer to memory to be initialized
55 * @param name A name for this semaphore.
56 * @param count The initial count for the semaphore.
57 *
58 * @return VCOS_SUCCESS if the semaphore was created.
59 *
60 */
61VCOS_INLINE_DECL
62VCOS_STATUS_T vcos_named_semaphore_create(VCOS_NAMED_SEMAPHORE_T *sem, const char *name, VCOS_UNSIGNED count);
63
64/**
65 * \brief Wait on a named semaphore.
66 *
67 * There is no timeout option on a semaphore, as adding this will slow down
68 * implementations on some platforms. If you need that kind of behaviour, use
69 * an event group.
70 *
71 * This always returns VCOS_SUCCESS and so should really be a void function. However
72 * too many lines of code would need to be changed in non-trivial ways, so for now
73 * it is non-void.
74 *
75 * @param sem Semaphore to wait on
76 * @return VCOS_SUCCESS - semaphore was taken.
77 *
78 */
79VCOS_INLINE_DECL
80void vcos_named_semaphore_wait(VCOS_NAMED_SEMAPHORE_T *sem);
81
82/**
83 * \brief Try to wait for a semaphore.
84 *
85 * Try to obtain the semaphore. If it is already taken, return VCOS_TIMEOUT.
86 * @param sem Semaphore to wait on
87 * @return VCOS_SUCCESS - semaphore was taken.
88 * VCOS_EAGAIN - could not take semaphore
89 */
90VCOS_INLINE_DECL
91VCOS_STATUS_T vcos_named_semaphore_trywait(VCOS_NAMED_SEMAPHORE_T *sem);
92
93/**
94 * \brief Post a semaphore.
95 *
96 * @param sem Semaphore to wait on
97 */
98VCOS_INLINE_DECL
99void vcos_named_semaphore_post(VCOS_NAMED_SEMAPHORE_T *sem);
100
101/**
102 * \brief Delete a semaphore, releasing any resources consumed by it.
103 *
104 * @param sem Semaphore to wait on
105 */
106void vcos_named_semaphore_delete(VCOS_NAMED_SEMAPHORE_T *sem);
107
108
109#ifdef __cplusplus
110}
111#endif
112#endif
113
114