chiptune.h

/* Simple soundengine for the BitBox
 * Copyright 2014, Adrien Destugues <pulkomandy@pulkomandy.tk>
 * Copyright 2007, Linus Akesson
 * Based on the "Hardware Chiptune" project */
#ifndef CHIPTUNE_H
#define CHIPTUNE_H
#include <stdint.h>

#define MAX_INSTRUMENT_LENGTH 16
#define MAX_DRUM_LENGTH (MAX_INSTRUMENT_LENGTH/4)
#define MAX_SONG_LENGTH 32
#define MAX_TRACK_LENGTH 32 
#define MAX_NOTE 84
#define CHIP_PLAYERS 4

extern uint8_t chip_play;
extern uint8_t chip_play_track;
extern uint8_t chip_repeat;
extern uint8_t chip_volume;

struct oscillator {
    uint8_t side;
    uint8_t volume;
    uint8_t waveform; // waveform (from the enum above)
    uint8_t bitcrush; // 0-f level of quantization (power of 2) 

    uint16_t duty; // duty cycle (pulse wave only)
    uint16_t freq; // frequency (except for noise, unused)
    uint16_t phase; // phase (except for noise, unused)
};

extern struct oscillator oscillator[CHIP_PLAYERS];

struct instrument 
{
    uint8_t is_drum;
    uint8_t octave;
    // commands which create the instrument sound
    // stuff in the cmd array can be modified externally.
    uint8_t cmd[MAX_INSTRUMENT_LENGTH];
};

extern struct instrument instrument[16];

extern uint8_t chip_track[16][CHIP_PLAYERS][MAX_TRACK_LENGTH];

struct chip_player 
{
    uint8_t wait;
    uint8_t cmd_index;
    uint8_t instrument;
    uint8_t max_drum_index;
    
    uint8_t note; // actual note being played    
    uint8_t track_note; // includes song_transpose
    uint8_t octave;
    uint8_t dutyd;

    uint8_t volume;
    int8_t volumed; 
    uint8_t track_volume;
    int8_t track_volumed; 

    uint16_t slur; // internally how we keep track of note with inertia 
    uint8_t inertia;
    uint8_t track_inertia;
    
    uint8_t vibrato_depth;
    uint8_t track_vibrato_depth;
    uint8_t vibrato_rate;
    uint8_t track_vibrato_rate; 
    
    uint8_t vibrato_phase; 
    int8_t bendd;
    int16_t bend;

    uint8_t track_wait;
    uint8_t track_cmd_index;
    uint8_t track_index; // current track index, 0 - 15
    uint8_t next_track_index;
};

void reset_player(int i);
extern struct chip_player chip_player[CHIP_PLAYERS];

extern uint16_t chip_song[MAX_SONG_LENGTH]; // a nibble for the track to play for each OSCILLATOR 

extern uint8_t track_pos;
extern uint8_t track_length;

extern uint8_t song_transpose;
extern uint8_t song_length;
extern uint8_t song_speed;
extern uint8_t song_pos;

void chip_init(); // initialize all variables at start of game (stuff that only happens once)
void chip_reset(); // put in a random tune.
void chip_kill(); // kill all tones 
void chip_play_init(); // re-initialize current tune to start over.
void chip_play_track_init(int track); // 

// play a note of this instrument now - useful for FX !
void chip_note(uint8_t p, uint8_t inst, uint8_t note, uint8_t track_volume);

// These are our possible waveforms. Any other value plays silence.
enum 
{
    WF_SINE = 0,  // 
    WF_TRIANGLE, // = /\/\,
    WF_SAW, // = /|/| 
    WF_PULSE, // = |_|- (adjustable duty)
    WF_NOISE, // = !*@?
    WF_RED, // = integral of NOISE
    WF_VIOLET // = derivative of NOISE
};

#define BREAK 0
#define SIDE 1
#define WAVEFORM 2
#define VOLUME 3
#define NOTE 4
#define WAIT 5
#define FADE_IN 6
#define FADE_OUT 7
#define INERTIA 8
#define VIBRATO 9
#define BEND 10
#define BITCRUSH 11
#define DUTY 12
#define DUTY_DELTA 13
#define RANDOMIZE 14
#define JUMP 15

#define TRACK_BREAK 0
#define TRACK_OCTAVE 1
#define TRACK_INSTRUMENT 2
#define TRACK_VOLUME 3
#define TRACK_NOTE 4
#define TRACK_WAIT 5
#define TRACK_NOTE_WAIT 6
#define TRACK_FADE_IN 7
#define TRACK_FADE_OUT 8
#define TRACK_INERTIA 9
#define TRACK_VIBRATO 10
#define TRACK_TRANSPOSE 11
#define TRACK_SPEED 12
#define TRACK_LENGTH 13
#define TRACK_RANDOMIZE 14
#define TRACK_JUMP 15

uint8_t instrument_max_index(uint8_t i, uint8_t j);
int instrument_jump_bad(uint8_t inst, uint8_t max_index, uint8_t jump_from_index, uint8_t j);
int track_jump_bad(uint8_t t, uint8_t i, uint8_t jump_from_index, uint8_t j);

#endif