From 36804d7c9b29724d7cc64918de9b82ddf09c8ae0 Mon Sep 17 00:00:00 2001
From: Zeta <zeta0134@reploid.cafe>
Date: Tue, 14 Nov 2023 03:27:03 -0500
Subject: [PATCH] Add an option to round volumes up when applying linear
 scaling

This is secretly a FamiTracker compatibility mode, but it's useful
in many other contexts. With upwards rounding, if both the channel
and the macro volume are positive, then the computed result is
also positive, ie, it will never become 0, which is silent on many
chips.

Still needs UI changes to expose the setting, and save/load work
to persist it to file.
---
 src/engine/dispatch.h | 2 +-
 src/engine/song.h     | 4 +++-
 2 files changed, 4 insertions(+), 2 deletions(-)

diff --git a/src/engine/dispatch.h b/src/engine/dispatch.h
index 2f6b7c04a..bfdcf6883 100644
--- a/src/engine/dispatch.h
+++ b/src/engine/dispatch.h
@@ -782,7 +782,7 @@ class DivDispatch {
 #define NOTE_FNUM_BLOCK(x,bits) parent->calcBaseFreqFNumBlock(chipClock,CHIP_FREQBASE,x,bits)
 
 // this is for volume scaling calculation.
-#define VOL_SCALE_LINEAR(x,y,range) (((x)*(y))/(range))
+#define VOL_SCALE_LINEAR(x,y,range) ((parent->song.ceilVolumeScaling)?((((x)*(y))+(range-1))/(range)):(((x)*(y))/(range)))
 #define VOL_SCALE_LOG(x,y,range) (CLAMP(((x)+(y))-(range),0,(range)))
 #define VOL_SCALE_LINEAR_BROKEN(x,y,range) ((parent->song.newVolumeScaling)?(VOL_SCALE_LINEAR(x,y,range)):(VOL_SCALE_LOG(x,y,range)))
 #define VOL_SCALE_LOG_BROKEN(x,y,range) ((parent->song.newVolumeScaling)?(VOL_SCALE_LOG(x,y,range)):(VOL_SCALE_LINEAR(x,y,range)))
diff --git a/src/engine/song.h b/src/engine/song.h
index 7a7e267c2..50435aee1 100644
--- a/src/engine/song.h
+++ b/src/engine/song.h
@@ -379,6 +379,7 @@ struct DivSong {
   bool preNoteNoEffect;
   bool oldDPCM;
   bool resetArpPhaseOnNewNote;
+  bool ceilVolumeScaling;
 
   std::vector<DivInstrument*> ins;
   std::vector<DivWavetable*> wave;
@@ -500,7 +501,8 @@ struct DivSong {
     brokenFMOff(false),
     preNoteNoEffect(false),
     oldDPCM(false),
-    resetArpPhaseOnNewNote(false) {
+    resetArpPhaseOnNewNote(false),
+    ceilVolumeScaling(false) { // DEBUG: before accepting PR, set this to false! (zeta hasn't touched the UI yet)
     for (int i=0; i<DIV_MAX_CHIPS; i++) {
       system[i]=DIV_SYSTEM_NULL;
       systemVol[i]=1.0;