view src/audio/dc/SDL_dcaudio.c @ 2349:0381047f2210 gsoc2008_iphone

The class SDL_uikitappdelegate acts as the UIApplicationDelegate for an iPhone SDL project. This class is reponsible for application control flow, including initial setup of working directory, forwarding command line arguments to the user's main function, and handling application termination.
author Holmes Futrell <hfutrell@umail.ucsb.edu>
date Thu, 17 Jul 2008 22:29:37 +0000
parents 866052b01ee5
children 99210400e8b9
line wrap: on
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/*
    SDL - Simple DirectMedia Layer
    Copyright (C) 1997-2006 Sam Lantinga

    This library is free software; you can redistribute it and/or
    modify it under the terms of the GNU Lesser General Public
    License as published by the Free Software Foundation; either
    version 2.1 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
    Lesser General Public License for more details.

    You should have received a copy of the GNU Lesser General Public
    License along with this library; if not, write to the Free Software
    Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA

    Sam Lantinga
    slouken@libsdl.org

*/
#include "SDL_config.h"

/* Output dreamcast aica */

#include "SDL_timer.h"
#include "SDL_audio.h"
#include "../SDL_audiomem.h"
#include "../SDL_audio_c.h"
#include "SDL_dcaudio.h"

#include "aica.h"
#include <dc/spu.h>

#define	SPU_RAM_BASE	0xa0800000

static void
spu_memload_stereo8(int leftpos, int rightpos, void *src0, size_t size)
{
    uint8 *src = src0;
    uint32 *left = (uint32 *) (leftpos + SPU_RAM_BASE);
    uint32 *right = (uint32 *) (rightpos + SPU_RAM_BASE);
    size = (size + 7) / 8;
    while (size--) {
        unsigned lval, rval;
        lval = *src++;
        rval = *src++;
        lval |= (*src++) << 8;
        rval |= (*src++) << 8;
        lval |= (*src++) << 16;
        rval |= (*src++) << 16;
        lval |= (*src++) << 24;
        rval |= (*src++) << 24;
        g2_write_32(left++, lval);
        g2_write_32(right++, rval);
        g2_fifo_wait();
    }
}

static void
spu_memload_stereo16(int leftpos, int rightpos, void *src0, size_t size)
{
    uint16 *src = src0;
    uint32 *left = (uint32 *) (leftpos + SPU_RAM_BASE);
    uint32 *right = (uint32 *) (rightpos + SPU_RAM_BASE);
    size = (size + 7) / 8;
    while (size--) {
        unsigned lval, rval;
        lval = *src++;
        rval = *src++;
        lval |= (*src++) << 16;
        rval |= (*src++) << 16;
        g2_write_32(left++, lval);
        g2_write_32(right++, rval);
        g2_fifo_wait();
    }
}

static void
DCAUD_PlayDevice(_THIS)
{
    SDL_AudioSpec *spec = &this->spec;
    unsigned int offset;

    if (this->hidden->playing) {
        /* wait */
        while (aica_get_pos(0) / spec->samples == this->hidden->nextbuf) {
            thd_pass();
        }
    }

    offset = this->hidden->nextbuf * spec->size;
    this->hidden->nextbuf ^= 1;
    /* Write the audio data, checking for EAGAIN on broken audio drivers */
    if (spec->channels == 1) {
        spu_memload(this->hidden->leftpos + offset, this->hidden->mixbuf,
                    this->hidden->mixlen);
    } else {
        offset /= 2;
        if ((this->spec.format & 255) == 8) {
            spu_memload_stereo8(this->hidden->leftpos + offset,
                                this->hidden->rightpos + offset,
                                this->hidden->mixbuf, this->hidden->mixlen);
        } else {
            spu_memload_stereo16(this->hidden->leftpos + offset,
                                 this->hidden->rightpos + offset,
                                 this->hidden->mixbuf, this->hidden->mixlen);
        }
    }

    if (!this->hidden->playing) {
        int mode;
        this->hidden->playing = 1;
        mode = (spec->format == AUDIO_S8) ? SM_8BIT : SM_16BIT;
        if (spec->channels == 1) {
            aica_play(0, mode, this->hidden->leftpos, 0,
                      spec->samples * 2, spec->freq, 255, 128, 1);
        } else {
            aica_play(0, mode, this->hidden->leftpos, 0,
                      spec->samples * 2, spec->freq, 255, 0, 1);
            aica_play(1, mode, this->hidden->rightpos, 0,
                      spec->samples * 2, spec->freq, 255, 255, 1);
        }
    }
}

static Uint8 *
DCAUD_GetDeviceBuf(_THIS)
{
    return (this->hidden->mixbuf);
}

/* This function waits until it is possible to write a full sound buffer */
static void
DCAUD_WaitDevice(_THIS)
{
    if (this->hidden->playing) {
        /* wait */
        while (aica_get_pos(0) / this->spec.samples == this->hidden->nextbuf) {
            thd_pass();
        }
    }
}

static void
DCAUD_CloseDevice(_THIS)
{
    if (this->hidden != NULL) {
        aica_stop(0);
        if (this->spec.channels == 2) {
            aica_stop(1);
        }
        if (this->hidden->mixbuf != NULL) {
            SDL_FreeAudioMem(this->hidden->mixbuf);
            this->hidden->mixbuf = NULL;
        }
        SDL_free(this->hidden);
        this->hidden = NULL;

        /* !!! FIXME: is there a reverse of spu_init()? */
    }
}

static int
DCAUD_OpenDevice(_THIS, SDL_AudioSpec * spec)
{
    SDL_AudioFormat test_format = SDL_FirstAudioFormat(spec->format);
    int valid_datatype = 0;

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

    spu_init();

    while ((!valid_datatype) && (test_format)) {
        spec->format = test_format;
        switch (test_format) {
            /* only formats Dreamcast accepts... */
        case AUDIO_S8:
        case AUDIO_S16LSB:
            valid_datatype = 1;
            break;

        default:
            test_format = SDL_NextAudioFormat();
            break;
        }
    }

    if (!valid_datatype) {      /* shouldn't happen, but just in case... */
        DCAUD_CloseDevice(this);
        SDL_SetError("Unsupported audio format");
        return 0;
    }

    if (spec->channels > 2)
        spec->channels = 2;     /* no more than stereo on the Dreamcast. */

    /* Update the fragment size as size in bytes */
    SDL_CalculateAudioSpec(spec);

    /* Allocate mixing buffer */
    this->hidden->mixlen = spec->size;
    this->hidden->mixbuf = (Uint8 *) SDL_AllocAudioMem(this->hidden->mixlen);
    if (this->hidden->mixbuf == NULL) {
        DCAUD_CloseDevice(this);
        SDL_OutOfMemory();
        return 0;
    }
    SDL_memset(this->hidden->mixbuf, spec->silence, spec->size);
    this->hidden->leftpos = 0x11000;
    this->hidden->rightpos = 0x11000 + spec->size;
    this->hidden->playing = 0;
    this->hidden->nextbuf = 0;

    /* We're ready to rock and roll. :-) */
    return 1;
}

static int
DCAUD_Init(SDL_AudioDriverImpl * impl)
{
    /* Set the function pointers */
    impl->OpenDevice = DCAUD_OpenDevice;
    impl->PlayDevice = DCAUD_PlayDevice;
    impl->WaitDevice = DCAUD_WaitDevice;
    impl->GetDeviceBuf = DCAUD_GetDeviceBuf;
    impl->CloseDevice = DCAUD_CloseDevice;
    impl->OnlyHasDefaultOutputDevice = 1;

    return 1;
}

AudioBootStrap DCAUD_bootstrap = {
    "dcaudio", "Dreamcast AICA audio", DCAUD_Init, 0
};

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