From 0f63db2dac6ca84a084693555c76e54378d86982 Mon Sep 17 00:00:00 2001
From: tildearrow <tildearrow@protonmail.com>
Date: Mon, 5 Dec 2022 19:13:21 -0500
Subject: [PATCH] BRR loop fixes!

---
 src/engine/brrUtils.c        | 67 +++++++++++++++++++++++++++++++++---
 src/engine/brrUtils.h        |  2 +-
 src/engine/platform/snes.cpp |  6 ++--
 src/engine/sample.cpp        |  6 ++--
 4 files changed, 69 insertions(+), 12 deletions(-)

diff --git a/src/engine/brrUtils.c b/src/engine/brrUtils.c
index ef354375..a147c6ae 100644
--- a/src/engine/brrUtils.c
+++ b/src/engine/brrUtils.c
@@ -171,10 +171,24 @@ long brrEncode(short* buf, unsigned char* out, long len, long loopStart) {
   memset(avgError,0,4*13*sizeof(int));
   memset(possibleOut,0,4*13*8);
 
-  len&=~15;
-  loopStart&=~15;
   for (long i=0; i<len; i+=16) {
-    memcpy(in,buf,16*sizeof(short));
+    if (i+16>len) {
+      long p=i;
+      for (int j=0; j<16; j++) {
+        if (p>=len) {
+          if (loopStart<0 || loopStart>=len) {
+            in[j]=0;
+          } else {
+            p=loopStart;
+            in[j]=buf[p++];
+          }
+        } else {
+          in[j]=buf[p++];
+        }
+      }
+    } else {
+      memcpy(in,&buf[i],16*sizeof(short));
+    }
 
     // encode
     for (int j=0; j<4; j++) {
@@ -206,7 +220,51 @@ long brrEncode(short* buf, unsigned char* out, long len, long loopStart) {
     }
 
     // write
-    out[0]=(range<<4)|(filter<<2)|((i+16>=len)?((loopStart>=0)?3:1):0);
+    out[0]=(range<<4)|(filter<<2)|((i+16>=len && loopStart<0)?1:0);
+    for (int j=0; j<8; j++) {
+      out[j+1]=possibleOut[filter][range][j];
+    }
+
+    for (int j=0; j<4; j++) {
+      for (int k=0; k<13; k++) {
+        last1[j][k]=last1[filter][range];
+        last2[j][k]=last2[filter][range];
+      }
+    }
+    out+=9;
+    total+=9;
+  }
+  // encode loop block
+  if (loopStart>=0) {
+    long p=loopStart;
+    for (int i=0; i<16; i++) {
+      if (p>=len) {
+        p=loopStart;
+      }
+      in[i]=buf[p++];
+    }
+
+    // encode (filter 0/1 only)
+    for (int j=0; j<2; j++) {
+      for (int k=0; k<13; k++) {
+        brrEncodeBlock(in,possibleOut[j][k],k,j,&last1[j][k],&last2[j][k],&avgError[j][k]);
+      }
+    }
+
+    // find best filter/range
+    int candError=0x7fffffff;
+    for (int j=0; j<2; j++) {
+      for (int k=0; k<13; k++) {
+        if (avgError[j][k]<candError) {
+          candError=avgError[j][k];
+          filter=j;
+          range=k;
+        }
+      }
+    }
+
+    // write
+    out[0]=(range<<4)|(filter<<2)|3;
     for (int j=0; j<8; j++) {
       out[j+1]=possibleOut[filter][range][j];
     }
@@ -217,7 +275,6 @@ long brrEncode(short* buf, unsigned char* out, long len, long loopStart) {
         last2[j][k]=last2[filter][range];
       }
     }
-    buf+=16;
     out+=9;
     total+=9;
   }
diff --git a/src/engine/brrUtils.h b/src/engine/brrUtils.h
index 5cc898e1..11e7f052 100644
--- a/src/engine/brrUtils.h
+++ b/src/engine/brrUtils.h
@@ -30,7 +30,7 @@ extern "C" {
 /**
  * read len samples from buf, encode in BRR and output to out.
  * @param buf input data.
- * @param out output buffer. shall be at least 9*(len/16) shorts in size.
+ * @param out output buffer. shall be at least 9*((15+len)/16) shorts in size (9 more if loopStart is not -1!)
  * @param len input length (should be a multiple of 16. if it isn't, the output will be padded).
  * @param loopStart beginning of loop area (may be -1 for no loop). this is used to ensure the respective block has no filter in order to loop properly.
  * @return number of written samples.
diff --git a/src/engine/platform/snes.cpp b/src/engine/platform/snes.cpp
index 2dd64de3..2ab2c62c 100644
--- a/src/engine/platform/snes.cpp
+++ b/src/engine/platform/snes.cpp
@@ -214,13 +214,13 @@ void DivPlatformSNES::tick(bool sysTick) {
           loop=start;
         } else if (chan[i].sample>=0 && chan[i].sample<parent->song.sampleLen) {
           start=sampleOff[chan[i].sample];
-          end=MIN(start+MAX(s->lengthBRR,1),getSampleMemCapacity());
+          end=MIN(start+MAX(s->lengthBRR+((s->loop && s->depth!=DIV_SAMPLE_DEPTH_BRR)?9:0),1),getSampleMemCapacity());
           loop=MAX(start,end-1);
           if (chan[i].audPos>0) {
             start=start+MIN(chan[i].audPos,s->lengthBRR-1)/16*9;
           }
           if (s->loopStart>=0) {
-            loop=start+s->loopStart/16*9;
+            loop=((s->depth!=DIV_SAMPLE_DEPTH_BRR)?9:0)+start+((s->loopStart/16)*9);
           }
         } else {
           start=0;
@@ -817,7 +817,7 @@ void DivPlatformSNES::renderSamples(int sysID) {
       continue;
     }
 
-    int length=s->lengthBRR;
+    int length=s->lengthBRR+((s->loop && s->depth!=DIV_SAMPLE_DEPTH_BRR)?9:0);
     int actualLength=MIN((int)(getSampleMemCapacity()-memPos)/9*9,length);
     if (actualLength>0) {
       sampleOff[i]=memPos;
diff --git a/src/engine/sample.cpp b/src/engine/sample.cpp
index 5460aed3..95066710 100644
--- a/src/engine/sample.cpp
+++ b/src/engine/sample.cpp
@@ -490,8 +490,8 @@ bool DivSample::initInternal(DivSampleDepth d, int count) {
     case DIV_SAMPLE_DEPTH_BRR: // BRR
       if (dataBRR!=NULL) delete[] dataBRR;
       lengthBRR=9*((count+15)/16);
-      dataBRR=new unsigned char[lengthBRR];
-      memset(dataBRR,0,lengthBRR);
+      dataBRR=new unsigned char[lengthBRR+9];
+      memset(dataBRR,0,lengthBRR+9);
       break;
     case DIV_SAMPLE_DEPTH_VOX: // VOX
       if (dataVOX!=NULL) delete[] dataVOX;
@@ -1100,7 +1100,7 @@ void DivSample::render(unsigned int formatMask) {
   }
   if (NOT_IN_FORMAT(DIV_SAMPLE_DEPTH_BRR)) { // BRR
     if (!initInternal(DIV_SAMPLE_DEPTH_BRR,samples)) return;
-    brrEncode(data16,dataBRR,(samples+15)&(~15),loop?loopStart:-1);
+    brrEncode(data16,dataBRR,samples,loop?loopStart:-1);
   }
   if (NOT_IN_FORMAT(DIV_SAMPLE_DEPTH_VOX)) { // VOX
     if (!initInternal(DIV_SAMPLE_DEPTH_VOX,samples)) return;