src/thread/pthread/SDL_syssem.c
author Sam Lantinga <slouken@libsdl.org>
Sun, 15 Jan 2012 03:34:14 -0500
changeset 6219 8e94af244f2c
parent 6138 4c64952a58fb
child 6298 9110462bfc57
permissions -rwxr-xr-x
Check for sem_timedwait(), which isn't available on some systems (including OpenBSD
slouken@1361
     1
/*
slouken@5535
     2
  Simple DirectMedia Layer
slouken@6138
     3
  Copyright (C) 1997-2012 Sam Lantinga <slouken@libsdl.org>
slouken@1361
     4
slouken@5535
     5
  This software is provided 'as-is', without any express or implied
slouken@5535
     6
  warranty.  In no event will the authors be held liable for any damages
slouken@5535
     7
  arising from the use of this software.
slouken@1361
     8
slouken@5535
     9
  Permission is granted to anyone to use this software for any purpose,
slouken@5535
    10
  including commercial applications, and to alter it and redistribute it
slouken@5535
    11
  freely, subject to the following restrictions:
slouken@1361
    12
slouken@5535
    13
  1. The origin of this software must not be misrepresented; you must not
slouken@5535
    14
     claim that you wrote the original software. If you use this software
slouken@5535
    15
     in a product, an acknowledgment in the product documentation would be
slouken@5535
    16
     appreciated but is not required.
slouken@5535
    17
  2. Altered source versions must be plainly marked as such, and must not be
slouken@5535
    18
     misrepresented as being the original software.
slouken@5535
    19
  3. This notice may not be removed or altered from any source distribution.
slouken@1361
    20
*/
slouken@1402
    21
#include "SDL_config.h"
slouken@1361
    22
slouken@5106
    23
#include <errno.h>
slouken@1361
    24
#include <pthread.h>
slouken@1361
    25
#include <semaphore.h>
icculus@5981
    26
#include <sys/time.h>
slouken@1361
    27
slouken@1361
    28
#include "SDL_thread.h"
slouken@1361
    29
#include "SDL_timer.h"
slouken@1361
    30
slouken@1361
    31
/* Wrapper around POSIX 1003.1b semaphores */
slouken@1361
    32
slouken@2765
    33
#if defined(__MACOSX__) || defined(__IPHONEOS__)
slouken@1627
    34
/* Mac OS X doesn't support sem_getvalue() as of version 10.4 */
slouken@1627
    35
#include "../generic/SDL_syssem.c"
slouken@1627
    36
#else
slouken@1361
    37
slouken@1895
    38
struct SDL_semaphore
slouken@1895
    39
{
slouken@1895
    40
    sem_t sem;
slouken@1361
    41
};
slouken@1361
    42
slouken@1361
    43
/* Create a semaphore, initialized with value */
slouken@1895
    44
SDL_sem *
slouken@1895
    45
SDL_CreateSemaphore(Uint32 initial_value)
slouken@1361
    46
{
slouken@1895
    47
    SDL_sem *sem = (SDL_sem *) SDL_malloc(sizeof(SDL_sem));
slouken@1895
    48
    if (sem) {
slouken@1895
    49
        if (sem_init(&sem->sem, 0, initial_value) < 0) {
slouken@1895
    50
            SDL_SetError("sem_init() failed");
slouken@1895
    51
            SDL_free(sem);
slouken@1895
    52
            sem = NULL;
slouken@1895
    53
        }
slouken@1895
    54
    } else {
slouken@1895
    55
        SDL_OutOfMemory();
slouken@1895
    56
    }
slouken@1895
    57
    return sem;
slouken@1361
    58
}
slouken@1361
    59
slouken@1895
    60
void
slouken@1895
    61
SDL_DestroySemaphore(SDL_sem * sem)
slouken@1361
    62
{
slouken@1895
    63
    if (sem) {
slouken@1895
    64
        sem_destroy(&sem->sem);
slouken@1895
    65
        SDL_free(sem);
slouken@1895
    66
    }
slouken@1361
    67
}
slouken@1361
    68
slouken@1895
    69
int
slouken@1895
    70
SDL_SemTryWait(SDL_sem * sem)
slouken@1361
    71
{
slouken@1895
    72
    int retval;
slouken@1361
    73
slouken@1895
    74
    if (!sem) {
slouken@1895
    75
        SDL_SetError("Passed a NULL semaphore");
slouken@1895
    76
        return -1;
slouken@1895
    77
    }
slouken@1895
    78
    retval = SDL_MUTEX_TIMEDOUT;
slouken@1895
    79
    if (sem_trywait(&sem->sem) == 0) {
slouken@1895
    80
        retval = 0;
slouken@1895
    81
    }
slouken@1895
    82
    return retval;
slouken@1361
    83
}
slouken@1361
    84
slouken@1895
    85
int
slouken@1895
    86
SDL_SemWait(SDL_sem * sem)
slouken@1361
    87
{
slouken@1895
    88
    int retval;
slouken@1361
    89
slouken@1895
    90
    if (!sem) {
slouken@1895
    91
        SDL_SetError("Passed a NULL semaphore");
slouken@1895
    92
        return -1;
slouken@1895
    93
    }
slouken@1361
    94
slouken@1895
    95
    retval = sem_wait(&sem->sem);
slouken@1895
    96
    if (retval < 0) {
slouken@1895
    97
        SDL_SetError("sem_wait() failed");
slouken@1895
    98
    }
slouken@1895
    99
    return retval;
slouken@1361
   100
}
slouken@1361
   101
slouken@1895
   102
int
slouken@1895
   103
SDL_SemWaitTimeout(SDL_sem * sem, Uint32 timeout)
slouken@1361
   104
{
slouken@1895
   105
    int retval;
slouken@6219
   106
#ifdef HAVE_SEM_TIMEDWAIT
slouken@5106
   107
    struct timeval now;
slouken@5106
   108
    struct timespec ts_timeout;
slouken@6219
   109
#else
slouken@6219
   110
    Uint32 end;
slouken@6219
   111
#endif
slouken@1361
   112
slouken@1895
   113
    if (!sem) {
slouken@1895
   114
        SDL_SetError("Passed a NULL semaphore");
slouken@1895
   115
        return -1;
slouken@1895
   116
    }
slouken@1361
   117
slouken@1895
   118
    /* Try the easy cases first */
slouken@1895
   119
    if (timeout == 0) {
slouken@1895
   120
        return SDL_SemTryWait(sem);
slouken@1895
   121
    }
slouken@1895
   122
    if (timeout == SDL_MUTEX_MAXWAIT) {
slouken@1895
   123
        return SDL_SemWait(sem);
slouken@1895
   124
    }
slouken@1361
   125
slouken@6219
   126
#ifdef HAVE_SEM_TIMEDWAIT
slouken@5106
   127
    /* Setup the timeout. sem_timedwait doesn't wait for
slouken@5106
   128
    * a lapse of time, but until we reach a certain time.
slouken@5106
   129
    * This time is now plus the timeout.
slouken@5106
   130
    */
slouken@5106
   131
    gettimeofday(&now, NULL);
slouken@5106
   132
slouken@5106
   133
    /* Add our timeout to current time */
slouken@5106
   134
    now.tv_usec += (timeout % 1000) * 1000;
slouken@5106
   135
    now.tv_sec += timeout / 1000;
slouken@5106
   136
slouken@5106
   137
    /* Wrap the second if needed */
slouken@5106
   138
    if ( now.tv_usec >= 1000000 ) {
slouken@5106
   139
        now.tv_usec -= 1000000;
slouken@5106
   140
        now.tv_sec ++;
slouken@5106
   141
    }
slouken@5106
   142
slouken@5106
   143
    /* Convert to timespec */
slouken@5106
   144
    ts_timeout.tv_sec = now.tv_sec;
slouken@5106
   145
    ts_timeout.tv_nsec = now.tv_usec * 1000;
slouken@5106
   146
slouken@5106
   147
    /* Wait. */
slouken@1895
   148
    do {
slouken@5106
   149
        retval = sem_timedwait(&sem->sem, &ts_timeout);
slouken@5106
   150
    } while (retval < 0 && errno == EINTR);
slouken@5106
   151
slouken@5106
   152
    if (retval < 0) {
slouken@5106
   153
        SDL_SetError("sem_timedwait() failed");
slouken@5106
   154
    }
slouken@6219
   155
#else
slouken@6219
   156
    end = SDL_GetTicks() + timeout;
slouken@6219
   157
    while ((retval = SDL_SemTryWait(sem)) == SDL_MUTEX_TIMEDOUT) {
slouken@6219
   158
        if ((SDL_GetTicks() - end) >= 0) {
slouken@6219
   159
            break;
slouken@6219
   160
        }
slouken@6219
   161
        SDL_Delay(0);
slouken@6219
   162
    }
slouken@6219
   163
#endif /* HAVE_SEM_TIMEDWAIT */
slouken@1361
   164
slouken@1895
   165
    return retval;
slouken@1361
   166
}
slouken@1361
   167
slouken@1895
   168
Uint32
slouken@1895
   169
SDL_SemValue(SDL_sem * sem)
slouken@1361
   170
{
slouken@1895
   171
    int ret = 0;
slouken@1895
   172
    if (sem) {
slouken@1895
   173
        sem_getvalue(&sem->sem, &ret);
slouken@1895
   174
        if (ret < 0) {
slouken@1895
   175
            ret = 0;
slouken@1895
   176
        }
slouken@1895
   177
    }
slouken@1895
   178
    return (Uint32) ret;
slouken@1361
   179
}
slouken@1361
   180
slouken@1895
   181
int
slouken@1895
   182
SDL_SemPost(SDL_sem * sem)
slouken@1361
   183
{
slouken@1895
   184
    int retval;
slouken@1361
   185
slouken@1895
   186
    if (!sem) {
slouken@1895
   187
        SDL_SetError("Passed a NULL semaphore");
slouken@1895
   188
        return -1;
slouken@1895
   189
    }
slouken@1361
   190
slouken@1895
   191
    retval = sem_post(&sem->sem);
slouken@1895
   192
    if (retval < 0) {
slouken@1895
   193
        SDL_SetError("sem_post() failed");
slouken@1895
   194
    }
slouken@1895
   195
    return retval;
slouken@1361
   196
}
slouken@1627
   197
slouken@1627
   198
#endif /* __MACOSX__ */
slouken@1895
   199
/* vi: set ts=4 sw=4 expandtab: */