@ -1,28 +1,34 @@
# include <stdio.h>
# include <math.h>
# include "synth.h"
# include "config.h"
# include "tables.inc"
// convert from 16.16 frequency to 16.16 period in samples
static fixed freq2period ( fixed freq ) {
uint64_t tmp = ( uint64_t ) SAMPLE_RATE < < 32 ;
return tmp / freq ;
}
void synth_init ( struct Synth * synth ) {
}
uint8_t midi_notes [ 128 ] ;
void synth_note_on ( struct Synth * synth , uint8_t note , uint8_t velocity ) {
printf ( " synth_note_on note=%d velocity=%d \n " , note , velocity ) ;
// find the first available voice, if any
for ( int i = 0 ; i < SYNTH_NUM_VOICES ; i + + ) {
struct Voice * voice = synth - > voices + i ;
if ( voice - > env_state = = None ) {
voice - > phase = voice - > time = 0 ;
voice - > freq = ( uint32_t ) ( midi_note_freq_table [ note & 0x7f ] * 256 ) ;
printf ( " starting voice %d \n " , i ) ;
midi_notes [ note & 0x7f ] = i ;
voice - > attack = synth - > attack ;
voice - > decay = synth - > decay ;
voice - > sustain = synth - > sustain ;
voice - > release = synth - > release ;
voice - > volume = velocity ;
voice - > env_state = Attack ;
printf ( " Attack %d \n " , synth - > attack ) ;
voice_note_start ( voice , note , velocity ) ;
break ;
}
}
@ -30,71 +36,128 @@ void synth_note_on(struct Synth *synth, uint8_t note, uint8_t velocity) {
void synth_note_off ( struct Synth * synth , uint8_t note , uint8_t velocity ) {
( void ) velocity ;
printf ( " synth_note_off note=%d velocity=%d \n " , note , velocity ) ;
printf ( " stopping voice %d \n " , note & 0x7f ) ;
struct Voice * voice = synth - > voices + midi_notes [ note & 0x7f ] ;
voice - > time = 0 ;
voice - > env_state = Release ;
printf ( " Release %d \n " , voice - > release ) ;
voice_stop ( voice ) ;
}
static uint8_t alt = 0 ;
int16_t synth_render_sample ( struct Synth * synth ) {
int32_t smpl = 0 ;
for ( int i = 0 ; i < SYNTH_NUM_VOICES ; i + + ) {
struct Voice * v = synth - > voices + i ;
if ( v - > env_state ! = None ) {
v - > time + + ;
int32_t amplitude = 0 ; // calculate based on velocity and envelope
uint32_t ms_time = v - > time * 1000 / SAMPLE_RATE ;
switch ( v - > env_state ) {
case Attack :
if ( v - > attack > 0 )
amplitude = v - > volume * ms_time / v - > attack ;
if ( ms_time > v - > attack ) {
printf ( " Decay %d \n " , v - > decay ) ;
v - > env_state = Decay ;
v - > time = 0 ;
}
break ;
case Decay :
if ( v - > decay > 0 )
amplitude = ( 100 * v - > volume * ( v - > decay - ms_time ) + v - > sustain * v - > volume * ms_time ) / v - > decay / 100 ;
if ( ms_time > v - > decay ) {
printf ( " Sustain %d \n " , v - > sustain ) ;
v - > env_state = Sustain ;
v - > time = 0 ;
}
break ;
case Sustain :
amplitude = v - > volume * v - > sustain / 100 ;
break ;
case Release :
amplitude = v - > volume * ( v - > release - ms_time ) * v - > sustain / v - > release / 100 ;
if ( ms_time > v - > release ) {
v - > time = 0 ;
v - > freq = 0 ;
v - > env_state = None ;
printf ( " None \n " ) ;
}
break ;
}
smpl + = voice_render_sample ( v ) ;
if ( smpl > 32767 ) smpl = 32767 ;
if ( smpl < - 32768 ) smpl = - 32768 ;
}
alt = ( alt + 1 ) & 1 ;
return smpl & 0xffff ;
}
if ( v - > env_state ! = None & & v - > freq ) {
v - > phase + = ( 1 < < 8 ) ;
uint32_t freq_phase = ( SAMPLE_RATE < < 16 ) / v - > freq ;
while ( v - > phase > = freq_phase )
v - > phase - = freq_phase ;
int sine_phase = 256 * v - > phase / freq_phase ;
int sine_phase_next = ( sine_phase + 1 ) & 0xff ;
int sine_remainder = v - > phase % freq_phase ;
// if(v->env_state == Release) {
// printf("amplitude %d volume=%d time=%d ms_time=%d v->release=%d v->sustain=%d\n", amplitude, v->volume, v->time, ms_time, v->release, v->sustain);
// }
smpl + = amplitude * sine_table_256 [ sine_phase ] / 255 ;
}
if ( smpl > 32767 ) smpl = 32767 ;
if ( smpl < - 32768 ) smpl = - 32768 ;
void synth_set_pulse_width ( struct Synth * synth , uint8_t w ) {
for ( int i = 0 ; i < SYNTH_NUM_VOICES ; i + + ) {
for ( int j = 0 ; j < 7 ; j + + )
synth - > voices [ i ] . osc [ j ] . pulse_width = w ;
}
}
void synth_set_unison_spread ( struct Synth * synth , uint8_t w ) {
for ( int i = 0 ; i < SYNTH_NUM_VOICES ; i + + ) {
for ( int j = 0 ; j < 7 ; j + + )
synth - > voices [ i ] . unison_spread = w ;
}
}
int16_t oscillator_render_sample ( struct Oscillator * osc ) {
osc - > phase + = 0x10000 ; // add one sample in fixed
if ( osc - > period > 0 ) // avoid a infinite loop below
while ( osc - > phase > osc - > period )
osc - > phase - = osc - > period ;
uint32_t edge = osc - > pulse_width * osc - > period / 127 ;
if ( osc - > type = = Rectangle ) {
if ( osc - > phase > = edge )
return - 20000 ;
else
return 20000 ;
} else if ( osc - > type = = Triangle ) {
if ( osc - > phase < = edge ) {
return ( ( ( ( osc - > phase > > 3 ) < < 6 ) / ( edge > > 3 ) ) < < 6 ) - ( 1 < < 11 ) ;
} else {
return ( ( ( ( ( osc - > period - osc - > phase ) > > 3 ) < < 6 ) / ( ( osc - > period - edge ) > > 3 ) ) < < 6 ) - ( 1 < < 11 ) ;
}
}
return smpl & 0xffff ;
}
int16_t voice_render_sample ( struct Voice * v ) {
if ( v - > env_state = = None )
return 0 ;
int32_t amplitude = 0 ; // calculate based on velocity and envelope
uint32_t ms_time = v - > time * 1000 / SAMPLE_RATE ;
switch ( v - > env_state ) {
case Attack :
if ( v - > attack > 0 )
amplitude = v - > volume * ms_time / v - > attack ;
if ( ms_time > v - > attack ) {
v - > env_state = Decay ;
v - > time = 0 ;
}
break ;
case Decay :
if ( v - > decay > 0 )
amplitude = ( 100 * v - > volume * ( v - > decay - ms_time ) + v - > sustain * v - > volume * ms_time ) / v - > decay / 100 ;
if ( ms_time > v - > decay ) {
v - > env_state = Sustain ;
v - > time = 0 ;
}
break ;
case Sustain :
amplitude = v - > volume * v - > sustain / 100 ;
break ;
case Release :
if ( v - > release > 0 )
amplitude = v - > volume * ( v - > release - ms_time ) * v - > sustain / v - > release / 100 ;
if ( ms_time > v - > release ) {
v - > time = 0 ;
v - > env_state = None ;
}
break ;
}
v - > time + + ;
if ( v - > env_state ! = None ) {
int32_t ret = 0 ;
for ( int i = 0 ; i < 7 ; i + + ) ret + = oscillator_render_sample ( & v - > osc [ i ] ) ;
return amplitude * ret / 32767 ;
}
}
void voice_note_start ( struct Voice * voice , uint8_t note , uint8_t velocity ) {
voice - > time = 0 ;
voice - > volume = velocity * 128 ;
voice - > env_state = Attack ;
note & = 0x7f ;
voice - > osc [ 0 ] . type = Triangle ;
voice - > osc [ 0 ] . freq = midi_note_freq_fixed [ note ] ;
int freq_below = voice - > osc [ 0 ] . freq - midi_note_freq_fixed [ note - 1 ] ;
int freq_above = midi_note_freq_fixed [ note + 1 ] - voice - > osc [ 0 ] . freq ;
voice - > osc [ 0 ] . period = freq2period ( voice - > osc [ 0 ] . freq ) ;
for ( int i = 1 ; i < = 3 ; i + + ) {
voice - > osc [ i ] . type = voice - > osc [ 0 ] . type ;
voice - > osc [ i ] . freq = voice - > osc [ 0 ] . freq - voice - > unison_spread * freq_below * i / 3 / 127 ;
voice - > osc [ i ] . period = freq2period ( voice - > osc [ i ] . freq ) ;
}
for ( int i = 4 ; i < 7 ; i + + ) {
voice - > osc [ i ] . type = voice - > osc [ 0 ] . type ;
voice - > osc [ i ] . freq = voice - > osc [ 0 ] . freq + voice - > unison_spread * freq_above * ( i - 3 ) / 3 / 127 ;
voice - > osc [ i ] . period = freq2period ( voice - > osc [ i ] . freq ) ;
}
}
void voice_stop ( struct Voice * voice ) {
voice - > time = 0 ;
voice - > env_state = Release ;
}
vampirefrog
6 years ago