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midiplay.c
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midiplay.c
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// midiplay
// Copyright 2022 by Steve Clark
#include "synth.h"
#include "midiplay.h"
#define ID(i, a) (i[0] == a[0] && i[1] == a[1] && i[2] == a[2] && i[3] == a[3])
#define LE16(i) ((i)[0] | ((i)[1] << 8))
#define BE16(i) (((i)[0] << 8) | (i)[1])
#define BE32(i) ((BE16(i) << 16) | BE16(i + 2))
// timer -----------------------------------------------------------------------
typedef struct
{
int rate;
int acc;
int remainder;
int divisor;
}
TIMER;
static TIMER timerPhase, timerSecond, timerBeat;
// event -----------------------------------------------------------------------
#define NOTE_OFF 0
#define NOTE_PLAY 1
#define CC_01 1 // mod wheel
#define CC_06 6 // data entry coarse
#define CC_07 7 // volume
#define CC_0a 10 // pan
#define CC_0b 11 // expression
#define CC_40 64 // sustain
#define CC_64 100 // reg lsb
#define CC_65 101 // reg msb
#define CC_78 120 // all sounds off
#define CC_79 121 // reset controllers
#define CC_7b 123 // all notes off
#define CC_80 128 // MUS instrument change
#define CC_ff 255
typedef struct
{
BYTE channel;
BYTE data[3];
}
EVENT;
typedef struct _voice VOICE;
struct _voice
{
VOICE *prev, *next;
int index;
int note;
int volume;
int playing;
};
typedef struct
{
VOICE voice;
int instrument;
int volume;
int pan;
int sustain;
int bend;
int bendRange;
int expression;
int rpn;
}
CHANNEL;
static UINT volumeTable[128] =
{
0x000, 0x001, 0x002, 0x004, 0x005, 0x007, 0x008, 0x009, 0x00b, 0x00c, 0x00e, 0x00f, 0x011, 0x012, 0x014, 0x015,
0x017, 0x018, 0x01a, 0x01b, 0x01d, 0x01f, 0x020, 0x022, 0x023, 0x025, 0x027, 0x028, 0x02a, 0x02b, 0x02d, 0x02f,
0x030, 0x032, 0x034, 0x035, 0x037, 0x039, 0x03b, 0x03c, 0x03e, 0x040, 0x041, 0x043, 0x045, 0x047, 0x049, 0x04a,
0x04c, 0x04e, 0x050, 0x052, 0x054, 0x055, 0x057, 0x059, 0x05b, 0x05d, 0x05f, 0x061, 0x063, 0x065, 0x067, 0x069,
0x06b, 0x06d, 0x06f, 0x071, 0x073, 0x075, 0x077, 0x079, 0x07b, 0x07d, 0x07f, 0x081, 0x083, 0x085, 0x087, 0x089,
0x08c, 0x08e, 0x090, 0x092, 0x094, 0x097, 0x099, 0x09b, 0x09d, 0x0a0, 0x0a2, 0x0a4, 0x0a6, 0x0a9, 0x0ab, 0x0ad,
0x0b0, 0x0b2, 0x0b5, 0x0b7, 0x0b9, 0x0bc, 0x0be, 0x0c1, 0x0c3, 0x0c6, 0x0c8, 0x0cb, 0x0cd, 0x0d0, 0x0d2, 0x0d5,
0x0d7, 0x0da, 0x0dc, 0x0df, 0x0e2, 0x0e4, 0x0e7, 0x0ea, 0x0ec, 0x0ef, 0x0f2, 0x0f4, 0x0f7, 0x0fa, 0x0fd, 0x100
};
static CHANNEL midChannel[16];
static VOICE midVoice[VOICES], unusedVoice;
static EVENT *eventData;
// control ---------------------------------------------------------------------
#define MICROSEC 1000000
typedef void (*DOEVENT)(void);
typedef struct
{
BYTE *data, *pos;
int clock; // accumulator
BYTE running;
DOEVENT DoEvent;
EVENT event;
int done;
}
TRACK;
static TRACK midTrack[65536], *curTrack, *endTrack;
static int numTracks, numTracksEnded;
static BYTE prevVolume[16]; // last known note volume on channel
static int beatTicks = 96, beatTempo = 500000;
static int playSamples;
static int musicClock;
#ifdef MP_TIME
static int timeTicks, timeTempo;
#endif
static DOEVENT MusicEvents;
// controller map for MUS
static int controllerMap[16] = // CMD_TYPE would suggest only 16
{
CC_80, CC_ff, CC_01, CC_07, CC_0a, CC_0b, CC_ff, CC_ff,
CC_40, CC_ff, CC_78, CC_7b, CC_ff, CC_ff, CC_79, CC_ff
};
static void (*AddEvent)(DOEVENT);
// midiplay --------------------------------------------------------------------
#define MUS_HDRSIZE 16
#define MID_HDRSIZE 14
static int musicInit = 0;
static int musicLooping;
static int musicPlaying = 0;
static int musicVolume = 0x100;
// timer -----------------------------------------------------------------------
static int Timer_Update(TIMER *timer)
{
timer->acc += timer->remainder;
if (timer->acc < timer->divisor)
{
return timer->rate;
}
timer->acc -= timer->divisor;
return timer->rate + 1;
}
static void Timer_Set(TIMER *timer, int numerator, int divisor)
{
timer->acc = 0;
timer->rate = numerator / divisor;
timer->remainder = numerator - timer->rate * divisor;
timer->divisor = divisor;
}
// event -----------------------------------------------------------------------
static void ResetChannel(int channel)
{
midChannel[channel].sustain = 0;
midChannel[channel].bend = 0;
midChannel[channel].expression = volumeTable[127];
midChannel[channel].rpn = (127 << 7) | 127;
}
static void Voice_Off(VOICE *voice)
{
Synth_KeyOff(voice->index);
voice->prev->next = voice->next;
voice->next->prev = voice->prev;
voice->next = &unusedVoice;
voice->prev = unusedVoice.prev;
unusedVoice.prev = voice;
voice->prev->next = voice;
}
static void VoiceVolume(CHANNEL *channel, VOICE *voice)
{
Synth_SetVolume(voice->index, channel->volume * channel->expression * voice->volume >> 16);
}
static void AllSoundOff(CHANNEL *channel)
{
while (channel->voice.next != &channel->voice)
{
Synth_SetVolume(channel->voice.next->index, 0x00);
Voice_Off(channel->voice.next);
}
}
static void ResetControllers()
{
ResetChannel(eventData->channel);
}
static void Event_NoteOff()
{
CHANNEL *channel = &midChannel[eventData->channel];
int note = eventData->data[0];
//int volume = eventData->data[1];
VOICE *voice = channel->voice.next;
while (voice != &channel->voice)
{
if (voice->note == note)
{
if (channel->sustain)
{
voice->playing = NOTE_OFF;
}
else
{
voice = voice->prev;
Voice_Off(voice->next);
}
}
voice = voice->next;
}
}
static void FrequencyStep(VOICE *voice, CHANNEL *channel)
{
int index, octave;
index = voice->note * 32 + channel->bend * channel->bendRange / 2;
if (index < 0)
{
index = 0;
}
else if (index > 128 * 32 - 1)
{
index = 128 * 32 - 1;
}
octave = index / 384;
index %= 384;
Synth_SetFrequency(voice->index, index, octave);
}
static void Event_NoteOn()
{
CHANNEL *channel = &midChannel[eventData->channel];
int note = eventData->data[0];
int volume = eventData->data[1];
VOICE *voice;
voice = channel->voice.next;
while (voice != &channel->voice)
{
if (voice->note == note)
{
voice->volume = volumeTable[volume];
VoiceVolume(channel, voice);
voice->playing = NOTE_PLAY;
}
voice = voice->next;
}
if (unusedVoice.next == &unusedVoice)
{
return;
}
voice = unusedVoice.next;
unusedVoice.next = voice->next;
voice->next->prev = &unusedVoice;
voice->next = channel->voice.next;
voice->next->prev = voice;
channel->voice.next = voice;
voice->prev = &channel->voice;
voice->note = note;
voice->volume = volumeTable[volume];
VoiceVolume(channel, voice);
Synth_SetPan(voice->index, channel->pan);
FrequencyStep(voice, channel);
Synth_KeyOn(voice->index);
voice->playing = NOTE_PLAY;
}
static void Event_MuteNotes()
{
CHANNEL *channel = &midChannel[eventData->channel];
VOICE *voice;
if (!channel->sustain)
{
while (channel->voice.next != &channel->voice)
{
Voice_Off(channel->voice.next);
}
return;
}
voice = channel->voice.next;
while (voice != &channel->voice)
{
voice->playing = NOTE_OFF;
voice = voice->next;
}
}
static void Event_PitchWheel()
{
CHANNEL *channel = &midChannel[eventData->channel];
int bend = ((eventData->data[0] & 0x7f) | (eventData->data[1] << 7));
VOICE *voice = channel->voice.next;
channel->bend = (bend >> 7) - 64; // 7 bit values
while (voice != &channel->voice)
{
FrequencyStep(voice, channel);
voice = voice->next;
}
}
static void Event_Aftertouch()
{
CHANNEL *channel = &midChannel[eventData->channel];
int note = eventData->data[0];
int volume = eventData->data[1];
VOICE *voice = channel->voice.next;
while (voice != &channel->voice)
{
if (voice->note == note)
{
voice->volume = volumeTable[volume];
VoiceVolume(channel, voice);
}
voice = voice->next;
}
}
static void Event_Sustain()
{
CHANNEL *channel = &midChannel[eventData->channel];
int sustain = eventData->data[1];
VOICE *voice;
channel->sustain = sustain < 64 ? 0 : 1;
if (channel->sustain)
{
return;
}
voice = channel->voice.next;
while (voice != &channel->voice)
{
if (voice->playing == NOTE_OFF)
{
voice = voice->prev;
Voice_Off(voice->next);
}
voice = voice->next;
}
}
static void Event_ChannelVolume()
{
CHANNEL *channel = &midChannel[eventData->channel];
int volume = eventData->data[1];
VOICE *voice = channel->voice.next;
channel->volume = volumeTable[volume & 0x7f];
while (voice != &channel->voice)
{
VoiceVolume(channel, voice);
voice = voice->next;
}
}
static void Event_Pan()
{
CHANNEL *channel = &midChannel[eventData->channel];
int pan = eventData->data[1] & 0x7f;
VOICE *voice = channel->voice.next;
channel->pan = pan;
while (voice != &channel->voice)
{
Synth_SetPan(voice->index, pan);
voice = voice->next;
}
}
static void Event_ChannelAftertouch()
{
CHANNEL *channel = &midChannel[eventData->channel];
int volume = eventData->data[0];
VOICE *voice = channel->voice.next;
while (voice != &channel->voice)
{
voice->volume = volumeTable[volume];
VoiceVolume(channel, voice);
voice = voice->next;
}
}
static void Event_Expression()
{
CHANNEL *channel = &midChannel[eventData->channel];
int expression = eventData->data[1] & 0x7f;
VOICE *voice = channel->voice.next;
channel->expression = volumeTable[expression];
while (voice != &channel->voice)
{
VoiceVolume(channel, voice);
voice = voice->next;
}
}
static void Event_ChangeInstrument()
{
CHANNEL *channel = &midChannel[eventData->channel];
channel->instrument = eventData->data[1];
}
static void DataEntry_Coarse()
{
CHANNEL *channel = &midChannel[eventData->channel];
if (channel->rpn == 0)
{
channel->bendRange = eventData->data[1];
}
}
static void Event_Message()
{
switch (eventData->data[0])
{
case CC_01:
break;
case CC_06:
DataEntry_Coarse();
break;
case CC_07:
Event_ChannelVolume();
break;
case CC_0a:
Event_Pan();
break;
case CC_0b:
Event_Expression();
break;
case CC_40: // FIXME
//Event_Sustain();
break;
case CC_64:
midChannel[eventData->channel].rpn &= (127 << 7);
midChannel[eventData->channel].rpn |= eventData->data[1];
break;
case CC_65:
midChannel[eventData->channel].rpn &= 127;
midChannel[eventData->channel].rpn |= (eventData->data[1] << 7);
break;
case CC_78:
AllSoundOff(&midChannel[eventData->channel]);
break;
case CC_79:
ResetControllers();
break;
case CC_7b:
Event_MuteNotes();
break;
case CC_80:
Event_ChangeInstrument();
break;
default: // event not handled
break;
}
}
// control ---------------------------------------------------------------------
#ifdef MP_TIME
static void UpdateScoreTime()
{
timeTempo += beatTempo;
timeTicks += (timeTempo / MICROSEC);
timeTempo %= MICROSEC;
}
#endif
// sometimes, you just want nothing to happen
static void DoNothing()
{
}
static void InitTracks()
{
int track, channel;
for (track = 0; track < numTracks; track++)
{
midTrack[track].pos = midTrack[track].data;
midTrack[track].done = 0;
midTrack[track].clock = 0;
midTrack[track].DoEvent = DoNothing;
}
for (channel = 0; channel < 16; channel++)
{
AllSoundOff(&midChannel[channel]);
ResetChannel(channel);
midChannel[channel].instrument = 0;
midChannel[channel].volume = volumeTable[100];
midChannel[channel].pan = 64;
midChannel[channel].bendRange = 2;
prevVolume[channel] = 0;
}
musicClock = 0;
playSamples = 0;
beatTempo = 500000;
Timer_Set(&timerBeat, beatTempo, beatTicks);
numTracksEnded = 0;
#ifdef MP_TIME
timeTicks = timeTempo = 0;
#endif
}
static void SetTempo()
{
// if the tempo changes, should playSamples be reset?
beatTempo = (curTrack->event.data[0] << 16) | (curTrack->event.data[1] << 8) | curTrack->event.data[2];
Timer_Set(&timerBeat, beatTempo, beatTicks);
}
static void EndOfTrack()
{
curTrack->done = 1;
numTracksEnded++;
}
static void EndOfMidiTrack()
{
EndOfTrack();
curTrack->DoEvent = DoNothing;
if (numTracksEnded < numTracks)
{
return;
}
if (musicLooping == 0)
{
musicPlaying = 0;
return;
}
InitTracks();
// at this point we need to parse a new event from track 0
curTrack = &midTrack[0];
// eventData does not need to be set
}
static UINT GetLength()
{
UINT length;
BYTE data;
// unrolled
data = *curTrack->pos++;
length = (data & 127);
if (data & 128)
{
data = *curTrack->pos++;
length = (length << 7) | (data & 127);
if (data & 128)
{
data = *curTrack->pos++;
length = (length << 7) | (data & 127);
if (data & 128)
{
data = *curTrack->pos++;
length = (length << 7) | (data & 127);
}
}
}
return length;
}
#ifdef MP_TIME
static void NoEvent(DOEVENT event)
{
(void)event;
}
#endif
static void NewEvent(DOEVENT event)
{
curTrack->DoEvent = event;
}
static int GetMusEvent(int *time)
{
BYTE data, last;
curTrack->DoEvent = DoNothing;
data = *curTrack->pos++;
curTrack->event.channel = data & 0x0f;
last = data & 0x80;
*time = 0;
switch (data & 0x70)
{
case 0x00: // release note
curTrack->event.data[0] = (*curTrack->pos++ & 0x7f);
AddEvent(Event_NoteOff);
break;
case 0x10: // play note
data = *curTrack->pos++;
curTrack->event.data[0] = (data & 0x7f);
if (data & 0x80)
{
curTrack->event.data[1] = *curTrack->pos++ & 0x7f;
// should the volume be saved if the value is 0?
prevVolume[curTrack->event.channel] = curTrack->event.data[1];
}
else
{
curTrack->event.data[1] = prevVolume[curTrack->event.channel];
}
if (curTrack->event.data[1] == 0)
{
AddEvent(Event_NoteOff);
}
else
{
AddEvent(Event_NoteOn);
}
break;
case 0x20: // pitch wheel (adjusted to 14 bit value)
curTrack->event.data[0] = (*curTrack->pos & 0x1) << 6;
curTrack->event.data[1] = *curTrack->pos++ >> 1;
AddEvent(Event_PitchWheel);
break;
case 0x30: // system event
curTrack->event.data[0] = controllerMap[*curTrack->pos++ & 0x0f];
AddEvent(Event_Message);
break;
case 0x40: // change controller
curTrack->event.data[0] = controllerMap[*curTrack->pos++ & 0x0f];
curTrack->event.data[1] = *curTrack->pos++;
AddEvent(Event_Message);
break;
case 0x50: // end of measure?
break;
case 0x60: // score end
if (musicLooping)
{
AddEvent(InitTracks);
}
else
{
curTrack->DoEvent = EndOfTrack;
}
last = 1 - musicLooping;
break;
case 0x70:
// requires one data byte but is unused
curTrack->event.data[0] = *curTrack->pos++;
break;
}
curTrack->DoEvent();
if (last & 0x80)
{
*time = GetLength();
}
return last;
}
static void GetMidEvent()
{
BYTE data, event = 0x0;
UINT length;
curTrack->DoEvent = DoNothing;
data = *curTrack->pos;
if (data & 0x80)
{
event = *curTrack->pos++;
}
else
{
data = curTrack->running;
}
curTrack->event.channel = data & 0x0f;
switch (data & 0xf0)
{
case 0x80:
curTrack->event.data[0] = *curTrack->pos++;
curTrack->event.data[1] = *curTrack->pos++;
AddEvent(Event_NoteOff);
break;
case 0x90:
curTrack->event.data[0] = *curTrack->pos++;
curTrack->event.data[1] = *curTrack->pos++;
if (curTrack->event.data[1] == 0)
{
AddEvent(Event_NoteOff);
}
else
{
AddEvent(Event_NoteOn);
}
break;
case 0xa0:
curTrack->event.data[0] = *curTrack->pos++;
curTrack->event.data[1] = *curTrack->pos++;
AddEvent(Event_Aftertouch);
break;
case 0xb0: // controller message
curTrack->event.data[0] = *curTrack->pos++;
curTrack->event.data[1] = *curTrack->pos++;
AddEvent(Event_Message);
break;
case 0xc0:
// instrument number must be in 2nd byte of event.data
// as that's where MUS puts it
curTrack->event.data[1] = *curTrack->pos++;
AddEvent(Event_ChangeInstrument);
break;
case 0xd0:
curTrack->event.data[0] = *curTrack->pos++;
AddEvent(Event_ChannelAftertouch);
break;
case 0xe0:
curTrack->event.data[0] = *curTrack->pos++;
curTrack->event.data[1] = *curTrack->pos++;
AddEvent(Event_PitchWheel);
break;
case 0xf0:
if ((data & 0x0f) == 0xf) // meta event
{
data = *curTrack->pos++;
if (data == 0x2f) // end of track
{
curTrack->DoEvent = EndOfMidiTrack;
return;
}
else if (data == 0x51 && *curTrack->pos == 3)
{
curTrack->event.data[0] = curTrack->pos[1];
curTrack->event.data[1] = curTrack->pos[2];
curTrack->event.data[2] = curTrack->pos[3];
curTrack->DoEvent = SetTempo;
}
}
length = GetLength();
curTrack->pos += length;
return; // don't want to affect running events
}
if (event & 0x80)
{
curTrack->running = event;
}
}
static void TrackMusEvents()
{
int ticks;
if (curTrack->done)
{
return;
}
if (curTrack->clock > musicClock)
{
return;
}
while (GetMusEvent(&ticks) == 0)
{
}
curTrack->clock += ticks;
}
static void TrackMidEvents()
{
int ticks;
curTrack = &midTrack[0];
do
{
if (curTrack->clock == musicClock)
{
do
{
eventData = &curTrack->event;
curTrack->DoEvent();
if (curTrack->done)
{
break;
}
ticks = GetLength();
curTrack->clock += ticks;
GetMidEvent();
}
while (ticks == 0);
}
curTrack++;
}
while (curTrack <= endTrack);
}
static void UpdateEvents()
{
#ifdef MP_TIME
UpdateScoreTime();
#endif
MusicEvents();
musicClock++;
}
static void LoadMusTrack(BYTE *data)
{
midTrack[0].data = data;
curTrack = &midTrack[0];
eventData = &curTrack->event;
numTracks = 1;
MusicEvents = TrackMusEvents;
}
static int LoadMidTracks(int count, BYTE *data, int size)
{
int track, length;
for (track = 0; track < count; track++)
{
if (size < 8)
{
return 1;
}
if (!ID(data, "MTrk"))
{
return 1;
}
length = BE32(data + 4);
data += 8;
size -= 8;
if (size < length)
{
return 1;
}
midTrack[track].data = data;
data += length;
size -= length;
}
numTracks = count;
endTrack = &midTrack[numTracks - 1];
MusicEvents = TrackMidEvents;
return 0;
}
// midiplay --------------------------------------------------------------------
void Midiplay_Init(int samplerate)
{
VOICE *voice;
CHANNEL *channel;
int index;
Timer_Set(&timerPhase, 65536, samplerate);
Timer_Set(&timerSecond, MICROSEC, samplerate);
unusedVoice.next = &unusedVoice;
unusedVoice.prev = &unusedVoice;
voice = &midVoice[0];
for (index = 0; index < VOICES; index++, voice++)
{
voice->index = index;
voice->next = &unusedVoice;
voice->prev = unusedVoice.prev;
unusedVoice.prev = voice;
voice->prev->next = voice;
}
channel = &midChannel[0];
for (index = 0; index < 16; index++, channel++)
{
channel->voice.next = &channel->voice;
channel->voice.prev = &channel->voice;
}
#ifndef MP_TIME
AddEvent = NewEvent;
#endif
musicInit = 1;
}
int Midiplay_Load(void *data, int size)
{
BYTE *byte = (BYTE *)data;
if (musicInit == 0)
{
return 0;
}
musicInit = 1;
musicPlaying = 0;
if (size < 4)
{
return 0;
}
if (ID(byte, "MUS" "\x1a"))
{
if (size < MUS_HDRSIZE)
{
return 0;
}
if (size < LE16(byte + 6) + LE16(byte + 4))
{
return 0;
}
beatTicks = LE16(byte + 14);
if (beatTicks == 0)
{
beatTicks = 70;
}
LoadMusTrack(byte + LE16(byte + 6));
}