/*
    sfx.h : Sound effects management for the Atari 2600
    Copyleft 2024 Bruno STEUX

    This file is distributed as a companion file to cc2600 - a subset of C compiler for the Atari 2600
*/

#ifndef __SFX_H__
#define __SFX_H__

#ifndef EXTRA_RAM
#define EXTRA_RAM
#endif

EXTRA_RAM char *_sfx_ptr[2];
EXTRA_RAM char _sfx_frames[2];
EXTRA_RAM char _sfx_priority[2];
EXTRA_RAM char _sfx_tick[2];

void sfx_init()
{
    _sfx_ptr[0] = 0;
    _sfx_ptr[1] = 0;
}

void sfx_schedule(char *_sfx_instrument)
{
#define channel X 
    channel = 0;
    if (_sfx_instrument[Y = 0] == 0x10) { // TIA sound
        if (_sfx_ptr[0] == 0) channel = 1;
        else if (_sfx_ptr[1] == 0) channel = 2;
        else if (_sfx_instrument[++Y]) {
            if (_sfx_priority[1] < _sfx_priority[0]) {
                channel = 2;
            } else {
                channel = 1;
            }
        }
        if (channel) {
            X = channel;
            X--;
            _sfx_priority[X] = _sfx_instrument[Y = 1];
            _sfx_frames[X] = _sfx_instrument[++Y];
            _sfx_tick[X] = 0;
            _sfx_ptr[X] = _sfx_instrument + 3;
        }
    }
}
#undef channel

void sfx_mute()
{
    _sfx_ptr[0] = 0;
    _sfx_ptr[1] = 0;
     for (X = 3; X >= 0; X--)
         AUDF0[X] = 0;
}

// Must be called every frame, regularly
void sfx_play()
{
    char *tmpptr, tmp, tmp2;
    for (X = 0; X != 2; X++) {
        if (_sfx_ptr[X] >> 8) {
            if (!_sfx_tick[X]) {
                // This chunk is over. Load the next one
                _sfx_tick[X] = _sfx_frames[X];
                // Play the sound
                tmpptr = _sfx_ptr[X];
                AUDF0[X] = tmp = tmpptr[Y = 0];
                AUDC0[X] = tmp2 = tmpptr[++Y];
                AUDV0[X] = tmpptr[++Y];
                if (!tmp && !tmp2 && !tmpptr[Y]) {
                    _sfx_ptr[X] = 0;
                } else {
                    _sfx_ptr[X] += 3;
                }
            } else {
                _sfx_tick[X]--;
            }
        }
    }
}

#endif // __SFX_H__