improved PWM code

plugin/ic29.cpp

@@ -25,11 +25,11 @@ Synth ic29;
 Synth::Synth() {
     d_debug("initialising synth\n");
     envAtk = 0x00;
-    envDcy = 0x50;
-    envStn = 0x7f;
-    envRls = 0x3f;
+    envDcy = 0x1f;
+    envStn = 0x00;
+    envRls = 0x1f;
     portaCoeff = 0x0;
-    lfo.speed = 0x1f;
+    lfo.speed = 0x06;
 }
 
 void Synth::buildTables(double sampleRate) {
@@ -49,6 +49,17 @@ void Synth::run() {
 
     masterPitch = 0x1818;
 
+    // need to calculate VCF "base" setting
+    // need to calculate PWM
+    // various on/off switches
+
+    // PWM is bit 0 sw2, 0 = fixed 1 = lfo
+    // 0 sets EA to 0x3fff, 1 adds
+    uint16_t pwmVal = 0x2000 - ic29.lfo.lfoOut;
+    if (0) pwmVal = 0x3fff;
+
+    ic29.pwm = pwmVal / 40960.0f * (1);  // 0.5 is knob val
+
     for (uint8_t i = 0; i < NUM_VOICES; i++) {
         ic29.voices[i].update();
     }
@@ -91,7 +102,7 @@ void LFO::run() {
         phase = 1;
     }
 
-    //printf("lfoOut=%04x\n", lfoOut);
+    // printf("lfoOut=%04x\n", lfoOut);
 }
 
 Envelope::Envelope() {
@@ -126,7 +137,7 @@ void Envelope::run() {
 }
 
 Voice::Voice() {
-    subosc = .11;
+    subosc = .1;
 }
 
 void Voice::calcPitch() {
@@ -173,6 +184,7 @@ void Voice::update() {
     // calculate the once-per-block values
     env.run();
     calcPitch();
+    pw = 0.5 - ic29.pwm;
     // do filter values
 }
 

plugin/ic29.hpp

@@ -81,7 +81,7 @@ class Voice {
     uint16_t pitch = 0x1818;  // calculated pitch value with porta and master pitch etc
     float delay;              // delay slot for polyblep
     bool pulseStage;
-    float lastpw;
+    float pw, lastpw, pwrc;
     float subosc = -1;
     float phase = 0, omega = 0;
     enum { V_DONE,
@@ -119,6 +119,8 @@ class Synth {
     Voice voices[NUM_VOICES];
     LFO lfo;
 
+    float pwm;
+
 };
 
 // global

plugin/oscillator.cpp

@@ -30,24 +30,25 @@ static inline float poly3blep1(float t) {
 void Voice::run(float *buffer, uint32_t samples) {
     // generate a full block of samples for the oscillator
 
-    float y, out, pw = .50, t;
-
+    float y, out, t;
     float saw = 0;
-    pw = 0.5-(ic29.lfo.lfoOut + 0x2000) / 61600.0f;
-
     float gain = env.level / 16384.0;
 
+
+
     // this uses an adaptation of Mystran's Polyblep oscillator
     for (uint32_t i = 0; i < samples; i++) {
         y = delay;
         delay = 0;
         phase += omega;
 
+        pwrc = ((pw - pwrc) *.01 ) + pwrc;
+
         // this is the clever bit
         while (true) {
             if (!pulseStage) {
-                if (phase < pw) break;                     // it's not time for the PWM output to step
-                t = (phase - pw) / (lastpw - pw + omega);  // calculate fractional sample allowing for PW amount
+                if (phase < pwrc) break;                     // it's not time for the PWM output to step
+                t = (phase - pwrc) / (lastpw - pwrc + omega);  // calculate fractional sample allowing for PW amount
                 y -= 0.63 * poly3blep0(t);                 // magic numbers observed on oscilloscope from real synth
                 delay -= 0.63 * poly3blep1(t);
                 pulseStage = true;
@@ -70,7 +71,8 @@ void Voice::run(float *buffer, uint32_t samples) {
         delay += subosc;
 
         out = y * 0.15;
-        lastpw = pw;
+        lastpw = pwrc;
         buffer[i] += out * gain;
     }
+
 }