ugfx/src/gos/gfx_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.org/license.html
 */

#include "gfx.h"

#if GFX_USE_OS_LINUX

#include <stdio.h>
#include <unistd.h>
#include <errno.h>
#include <time.h>

static gfxMutex		SystemMutex;

void _gosInit(void)
{
	/* No initialization of the operating system itself is needed */
	gfxMutexInit(&SystemMutex);
}

void _gosDeinit(void)
{
	/* ToDo */
}

void gfxSystemLock(void) {
	gfxMutexEnter(&SystemMutex);
}

void gfxSystemUnlock(void) {
	gfxMutexExit(&SystemMutex);
}

void gfxHalt(const char *msg) {
	if (msg)
		fprintf(stderr, "%s\n", msg);
	exit(1);
}

void gfxSleepMilliseconds(delaytime_t ms) {
	struct timespec	ts;

	switch(ms) {
		case TIME_IMMEDIATE:
			pthread_yield();
			return;

		case TIME_INFINITE:
			while(1)
				sleep(60);
			return;

		default:
			ts.tv_sec = ms / 1000;
			ts.tv_nsec = (ms % 1000) * 1000;
			nanosleep(&ts, 0);
			return;
	}
}

void gfxSleepMicroseconds(delaytime_t ms) {
	struct timespec	ts;

	switch(ms) {
		case TIME_IMMEDIATE:
			pthread_yield();
			return;

		case TIME_INFINITE:
			while(1)
				sleep(60);
			return;

		default:
			ts.tv_sec = ms / 1000000;
			ts.tv_nsec = ms % 1000000;
			nanosleep(&ts, 0);
			return;
	}
}

systemticks_t gfxSystemTicks(void) {
	struct timespec	ts;

	clock_gettime(CLOCK_MONOTONIC, &ts);

	return ts.tv_sec * 1000UL + ts.tv_nsec / 1000UL;
}

gfxThreadHandle gfxThreadCreate(void *stackarea, size_t stacksz, threadpriority_t prio, DECLARE_THREAD_FUNCTION((*fn),p), void *param) {
	gfxThreadHandle		th;

	// 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;
}

threadreturn_t gfxThreadWait(gfxThreadHandle thread) {
	threadreturn_t	retval;

	if (pthread_join(thread, &retval))
		return 0;

	return retval;
}

void gfxSemInit(gfxSem *pSem, semcount_t val, semcount_t 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(gfxSem *pSem) {
	pthread_mutex_destroy(&pSem->mtx);
	pthread_cond_destroy(&pSem->cond);
}

bool_t gfxSemWait(gfxSem *pSem, delaytime_t ms) {
	pthread_mutex_lock(&pSem->mtx);

	switch (ms) {
		case TIME_INFINITE:
			while (!pSem->cnt)
				pthread_cond_wait(&pSem->cond, &pSem->mtx);
			break;

		case TIME_IMMEDIATE:
			if (!pSem->cnt) {
				pthread_mutex_unlock(&pSem->mtx);
				return FALSE;
			}
			break;

		default:
			{
				struct timeval now;
				struct timespec	tm;

				gettimeofday(&now);
				tm.tv_sec = now.tv_sec + ms / 1000;
				tm.tv_nsec = (now.tv_usec + ms % 1000) * 1000;
				while (!pSem->cnt) {
					if (pthread_cond_timedwait(&pSem->cond, &pSem->mtx, &tm) == ETIMEDOUT) {
						pthread_mutex_unlock(&pSem->mtx);
						return FALSE;
					}
				}
			}
			break;
	}

	pSem->cnt--;
	pthread_mutex_unlock(&pSem->mtx);

	return TRUE;
}

void gfxSemSignal(gfxSem *pSem) {
	pthread_mutex_lock(&pSem->mtx);

	if (pSem->cnt < pSem->max) {
		pSem->cnt++;
		pthread_cond_signal(&pSem->cond);
	}

	pthread_mutex_unlock(&pSem->mtx);
}

semcount_t gfxSemCounter(gfxSem *pSem) {
	semcount_t	res;

	// The locking is really only required if obtaining the count is a divisible operation
	//	which it might be on a 8/16 bit processor with a 32 bit semaphore count.
	pthread_mutex_lock(&pSem->mtx);
	res = pSem->cnt;
	pthread_mutex_unlock(&pSem->mtx);

	return res;
}

#endif /* GFX_USE_OS_LINUX */