From 3c043bd100855af8570980513c663e18720c9987 Mon Sep 17 00:00:00 2001
From: tildearrow <me@tildearrow.org>
Date: Sat, 10 Jan 2026 18:58:06 -0500
Subject: [PATCH] pad ADPCM-A/B samples to 256 bytes upon conversion

issue #1910
also warn if the sample is an ADPCM-A or ADPCM-B one and it is not padded
---
 src/engine/sample.cpp  | 8 ++++----
 src/gui/sampleEdit.cpp | 7 +++++++
 2 files changed, 11 insertions(+), 4 deletions(-)

diff --git a/src/engine/sample.cpp b/src/engine/sample.cpp
index a52d937b7..0bdcd2d47 100644
--- a/src/engine/sample.cpp
+++ b/src/engine/sample.cpp
@@ -579,13 +579,13 @@ bool DivSample::initInternal(DivSampleDepth d, int count) {
       break;
     case DIV_SAMPLE_DEPTH_ADPCM_A: // ADPCM-A
       if (dataA!=NULL) delete[] dataA;
-      lengthA=(count+1)/2;
+      lengthA=(((count+1)/2)+255)&(~0xff);
       dataA=new unsigned char[(lengthA+255)&(~0xff)];
       memset(dataA,0x80,(lengthA+255)&(~0xff));
       break;
     case DIV_SAMPLE_DEPTH_ADPCM_B: // ADPCM-B
       if (dataB!=NULL) delete[] dataB;
-      lengthB=(count+1)/2;
+      lengthB=(((count+1)/2)+255)&(~0xff);
       dataB=new unsigned char[(lengthB+255)&(~0xff)];
       memset(dataB,0x80,(lengthB+255)&(~0xff));
       break;
@@ -872,10 +872,10 @@ void DivSample::convert(DivSampleDepth newDepth, unsigned int formatMask) {
       setSampleCount((samples+1)&(~1));
       break;
     case DIV_SAMPLE_DEPTH_ADPCM_A: // ADPCM-A
-      setSampleCount((samples+1)&(~1));
+      setSampleCount((samples+511)&(~511));
       break;
     case DIV_SAMPLE_DEPTH_ADPCM_B: // ADPCM-B
-      setSampleCount((samples+1)&(~1));
+      setSampleCount((samples+511)&(~511));
       break;
     case DIV_SAMPLE_DEPTH_ADPCM_K: // K05 ADPCM
       setSampleCount((samples+1)&(~1));
diff --git a/src/gui/sampleEdit.cpp b/src/gui/sampleEdit.cpp
index 9160fdfa9..8666bec5e 100644
--- a/src/gui/sampleEdit.cpp
+++ b/src/gui/sampleEdit.cpp
@@ -593,6 +593,13 @@ void FurnaceGUI::drawSampleEdit() {
           }
         }
 
+        // ADPCM-A/B specific warnings
+        if (sample->depth==DIV_SAMPLE_DEPTH_ADPCM_A || sample->depth==DIV_SAMPLE_DEPTH_ADPCM_B) {
+          if (sample->samples&511) {
+            SAMPLE_WARN(warnLength,_("ADPCM sample is not padded to 256 bytes!"));
+          }
+        }
+
         // chips grid
         if (dispatch==NULL) continue;