testsem.c
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/* Simple test of the SDL semaphore code */
#include <stdio.h>
#include <stdlib.h>
#include <signal.h>
#include "SDL.h"
#include "SDL_thread.h"
#define NUM_THREADS 10
static SDL_sem *sem;
int alive = 1;
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/* Call this instead of exit(), so we can clean up SDL: atexit() is evil. */
static void quit(int rc)
{
SDL_Quit();
exit(rc);
}
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int ThreadFunc(void *data)
{
while ( alive ) {
SDL_SemWait(sem);
fprintf(stderr, "Thread number %d has got the semaphore (value = %d)!\n", (int)data, SDL_SemValue(sem));
SDL_Delay(200);
SDL_SemPost(sem);
fprintf(stderr, "Thread number %d has released the semaphore (value = %d)!\n", (int)data, SDL_SemValue(sem));
SDL_Delay(1); /* For the scheduler */
}
printf("Thread number %d exiting.\n", (int)data);
return 0;
}
static void killed(int sig)
{
alive = 0;
}
int main(int argc, char **argv)
{
SDL_Thread *threads[NUM_THREADS];
int i, init_sem;
if(argc < 2) {
fprintf(stderr,"Usage: %s init_value\n", argv[0]);
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}
/* Load the SDL library */
if ( SDL_Init(0) < 0 ) {
fprintf(stderr, "Couldn't initialize SDL: %s\n",SDL_GetError());
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}
signal(SIGTERM, killed);
signal(SIGINT, killed);
init_sem = atoi(argv[1]);
sem = SDL_CreateSemaphore(init_sem);
printf("Running %d threads, semaphore value = %d\n", NUM_THREADS, init_sem);
/* Create all the threads */
for( i = 0; i < NUM_THREADS; ++i ) {
threads[i] = SDL_CreateThread(ThreadFunc, (void*)i);
}
/* Wait 10 seconds */
SDL_Delay(10 * 1000);
/* Wait for all threads to finish */
printf("Waiting for threads to finish\n");
alive = 0;
for( i = 0; i < NUM_THREADS; ++i ) {
SDL_WaitThread(threads[i], NULL);
}
printf("Finished waiting for threads\n");
SDL_DestroySemaphore(sem);
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return(0);
}