From 7ff0bf0659eac3e827322a1a5654b90e8aeb9f97 Mon Sep 17 00:00:00 2001
From: Gordon JC Pearce <gordonjcp@gmail.com>
Date: Tue, 6 Jan 2026 20:20:30 +0000
Subject: [PATCH] better LFO and PW

---
 plugin/module.cpp | 24 ++++++++++++++++--------
 plugin/module.hpp |  4 +++-
 2 files changed, 19 insertions(+), 9 deletions(-)

diff --git a/plugin/module.cpp b/plugin/module.cpp
index a6350a9..c2405b0 100644
--- a/plugin/module.cpp
+++ b/plugin/module.cpp
@@ -70,15 +70,23 @@ void Module::runLFO() {
         lfoDelay = 0x3fff;
     }
 
-    lfoPhase += lfoRateTable[patchRam.lfoRate];
-    if (lfoPhase & 0x4000)
-        lfo = 0x1fff - (lfoPhase & 0x3fff);
-    else
-        lfo = (lfoPhase & 0x3fff) - 0x1fff;
+    lfoRate = lfoRateTable[patchRam.lfoRate];  // FIXME move to parameters
 
-    pw = 0x3fff - (((0x2000 + lfo) * patchRam.pwmLfo) >> 7);
-    pw = (patchRam.switch2 & 0x01) ? 0x3fff - (patchRam.pwmLfo << 7) : pw;
-    lfo = (lfo * lfoDelay) >> 14;
+    lfoPhase += (lfoState & 0x01) ? -lfoRate : lfoRate;
+    if (lfoPhase > 0x1fff) {
+        lfoPhase = 0x1fff;
+        lfoState++;
+    }
+    if (lfoPhase < 0x0000) {
+        lfoPhase = 0x0000;
+        lfoState++;
+    }
+    lfo = (lfoState & 0x02) ? -lfoPhase : lfoPhase;
+
+    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) {
diff --git a/plugin/module.hpp b/plugin/module.hpp
index cce369c..3f75a8c 100644
--- a/plugin/module.hpp
+++ b/plugin/module.hpp
@@ -130,7 +130,9 @@ class Module {
     float pwmRC = 0, subRC = 0, vcaRC = 0;
 
     int16_t lfo, pw;
-    uint32_t lfoPhase;
+    int16_t lfoPhase;
+    uint8_t lfoState = 0;
+    uint16_t lfoRate;
 
     uint32_t noiseRNG = 1;