From 39ecab5abd3e422de87b5b0c7bfe91e517fed7fb Mon Sep 17 00:00:00 2001
From: tildearrow <me@tildearrow.org>
Date: Wed, 21 May 2025 18:00:51 -0500
Subject: [PATCH] OPN: ExtCh ALG effect

---
 src/engine/platform/genesisext.cpp | 6 ++++++
 src/engine/platform/ym2203ext.cpp  | 6 ++++++
 src/engine/platform/ym2608ext.cpp  | 6 ++++++
 src/engine/platform/ym2610bext.cpp | 6 ++++++
 src/engine/platform/ym2610ext.cpp  | 6 ++++++
 5 files changed, 30 insertions(+)

diff --git a/src/engine/platform/genesisext.cpp b/src/engine/platform/genesisext.cpp
index 068a7fc78..11314aa5e 100644
--- a/src/engine/platform/genesisext.cpp
+++ b/src/engine/platform/genesisext.cpp
@@ -237,6 +237,12 @@ int DivPlatformGenesisExt::dispatch(DivCommand c) {
       rWrite(0x22,lfoValue);
       break;
     }
+    case DIV_CMD_FM_ALG: {
+      chan[extChanOffs].state.alg=c.value&7;
+      // TODO: TL compensation?
+      rWrite(ADDR_FB_ALG+chanOffs[extChanOffs],(chan[extChanOffs].state.alg&7)|(chan[extChanOffs].state.fb<<3));
+      break;
+    }
     case DIV_CMD_FM_FB: {
       chan[extChanOffs].state.fb=c.value&7;
       rWrite(chanOffs[extChanOffs]+ADDR_FB_ALG,(chan[extChanOffs].state.alg&7)|(chan[extChanOffs].state.fb<<3));
diff --git a/src/engine/platform/ym2203ext.cpp b/src/engine/platform/ym2203ext.cpp
index 6f983a41c..1d03bb4f0 100644
--- a/src/engine/platform/ym2203ext.cpp
+++ b/src/engine/platform/ym2203ext.cpp
@@ -193,6 +193,12 @@ int DivPlatformYM2203Ext::dispatch(DivCommand c) {
       }
       break;
     }
+    case DIV_CMD_FM_ALG: {
+      chan[extChanOffs].state.alg=c.value&7;
+      // TODO: TL compensation?
+      rWrite(ADDR_FB_ALG+chanOffs[extChanOffs],(chan[extChanOffs].state.alg&7)|(chan[extChanOffs].state.fb<<3));
+      break;
+    }
     case DIV_CMD_FM_FB: {
       chan[2].state.fb=c.value&7;
       rWrite(chanOffs[2]+ADDR_FB_ALG,(chan[2].state.alg&7)|(chan[2].state.fb<<3));
diff --git a/src/engine/platform/ym2608ext.cpp b/src/engine/platform/ym2608ext.cpp
index 21449f1ed..798c121bc 100644
--- a/src/engine/platform/ym2608ext.cpp
+++ b/src/engine/platform/ym2608ext.cpp
@@ -218,6 +218,12 @@ int DivPlatformYM2608Ext::dispatch(DivCommand c) {
       rWrite(0x22,lfoValue);
       break;
     }
+    case DIV_CMD_FM_ALG: {
+      chan[extChanOffs].state.alg=c.value&7;
+      // TODO: TL compensation?
+      rWrite(ADDR_FB_ALG+chanOffs[extChanOffs],(chan[extChanOffs].state.alg&7)|(chan[extChanOffs].state.fb<<3));
+      break;
+    }
     case DIV_CMD_FM_FB: {
       chan[2].state.fb=c.value&7;
       rWrite(chanOffs[2]+ADDR_FB_ALG,(chan[2].state.alg&7)|(chan[2].state.fb<<3));
diff --git a/src/engine/platform/ym2610bext.cpp b/src/engine/platform/ym2610bext.cpp
index abedea0f5..e8757590c 100644
--- a/src/engine/platform/ym2610bext.cpp
+++ b/src/engine/platform/ym2610bext.cpp
@@ -214,6 +214,12 @@ int DivPlatformYM2610BExt::dispatch(DivCommand c) {
       rWrite(0x22,lfoValue);
       break;
     }
+    case DIV_CMD_FM_ALG: {
+      chan[extChanOffs].state.alg=c.value&7;
+      // TODO: TL compensation?
+      rWrite(ADDR_FB_ALG+chanOffs[extChanOffs],(chan[extChanOffs].state.alg&7)|(chan[extChanOffs].state.fb<<3));
+      break;
+    }
     case DIV_CMD_FM_FB: {
       chan[extChanOffs].state.fb=c.value&7;
       rWrite(chanOffs[extChanOffs]+ADDR_FB_ALG,(chan[extChanOffs].state.alg&7)|(chan[extChanOffs].state.fb<<3));
diff --git a/src/engine/platform/ym2610ext.cpp b/src/engine/platform/ym2610ext.cpp
index e61ff6d68..2cab7c326 100644
--- a/src/engine/platform/ym2610ext.cpp
+++ b/src/engine/platform/ym2610ext.cpp
@@ -214,6 +214,12 @@ int DivPlatformYM2610Ext::dispatch(DivCommand c) {
       rWrite(0x22,lfoValue);
       break;
     }
+    case DIV_CMD_FM_ALG: {
+      chan[extChanOffs].state.alg=c.value&7;
+      // TODO: TL compensation?
+      rWrite(ADDR_FB_ALG+chanOffs[extChanOffs],(chan[extChanOffs].state.alg&7)|(chan[extChanOffs].state.fb<<3));
+      break;
+    }
     case DIV_CMD_FM_FB: {
       chan[extChanOffs].state.fb=c.value&7;
       rWrite(chanOffs[extChanOffs]+ADDR_FB_ALG,(chan[extChanOffs].state.alg&7)|(chan[extChanOffs].state.fb<<3));