/*
 * pwplib SDL (Simple Directmedia Layer) audio "driver"
 * (C) Copyright 2010 ccr/TNSP^PWP <ccr@tnsp.org>
 *
 * This file and other changes are distributed under same
 * license as pwplib itself.
 */

#include "config.h"

#ifdef DRIVE_SDL

#include "sound.h"
#include <SDL.h>

static int pwp_SDL_audio_run = 1;
static int pwp_SDL_audio_frag = -1, pwp_SDL_audio_curr;


static void pwp_SDL_audio_fill(void * udata, Uint8 * buf, int len)
{
    (void) udata;
    while (len > 0) {
        if (pwp_SDL_audio_curr >= len) {
            pwp_SDL_audio_curr -= len;
            gb_genwave(buf, len);
            len = 0;
        } else {
            gb_genwave(buf, pwp_SDL_audio_curr);
            buf += pwp_SDL_audio_curr;
            len -= pwp_SDL_audio_curr;
            pwp_SDL_audio_curr = pwp_SDL_audio_frag;
            pwplib.player();
        }
    }

    pwp_SDL_audio_run = 0;
}

static void pwp_SDL_audio_start(void)
{
    if (pwp_SDL_audio_run)
        SDL_PauseAudio(0);

    while (pwp_SDL_audio_run)
        SDL_Delay(10);
    
    /* NOTICE! A small delay is used here, because the prods using pwplib
     * run in a tight loop (they expect that audio rendering blocks,
     * which it doesn't in case of SDL.) This way we avoid consuming
     * excessive amounts of CPU.
     *
     * -- ccr
     */
    SDL_Delay(10);
}

int pwp_SDL_audio_init(void)
{
    SDL_AudioSpec fmt;

    pwp_SDL_audio_run = 1;

    fmt.freq = 44100;
    fmt.format = AUDIO_U8;
    fmt.channels = 1;
    fmt.samples = 512;
    fmt.callback = pwp_SDL_audio_fill;

    if (SDL_OpenAudio(&fmt, NULL) < 0)
    {
        pwpwrite("* SDL: Could not get desired audio format.\n");
        return 0;
    }

    pwp_SDL_audio_frag = fmt.freq / TIMERHZ;
    pwp_SDL_audio_curr = pwp_SDL_audio_frag;
    pwp_SDL_audio_run = 1;

    pwpwrite("* SDL sound (freq=%d, fmt=%d, chn=%d, buf=%d, frag=%d)\n",
        fmt.freq, fmt.format, fmt.channels, fmt.samples, pwp_SDL_audio_frag);

    pwplib.sound = gb_sound;
    pwplib.loopflush = pwp_SDL_audio_start;
    gb_init(fmt.freq);

    return 1;
}
#endif