From e3add1d30695c215a5446ad2407a687a5fa0dba4 Mon Sep 17 00:00:00 2001
From: Gordon JC Pearce <gordonjcp@gmail.com>
Date: Fri, 6 Sep 2024 21:44:41 +0100
Subject: [PATCH] mystran polyblep

---
 plugin/voice.cpp | 86 +++++++++++++++++++++++++++++++++++++++---------
 plugin/voice.hpp |  5 ++-
 2 files changed, 75 insertions(+), 16 deletions(-)

diff --git a/plugin/voice.cpp b/plugin/voice.cpp
index 6beb7b7..ac76a39 100644
--- a/plugin/voice.cpp
+++ b/plugin/voice.cpp
@@ -19,6 +19,7 @@
 #include "voice.hpp"
 
 #include <math.h>
+
 #include <cstdio>
 
 static float blep(float p, float theta) {
@@ -26,18 +27,18 @@ static float blep(float p, float theta) {
 
     // low (late) side of step
     if (p < theta) {
-        //printf("phase < theta, %f %f\n", p, theta);
+        printf("phase < theta, %f %f\n", p, theta);
         t = p / theta;
         return (2 * t) - (t * t) - 1;
     }
     // high (early) side of step
     if (p > (1 - theta)) {
-        //printf("phase > 1-theta %f %f \n", p, theta);
+        printf("phase > 1-theta %f %f \n", p, theta);
         t = (p - 1) / theta;
         return (2 * t) + (t * t) + 1;
     }
 
-    //printf("no action\n");
+    // printf("no action\n");
     return 0;
 }
 
@@ -53,12 +54,11 @@ void Voice::on(uint32_t key, bool reset = 0) {
     omega = (261.63 * powf(2, (note - 60) / 12.0f)) / 48000.0f;
     target = 1;
     env = 1;
-
 }
 
 void Voice::off() {
     keyState = K_OFF;
-     envState = RELEASE;
+    envState = RELEASE;
     target = 0;
 }
 
@@ -76,20 +76,78 @@ void Voice::gate() {
     }
 */
     env = ((target - env) * 0.005f) + env;
+    if (env < 0.001) env = 0;
+}
+
+static inline float poly3blep0(float t) {
+    // these are just sanity checks
+    // correct code doesn't need them
+    if (t < 0) return 0;
+    if (t > 1) return 1;
+
+    float t2 = t * t;
+    return t * t2 - 0.5f * t2 * t2;
+}
+
+// And second sample as wrapper, optimize if you want.
+static inline float poly3blep1(float t) {
+    return -poly3blep0(1 - t);
 }
 
 void Voice::run(Synth &s, float *buffer, uint32_t samples) {
-    float y, offset, pw = 0;
+    float y, out, pw = 0, t;
 
     s.p.sqr = 1;
     s.p.saw = 1;
 
-
-
+    float mix = 1;
     for (uint32_t i = 0; i < samples; i++) {
+#if 1
+        y = delay;
+        delay = 0;
+
+        phase += omega;
+
+        float pulseWidth = 0.5;  // pwm[i];
+
+        // if(pulseWidth > 1) pulseWidth = 1;
+        // if(pulseWidth < 0) pulseWidth = 0;
+
+        while (true) {
+            if (pulseStage == 0) {
+                if (phase < pulseWidth) break;
+#if 1
+                float t = (phase - pulseWidth) / omega;
+#else
+                float t = (phase - pulseWidth) / (widthDelay - pulseWidth + freq);
+#endif
+                y += mix * poly3blep0(t);
+                delay += mix * poly3blep1(t);
+                pulseStage = 1;
+            }
+
+            if (pulseStage == 1) {
+                if (phase < 1) break;
+
+                float t = (phase - 1) / omega;
+                y -= poly3blep0(t);
+                delay -= poly3blep1(t);
+                pulseStage = 0;
+                phase -= 1;
+                subosc = (1-subosc);
+            }
+        }
+        delay += (1 - mix) * phase + mix * (pulseStage ? 1.f : 0.f);
+        delay += subosc;
+
+        out = (2 * y) - 1;
+        // widthDelay = pulseWidth;
+
+#else
         // sawtooth
+
         y = 1 - (2 * phase);
-       // y += blep(phase, omega);
+        y += blep(phase, omega);
 
         // need this if either saw or square is on;
         y *= (s.p.saw + s.p.sqr);
@@ -103,17 +161,15 @@ void Voice::run(Synth &s, float *buffer, uint32_t samples) {
         if (offset > 1) offset -= 1;
 
         y -= (1 - (2 * offset)) * s.p.sqr;
-       // y -= blep(offset, omega) * s.p.sqr;
+        y -= blep(offset, omega) * s.p.sqr;
         // s.lastpw = pw_rc;
 
         phase += omega;
         if (phase > 1) {
-           // printf("step\n");
+            // printf("step\n");
             phase -= 1;
         }
-
-        buffer[i] += (0.125 * y * env);
-        
+#endif
+        buffer[i] += (0.25 * out * env);
     }
 }
-
diff --git a/plugin/voice.hpp b/plugin/voice.hpp
index ba7e387..60eea31 100644
--- a/plugin/voice.hpp
+++ b/plugin/voice.hpp
@@ -51,8 +51,11 @@ class Voice {
            K_ON,
            K_SUSTAIN } keyState = K_OFF;
 
-    float phase = 0, omega = 260 / 48000.0;
+    float phase = 0, omega = 260 / 48000.0, subosc = 0;
     float env, target;
+    float delay;
+uint8_t pulseStage = 0;
+
 
     float pw_rc = 0;
 };