/* Audio Library for Teensy 3.X
* Copyright (c) 2018, Paul Stoffregen, paul@pjrc.com
*
* Development of this audio library was funded by PJRC.COM, LLC by sales of
* Teensy and Audio Adaptor boards. Please support PJRC's efforts to develop
* open source software by purchasing Teensy or other PJRC products.
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice, development funding notice, and this permission
* notice shall be included in all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
ElectroTechnique 2020
Added WAVEFORM_SILENT, syncFlag
*/
#include <Arduino.h>
#include "synth_waveform.h"
#include "arm_math.h"
#include "utility/dspinst.h"
// uncomment for more accurate but more computationally expensive frequency modulation
//#define IMPROVE_EXPONENTIAL_ACCURACY
#define BASE_AMPLITUDE 0x6000 // 0x7fff won't work due to Gibb's phenomenon, so use 3/4 of full range.
void AudioSynthWaveformTS::update(void)
{
audio_block_t *block;
int16_t *bp, *end;
int32_t val1, val2;
int16_t val3;
int16_t magnitude15;
uint32_t i, ph, index, index2, scale;
const uint32_t inc = phase_increment;
uint32_t phaseX;
if(syncFlag == 1) {
phase_accumulator = 0;
phaseX = 0;
syncFlag = 0;
LFO1randomFlag = false;
LFO2randomFlag = false;
}
ph = phase_accumulator + phase_offset;
phaseX = phase_accumulator;
if (magnitude == 0) {
phase_accumulator += inc * AUDIO_BLOCK_SAMPLES;
return;
}
block = allocate();
if (!block) {
phase_accumulator += inc * AUDIO_BLOCK_SAMPLES;
return;
}
bp = block->data;
switch(tone_type) {
// PWM SINE
case PWM_WAVEFORM_SINE:
for (i=0; i < AUDIO_BLOCK_SAMPLES; i++) {
index = ph >> 24;
val1 = AudioWaveformSine[index];
val2 = AudioWaveformSine[index+1];
scale = (ph >> 8) & 0xFFFF;
val2 *= scale;
val1 *= 0x10000 - scale;
*bp++ = multiply_32x32_rshift32(val1 + val2, magnitude);
ph += inc;
}
break;
case PWM_WAVEFORM_TRIANGLE:
for (i=0; i < AUDIO_BLOCK_SAMPLES; i++) {
uint32_t phtop = ph >> 30;
if (phtop == 1 || phtop == 2) {
*bp++ = ((0xFFFF - (ph >> 15)) * magnitude) >> 16;
} else {
*bp++ = (((int32_t)ph >> 15) * magnitude) >> 16;
}
ph += inc;
}
break;
// PWM SAWTOOTH (LFO offset 0.0f)
case PWM_WAVEFORM_SAWTOOTH: // normal sawtooth and inv sawtooth
for (i=0; i < AUDIO_BLOCK_SAMPLES; i++) {
*bp++ = signed_multiply_32x16t(magnitude, ph >> 1);
ph += inc;
}
break;
// PWM SQUARE (LFO offset 1.0)
case PWM_WAVEFORM_SQUARE:
magnitude15 = signed_saturate_rshift(magnitude, 16, 1);
for (i=0; i < AUDIO_BLOCK_SAMPLES; i++) {
//if (ph & 0x80000000) {
if (ph & 0x80000000) {
*bp++ = -magnitude15;
} else {
*bp++ = magnitude15;
}
ph += inc;
}
break;
case WAVEFORM_ARBITRARY1:
if (!arbdata) {
release(block);
phase_accumulator += inc * AUDIO_BLOCK_SAMPLES;
return;
}
// len = 256
for (i=0; i < AUDIO_BLOCK_SAMPLES; i++) {
index = ph >> 24;
index2 = index + 1;
if (LFO1mode == 0) {
if (index2 >= 256) index2 = 0; // loop
}
else {
if (index2 >= 256) index2 = 255; // one shot
}
val1 = *(arbdata + index);
val2 = *(arbdata + index2);
scale = (ph >> 8) & 0xFFFF;
val2 *= scale;
val1 *= 0x10000 - scale;
*bp++ = multiply_32x32_rshift32(val1 + val2, magnitude);
uint32_t ph_old = ph;
uint32_t phaseX_old = phaseX;
if (LFO1phase == 0) { // Shape normal
ph += inc;
phaseX += inc;
}
else {
ph -= inc;
phaseX -= inc; // Shape inverse
}
if (lfo1oneShoot == true && phaseX < inc) {
ph = ph_old;
phaseX = phaseX_old;
}
}
break;
case WAVEFORM_ARBITRARY2:
if (!arbdata) {
release(block);
phase_accumulator += inc * AUDIO_BLOCK_SAMPLES;
return;
}
// len = 256
for (i=0; i < AUDIO_BLOCK_SAMPLES; i++) {
index = ph >> 24;
index2 = index + 1;
if (LFO2mode == 0) {
if (index2 >= 256) index2 = 0; // loop
}
else {
if (index2 >= 255) index2 = 255; // one shot
}
val1 = *(arbdata + index);
val2 = *(arbdata + index2);
scale = (ph >> 8) & 0xFFFF;
val2 *= scale;
val1 *= 0x10000 - scale;
*bp++ = multiply_32x32_rshift32(val1 + val2, magnitude);
uint32_t ph_old = ph;
uint32_t phaseX_old = phaseX;
if (LFO2phase == 0) { // Shape normal
ph += inc;
phaseX += inc;
}
else {
ph -= inc;
phaseX -= inc; // Shape inverse
}
if (lfo2oneShoot == true && phaseX < inc) {
ph = ph_old;
phaseX = phaseX_old;
}
}
break;
case WAVEFORM_ARBITRARY3:
if (!arbdata) {
release(block);
phase_accumulator += inc * AUDIO_BLOCK_SAMPLES;
return;
}
// len = 256
for (i=0; i < AUDIO_BLOCK_SAMPLES; i++) {
index = ph >> 24;
index2 = index + 1;
if (LFO3mode == 0) {
if (index2 >= 256) index2 = 0; // loop
}
else {
if (index2 >= 255) index2 = 255; // one shot
}
val1 = *(arbdata + index);
val2 = *(arbdata + index2);
scale = (ph >> 8) & 0xFFFF;
val2 *= scale;
val1 *= 0x10000 - scale;
//*bp++ = multiply_32x32_rshift32(val1 + val2, magnitude);
val3 = multiply_32x32_rshift32(val1 + val2, magnitude);
*bp++ = val3;
Lfo3Modoutput = val3 >> 8;
uint32_t ph_old = ph;
uint32_t phaseX_old = phaseX;
if (LFO3phase == 0) { // Shape normal
ph += inc;
phaseX += inc;
}
else {
ph -= inc;
phaseX -= inc; // Shape inverse
}
if (lfo3oneShoot == true && phaseX < inc) {
ph = ph_old;
phaseX = phaseX_old;
}
}
break;
case WAVEFORM_SAMPLE_HOLD1:
for (i=0; i < AUDIO_BLOCK_SAMPLES; i++) {
uint32_t newph = ph + inc;
if (lfo1oneShoot == true && LFO1randomFlag == false) { // one shot
sample = random(magnitude) - (magnitude >> 1);
sample2 = sample;
LFO1randomFlag = true;
}
else if (newph < ph && lfo1oneShoot == false) {
sample = random(magnitude) - (magnitude >> 1);
}
else if (lfo1oneShoot == true && LFO1randomFlag == true) {
sample = sample2;
}
*bp++ = sample;
ph = newph;
}
break;
case WAVEFORM_SAMPLE_HOLD2:
for (i=0; i < AUDIO_BLOCK_SAMPLES; i++) {
uint32_t newph = ph + inc;
if (lfo2oneShoot == true && LFO2randomFlag == false) { // one shot
sample = random(magnitude) - (magnitude >> 1);
sample2 = sample;
LFO2randomFlag = true;
}
else if (newph < ph && lfo2oneShoot == false) {
sample = random(magnitude) - (magnitude >> 1);
}
else if (lfo2oneShoot == true && LFO2randomFlag == true) {
sample = sample2;
}
*bp++ = sample;
ph = newph;
}
break;
case WAVEFORM_SAMPLE_HOLD3:
for (i=0; i < AUDIO_BLOCK_SAMPLES; i++) {
uint32_t newph = ph + inc;
if (lfo3oneShoot == true && LFO3randomFlag == false) { // one shot
sample = random(magnitude) - (magnitude >> 1);
sample2 = sample;
LFO3randomFlag = true;
}
else if (newph < ph && lfo3oneShoot == false) {
sample = random(magnitude) - (magnitude >> 1);
}
else if (lfo3oneShoot == true && LFO3randomFlag == true) {
sample = sample2;
}
*bp++ = sample;
ph = newph;
}
break;
}
phase_accumulator = ph - phase_offset;
if (tone_offset) {
bp = block->data;
end = bp + AUDIO_BLOCK_SAMPLES;
do {
val1 = *bp;
*bp++ = signed_saturate_rshift(val1 + tone_offset, 16, 0);
} while (bp < end);
}
transmit(block, 0);
release(block);
}
//--------------------------------------------------------------------------------
void AudioSynthWaveformModulatedTS::update(void)
{
audio_block_t *block, *moddata, *shapedata;
int16_t *bp, *end;
int32_t val1, val2;
int16_t magnitude15;
uint32_t i, ph, index, index2, scale, priorphase;
const uint32_t inc = phase_increment;
uint32_t phase_spread;
uint32_t saw_phase_increment;
uint32_t increments[3];
uint32_t ph_1;
uint32_t ph_2;
uint32_t ph_3;
uint32_t ph_4;
int16_t Ssaw_value;
moddata = receiveReadOnly(0);
shapedata = receiveReadOnly(1);
if(syncFlag==1){
phase_accumulator = 0;
syncFlag = 0;
}
// Pre-compute the phase angle for every output sample of this update
ph = phase_accumulator;
priorphase = phasedata[AUDIO_BLOCK_SAMPLES-1];
if (moddata && modulation_type == 0) {
// Frequency Modulation
bp = moddata->data;
for (i=0; i < AUDIO_BLOCK_SAMPLES; i++) {
int32_t n = (*bp++) * modulation_factor; // n is # of octaves to mod
int32_t ipart = n >> 27; // 4 integer bits
n &= 0x7FFFFFF; // 27 fractional bits
#ifdef IMPROVE_EXPONENTIAL_ACCURACY
// exp2 polynomial suggested by Stefan Stenzel on "music-dsp"
// mail list, Wed, 3 Sep 2014 10:08:55 +0200
int32_t x = n << 3;
n = multiply_accumulate_32x32_rshift32_rounded(536870912, x, 1494202713);
int32_t sq = multiply_32x32_rshift32_rounded(x, x);
n = multiply_accumulate_32x32_rshift32_rounded(n, sq, 1934101615);
n = n + (multiply_32x32_rshift32_rounded(sq,
multiply_32x32_rshift32_rounded(x, 1358044250)) << 1);
n = n << 1;
#else
// exp2 algorithm by Laurent de Soras
// https://www.musicdsp.org/en/latest/Other/106-fast-exp2-approximation.html
n = (n + 134217728) << 3;
n = multiply_32x32_rshift32_rounded(n, n);
n = multiply_32x32_rshift32_rounded(n, 715827883) << 3;
n = n + 715827882;
#endif
uint32_t scale = n >> (14 - ipart);
uint64_t phstep = (uint64_t)inc * scale;
uint32_t phstep_msw = phstep >> 32;
if (phstep_msw < 0x7FFE) {
ph += phstep >> 16;
} else {
ph += 0x7FFE0000;
}
phasedata[i] = ph;
}
release(moddata);
} else if (moddata) {
// Phase Modulation
bp = moddata->data;
for (i=0; i < AUDIO_BLOCK_SAMPLES; i++) {
// more than +/- 180 deg shift by 32 bit overflow of "n"
uint32_t n = (uint16_t)(*bp++) * modulation_factor;
phasedata[i] = ph + n;
ph += inc;
}
release(moddata);
} else {
// No Modulation Input
for (i=0; i < AUDIO_BLOCK_SAMPLES; i++) {
phasedata[i] = ph;
ph += inc;
}
}
phase_accumulator = ph;
//Amplitude is always 1 on TSynth when oscillator is sounding
//magnitude must be set to zero, otherwise digital noise comes through
if(tone_type == WAVEFORM_SILENT){
magnitude = 0;
}else{
magnitude = 65536.0;
}
// If the amplitude is zero, no output, but phase still increments properly
if (magnitude == 0) {
if (shapedata) release(shapedata);
return;
}
block = allocate();
if (!block) {
if (shapedata) release(shapedata);
return;
}
bp = block->data;
// Now generate the output samples using the pre-computed phase angles
switch(tone_type) {
case WAVEFORM_SINE:
for (i=0; i < AUDIO_BLOCK_SAMPLES; i++) {
ph = phasedata[i];
index = ph >> 24;
val1 = AudioWaveformSine[index];
val2 = AudioWaveformSine[index+1];
scale = (ph >> 8) & 0xFFFF;
val2 *= scale;
val1 *= 0x10000 - scale;
*bp++ = multiply_32x32_rshift32(val1 + val2, magnitude);
}
break;
case WAVEFORM_ARBITRARY:
if (!arbdata) {
release(block);
if (shapedata) release(shapedata);
return;
}
// len = 256
for (i=0; i < AUDIO_BLOCK_SAMPLES; i++) {
ph = phasedata[i];
index = ph >> 24;
index2 = index + 1;
if (index2 >= 256) index2 = 0;
val1 = *(arbdata + index);
val2 = *(arbdata + index2);
scale = (ph >> 8) & 0xFFFF;
val2 *= scale;
val1 *= 0x10000 - scale;
*bp++ = multiply_32x32_rshift32(val1 + val2, magnitude);
}
break;
case WAVEFORM_PULSE:
if (shapedata) {
magnitude15 = signed_saturate_rshift(magnitude, 16, 1);
for (i=0; i < AUDIO_BLOCK_SAMPLES; i++) {
uint32_t width = ((shapedata->data[i] + 0x8000) & 0xFFFF) << 16;
if (phasedata[i] < width) {
*bp++ = magnitude15;
} else {
*bp++ = -magnitude15;
}
}
break;
} // else fall through to orginary square without shape modulation
case WAVEFORM_SQUARE:
magnitude15 = signed_saturate_rshift(magnitude, 16, 1);
for (i=0; i < AUDIO_BLOCK_SAMPLES; i++) {
if (phasedata[i] & 0x80000000) {
*bp++ = -magnitude15;
} else {
*bp++ = magnitude15;
}
}
break;
case WAVEFORM_BANDLIMIT_PULSE:
if (shapedata)
{
for (i=0; i < AUDIO_BLOCK_SAMPLES; i++)
{
uint32_t width = ((shapedata->data[i] + 0x8000) & 0xFFFF) << 16;
int32_t val = band_limit_waveform.generate_pulse (phasedata[i], width, i) ;
*bp++ = (int16_t) ((val * magnitude) >> 16) ;
}
break;
} // else fall through to orginary square without shape modulation
case WAVEFORM_BANDLIMIT_SQUARE:
for (i = 0 ; i < AUDIO_BLOCK_SAMPLES ; i++)
{
int32_t val = band_limit_waveform.generate_square (phasedata[i], i) ;
*bp++ = (int16_t) ((val * magnitude) >> 16);
}
break;
// Quadsaw
case WAVEFORM_SAWTOOTH:
phase_spread = (phase_increment >> 14) * SupersawSpreadA;
++phase_spread;
saw_phase_increment = (phase_increment & 0x0000F9F3);
for (uint8_t i = 0; i < 3; ++i) {
saw_phase_increment += phase_spread;
increments[i] = saw_phase_increment;
}
for (i=0; i < AUDIO_BLOCK_SAMPLES; i++) {
data_qs_phase[0] += increments[0];
data_qs_phase[1] += increments[1];
data_qs_phase[2] += increments[2];
ph_1 = phasedata[i];
ph_2 = (ph_1 + data_qs_phase[0]);
ph_3 = (ph_2 + data_qs_phase[1]);
ph_4 = (ph_1 + data_qs_phase[2]);
Ssaw_value = signed_multiply_32x16t(magnitude * Supersaw_gain1A, ph_1);
Ssaw_value += signed_multiply_32x16t(magnitude * Supersaw_gain2A, ph_2);
Ssaw_value += signed_multiply_32x16t(magnitude * Supersaw_gain2A, ph_3);
Ssaw_value += signed_multiply_32x16t(magnitude * Supersaw_gain2A, ph_4);
*bp++ = Ssaw_value;
}
break;
// Quadsaw 2
case WAVEFORM_SAWTOOTH2:
phase_spread = (phase_increment >> 14) * SupersawSpreadB;
++phase_spread;
saw_phase_increment = (phase_increment & 0x0000FFFF);
for (uint8_t i = 0; i < 3; ++i) {
saw_phase_increment += phase_spread;
increments[i] = saw_phase_increment;
}
for (i=0; i < AUDIO_BLOCK_SAMPLES; i++) {
data_qs_phase_2[0] += increments[0];
data_qs_phase_2[1] += increments[1];
data_qs_phase_2[2] += increments[2];
ph_1 = phasedata[i];
ph_2 = (ph_1 + data_qs_phase_2[0]);
ph_3 = (ph_2 + data_qs_phase_2[1]);
ph_4 = (ph_3 + data_qs_phase_2[2]);
Ssaw_value = signed_multiply_32x16t(magnitude * Supersaw_gain1B, ph_1);
Ssaw_value += signed_multiply_32x16t(magnitude * Supersaw_gain2B, ph_2);
Ssaw_value += signed_multiply_32x16t(magnitude * Supersaw_gain2B, ph_3);
Ssaw_value += signed_multiply_32x16t(magnitude * Supersaw_gain2B, ph_4);
*bp++ = Ssaw_value;
}
break;
case WAVEFORM_SAWTOOTH_REVERSE:
for (i=0; i < AUDIO_BLOCK_SAMPLES; i++) {
*bp++ = signed_multiply_32x16t(0xFFFFFFFFu - magnitude, phasedata[i]);
}
break;
case WAVEFORM_BANDLIMIT_SAWTOOTH:
case WAVEFORM_BANDLIMIT_SAWTOOTH_REVERSE:
for (i = 0 ; i < AUDIO_BLOCK_SAMPLES ; i++)
{
int16_t val = band_limit_waveform.generate_sawtooth (phasedata[i], i) ;
val = (int16_t) ((val * magnitude) >> 16) ;
*bp++ = tone_type == WAVEFORM_BANDLIMIT_SAWTOOTH_REVERSE ? (int16_t) -val : (int16_t) +val ;
}
break;
case WAVEFORM_TRIANGLE_VARIABLE:
if (shapedata) {
for (i=0; i < AUDIO_BLOCK_SAMPLES; i++) {
uint32_t width = (shapedata->data[i] + 0x8000) & 0xFFFF;
uint32_t rise = 0xFFFFFFFF / width;
uint32_t fall = 0xFFFFFFFF / (0xFFFF - width);
uint32_t halfwidth = width << 15;
uint32_t n;
ph = phasedata[i];
if (ph < halfwidth) {
n = (ph >> 16) * rise;
*bp++ = ((n >> 16) * magnitude) >> 16;
} else if (ph < 0xFFFFFFFF - halfwidth) {
n = 0x7FFFFFFF - (((ph - halfwidth) >> 16) * fall);
*bp++ = (((int32_t)n >> 16) * magnitude) >> 16;
} else {
n = ((ph + halfwidth) >> 16) * rise + 0x80000000;
*bp++ = (((int32_t)n >> 16) * magnitude) >> 16;
}
ph += inc;
}
break;
} // else fall through to orginary triangle without shape modulation
case WAVEFORM_TRIANGLE:
for (i=0; i < AUDIO_BLOCK_SAMPLES; i++) {
ph = phasedata[i];
uint32_t phtop = ph >> 30;
if (phtop == 1 || phtop == 2) {
*bp++ = ((0xFFFF - (ph >> 15)) * magnitude) >> 16;
} else {
*bp++ = (((int32_t)ph >> 15) * magnitude) >> 16;
}
}
break;
case WAVEFORM_SAMPLE_HOLD:
for (i=0; i < AUDIO_BLOCK_SAMPLES; i++) {
ph = phasedata[i];
if (ph < priorphase) { // does not work for phase modulation
sample = random(magnitude) - (magnitude >> 1);
}
priorphase = ph;
*bp++ = sample;
}
break;
}
if (tone_offset) {
bp = block->data;
end = bp + AUDIO_BLOCK_SAMPLES;
do {
val1 = *bp;
*bp++ = signed_saturate_rshift(val1 + tone_offset, 16, 0);
} while (bp < end);
}
if (shapedata) release(shapedata);
transmit(block, 0);
release(block);
}
// BandLimitedWaveform
#define SUPPORT_SHIFT 4
#define SUPPORT (1 << SUPPORT_SHIFT)
#define PTRMASK ((2 << SUPPORT_SHIFT) - 1)
#define SCALE 16
#define SCALE_MASK (SCALE-1)
#define N (SCALE * SUPPORT * 2)
#define GUARD_BITS 8
#define GUARD (1 << GUARD_BITS)
#define HALF_GUARD (1 << (GUARD_BITS-1))
#define DEG180 0x80000000u
#define PHASE_SCALE (0x100000000L / (2 * BASE_AMPLITUDE))
extern "C"
{
extern const int16_t step_table [258] ;
}
int32_t BandLimitedWaveform::lookup (int offset)
{
int off = offset >> GUARD_BITS ;
int frac = offset & (GUARD-1) ;
int32_t a, b ;
if (off < N/2) // handle odd symmetry by reflecting table
{
a = step_table [off+1] ;
b = step_table [off+2] ;
}
else
{
a = - step_table [N-off] ;
b = - step_table [N-off-1] ;
}
return BASE_AMPLITUDE + ((frac * b + (GUARD - frac) * a + HALF_GUARD) >> GUARD_BITS) ; // interpolated
}
// create a new step, apply its past waveform into the cyclic sample buffer
// and add a step_state object into active list so it can be added for the future samples
void BandLimitedWaveform::insert_step (int offset, bool rising, int i)
{
while (offset <= (N/2-SCALE)<<GUARD_BITS)
{
if (offset >= 0)
cyclic [i & 15] += rising ? lookup (offset) : -lookup (offset) ;
offset += SCALE<<GUARD_BITS ;
i ++ ;
}
states[newptr].offset = offset ;
states[newptr].positive = rising ;
newptr = (newptr+1) & PTRMASK ;
}
// generate value for current sample from one active step, checking for the
// dc_offset adjustment at the end of the table.
int32_t BandLimitedWaveform::process_step (int i)
{
int off = states[i].offset ;
bool positive = states[i].positive ;
int32_t entry = lookup (off) ;
off += SCALE<<GUARD_BITS ;
states[i].offset = off ; // update offset in table for next sample
if (off >= N<<GUARD_BITS) // at end of step table we alter dc_offset to extend the step into future
dc_offset += positive ? 2*BASE_AMPLITUDE : -2*BASE_AMPLITUDE ;
return positive ? entry : -entry ;
}
// process all active steps for current sample, basically generating the waveform portion
// due only to steps
// square waves use this directly.
int32_t BandLimitedWaveform::process_active_steps (uint32_t new_phase)
{
int32_t sample = dc_offset ;
int step_count = (newptr - delptr) & PTRMASK ;
if (step_count > 0) // for any steps in-flight we sum in table entry and update its state
{
int i = newptr ;
do
{
i = (i-1) & PTRMASK ;
sample += process_step (i) ;
} while (i != delptr) ;
if (states[delptr].offset >= N<<GUARD_BITS) // remove any finished entries from the buffer.
{
delptr = (delptr+1) & PTRMASK ;
// can be upto two steps per sample now for pulses
if (newptr != delptr && states[delptr].offset >= N<<GUARD_BITS)
delptr = (delptr+1) & PTRMASK ;
}
}
return sample ;
}
// for sawtooth need to add in the slope and compensate for all the steps being one way
int32_t BandLimitedWaveform::process_active_steps_saw (uint32_t new_phase)
{
int32_t sample = process_active_steps (new_phase) ;
sample += (int16_t) ((((uint64_t)phase_word * (2*BASE_AMPLITUDE)) >> 32) - BASE_AMPLITUDE) ; // generate the sloped part of the wave
if (new_phase < DEG180 && phase_word >= DEG180) // detect wrap around, correct dc offset
dc_offset += 2*BASE_AMPLITUDE ;
return sample ;
}
// for pulse need to adjust the baseline according to the pulse width to cancel the DC component.
int32_t BandLimitedWaveform::process_active_steps_pulse (uint32_t new_phase, uint32_t pulse_width)
{
int32_t sample = process_active_steps (new_phase) ;
return sample + BASE_AMPLITUDE/2 - pulse_width / (0x80000000u / BASE_AMPLITUDE) ; // correct DC offset for duty cycle
}
// Check for new steps using the phase update for the current sample for a square wave
void BandLimitedWaveform::new_step_check_square (uint32_t new_phase, int i)
{
if (new_phase >= DEG180 && phase_word < DEG180) // detect falling step
{
int32_t offset = (int32_t) ((uint64_t) (SCALE<<GUARD_BITS) * (sampled_width - phase_word) / (new_phase - phase_word)) ;
if (offset == SCALE<<GUARD_BITS)
offset -- ;
if (pulse_state) // guard against two falling steps in a row (if pulse width changing for instance)
{
insert_step (- offset, false, i) ;
pulse_state = false ;
}
}
else if (new_phase < DEG180 && phase_word >= DEG180) // detect wrap around, rising step
{
int32_t offset = (int32_t) ((uint64_t) (SCALE<<GUARD_BITS) * (- phase_word) / (new_phase - phase_word)) ;
if (offset == SCALE<<GUARD_BITS)
offset -- ;
if (!pulse_state) // guard against two rising steps in a row (if pulse width changing for instance)
{
insert_step (- offset, true, i) ;
pulse_state = true ;
}
}
}
// Checking for new steps for pulse waveform has to deal with changing frequency and pulse width and
// not letting a pulse glitch out of existence as these change across a single period of the waveform
// now we detect the rising edge just like for a square wave and use that to sample the pulse width
// parameter, which then has to be checked against the instantaneous frequency every sample.
void BandLimitedWaveform::new_step_check_pulse (uint32_t new_phase, uint32_t pulse_width, int i)
{
if (pulse_state && phase_word < sampled_width && (new_phase >= sampled_width || new_phase < phase_word)) // falling edge
{
int32_t offset = (int32_t) ((uint64_t) (SCALE<<GUARD_BITS) * (sampled_width - phase_word) / (new_phase - phase_word)) ;
if (offset == SCALE<<GUARD_BITS)
offset -- ;
insert_step (- offset, false, i) ;
pulse_state = false ;
}
if ((!pulse_state) && phase_word >= DEG180 && new_phase < DEG180) // detect wrap around, rising step
{
// sample the pulse width value so its not changing under our feet later in cycle due to modulation
sampled_width = pulse_width ;
int32_t offset = (int32_t) ((uint64_t) (SCALE<<GUARD_BITS) * (- phase_word) / (new_phase - phase_word)) ;
if (offset == SCALE<<GUARD_BITS)
offset -- ;
insert_step (- offset, true, i) ;
pulse_state = true ;
if (pulse_state && new_phase >= sampled_width) // detect falling step directly after a rising edge
//if (new_phase - sampled_width < DEG180) // detect falling step directly after a rising edge
{
int32_t offset = (int32_t) ((uint64_t) (SCALE<<GUARD_BITS) * (sampled_width - phase_word) / (new_phase - phase_word)) ;
if (offset == SCALE<<GUARD_BITS)
offset -- ;
insert_step (- offset, false, i) ;
pulse_state = false ;
}
}
}
// new steps for sawtooth are at 180 degree point, always falling.
void BandLimitedWaveform::new_step_check_saw (uint32_t new_phase, int i)
{
if (new_phase >= DEG180 && phase_word < DEG180) // detect falling step
{
int32_t offset = (int32_t) ((uint64_t) (SCALE<<GUARD_BITS) * (DEG180 - phase_word) / (new_phase - phase_word)) ;
if (offset == SCALE<<GUARD_BITS)
offset -- ;
insert_step (- offset, false, i) ;
}
}
// the generation function pushd new sample into cyclic buffer, having taken out the oldest entry
// to return. The output is thus 16 samples behind, which allows the non-casual step function to
// work in real time.
int16_t BandLimitedWaveform::generate_sawtooth (uint32_t new_phase, int i)
{
new_step_check_saw (new_phase, i) ;
int32_t val = process_active_steps_saw (new_phase) ;
int16_t sample = (int16_t) cyclic [i&15] ;
cyclic [i&15] = val ;
phase_word = new_phase ;
return sample ;
}
int16_t BandLimitedWaveform::generate_square (uint32_t new_phase, int i)
{
new_step_check_square (new_phase, i) ;
int32_t val = process_active_steps (new_phase) ;
int16_t sample = (int16_t) cyclic [i&15] ;
cyclic [i&15] = val ;
phase_word = new_phase ;
return sample ;
}
int16_t BandLimitedWaveform::generate_pulse (uint32_t new_phase, uint32_t pulse_width, int i)
{
new_step_check_pulse (new_phase, pulse_width, i) ;
int32_t val = process_active_steps_pulse (new_phase, pulse_width) ;
int32_t sample = cyclic [i&15] ;
cyclic [i&15] = val ;
phase_word = new_phase ;
return (int16_t) ((sample >> 1) - (sample >> 5)) ; // scale down to avoid overflow on narrow pulses, where the DC shift is big
}
void BandLimitedWaveform::init_sawtooth (uint32_t freq_word)
{
phase_word = 0 ;
newptr = 0 ;
delptr = 0 ;
for (int i = 0 ; i < 2*SUPPORT ; i++)
phase_word -= freq_word ;
dc_offset = phase_word < DEG180 ? BASE_AMPLITUDE : -BASE_AMPLITUDE ;
for (int i = 0 ; i < 2*SUPPORT ; i++)
{
uint32_t new_phase = phase_word + freq_word ;
new_step_check_saw (new_phase, i) ;
cyclic [i & 15] = (int16_t) process_active_steps_saw (new_phase) ;
phase_word = new_phase ;
}
}
void BandLimitedWaveform::init_square (uint32_t freq_word)
{
init_pulse (freq_word, DEG180) ;
}
void BandLimitedWaveform::init_pulse (uint32_t freq_word, uint32_t pulse_width)
{
phase_word = 0 ;
sampled_width = pulse_width ;
newptr = 0 ;
delptr = 0 ;
for (int i = 0 ; i < 2*SUPPORT ; i++)
phase_word -= freq_word ;
if (phase_word < pulse_width)
{
dc_offset = BASE_AMPLITUDE ;
pulse_state = true ;
}
else
{
dc_offset = -BASE_AMPLITUDE ;
pulse_state = false ;
}
for (int i = 0 ; i < 2*SUPPORT ; i++)
{
uint32_t new_phase = phase_word + freq_word ;
new_step_check_pulse (new_phase, pulse_width, i) ;
cyclic [i & 15] = (int16_t) process_active_steps_pulse (new_phase, pulse_width) ;
phase_word = new_phase ;
}
}
BandLimitedWaveform::BandLimitedWaveform()
{
newptr = 0 ;
delptr = 0 ;
dc_offset = BASE_AMPLITUDE ;
phase_word = 0 ;
}