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 - public header file for events
30=============================================================================*/
31
32#ifndef VCOS_EVENT_H
33#define VCOS_EVENT_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 * An event is akin to the Win32 auto-reset event.
46 *
47 *
48 * Signalling an event will wake up one waiting thread only. Once one
49 * thread has been woken the event atomically returns to the unsignalled
50 * state.
51 *
52 * If no threads are waiting on the event when it is signalled it remains
53 * signalled.
54 *
55 * This is almost, but not quite, completely unlike the "event flags"
56 * object based on Nucleus event groups and ThreadX event flags.
57 *
58 * In particular, it should be similar in speed to a semaphore, unlike
59 * the event flags.
60 */
61
62/**
63 * Create an event instance.
64 *
65 * @param event Filled in with constructed event.
66 * @param name Name of the event (for debugging)
67 *
68 * @return VCOS_SUCCESS on success, or error code.
69 */
70VCOS_INLINE_DECL
71VCOS_STATUS_T vcos_event_create(VCOS_EVENT_T *event, const char *name);
72
73#ifndef vcos_event_signal
74
75/**
76 * Signal the event. The event will return to being unsignalled
77 * after exactly one waiting thread has been woken up. If no
78 * threads are waiting it remains signalled.
79 *
80 * @param event The event to signal
81 */
82VCOS_INLINE_DECL
83void vcos_event_signal(VCOS_EVENT_T *event);
84
85/**
86 * Wait for the event.
87 *
88 * @param event The event to wait for
89 * @return VCOS_SUCCESS on success, VCOS_EAGAIN if the wait was interrupted.
90 */
91VCOS_INLINE_DECL
92VCOS_STATUS_T vcos_event_wait(VCOS_EVENT_T *event);
93
94/**
95 * Try event, but don't block.
96 *
97 * @param event The event to try
98 * @return VCOS_SUCCESS on success, VCOS_EAGAIN if the event is not currently signalled
99 */
100VCOS_INLINE_DECL
101VCOS_STATUS_T vcos_event_try(VCOS_EVENT_T *event);
102
103#endif
104
105/*
106 * Destroy an event.
107 */
108VCOS_INLINE_DECL
109void vcos_event_delete(VCOS_EVENT_T *event);
110
111#ifdef __cplusplus
112}
113#endif
114
115#endif
116
117
118