pitch computation

plugin/chassis.cpp

@@ -38,6 +38,10 @@ void Chassis::initAudioPort(bool input, uint32_t index, AudioPort &port) {
 void Chassis::activate() {
     // calculate filter coefficients and stuff
     printf("called activate()\n");
+
+    for (uint8_t i=0; i<104; i++) {
+        s.pitchCV[i] = (261.63 * powf(2, (i-24) / 12.0f)) / sampleRate;
+    }
 }
 
 void Chassis::deactivate() {
@@ -126,6 +130,15 @@ void Chassis::run(const float **, float **outputs, uint32_t frames, const MidiEv
             s.runLFO();
 
             for (uint32_t i = 0; i < NUM_VOICES; i++) {
+                s.voice[i].calcPitch(s);
+
+                    switch(s.patchRam.switch1 & 0x03) {
+        case 1: s.voice[i].omega /= 4; break;
+        case 2: s.voice[i].omega /= 2;
+        default: break;
+    }
+
+                //printf("voice %d note = %02x ff71 = %04x\n",i, s.voice[i].note, s.voice[i].ff71 );
                 s.voice[i].gate(s);
             }
         }

plugin/digital.cpp

@@ -28,6 +28,119 @@ bool Voice::isFree() {
     return ff10 == false;
 }
 
+void Voice::calcPitch(Synth &s) {
+    uint32_t bc, de, ea, a;
+
+    // 03ad
+    ea = 0x1818;
+
+    // add in tuning value from ff61, not implemented
+
+    // 03ba
+    bc = s.ff51;  // computed pitch LFO
+    if (s.ff4a & 0x02) {
+        ea -= bc;
+    } else {
+        ea += bc;
+    }
+
+    // 03c6
+    // add in bender from ff68
+
+    // 03d2
+    s.ff6f = ea;
+
+    ea = ff71;
+    a = note;
+
+    // 03e3
+    bc = a << 8;
+
+    // 03e6
+    a = 0;  // set from porta coefficient ff7d
+
+    if (a != 0) goto h03f5;
+
+    // 3eb
+    ea = bc;
+h03ec:
+    ff71 = ea;  // STEAX (DE++)
+
+    // we're not looping so we can ignore until
+    // 03ee inrw ff0f voice counter
+    // 03f0 eqiw ff0f, 06
+    // 03f3 jr 03e0
+
+    goto h0407;
+
+h03f5:
+    if (ea == bc) goto h03ec;    // DNE EA, BC; JR 03EC store value
+    if (!(ea > bc)) goto h0401;  // DGT EA, BC; JR 0401
+    ea -= a;
+    if (!(ea > bc)) ea = bc;
+    goto h03ec;
+h0401:
+    ea += a;
+    if (!(ea < bc)) ea = bc;
+    goto h03ec;
+
+h0407:
+    // this outputs the Sub Osc CV
+    // ignore until
+    // 0413 mviw ff0f, 0 reset voice counter
+    s.ff34 = 1;  // unsure what this is used for
+
+    // 0419
+    ea = ff71;    // pitch + fraction per voice
+    bc = s.ff6f;  // tune + lfo + bend
+    ea += bc;
+    // 0424
+    s.ff6e = ea & 0xff;  // MOV A, EAL; STAW 006e
+    a = ea >> 8;         // mov a, EAH
+
+    // 0428
+    if (a <= 0x2f) goto h04a5;  // GTI A,$2F; JRE $04A5
+    if (a >= 0x97) goto h04ac;  // LTI A,$97; JRE $04AC
+
+    a -= 0x30;
+
+h0432:
+    // printf("setting omega for note %d \n", a);
+    omega = ((s.pitchCV[a + 1] - s.pitchCV[a]) * (s.ff6e / 256.0)) + s.pitchCV[a];
+    // 0432 onwards calculates the address for the CV
+    // table at E60 and stacks it
+    // 043a onwards fetches the value from the divider
+    // table and computes a linear interpolation with the next one up
+    // using the fractional value stored in ff6e
+
+    // 045a onwards decides which divider to program
+
+    // 0471 unstacks the CV table address and calculates a linear
+    // interpolation of this and the next CV value using ff6e
+    // 048b onwards sends it to the correct DAC
+
+    // 0496 onwards works out which vocie to do next and loops
+
+    // 04a3
+    goto h04d5;
+
+h04a5:  // pitch too low
+    s.ff6e = 0;
+    a = 0;
+    goto h0432;
+
+h04ac:  // pitch too high
+    s.ff6e = 0;
+    a = 0x66;
+    goto h0432;
+
+    // 04b3 programs the dividers somehow
+    // ignore until 04d5
+
+h04d5:
+    return;
+}
+
 void Voice::on(uint32_t key, bool reset = 0) {
     // what's with the crazy private variables and all the gotos with crazy labels?
     // this code emulates the 78C11 code directly (probably inefficiently)
@@ -37,6 +150,8 @@ void Voice::on(uint32_t key, bool reset = 0) {
     // this current implementation doesn't reset the voice
     (void)reset;
 
+    // printf("called with key=%d\n", note);
+
     ff10 = true;  // note held from keyboard
     ff07 = true;  // attack phase
     if (note == key) goto h0144;
@@ -57,7 +172,9 @@ h0144:
 h0149:
     // this is in the wrong place really but is the equivalent of programming the counter
     // and VCO ramp DAC
-    omega = (261.63 * powf(2, (note - 60) / 12.0f)) / 48000.0f;
+    // omega = (261.63 * powf(2, (note - 60) / 12.0f)) / 48000.0f;
+    // printf("note, key = %d, %d\n", note, key);
+    return;
 }
 
 void Voice::off() {
@@ -178,7 +295,8 @@ h032d:
     ea = (bc & 0xff) * a;  // MUL C
     d = a;                 // MOV D,A
     a = (ea >> 8);         // MOV A,EAH
-    bc &= 0xff00; bc |= a; // MOV C,A
+    bc &= 0xff00;
+    bc |= a;  // MOV C,A
     a = d;    // MOV A,D
 
     // 0345
@@ -203,7 +321,8 @@ h032d:
     ea = (bc & 0xff) * a;  // MUL C
     d = a;                 // MOV D,A
     a = ea >> 8;           // MOV A, EAH
-    bc &= 0xff00; bc |= a;   // MOV C,A
+    bc &= 0xff00;
+    bc |= a;             // MOV C,A
     a = d;               // MOV A,D
     ea = (bc >> 8) * a;  // MUL B
     ea += (bc & 0xff);   // EADD EA,C

plugin/voice.cpp

@@ -19,10 +19,11 @@
 // contains the actual sound generation code
 
 #include "voice.hpp"
-#include <cstdio>
 
 #include <math.h>
 
+#include <cstdio>
+
 static inline float poly3blep0(float t) {
     float t2 = t * t;
     return 2 * (t * t2 - 0.5f * t2 * t2);
@@ -40,7 +41,6 @@ void Voice::run(Synth &s, float *buffer, uint32_t samples) {
     // there's a resistor on the panel board to sprag the range
     float pw = s.ff4f / 32768.0f;
 
-   
     float sqr = 0.175;
     float saw = (s.patchRam.switch1 & 0x10) ? 0.220 : 0;
     float sub = (s.patchRam.sub / 127.0f) * 0.275;

plugin/voice.hpp

@@ -29,14 +29,14 @@ class Voice {
     uint8_t note = 60;  // per-voice note, set to middle C at 02b1h
 
     void on(uint32_t key, bool reset);
-
     void off();
-
     bool isFree();
-
     void run(Synth &s, float *buffer, uint32_t samples);
-
     void gate(Synth &s);
+    void calcPitch(Synth &s);
+    uint16_t ff71 = 0; // stores pitch + fraction
+
+    float omega;
 
    private:
     enum { ATTACK,
@@ -57,7 +57,7 @@ class Voice {
 
     uint16_t env;
 
-    float phase = 0, omega = 260 / 48000.0, subosc = 1;
+    float phase = 0, subosc = 1;
     // float env, target;
     float delay;
     uint8_t pulseStage = 0;
@@ -111,6 +111,7 @@ class Synth {
     // RAM from ff00h to ffffh is cleared to zero
     // this is in the startup routine at 0280h
     uint8_t ff1e = 0;
+    uint8_t ff34 = 0;
     uint8_t ff4a = 0;   // LFO flags
     uint16_t ff4d = 0;  // LFO output value
     uint16_t ff4f = 0;  // computed PWM LFO
@@ -119,6 +120,9 @@ class Synth {
     uint16_t ff56 = 0;  // LFO Delay envelope
     uint16_t ff5a = 0;  // LFO Delay holdoff
     uint8_t ff64 = 0;   // LFO mod sens amount
+    uint8_t ff6e = 0; // fractional pitch temp
+    uint16_t ff6f = 0;  // computed pitch amount
+    //uint16_t ff71 = 0; // unsure, to do with pitch
 
     // okay, not the greatest, this right here
     // this struct contains the bytes that make up a Juno 106 patch in
@@ -200,6 +204,8 @@ class Synth {
     uint16_t lfoDelayTable[8] = {
         0xffff, 0x0419, 0x020c, 0x015e, 0x0100, 0x0100, 0x0100, 0x0100};
 
+    float pitchCV[104];
+
     void runLFO();
     void lfoDelay();
 };