PWM LFO working

plugin/chassis.cpp

@@ -121,6 +121,7 @@ void Chassis::run(const float **, float **outputs, uint32_t frames, const MidiEv
             doMidi(midiEvents, midiEventCount, framePos + s.blockLeft);
 
             // printf("compute params and reset block size\n");
+                s.runLFO();
 
             for (uint32_t i = 0; i < NUM_VOICES; i++) {
                 s.voice[i].gate(s);

plugin/digital.cpp

@@ -1,14 +1,34 @@
 
-#include "voice.hpp"
+/*
+   Chassis polysynth framework
+
+   Copyright 2024 Gordon JC Pearce <gordonjcp@gjcp.net>
+
+   Permission to use, copy, modify, and/or distribute this software for any
+   purpose with or without fee is hereby granted, provided that the above
+   copyright notice and this permission notice appear in all copies.
+
+   THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+   WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+   MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
+   SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+   WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION
+   OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
+   CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+*/
+
+// contains the emulation of the digital bits
 
 #include <cmath>
+#include <cstdio>
+
+#include "voice.hpp"
 
 bool Voice::isFree() {
     return ff10 == false;
 }
 
 void Voice::on(uint32_t key, bool reset = 0) {
-    // printf("======================================================================================\n");
     // what's with the crazy private variables and all the gotos with crazy labels?
     // this code emulates the 78C11 code directly (probably inefficiently)
     // to allow for documenting what the variables actually do
@@ -35,8 +55,6 @@ h0144:
     if (!ff11) goto h0132;  // unsure, copied from ff10 at start of mainloop
 
 h0149:
-    // printf("after 0144h, %d %x %x %x %x\n", note, ff07, ff10, ff11, ff33);
-
     // 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;
@@ -48,12 +66,8 @@ void Voice::off() {
     if (!sustain) {  // dummy sustain
         ff33 = false;
     }
-
-    // printf("after note off, %d %x %x %x %x\n", note, ff07, ff10, ff11, ff33);
 }
 
-
-
 void Voice::gate(Synth &s) {
     uint16_t bc, ea = env;
 
@@ -113,3 +127,60 @@ h0590:
     env = ea;
     // printf("%04x %d %d %d %d %d \n", ea, ff07, ff08, ff10, ff11, ff33);
 }
+
+void Synth::runLFO() {
+    // compute a loop's worth of LFO
+
+    uint16_t a, b, c, d;
+    uint16_t bc, hl, ea, tos;
+
+    // 074e
+    ea = ff4d;  // lfo value
+    bc = lfoRateTable[patchRam.lfoRate];
+
+    if (!(ff4a & 0x01)) goto h078b;
+
+    ea -= bc;
+    if (ea < bc) goto h079a;
+h075f:
+    ff4d = ea;
+    if (!(ff4a & 0x02)) goto h07a2;
+
+    // 0765
+    bc = ea;
+    ea = 0x2000;
+    ea -= bc;
+h076b:
+    bc = ea;
+    if (patchRam.switch2 & 0x01) {
+        bc = 0x3fff;
+    }
+
+    bc = (bc * patchRam.pwmLfo) >> 7;
+    bc = 0x3fff - bc;
+    if (!(patchRam.switch1 & 0x08)) bc = 0x0000;   // square off
+    ff4f = bc;
+
+    // 078a
+    goto h07a9;
+
+h078b:
+    ea += bc;
+    if (ea & 0xe000) {
+        ea = 0x1fff;
+        ff4a++;
+    }
+    goto h075f;
+
+h079a:
+    ea = 0;
+    ff4a++;
+    goto h075f;
+
+h07a2:
+    ea += 0x2000;
+    goto h076b;
+
+h07a9:
+    return;
+}

plugin/parameters.cpp

@@ -265,7 +265,7 @@ void Chassis::setParameterValue(uint32_t index, float value) {
             s.patchRam.vcoLfo = value;
             break;
         case paramPWMLFO:
-            s.patchRam.pwmLfo = value;
+            s.patchRam.pwmLfo = value/1.27;
             break;
         case paramSub:
             s.patchRam.sub = value;

plugin/voice.cpp

@@ -16,13 +16,12 @@
    CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */
 
+// contains the actual sound generation code
+
 #include "voice.hpp"
-
-#include <math.h>
-
 #include <cstdio>
 
-
+#include <math.h>
 
 static inline float poly3blep0(float t) {
     float t2 = t * t;
@@ -39,15 +38,16 @@ void Voice::run(Synth &s, float *buffer, uint32_t samples) {
     // 325, because it needs PW to be from 0 to 0.5
     // but really the control range is limited from 0 to 100
     // there's a resistor on the panel board to sprag the range
-    float pw = 0.5 - s.patchRam.pwmLfo/325.0f;
+    float pw = s.ff4f / 32768.0f;
 
-    float sqr = (s.patchRam.switch1 & 0x08) ? 0.175 : 0;
+   
+    float sqr =  0.175;
     float saw = (s.patchRam.switch1 & 0x10) ? 0.220 : 0;
     float sub = (s.patchRam.sub / 127.0f) * 0.275;
 
     float gain = 0.5 * powf(2, (s.patchRam.vca / 64.0f) - 1);
 
-    float vcaEnv = (s.patchRam.switch2 & 0x04)?(float)ff11:(env / 16384.0f);
+    float vcaEnv = (s.patchRam.switch2 & 0x04) ? (float)ff11 : (env / 16384.0f);
 
     for (uint32_t i = 0; i < samples; i++) {
         y = delay;
@@ -61,10 +61,10 @@ void Voice::run(Synth &s, float *buffer, uint32_t samples) {
         while (true) {
             if (pulseStage == 0) {
                 if (phase < pw) break;
-#if 1
+#if 0
                 t = (phase - pw) / omega;
 #else
-                t = (phase - pw) / (widthDelay - pw + freq);
+                t = (phase - pw) / (lastpw - pw + omega);
 #endif
                 y -= poly3blep0(t) * sqr;
                 delay -= poly3blep1(t) * sqr;
@@ -97,7 +97,8 @@ void Voice::run(Synth &s, float *buffer, uint32_t samples) {
         out = y;
         // widthDelay = pw;
 
-        vr58c106 += ((vcaEnv- vr58c106) * 0.0075);
+        vr58c106 += ((vcaEnv - vr58c106) * 0.0075);
+        lastpw = pw;
         buffer[i] += (gain * out * vr58c106);
     }
 }

plugin/voice.hpp

@@ -24,12 +24,6 @@
 
 class Synth;
 
-class Patch {
-   public:
-    float saw, sqr, sub;
-    uint16_t attack, decay, sustain, release;
-};
-
 class Voice {
    public:
     // uint8_t note = 72;
@@ -55,11 +49,11 @@ class Voice {
            K_ON,
            K_SUSTAIN } keyState = K_OFF;
 
-    bool ff00 = 0;  // reset bit
+    bool ff00 = 0;  // reset DCO clock flag
-    bool ff07 = 0;  // status bit
+    bool ff07 = 0;  // set to indicate attack phase
-    bool ff08 = 0;  // set to indicate attack phase complete
+    bool ff08 = 0;  // set to indicate decay/sustain phase
     bool ff10 = 0;  // note on bit
-    bool ff11 = 0;  // sustain flag
+    bool ff11 = 0;  // drives the "gate" signal for VCA
     bool ff33 = 0;  // releasing flag
 
     uint16_t env;
@@ -69,7 +63,7 @@ class Voice {
     float delay;
     uint8_t pulseStage = 0;
 
-    float pw_rc = 0;
+    float lastpw = 0;
     float vr58c106 = 0;
     uint16_t attack_table[128] = {
         0x4000, 0x2000, 0x1000, 0x0aaa, 0x0800, 0x0666, 0x0555, 0x0492, 0x0400,
@@ -88,7 +82,7 @@ class Voice {
         0x001d, 0x001c, 0x001c, 0x001b, 0x001b, 0x001a, 0x0019, 0x0018, 0x0017,
         0x0016, 0x0015};
 
-uint16_t decay_table[128] = {
+    uint16_t decay_table[128] = {
         0x1000, 0x3000, 0x5000, 0x7000, 0x9000, 0xa000, 0xa800, 0xb000, 0xb800,
         0xc000, 0xc800, 0xd000, 0xd800, 0xe000, 0xe800, 0xf000, 0xf080, 0xf100,
         0xf180, 0xf200, 0xf280, 0xf300, 0xf380, 0xf400, 0xf480, 0xf500, 0xf580,
@@ -105,16 +99,24 @@ uint16_t decay_table[128] = {
         0xffd8, 0xffdc, 0xffe0, 0xffe4, 0xffe8, 0xffec, 0xfff0, 0xfff1, 0xfff2,
         0xfff3, 0xfff4};
 };
-
 class Synth {
    public:
-    Patch patch;
     Voice voice[8];
     float lfo = 0, lfosw = 0.01;
     float lastpw = 0;
     uint32_t blockLeft;
     uint32_t framesLeft = 0;
 
+    uint8_t ff1e;
+    uint8_t ff4a;   // LFO flags
+    uint16_t ff4d = 0;  // LFO output value
+    uint16_t ff4f; // computed PWM LFO
+    uint16_t ff51;  // computed pitch LFO
+    uint16_t ff53;  // computed VCF LFO
+    uint16_t ff56;  // LFO Delay envelope
+    uint16_t ff5a;  // LFO Delay holdoff
+    uint8_t ff64;   // LFO mod sens amount
+
     // okay, not the greatest, this right here
     // this struct contains the bytes that make up a Juno 106 patch in
     // sysex order, exactly as they'd be transmitted or received by a
@@ -142,6 +144,35 @@ class Synth {
         uint8_t switch1 = 26;
         uint8_t switch2 = 24;
     } patchRam;
+
+    uint8_t lfoDepthTable[128] = {
+        0x00, 0x00, 0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08, 0x09,
+        0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f, 0x10, 0x11, 0x12, 0x13, 0x14, 0x15,
+        0x16, 0x17, 0x18, 0x19, 0x1a, 0x1b, 0x1c, 0x1d, 0x1e, 0x1f, 0x20, 0x21,
+        0x22, 0x23, 0x24, 0x25, 0x26, 0x27, 0x28, 0x29, 0x2a, 0x2b, 0x2c, 0x2d,
+        0x2e, 0x2f, 0x30, 0x31, 0x32, 0x33, 0x34, 0x35, 0x36, 0x37, 0x38, 0x39,
+        0x3a, 0x3b, 0x3c, 0x3d, 0x3e, 0x40, 0x42, 0x44, 0x46, 0x48, 0x4a, 0x4c,
+        0x4e, 0x50, 0x52, 0x54, 0x56, 0x58, 0x5a, 0x5c, 0x5e, 0x60, 0x62, 0x64,
+        0x66, 0x68, 0x6a, 0x6c, 0x6e, 0x70, 0x72, 0x74, 0x76, 0x78, 0x7a, 0x7c,
+        0x80, 0x84, 0x88, 0x8c, 0x90, 0x94, 0x98, 0x9c, 0xa0, 0xa4, 0xa8, 0xac,
+        0xb0, 0xb4, 0xb8, 0xbc, 0xc0, 0xc4, 0xc8, 0xcc, 0xd0, 0xd4, 0xd8, 0xdc,
+        0xe0, 0xe4, 0xe8, 0xec, 0xf0, 0xf8, 0xff, 0xff};
+    uint16_t lfoRateTable[128] = {
+        0x0005, 0x000f, 0x0019, 0x0028, 0x0037, 0x0046, 0x0050, 0x005a, 0x0064,
+        0x006e, 0x0078, 0x0082, 0x008c, 0x0096, 0x00a0, 0x00aa, 0x00b4, 0x00be,
+        0x00c8, 0x00d2, 0x00dc, 0x00e6, 0x00f0, 0x00fa, 0x0104, 0x010e, 0x0118,
+        0x0122, 0x012c, 0x0136, 0x0140, 0x014a, 0x0154, 0x015e, 0x0168, 0x0172,
+        0x017c, 0x0186, 0x0190, 0x019a, 0x01a4, 0x01ae, 0x01b8, 0x01c2, 0x01cc,
+        0x01d6, 0x01e0, 0x01ea, 0x01f4, 0x01fe, 0x0208, 0x0212, 0x021c, 0x0226,
+        0x0230, 0x023a, 0x0244, 0x024e, 0x0258, 0x0262, 0x026c, 0x0276, 0x0280,
+        0x028a, 0x029a, 0x02aa, 0x02ba, 0x02ca, 0x02da, 0x02ea, 0x02fa, 0x030a,
+        0x031a, 0x032a, 0x033a, 0x034a, 0x035a, 0x036a, 0x037a, 0x038a, 0x039a,
+        0x03aa, 0x03ba, 0x03ca, 0x03da, 0x03ea, 0x03fa, 0x040a, 0x041a, 0x042a,
+        0x043a, 0x044a, 0x045a, 0x046a, 0x047a, 0x048a, 0x04be, 0x04f2, 0x0526,
+        0x055a, 0x058e, 0x05c2, 0x05f6, 0x062c, 0x0672, 0x06b8, 0x0708, 0x0758,
+        0x07a8, 0x07f8, 0x085c, 0x08c0, 0x0924, 0x0988, 0x09ec, 0x0a50, 0x0ab4,
+        0x0b18, 0x0b7c, 0x0be0, 0x0c58, 0x0cd0, 0x0d48, 0x0dde, 0x0e74, 0x0f0a,
+        0x0fa0, 0x1000};
+
+    void runLFO();
 };
-
-