src/audio/mint/SDL_mintaudio.c

/*
    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
*/
#include "SDL_config.h"

/*
	Audio interrupt variables and callback function

	Patrice Mandin
*/

#include <unistd.h>

#include <mint/osbind.h>
#include <mint/falcon.h>
#include <mint/mintbind.h>

#include "SDL_audio.h"
#include "SDL_mintaudio.h"
#include "SDL_mintaudio_stfa.h"

/* The audio device */

SDL_AudioDevice *SDL_MintAudio_device;
Uint8 *SDL_MintAudio_audiobuf[2];       /* Pointers to buffers */
unsigned long SDL_MintAudio_audiosize;  /* Length of audio buffer=spec->size */
volatile unsigned short SDL_MintAudio_numbuf;   /* Buffer to play */
volatile unsigned short SDL_MintAudio_mutex;
volatile unsigned long SDL_MintAudio_clocktics;
cookie_stfa_t *SDL_MintAudio_stfa;

/* MiNT thread variables */
SDL_bool SDL_MintAudio_mint_present;
SDL_bool SDL_MintAudio_quit_thread;
SDL_bool SDL_MintAudio_thread_finished;
long SDL_MintAudio_thread_pid;

/* The callback function, called by each driver whenever needed */

void
SDL_MintAudio_Callback(void)
{
    Uint8 *buffer;
    SDL_AudioDevice *audio = SDL_MintAudio_device;

    buffer = SDL_MintAudio_audiobuf[SDL_MintAudio_numbuf];
    SDL_memset(buffer, audio->spec.silence, audio->spec.size);

    if (audio->paused)
        return;

    if (audio->convert.needed) {
        int silence;

        if (audio->convert.src_format == AUDIO_U8) {
            silence = 0x80;
        } else {
            silence = 0;
        }
        SDL_memset(audio->convert.buf, silence, audio->convert.len);
        audio->spec.callback(audio->spec.userdata,
                             (Uint8 *) audio->convert.buf,
                             audio->convert.len);
        SDL_ConvertAudio(&audio->convert);
        SDL_memcpy(buffer, audio->convert.buf, audio->convert.len_cvt);
    } else {
        audio->spec.callback(audio->spec.userdata, buffer, audio->spec.size);
    }
}

/* Add a new frequency/clock/predivisor to the current list */
void
SDL_MintAudio_AddFrequency(_THIS, Uint32 frequency, Uint32 clock,
                           Uint32 prediv, int gpio_bits)
{
    int i, p;

    if (MINTAUDIO_freqcount == MINTAUDIO_maxfreqs) {
        return;
    }

    /* Search where to insert the frequency (highest first) */
    for (p = 0; p < MINTAUDIO_freqcount; p++) {
        if (frequency > MINTAUDIO_frequencies[p].frequency) {
            break;
        }
    }

    /* Put all following ones farer */
    if (MINTAUDIO_freqcount > 0) {
        for (i = MINTAUDIO_freqcount; i > p; i--) {
            SDL_memcpy(&MINTAUDIO_frequencies[i],
                       &MINTAUDIO_frequencies[i - 1],
                       sizeof(mint_frequency_t));
        }
    }

    /* And insert new one */
    MINTAUDIO_frequencies[p].frequency = frequency;
    MINTAUDIO_frequencies[p].masterclock = clock;
    MINTAUDIO_frequencies[p].predivisor = prediv;
    MINTAUDIO_frequencies[p].gpio_bits = gpio_bits;

    MINTAUDIO_freqcount++;
}

/* Search for the nearest frequency */
int
SDL_MintAudio_SearchFrequency(_THIS, int desired_freq)
{
    int i;

    /* Only 1 freq ? */
    if (MINTAUDIO_freqcount == 1) {
        return 0;
    }

    /* Check the array */
    for (i = 0; i < MINTAUDIO_freqcount; i++) {
        if (desired_freq >= ((MINTAUDIO_frequencies[i].frequency +
                              MINTAUDIO_frequencies[i + 1].frequency) >> 1)) {
            return i;
        }
    }

    /* Not in the array, give the latest */
    return MINTAUDIO_freqcount - 1;
}

/* Check if FPU is present */
void
SDL_MintAudio_CheckFpu(void)
{
    unsigned long cookie_fpu;

    SDL_MintAudio_hasfpu = 0;
    if (Getcookie(C__FPU, &cookie_fpu) != C_FOUND) {
        return;
    }
    switch ((cookie_fpu >> 16) & 0xfffe) {
    case 2:
    case 4:
    case 6:
    case 8:
    case 16:
        SDL_MintAudio_hasfpu = 1;
        break;
    }
}

/* The thread function, used under MiNT with xbios */
int
SDL_MintAudio_Thread(long param)
{
    SndBufPtr pointers;
    SDL_bool buffers_filled[2] = { SDL_FALSE, SDL_FALSE };

    SDL_MintAudio_thread_finished = SDL_FALSE;
    while (!SDL_MintAudio_quit_thread) {
        if (Buffptr(&pointers) != 0)
            continue;

        if (((unsigned long) pointers.play >=
             (unsigned long) SDL_MintAudio_audiobuf[0])
            && ((unsigned long) pointers.play <=
                (unsigned long) SDL_MintAudio_audiobuf[1])) {
            /* DMA is reading buffer #0, setup buffer #1 if not already done */
            if (!buffers_filled[1]) {
                SDL_MintAudio_numbuf = 1;
                SDL_MintAudio_Callback();
                Setbuffer(0, SDL_MintAudio_audiobuf[1],
                          SDL_MintAudio_audiobuf[1] +
                          SDL_MintAudio_audiosize);
                buffers_filled[1] = SDL_TRUE;
                buffers_filled[0] = SDL_FALSE;
            }
        } else {
            /* DMA is reading buffer #1, setup buffer #0 if not already done */
            if (!buffers_filled[0]) {
                SDL_MintAudio_numbuf = 0;
                SDL_MintAudio_Callback();
                Setbuffer(0, SDL_MintAudio_audiobuf[0],
                          SDL_MintAudio_audiobuf[0] +
                          SDL_MintAudio_audiosize);
                buffers_filled[0] = SDL_TRUE;
                buffers_filled[1] = SDL_FALSE;
            }
        }

        usleep(100);
    }
    SDL_MintAudio_thread_finished = SDL_TRUE;
    return 0;
}

void
SDL_MintAudio_WaitThread(void)
{
    if (!SDL_MintAudio_mint_present)
        return;

    if (SDL_MintAudio_thread_finished)
        return;

    SDL_MintAudio_quit_thread = SDL_TRUE;
    while (!SDL_MintAudio_thread_finished) {
        Syield();
    }
}

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