gos_linux.c

/*
 * This file is subject to the terms of the GFX License. If a copy of
 * the license was not distributed with this file, you can obtain one at:
 *
 *              http://ugfx.io/license.html
 */
 
// We need to include stdio.h below. Turn off GFILE_NEED_STDIO just for this file to prevent conflicts
#define GFILE_NEED_STDIO_MUST_BE_OFF
 
#include "../../gfx.h"
 
#if GFX_USE_OS_LINUX
 
// Linux seems to have deprecated pthread_yield() and now says to use sched_yield()
#define     USE_SCHED_NOT_PTHREAD_YIELD     GFXON
 
#include <stdio.h>
#include <unistd.h>
#include <time.h>
#if USE_SCHED_NOT_PTHREAD_YIELD
    #include <sched.h>
    #define linuxyield()    sched_yield()
#else
    #define linuxyield()    pthread_yield()
#endif
 
static gMutex       SystemMutex;
 
void _gosInit(void)
{
    /* No initialization of the operating system itself is needed */
    gfxMutexInit(&SystemMutex);
}
 
void _gosPostInit(void)
{
}
 
void _gosDeinit(void)
{
    /* ToDo */
}
 
void gfxSystemLock(void) {
    gfxMutexEnter(&SystemMutex);
}
 
void gfxSystemUnlock(void) {
    gfxMutexExit(&SystemMutex);
}
 
void gfxYield(void) {
    linuxyield();
}
 
void gfxHalt(const char *msg) {
    if (msg)
        fprintf(stderr, "%s\n", msg);
    exit(1);
}
 
void gfxSleepMilliseconds(gDelay ms) {
    struct timespec ts;
 
    switch(ms) {
        case gDelayNone:
            linuxyield();
            return;
 
        case gDelayForever:
            while(1)
                sleep(60);
            return;
 
        default:
            ts.tv_sec = ms / 1000;
            ts.tv_nsec = (ms % 1000) * 1000000;
            nanosleep(&ts, 0);
            return;
    }
}
 
void gfxSleepMicroseconds(gDelay us) {
    struct timespec ts;
 
    switch(us) {
        case gDelayNone:
            linuxyield();
            return;
 
        case gDelayForever:
            while(1)
                sleep(60);
            return;
 
        default:
            ts.tv_sec = us / 1000000;
            ts.tv_nsec = (us % 1000000) * 1000;
            nanosleep(&ts, 0);
            return;
    }
}
 
gTicks gfxSystemTicks(void) {
    struct timespec ts;
 
    clock_gettime(CLOCK_MONOTONIC, &ts);
    return ts.tv_sec * 1000 + ts.tv_nsec / 1000000;
}
 
gThread gfxThreadCreate(void *stackarea, gMemSize stacksz, gThreadpriority prio, GFX_THREAD_FUNCTION((*fn),p), void *param) {
    gThread     th;
    (void)              stackarea;
    (void)              stacksz;
    (void)              prio;
 
    // Implementing priority with pthreads is a rats nest that is also pthreads implementation dependent.
    // Only some pthreads schedulers support it, some implementations use the operating system process priority mechanisms.
    // Even those that do support it can have different ranges of priority and "normal" priority is an undefined concept.
    // Across different UNIX style operating systems things can be very different (let alone OS's such as Windows).
    // Even just Linux changes the way priority works with different kernel schedulers and across kernel versions.
    // For these reasons we ignore the priority.
 
    if (pthread_create(&th, 0, fn, param))
        return 0;
 
    return th;
}
 
gThreadreturn gfxThreadWait(gThread thread) {
    gThreadreturn   retval;
 
    if (pthread_join(thread, &retval))
        return 0;
 
    return retval;
}
 
#if GFX_USE_POSIX_SEMAPHORES
    void gfxSemInit(gSem *pSem, gSemcount val, gSemcount limit) {
        pSem->max = limit;
        sem_init(&pSem->sem, 0, val);
    }
    void gfxSemDestroy(gSem *pSem) {
        sem_destroy(&pSem->sem);
    }
    gBool gfxSemWait(gSem *pSem, gDelay ms) {
        switch (ms) {
        case gDelayForever:
            return sem_wait(&pSem->sem) ? gFalse : gTrue;
 
        case gDelayNone:
            return sem_trywait(&pSem->sem) ? gFalse : gTrue;
 
        default:
            {
                struct timespec tm;
 
                clock_gettime(CLOCK_REALTIME, &tm);
                tm.tv_sec += ms / 1000;
                tm.tv_nsec += (ms % 1000) * 1000000;
                return sem_timedwait(&pSem->sem, &tm) ? gFalse : gTrue;
            }
        }
    }
    void gfxSemSignal(gSem *pSem) {
        int res;
 
        res = 0;
        sem_getvalue(&pSem->sem, &res);
        if (res < pSem->max)
            sem_post(&pSem->sem);
    }
#else
    void gfxSemInit(gSem *pSem, gSemcount val, gSemcount limit) {
        pthread_mutex_init(&pSem->mtx, 0);
        pthread_cond_init(&pSem->cond, 0);
        pthread_mutex_lock(&pSem->mtx);
        pSem->cnt = val;
        pSem->max = limit;
        pthread_mutex_unlock(&pSem->mtx);
    }
    void gfxSemDestroy(gSem *pSem) {
        pthread_mutex_destroy(&pSem->mtx);
        pthread_cond_destroy(&pSem->cond);
    }
    gBool gfxSemWait(gSem *pSem, gDelay ms) {
        pthread_mutex_lock(&pSem->mtx);
 
        switch (ms) {
            case gDelayForever:
                while (!pSem->cnt)
                    pthread_cond_wait(&pSem->cond, &pSem->mtx);
                break;
 
            case gDelayNone:
                if (!pSem->cnt) {
                    pthread_mutex_unlock(&pSem->mtx);
                    return gFalse;
                }
                break;
 
            default:
                {
                    struct timespec tm;
 
                    clock_gettime(CLOCK_REALTIME, &tm);
                    tm.tv_sec += ms / 1000;
                    tm.tv_nsec += (ms % 1000) * 1000000;
                    while (!pSem->cnt) {
                        // We used to test the return value for ETIMEDOUT. This doesn't
                        //  work in some current pthread libraries which return -1 instead
                        //  and set errno to ETIMEDOUT. So, we will return gFalse on any error
                        //  including a ETIMEDOUT.
                        if (pthread_cond_timedwait(&pSem->cond, &pSem->mtx, &tm)) {
                            pthread_mutex_unlock(&pSem->mtx);
                            return gFalse;
                        }
                    }
                }
                break;
        }
 
        pSem->cnt--;
        pthread_mutex_unlock(&pSem->mtx);
        return gTrue;
    }
    void gfxSemSignal(gSem *pSem) {
        pthread_mutex_lock(&pSem->mtx);
 
        if (pSem->cnt < pSem->max) {
            pSem->cnt++;
            pthread_cond_signal(&pSem->cond);
        }
 
        pthread_mutex_unlock(&pSem->mtx);
    }
#endif // GFX_USE_POSIX_SEMAPHORES
 
#endif /* GFX_USE_OS_LINUX */