From 986b64bbf04b02bb89a844d562897e607c22f5c9 Mon Sep 17 00:00:00 2001
From: LTVA1 <87536432+LTVA1@users.noreply.github.com>
Date: Sun, 4 Aug 2024 12:19:33 +0300
Subject: [PATCH] better phase mod accuracy, optimized panning reg writes

---
 src/engine/platform/sid3.cpp     | 11 +++++++++--
 src/engine/platform/sound/sid3.c |  8 ++++----
 2 files changed, 13 insertions(+), 6 deletions(-)

diff --git a/src/engine/platform/sid3.cpp b/src/engine/platform/sid3.cpp
index 8b14febd2..b41ff8a3b 100644
--- a/src/engine/platform/sid3.cpp
+++ b/src/engine/platform/sid3.cpp
@@ -94,7 +94,7 @@ void DivPlatformSID3::acquire(short** buf, size_t len)
 
       for(int j = 0; j < SID3_NUM_CHANNELS; j++)
       {
-        oscBuf[j]->data[oscBuf[j]->needle++] = sid3->muted[j] ? 0 : sid3->channel_output[j];
+        oscBuf[j]->data[oscBuf[j]->needle++] = sid3->muted[j] ? 0 : (sid3->channel_output[j] / 4);
       }
     }
   }
@@ -169,6 +169,8 @@ void DivPlatformSID3::tick(bool sysTick)
   {
     chan[i].std.next();
 
+    bool panChanged = false;
+
     if (chan[i].std.vol.had) 
     {
       chan[i].outVol=VOL_SCALE_LINEAR(chan[i].vol&255,MIN(255,chan[i].std.vol.val),255);
@@ -202,11 +204,16 @@ void DivPlatformSID3::tick(bool sysTick)
       updateDuty(i);
     }
     if (chan[i].std.panL.had) {
+      panChanged = true;
       chan[i].panLeft = chan[i].std.panL.val & 0xff;
-      updatePanning(i);
     }
     if (chan[i].std.panR.had) {
+      panChanged = true;
       chan[i].panRight = chan[i].std.panR.val & 0xff;
+    }
+
+    if(panChanged)
+    {
       updatePanning(i);
     }
 
diff --git a/src/engine/platform/sound/sid3.c b/src/engine/platform/sound/sid3.c
index cec277ab2..bd343cc53 100644
--- a/src/engine/platform/sound/sid3.c
+++ b/src/engine/platform/sound/sid3.c
@@ -2494,7 +2494,7 @@ void sid3_adsr_clock(sid3_channel_adsr* adsr)
 
 int32_t sid3_adsr_output(sid3_channel_adsr* adsr, int32_t input)
 {
-    return (int32_t)((int64_t)input * (int64_t)adsr->envelope_counter / (int64_t)0xff0000 / (int64_t)8 * (int64_t)adsr->vol / (int64_t)SID3_MAX_VOL); //"/ (int64_t)8" so that there's enough amplitude for all 7 chans! 
+    return (int32_t)((int64_t)input * (int64_t)adsr->envelope_counter / (int64_t)0xff0000 * (int64_t)adsr->vol / (int64_t)SID3_MAX_VOL);
 }
 
 void sid3_set_filter_settings(sid3_filter* filt)
@@ -2931,7 +2931,7 @@ void sid3_clock(SID3* sid3)
 
         if(ch->flags & SID3_CHAN_ENABLE_PHASE_MOD)
         {
-            ch->accumulator += ch->phase_mod_source == SID3_NUM_CHANNELS - 1 ? ((uint64_t)sid3->wave_channel_output << 19) : ((uint64_t)sid3->channel_output[ch->phase_mod_source] << 19);
+            ch->accumulator += ch->phase_mod_source == SID3_NUM_CHANNELS - 1 ? ((uint64_t)sid3->wave_channel_output << 18) : ((uint64_t)sid3->channel_output[ch->phase_mod_source] << 18);
         }
 
         ch->accumulator &= SID3_ACC_MASK;
@@ -2972,8 +2972,8 @@ void sid3_clock(SID3* sid3)
 
         if(!sid3->muted[i])
         {
-            sid3->output_l += output * ch->panning_left / 0xff;
-            sid3->output_r += output * ch->panning_right / 0xff;
+            sid3->output_l += output * ch->panning_left / 0x8f0;
+            sid3->output_r += output * ch->panning_right / 0x8f0;
         }
 
         sid3->channel_output[i] = output;