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FORK: Simple Directmedia Layer
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SDL_syscond.c (3994B)

      1 /*
      2   Simple DirectMedia Layer
      3   Copyright (C) 1997-2020 Sam Lantinga <slouken@libsdl.org>
      4 
      5   This software is provided 'as-is', without any express or implied
      6   warranty.  In no event will the authors be held liable for any damages
      7   arising from the use of this software.
      8 
      9   Permission is granted to anyone to use this software for any purpose,
     10   including commercial applications, and to alter it and redistribute it
     11   freely, subject to the following restrictions:
     12 
     13   1. The origin of this software must not be misrepresented; you must not
     14      claim that you wrote the original software. If you use this software
     15      in a product, an acknowledgment in the product documentation would be
     16      appreciated but is not required.
     17   2. Altered source versions must be plainly marked as such, and must not be
     18      misrepresented as being the original software.
     19   3. This notice may not be removed or altered from any source distribution.
     20 */
     21 #include "../../SDL_internal.h"
     22 
     23 #include <sys/time.h>
     24 #include <time.h>
     25 #include <unistd.h>
     26 #include <errno.h>
     27 #include <pthread.h>
     28 
     29 #include "SDL_thread.h"
     30 #include "SDL_sysmutex_c.h"
     31 
     32 struct SDL_cond
     33 {
     34     pthread_cond_t cond;
     35 };
     36 
     37 /* Create a condition variable */
     38 SDL_cond *
     39 SDL_CreateCond(void)
     40 {
     41     SDL_cond *cond;
     42 
     43     cond = (SDL_cond *) SDL_malloc(sizeof(SDL_cond));
     44     if (cond) {
     45         if (pthread_cond_init(&cond->cond, NULL) != 0) {
     46             SDL_SetError("pthread_cond_init() failed");
     47             SDL_free(cond);
     48             cond = NULL;
     49         }
     50     }
     51     return (cond);
     52 }
     53 
     54 /* Destroy a condition variable */
     55 void
     56 SDL_DestroyCond(SDL_cond * cond)
     57 {
     58     if (cond) {
     59         pthread_cond_destroy(&cond->cond);
     60         SDL_free(cond);
     61     }
     62 }
     63 
     64 /* Restart one of the threads that are waiting on the condition variable */
     65 int
     66 SDL_CondSignal(SDL_cond * cond)
     67 {
     68     int retval;
     69 
     70     if (!cond) {
     71         return SDL_SetError("Passed a NULL condition variable");
     72     }
     73 
     74     retval = 0;
     75     if (pthread_cond_signal(&cond->cond) != 0) {
     76         return SDL_SetError("pthread_cond_signal() failed");
     77     }
     78     return retval;
     79 }
     80 
     81 /* Restart all threads that are waiting on the condition variable */
     82 int
     83 SDL_CondBroadcast(SDL_cond * cond)
     84 {
     85     int retval;
     86 
     87     if (!cond) {
     88         return SDL_SetError("Passed a NULL condition variable");
     89     }
     90 
     91     retval = 0;
     92     if (pthread_cond_broadcast(&cond->cond) != 0) {
     93         return SDL_SetError("pthread_cond_broadcast() failed");
     94     }
     95     return retval;
     96 }
     97 
     98 int
     99 SDL_CondWaitTimeout(SDL_cond * cond, SDL_mutex * mutex, Uint32 ms)
    100 {
    101     int retval;
    102 #ifndef HAVE_CLOCK_GETTIME
    103     struct timeval delta;
    104 #endif
    105     struct timespec abstime;
    106 
    107     if (!cond) {
    108         return SDL_SetError("Passed a NULL condition variable");
    109     }
    110 
    111 #ifdef HAVE_CLOCK_GETTIME
    112     clock_gettime(CLOCK_REALTIME, &abstime);
    113 
    114     abstime.tv_nsec += (ms % 1000) * 1000000;
    115     abstime.tv_sec += ms / 1000;
    116 #else
    117     gettimeofday(&delta, NULL);
    118 
    119     abstime.tv_sec = delta.tv_sec + (ms / 1000);
    120     abstime.tv_nsec = (delta.tv_usec + (ms % 1000) * 1000) * 1000;
    121 #endif
    122     if (abstime.tv_nsec > 1000000000) {
    123         abstime.tv_sec += 1;
    124         abstime.tv_nsec -= 1000000000;
    125     }
    126 
    127   tryagain:
    128     retval = pthread_cond_timedwait(&cond->cond, &mutex->id, &abstime);
    129     switch (retval) {
    130     case EINTR:
    131         goto tryagain;
    132         /* break; -Wunreachable-code-break */
    133     case ETIMEDOUT:
    134         retval = SDL_MUTEX_TIMEDOUT;
    135         break;
    136     case 0:
    137         break;
    138     default:
    139         retval = SDL_SetError("pthread_cond_timedwait() failed");
    140     }
    141     return retval;
    142 }
    143 
    144 /* Wait on the condition variable, unlocking the provided mutex.
    145    The mutex must be locked before entering this function!
    146  */
    147 int
    148 SDL_CondWait(SDL_cond * cond, SDL_mutex * mutex)
    149 {
    150     if (!cond) {
    151         return SDL_SetError("Passed a NULL condition variable");
    152     } else if (pthread_cond_wait(&cond->cond, &mutex->id) != 0) {
    153         return SDL_SetError("pthread_cond_wait() failed");
    154     }
    155     return 0;
    156 }
    157 
    158 /* vi: set ts=4 sw=4 expandtab: */