blob: 011ee6bd3d278da7a9c8bb64c1a8ad01b630ff5b (
plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
|
/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
#include <kernel/OS.h>
#include "primpl.h"
/*
** Create a new semaphore object.
*/
PR_IMPLEMENT(PRSemaphore*)
PR_NewSem (PRUintn value)
{
PRSemaphore *semaphore;
if (!_pr_initialized) _PR_ImplicitInitialization();
semaphore = PR_NEWZAP(PRSemaphore);
if (NULL != semaphore) {
if ((semaphore->sem = create_sem(value, "nspr_sem")) < B_NO_ERROR)
return NULL;
else
return semaphore;
}
return NULL;
}
/*
** Destroy the given semaphore object.
**
*/
PR_IMPLEMENT(void)
PR_DestroySem (PRSemaphore *sem)
{
status_t result;
PR_ASSERT(sem != NULL);
result = delete_sem(sem->sem);
PR_ASSERT(result == B_NO_ERROR);
PR_DELETE(sem);
}
/*
** Wait on a Semaphore.
**
** This routine allows a calling thread to wait or proceed depending upon
** the state of the semahore sem. The thread can proceed only if the
** counter value of the semaphore sem is currently greater than 0. If the
** value of semaphore sem is positive, it is decremented by one and the
** routine returns immediately allowing the calling thread to continue. If
** the value of semaphore sem is 0, the calling thread blocks awaiting the
** semaphore to be released by another thread.
**
** This routine can return PR_PENDING_INTERRUPT if the waiting thread
** has been interrupted.
*/
PR_IMPLEMENT(PRStatus)
PR_WaitSem (PRSemaphore *sem)
{
PR_ASSERT(sem != NULL);
if (acquire_sem(sem->sem) == B_NO_ERROR)
return PR_SUCCESS;
else
return PR_FAILURE;
}
/*
** This routine increments the counter value of the semaphore. If other
** threads are blocked for the semaphore, then the scheduler will
** determine which ONE thread will be unblocked.
*/
PR_IMPLEMENT(void)
PR_PostSem (PRSemaphore *sem)
{
status_t result;
PR_ASSERT(sem != NULL);
result = release_sem_etc(sem->sem, 1, B_DO_NOT_RESCHEDULE);
PR_ASSERT(result == B_NO_ERROR);
}
/*
** Returns the value of the semaphore referenced by sem without affecting
** the state of the semaphore. The value represents the semaphore value
** at the time of the call, but may not be the actual value when the
** caller inspects it.
*/
PR_IMPLEMENT(PRUintn)
PR_GetValueSem (PRSemaphore *sem)
{
sem_info info;
PR_ASSERT(sem != NULL);
get_sem_info(sem->sem, &info);
return info.count;
}
|
