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fix lfo and pitch calculation

This commit is contained in:
Gordon JC Pearce 2026-01-06 22:16:39 +00:00
parent 7ff0bf0659
commit a3a2e0dd04
2 changed files with 42 additions and 27 deletions
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53
plugin/module.cpp
View File

@ -58,16 +58,16 @@ void Module::lfoRampOn() {
void Module::runLFO() {
if (lfoDelayState == 1) {
lfoDelayTimer += lfoDelayTable[patchRam.lfoDelay >> 4];
if (lfoDelayTimer & 0xc000) lfoDelayState = 2;
lfoDelayTimer += attackTable[patchRam.lfoDelay];
if (lfoDelayTimer > 0x3fff) lfoDelayState = 2;
}
if ((lfoDelayState == 2)) {
lfoDelay += attackTable[patchRam.lfoDelay];
lfoDelay += lfoDelayTable[patchRam.lfoDelay >> 4];
}
if (lfoDelay & 0xc000) {
if (lfoDelay > 0xff) {
lfoDelayState = 0;
lfoDelay = 0x3fff;
lfoDelay = 0xff;
}
lfoRate = lfoRateTable[patchRam.lfoRate]; // FIXME move to parameters
@ -86,12 +86,13 @@ void Module::runLFO() {
pw = (lfoState & 0x02) ? lfoPhase + 0x2000 : 0x2000 - lfoPhase; // PW LFO is unipolar
pw = (patchRam.switch2 & 0x01) ? 0x3fff : pw; // either LFO or "all on"
pw = 0x3fff - ((pw * patchRam.pwmLfo) >> 7); // scaled by PWM pot
// lfo = (lfo * lfoDelay) >> 14;
}
void Module::run(Voice* voices, uint32_t blockSize) {
// run updates for module board
int16_t lfoToVco = 0, lfoToVcf = 0;
// FIXME break these out to the patch setter
a = attackTable[patchRam.env_a]; // attack time coeff looked up in table
d = decayTable[patchRam.env_d]; // decay time coeff looked up in table
@ -116,10 +117,11 @@ void Module::run(Voice* voices, uint32_t blockSize) {
runLFO();
float pwf = pw / 32768.0f;
// calculate "smoothed" parameters
// these are single outputs with heavy RC smoothing
for (uint32_t i = 0; i < blockSize; i++) {
vcaRC = (master - vcaRC) * subTC + vcaRC;
pwmRC = (pwf - pwmRC) * pwmTC + pwmRC;
pwmRC = ((pw / 32768.0f) - pwmRC) * pwmTC + pwmRC;
subRC = (sub - subRC) * vcaTC + subRC;
vcaBuf[i] = vcaRC;
@ -129,13 +131,27 @@ void Module::run(Voice* voices, uint32_t blockSize) {
if (bufPtr < bufferSize) bufPtr++;
}
int16_t vcf = (patchRam.vcfEnv << 7) * ((patchRam.switch2 & 0x02) ? -1 : 1);
lfoToVco = (lfoDepthTable[patchRam.vcoLfo] * lfoDelay) >> 8; // lookup table is 0-255
lfoToVco += /* lfo from modwheel FIXME */ 0;
if (lfoToVco > 0xff) lfoToVco = 0xff;
lfoToVco = (lfo * lfoToVco) >> 11; // 8 for normalisation plus three additional DSLR EA
int16_t pitchBase = 0x1818;
pitchBase += (lfo * lfoDepthTable[patchRam.vcoLfo]) >> 11;
lfoToVcf = (patchRam.vcfLfo * lfoDelay) >> 7; // value is 0-127
lfoToVcf = (lfo * lfoToVcf) >> 9; // 8 for normalisation plus one additional DSLR EA
int16_t pitchBase = 0x1818, vcfBase = 0;
pitchBase += lfoToVco;
pitchBase += /* pitch bend FIXME */ 0;
// int16_t vcf = (patchRam.vcfEnv << 7) * ((patchRam.switch2 & 0x02) ? -1 : 1);
vcfBase = (patchRam.vcfFreq << 7) + /* vcf bend FIXME */ 0;
vcfBase += lfoToVcf;
if (vcfBase > 0x3fff) vcfBase = 0x3fff;
if (vcfBase < 0x0000) vcfBase = 0x0000;
// per-voice calculations
for (uint32_t i = 0; i < NUM_VOICES; i++) {
// maybe move all this into voice.cpp FIXME
// run one step of the envelope
Voice* v = &voices[i];
switch (v->envPhase) {
case 0: // release phase FIXME use an enum I guess
@ -154,21 +170,20 @@ void Module::run(Voice* voices, uint32_t blockSize) {
}
// pitch
// FIXME clean this all up a bit
int16_t pitch = pitchBase + (v->note << 8);
int16_t semi = pitch >> 8;
uint16_t pitch = pitchBase + (v->note << 8);
uint8_t semi = pitch >> 8;
float frac = (pitch & 0xff) / 256.0;
float p1 = pitchTable[semi], p2 = pitchTable[semi + 1];
int16_t px = ((p2 - p1) * frac + p1);
int16_t px = ((p2 - p1) * frac + p1); // interpolated pitch from table
// octave divider
px *= (patchRam.switch1 & 0x07);
v->omega = px / (sampleRate * 8.0f); // fixme use proper scaler
v->omega = px / (sampleRate * 8.0f); // FIXME recalculate table using proper scaler
// per voice we need to calculate the key follow amount and envelope amount
v->vcfCut = (patchRam.vcfFreq << 7) + ((vcf * v->env) >> 14);
v->vcfCut += (lfo * patchRam.vcfLfo) >> 9;
v->vcfCut = vcfBase + (((v->env * patchRam.vcfEnv)>>7) * ((patchRam.switch1 & 0x02) ? -1 : 1));
v->vcfCut += (int)((v->note - 36) * (patchRam.vcfKey << 1) * 0.375);

10
plugin/module.hpp
View File

@ -156,11 +156,11 @@ class Voice {
uint8_t pulseStage = 1; // pulse wave phase
float subosc = 1; // sub oscillator flipflop output
uint8_t envPhase = 0;
int16_t env = 0; // output amplitude
uint16_t vcfCut;
int16_t vcaEnv;
float vcaRC = 0, vcfRC = 0;
uint8_t envPhase = 0; // current running state of envelope
int16_t env = 0; // calculated envelope amount
int16_t vcfCut; // calculated cutoff to filter
int16_t vcaEnv; // calculated level to VCA (env/gate)
float vcaRC = 0, vcfRC = 0; // RC circuit state values
uint8_t note = 0;