test/testsem.c
author Patrice Mandin <patmandin@gmail.com>
Thu, 19 Jan 2006 21:28:52 +0000
changeset 1257 448a9a64537b
parent 1151 be9c9c8f6d53
child 1439 4d3bb026cd16
permissions -rw-r--r--
[PATCH] SDL_GetVideoMode() does not find best mode, part 2

Following commit 1.51, I come accross a problem when SDL must choose between
several video modes that could suit the one asked.

If I ask 320x240 with this list:
768x480 768x240 640x400 640x200 384x480 384x240 320x400 320x200

The smallest selectables modes are 384x240 and 320x400. And SDL choose the later
in this list, but 384x240 is more suitable. So I added a check to compare
the pixel count (surface) of modes, and select the one which has the smallest
pixel count.

In my example, 384x240 has 92160 pixels, and 320x400 has 128000 pixels. So now
SDL will choose 384x240 for the asked 320x240 mode.
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/* Simple test of the SDL semaphore code */
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#include <stdio.h>
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#include <stdlib.h>
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#include <signal.h>
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#include "SDL.h"
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#include "SDL_thread.h"
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#define NUM_THREADS 10
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static SDL_sem *sem;
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int alive = 1;
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/* Call this instead of exit(), so we can clean up SDL: atexit() is evil. */
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static void quit(int rc)
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{
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	SDL_Quit();
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	exit(rc);
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}
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int ThreadFunc(void *data)
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{
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	while ( alive ) {
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		SDL_SemWait(sem);
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		fprintf(stderr, "Thread number %d has got the semaphore (value = %d)!\n", (int)data, SDL_SemValue(sem));
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		SDL_Delay(200);
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		SDL_SemPost(sem);
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		fprintf(stderr, "Thread number %d has released the semaphore (value = %d)!\n", (int)data, SDL_SemValue(sem));
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		SDL_Delay(1); /* For the scheduler */
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	}
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	printf("Thread number %d exiting.\n", (int)data);
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	return 0;
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}
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static void killed(int sig)
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{
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	alive = 0;
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}
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int main(int argc, char **argv)
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{
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	SDL_Thread *threads[NUM_THREADS];
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	int i, init_sem;
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	if(argc < 2) {
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		fprintf(stderr,"Usage: %s init_value\n", argv[0]);
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		return(1);
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	}
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	/* Load the SDL library */
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	if ( SDL_Init(0) < 0 ) {
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		fprintf(stderr, "Couldn't initialize SDL: %s\n",SDL_GetError());
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		return(1);
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	}
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	signal(SIGTERM, killed);
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	signal(SIGINT, killed);
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	init_sem = atoi(argv[1]);
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	sem = SDL_CreateSemaphore(init_sem);
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	printf("Running %d threads, semaphore value = %d\n", NUM_THREADS, init_sem);
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	/* Create all the threads */
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	for( i = 0; i < NUM_THREADS; ++i ) {
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		threads[i] = SDL_CreateThread(ThreadFunc, (void*)i);
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	}
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	/* Wait 10 seconds */
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	SDL_Delay(10 * 1000);
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	/* Wait for all threads to finish */
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	printf("Waiting for threads to finish\n");
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	alive = 0;
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	for( i = 0; i < NUM_THREADS; ++i ) {
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		SDL_WaitThread(threads[i], NULL);
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	}
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	printf("Finished waiting for threads\n");
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	SDL_DestroySemaphore(sem);
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	SDL_Quit();
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	return(0);
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}