view src/audio/mint/SDL_mintaudio_mcsn.c @ 968:4675910b0b7b

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.
author Sam Lantinga <slouken@libsdl.org>
date Fri, 12 Nov 2004 21:39:04 +0000
parents 176240cf4405
children f10892fa2e48
line wrap: on
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/*
    SDL - Simple DirectMedia Layer
    Copyright (C) 1997-2004 Sam Lantinga

    This library is free software; you can redistribute it and/or
    modify it under the terms of the GNU Library General Public
    License as published by the Free Software Foundation; either
    version 2 of the License, or (at your option) any later version.

    This library is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
    Library General Public License for more details.

    You should have received a copy of the GNU Library General Public
    License along with this library; if not, write to the Free
    Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA

    Sam Lantinga
    slouken@libsdl.org
*/

/*
	MiNT audio driver
	using XBIOS functions (MacSound compatible driver)

	Patrice Mandin
*/

#include <stdlib.h>
#include <stdio.h>
#include <string.h>

/* Mint includes */
#include <mint/osbind.h>
#include <mint/falcon.h>
#include <mint/cookie.h>

#include "SDL_endian.h"
#include "SDL_audio.h"
#include "SDL_audio_c.h"
#include "SDL_audiomem.h"
#include "SDL_sysaudio.h"

#include "SDL_atarimxalloc_c.h"

#include "SDL_mintaudio.h"
#include "SDL_mintaudio_mcsn.h"

/*--- Defines ---*/

#define MINT_AUDIO_DRIVER_NAME "mint_mcsn"

/* Debug print info */
#define DEBUG_NAME "audio:mcsn: "
#if 0
#define DEBUG_PRINT(what) \
	{ \
		printf what; \
	}
#else
#define DEBUG_PRINT(what)
#endif

/*--- Static variables ---*/

static unsigned long cookie_snd, cookie_mch;
static cookie_mcsn_t *cookie_mcsn;

/*--- Audio driver functions ---*/

static void Mint_CloseAudio(_THIS);
static int Mint_OpenAudio(_THIS, SDL_AudioSpec *spec);
static void Mint_LockAudio(_THIS);
static void Mint_UnlockAudio(_THIS);

/* To check/init hardware audio */
static int Mint_CheckAudio(_THIS, SDL_AudioSpec *spec);
static void Mint_InitAudio(_THIS, SDL_AudioSpec *spec);

/*--- Audio driver bootstrap functions ---*/

static int Audio_Available(void)
{
	const char *envr = getenv("SDL_AUDIODRIVER");

	/* Check if user asked a different audio driver */
	if ((envr) && (strcmp(envr, MINT_AUDIO_DRIVER_NAME)!=0)) {
		DEBUG_PRINT((DEBUG_NAME "user asked a different audio driver\n"));
		return(0);
	}

	/* Cookie _MCH present ? if not, assume ST machine */
	if (Getcookie(C__MCH, &cookie_mch) == C_NOTFOUND) {
		cookie_mch = MCH_ST;
	}

	/* Cookie _SND present ? if not, assume ST machine */
	if (Getcookie(C__SND, &cookie_snd) == C_NOTFOUND) {
		cookie_snd = SND_PSG;
	}

	/* Check if we have 16 bits audio */
	if ((cookie_snd & SND_16BIT)==0) {
		DEBUG_PRINT((DEBUG_NAME "no 16 bits sound\n"));
	    return(0);
	}

	/* Cookie MCSN present ? */
	if (Getcookie(C_McSn, (long *) &cookie_mcsn) != C_FOUND) {
		DEBUG_PRINT((DEBUG_NAME "no MCSN audio\n"));
		return(0);
	}

	/* Check if interrupt at end of replay */
	if (cookie_mcsn->pint == 0) {
		DEBUG_PRINT((DEBUG_NAME "no interrupt at end of replay\n"));
		return(0);
	}

	/* Check if audio is lockable */
	if (Locksnd()!=1) {
		DEBUG_PRINT((DEBUG_NAME "audio locked by other application\n"));
		return(0);
	}

	Unlocksnd();

	DEBUG_PRINT((DEBUG_NAME "MCSN audio available!\n"));
	return(1);
}

static void Audio_DeleteDevice(SDL_AudioDevice *device)
{
    free(device->hidden);
    free(device);
}

static SDL_AudioDevice *Audio_CreateDevice(int devindex)
{
	SDL_AudioDevice *this;

	/* Initialize all variables that we clean on shutdown */
	this = (SDL_AudioDevice *)malloc(sizeof(SDL_AudioDevice));
    if ( this ) {
        memset(this, 0, (sizeof *this));
        this->hidden = (struct SDL_PrivateAudioData *)
                malloc((sizeof *this->hidden));
    }
    if ( (this == NULL) || (this->hidden == NULL) ) {
        SDL_OutOfMemory();
        if ( this ) {
            free(this);
        }
        return(0);
    }
    memset(this->hidden, 0, (sizeof *this->hidden));

    /* Set the function pointers */
    this->OpenAudio   = Mint_OpenAudio;
    this->CloseAudio  = Mint_CloseAudio;
    this->LockAudio   = Mint_LockAudio;
    this->UnlockAudio = Mint_UnlockAudio;
    this->free        = Audio_DeleteDevice;

    return this;
}

AudioBootStrap MINTAUDIO_MCSN_bootstrap = {
	MINT_AUDIO_DRIVER_NAME, "MiNT MCSN audio driver",
	Audio_Available, Audio_CreateDevice
};

static void Mint_LockAudio(_THIS)
{
	/* Stop replay */
	Buffoper(0);
}

static void Mint_UnlockAudio(_THIS)
{
	/* Restart replay */
	Buffoper(SB_PLA_ENA|SB_PLA_RPT);
}

static void Mint_CloseAudio(_THIS)
{
	/* Stop replay */
	Buffoper(0);

	/* Uninstall interrupt */
	Jdisint(MFP_DMASOUND);

	/* Wait if currently playing sound */
	while (SDL_MintAudio_mutex != 0) {
	}

	/* Clear buffers */
	if (SDL_MintAudio_audiobuf[0]) {
		Mfree(SDL_MintAudio_audiobuf[0]);
		SDL_MintAudio_audiobuf[0] = SDL_MintAudio_audiobuf[1] = NULL;
	}

	/* Unlock sound system */
	Unlocksnd();
}

static int Mint_CheckAudio(_THIS, SDL_AudioSpec *spec)
{
	int i;
	unsigned long masterclock, masterprediv;

	DEBUG_PRINT((DEBUG_NAME "asked: %d bits, ",spec->format & 0x00ff));
	DEBUG_PRINT(("signed=%d, ", ((spec->format & 0x8000)!=0)));
	DEBUG_PRINT(("big endian=%d, ", ((spec->format & 0x1000)!=0)));
	DEBUG_PRINT(("channels=%d, ", spec->channels));
	DEBUG_PRINT(("freq=%d\n", spec->freq));

	/* Check formats available */
	MINTAUDIO_freqcount=0;
	switch(cookie_mcsn->play) {
		case MCSN_ST:
			spec->channels=1;
			spec->format=8; /* FIXME: is it signed or unsigned ? */
			SDL_MintAudio_AddFrequency(this, 12500, 0, 0);
			break;
		case MCSN_TT:	/* Also STE, Mega STE */
			spec->format=AUDIO_S8;
			masterclock=MASTERCLOCK_STE;
			masterprediv=MASTERPREDIV_STE;
			if ((cookie_mch>>16)==MCH_TT) {
				masterclock=MASTERCLOCK_TT;
				masterprediv=MASTERPREDIV_TT;
			}
			for (i=0; i<4; i++) {
				SDL_MintAudio_AddFrequency(this, masterclock/(masterprediv*(1<<i)), masterclock, 3-i);
			}
			break;
		case MCSN_FALCON:	/* Also Mac */
			for (i=1; i<12; i++) {
				/* Remove unusable Falcon codec predivisors */
				if ((i==6) || (i==8) || (i==10)) {
					continue;
				}
				SDL_MintAudio_AddFrequency(this, MASTERCLOCK_FALCON1/(MASTERPREDIV_FALCON*(i+1)), CLK25M, i+1);
			}
			if (cookie_mcsn->res1 != 0) {
				for (i=1; i<4; i++) {
					SDL_MintAudio_AddFrequency(this, (cookie_mcsn->res1)/(MASTERPREDIV_FALCON*(1<<i)), CLKEXT, (1<<i)-1);
				}
			}
			spec->format |= 0x8000;	/* Audio is always signed */
			if ((spec->format & 0x00ff)==16) {
				spec->format |= 0x1000;	/* Audio is always big endian */
				spec->channels=2;	/* 16 bits always stereo */
			}
			break;
	}

#if 1
	for (i=0; i<MINTAUDIO_freqcount; i++) {
		DEBUG_PRINT((DEBUG_NAME "freq %d: %lu Hz, clock %lu, prediv %d\n",
			i, MINTAUDIO_frequencies[i].frequency, MINTAUDIO_frequencies[i].masterclock,
			MINTAUDIO_frequencies[i].predivisor
		));
	}
#endif

	MINTAUDIO_numfreq=SDL_MintAudio_SearchFrequency(this, spec->freq);
	spec->freq=MINTAUDIO_frequencies[MINTAUDIO_numfreq].frequency;

	DEBUG_PRINT((DEBUG_NAME "obtained: %d bits, ",spec->format & 0x00ff));
	DEBUG_PRINT(("signed=%d, ", ((spec->format & 0x8000)!=0)));
	DEBUG_PRINT(("big endian=%d, ", ((spec->format & 0x1000)!=0)));
	DEBUG_PRINT(("channels=%d, ", spec->channels));
	DEBUG_PRINT(("freq=%d\n", spec->freq));

	return 0;
}

static void Mint_InitAudio(_THIS, SDL_AudioSpec *spec)
{
	int channels_mode, prediv, dmaclock;
	void *buffer;

	/* Stop currently playing sound */
	Buffoper(0);

	/* Set replay tracks */
	Settracks(0,0);
	Setmontracks(0);

	/* Select replay format */
	channels_mode=STEREO16;
	switch (spec->format & 0xff) {
		case 8:
			if (spec->channels==2) {
				channels_mode=STEREO8;
			} else {
				channels_mode=MONO8;
			}
			break;
	}
	if (Setmode(channels_mode)<0) {
		DEBUG_PRINT((DEBUG_NAME "Setmode() failed\n"));
	}

	dmaclock = MINTAUDIO_frequencies[MINTAUDIO_numfreq].masterclock;
	prediv = MINTAUDIO_frequencies[MINTAUDIO_numfreq].predivisor;
	switch(cookie_mcsn->play) {
		case MCSN_TT:
			Devconnect(DMAPLAY, DAC, CLK25M, CLKOLD, 1);
			Soundcmd(SETPRESCALE, prediv);
			DEBUG_PRINT((DEBUG_NAME "STE/TT prescaler selected\n"));
			break;
		case MCSN_FALCON:
			Devconnect(DMAPLAY, DAC, dmaclock, prediv, 1);
			DEBUG_PRINT((DEBUG_NAME "Falcon prescaler selected\n"));
			break;
	}

	/* Set buffer */
	buffer = SDL_MintAudio_audiobuf[SDL_MintAudio_numbuf];
	if (Setbuffer(0, buffer, buffer + spec->size)<0) {
		DEBUG_PRINT((DEBUG_NAME "Setbuffer() failed\n"));
	}
	
	/* Install interrupt */
	Jdisint(MFP_DMASOUND);
	Xbtimer(XB_TIMERA, 8, 1, SDL_MintAudio_XbiosInterrupt);
	Jenabint(MFP_DMASOUND);

	if (Setinterrupt(SI_TIMERA, SI_PLAY)<0) {
		DEBUG_PRINT((DEBUG_NAME "Setinterrupt() failed\n"));
	}

	/* Go */
	Buffoper(SB_PLA_ENA|SB_PLA_RPT);
	DEBUG_PRINT((DEBUG_NAME "hardware initialized\n"));
}

static int Mint_OpenAudio(_THIS, SDL_AudioSpec *spec)
{
	/* Lock sound system */
	if (Locksnd()!=1) {
   	    SDL_SetError("Mint_OpenAudio: Audio system already in use");
        return(-1);
	}

	SDL_MintAudio_device = this;

	/* Check audio capabilities */
	if (Mint_CheckAudio(this, spec)==-1) {
		return -1;
	}

	SDL_CalculateAudioSpec(spec);

	/* Allocate memory for audio buffers in DMA-able RAM */
	DEBUG_PRINT((DEBUG_NAME "buffer size=%d\n", spec->size));

	SDL_MintAudio_audiobuf[0] = Atari_SysMalloc(spec->size *2, MX_STRAM);
	if (SDL_MintAudio_audiobuf[0]==NULL) {
		SDL_SetError("MINT_OpenAudio: Not enough memory for audio buffer");
		return (-1);
	}
	SDL_MintAudio_audiobuf[1] = SDL_MintAudio_audiobuf[0] + spec->size ;
	SDL_MintAudio_numbuf=0;
	memset(SDL_MintAudio_audiobuf[0], spec->silence, spec->size *2);
	SDL_MintAudio_audiosize = spec->size;
	SDL_MintAudio_mutex = 0;

	DEBUG_PRINT((DEBUG_NAME "buffer 0 at 0x%08x\n", SDL_MintAudio_audiobuf[0]));
	DEBUG_PRINT((DEBUG_NAME "buffer 1 at 0x%08x\n", SDL_MintAudio_audiobuf[1]));

	/* Setup audio hardware */
	Mint_InitAudio(this, spec);

    return(1);	/* We don't use threaded audio */
}