Date: Mon, 11 Oct 2004 15:17:27 +0300 (EEST) From: Hannu Savolainen Subject: Re: SDL uses obsolete OSS features I did some work on getting OSS to work better with SDL. There have been some problems with select which should be fixed now. I'm having some problems in understanding what is the purpose of the DSP_WaitAudio() routine. I added a return to the very beginning of this routine and commendted out the define for USE_BLOCKING_WRITES. At least lbreakout2 seems to work as well as earlier. The latencies are the same. An ordinary blocking write does exactly the same thing than DSP_WaitAudio does. So I would recommend using the USE_BLOCKING_WRITES approach and removing everything from the DSP_WaitAudio routine. Also enabling USE_BLOCKING_WRITES makes it possible to simplify DSP_PlayAudio() because you don't need to handle the partial writes (the do-while loop). Attached is a patch against SDL-1.2.7. After these changes SDL will use OSS as it's designed to be used (make it as simple as possible). This code should work with all OSS implementations because it uses only the very fundamental features that have been there since the jurassic times.

/* Test program to check SDL's CPU endian detection and byte swapping routines */

#include <stdio.h>

#include "SDL.h"
#include "SDL_endian.h"

int main(int argc, char *argv[])
{
	Uint16 value16 = 0xCDAB;
	Uint32 value32 = 0xEFBEADDE;
#if defined(__GNUC__) && defined(SDL_HAS_64BIT_TYPE)
	Uint64 value64 = 0xEFBEADDECDAB3412LL;
#endif

	printf("This is a %s endian machine.\n",
		(SDL_BYTEORDER == SDL_LIL_ENDIAN) ? "little" : "big");
	printf("Value 16 = 0x%X, swapped = 0x%X\n", value16, SDL_Swap16(value16));
	printf("Value 32 = 0x%X, swapped = 0x%X\n", value32, SDL_Swap32(value32));
#if defined(__GNUC__) && defined(SDL_HAS_64BIT_TYPE)
	printf("Value 64 = 0x%llX, swapped = 0x%llX\n", value64, SDL_Swap64(value64));
#endif
	return(0);
}