Atlas - SDL_syscond.c
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1/*
2  Simple DirectMedia Layer
3  Copyright (C) 1997-2018 Sam Lantinga <[email protected]>
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
32struct SDL_cond
33{
34    pthread_cond_t cond;
35};
36
37/* Create a condition variable */
38SDL_cond *
39SDL_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 */
55void
56SDL_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 */
65int
66SDL_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 */
82int
83SDL_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
98int
99SDL_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 */
147int
148SDL_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: */
159
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