From e1746def3ac8728f13b4c74a86c8555fced10407 Mon Sep 17 00:00:00 2001
From: tildearrow <me@tildearrow.org>
Date: Wed, 26 Jun 2024 04:03:49 -0500
Subject: [PATCH] better subsong detection for import

---
 src/engine/engine.cpp      |  75 +-------------
 src/engine/fileOps/it.cpp  |   4 +-
 src/engine/fileOps/mod.cpp |   2 +-
 src/engine/fileOps/s3m.cpp |   2 +-
 src/engine/fileOps/xm.cpp  |   2 +-
 src/engine/song.cpp        | 199 ++++++++++++++++++++++++++++++++++++-
 src/engine/song.h          |   7 +-
 7 files changed, 211 insertions(+), 80 deletions(-)

diff --git a/src/engine/engine.cpp b/src/engine/engine.cpp
index df24c917d..1b89b34c6 100644
--- a/src/engine/engine.cpp
+++ b/src/engine/engine.cpp
@@ -188,79 +188,8 @@ const char* DivEngine::getEffectDesc(unsigned char effect, int chan, bool notNul
 }
 
 void DivEngine::walkSong(int& loopOrder, int& loopRow, int& loopEnd) {
-  loopOrder=0;
-  loopRow=0;
-  loopEnd=-1;
-  int nextOrder=-1;
-  int nextRow=0;
-  int effectVal=0;
-  int lastSuspectedLoopEnd=-1;
-  DivPattern* pat[DIV_MAX_CHANS];
-  unsigned char wsWalked[8192];
-  memset(wsWalked,0,8192);
-  for (int i=0; i<curSubSong->ordersLen; i++) {
-    for (int j=0; j<chans; j++) {
-      pat[j]=curPat[j].getPattern(curOrders->ord[j][i],false);
-    }
-    if (i>lastSuspectedLoopEnd) {
-      lastSuspectedLoopEnd=i;
-    }
-    for (int j=nextRow; j<curSubSong->patLen; j++) {
-      nextRow=0;
-      bool changingOrder=false;
-      bool jumpingOrder=false;
-      if (wsWalked[((i<<5)+(j>>3))&8191]&(1<<(j&7))) {
-        loopOrder=i;
-        loopRow=j;
-        loopEnd=lastSuspectedLoopEnd;
-        return;
-      }
-      for (int k=0; k<chans; k++) {
-        for (int l=0; l<curPat[k].effectCols; l++) {
-          effectVal=pat[k]->data[j][5+(l<<1)];
-          if (effectVal<0) effectVal=0;
-          if (pat[k]->data[j][4+(l<<1)]==0x0d) {
-            if (song.jumpTreatment==2) {
-              if ((i<curSubSong->ordersLen-1 || !song.ignoreJumpAtEnd)) {
-                nextOrder=i+1;
-                nextRow=effectVal;
-                jumpingOrder=true;
-              }
-            } else if (song.jumpTreatment==1) {
-              if (nextOrder==-1 && (i<curSubSong->ordersLen-1 || !song.ignoreJumpAtEnd)) {
-                nextOrder=i+1;
-                nextRow=effectVal;
-                jumpingOrder=true;
-              }
-            } else {
-              if ((i<curSubSong->ordersLen-1 || !song.ignoreJumpAtEnd)) {
-                if (!changingOrder) {
-                  nextOrder=i+1;
-                }
-                jumpingOrder=true;
-                nextRow=effectVal;
-              }
-            }
-          } else if (pat[k]->data[j][4+(l<<1)]==0x0b) {
-            if (nextOrder==-1 || song.jumpTreatment==0) {
-              nextOrder=effectVal;
-              if (song.jumpTreatment==1 || song.jumpTreatment==2 || !jumpingOrder) {
-                nextRow=0;
-              }
-              changingOrder=true;
-            }
-          }
-        }
-      }
-
-      wsWalked[((i<<5)+(j>>3))&8191]|=1<<(j&7);
-      
-      if (nextOrder!=-1) {
-        i=nextOrder-1;
-        nextOrder=-1;
-        break;
-      }
-    }
+  if (curSubSong!=NULL) {
+    curSubSong->walk(loopOrder,loopRow,loopEnd,chans,song.jumpTreatment,song.ignoreJumpAtEnd);
   }
 }
 
diff --git a/src/engine/fileOps/it.cpp b/src/engine/fileOps/it.cpp
index 20e751b2f..09e250f39 100644
--- a/src/engine/fileOps/it.cpp
+++ b/src/engine/fileOps/it.cpp
@@ -1031,7 +1031,7 @@ bool DivEngine::loadIT(unsigned char* file, size_t len) {
     logV("maxChan: %d",maxChan);
 
     // set channel visibility
-    for (int i=maxChan+1; i<((maxChan+32)&(~31)); i++) {
+    for (int i=maxChan; i<((maxChan+32)&(~31)); i++) {
       ds.subsong[0]->chanShow[i]=false;
       ds.subsong[0]->chanShowChanOsc[i]=false;
     }
@@ -1085,7 +1085,7 @@ bool DivEngine::loadIT(unsigned char* file, size_t len) {
     ds.systemLen=(maxChan+32)>>5;
 
     // find subsongs
-    ds.findSubSongs();    
+    ds.findSubSongs(maxChan);    
 
     if (active) quitDispatch();
     BUSY_BEGIN_SOFT;
diff --git a/src/engine/fileOps/mod.cpp b/src/engine/fileOps/mod.cpp
index 8cb3ea0c1..7198ca5c8 100644
--- a/src/engine/fileOps/mod.cpp
+++ b/src/engine/fileOps/mod.cpp
@@ -419,7 +419,7 @@ bool DivEngine::loadMod(unsigned char* file, size_t len) {
     ds.insLen=ds.ins.size();
 
     // find subsongs
-    ds.findSubSongs();
+    ds.findSubSongs(chCount);
     
     if (active) quitDispatch();
     BUSY_BEGIN_SOFT;
diff --git a/src/engine/fileOps/s3m.cpp b/src/engine/fileOps/s3m.cpp
index 8ae357991..70ec42caa 100644
--- a/src/engine/fileOps/s3m.cpp
+++ b/src/engine/fileOps/s3m.cpp
@@ -1026,7 +1026,7 @@ bool DivEngine::loadS3M(unsigned char* file, size_t len) {
     }
 
     // find subsongs
-    ds.findSubSongs();    
+    ds.findSubSongs(DIV_MAX_CHANS);    
 
     if (active) quitDispatch();
     BUSY_BEGIN_SOFT;
diff --git a/src/engine/fileOps/xm.cpp b/src/engine/fileOps/xm.cpp
index 3fb8cbab0..a451e7f1f 100644
--- a/src/engine/fileOps/xm.cpp
+++ b/src/engine/fileOps/xm.cpp
@@ -371,7 +371,7 @@ bool DivEngine::loadXM(unsigned char* file, size_t len) {
     ds.sampleLen=ds.sample.size();
 
     // find subsongs
-    ds.findSubSongs();
+    ds.findSubSongs(totalChans);
 
     if (active) quitDispatch();
     BUSY_BEGIN_SOFT;
diff --git a/src/engine/song.cpp b/src/engine/song.cpp
index 760692bb6..7d1215225 100644
--- a/src/engine/song.cpp
+++ b/src/engine/song.cpp
@@ -20,6 +20,88 @@
 #include "song.h"
 #include "../ta-log.h"
 
+
+bool DivSubSong::walk(int& loopOrder, int& loopRow, int& loopEnd, int chans, int jumpTreatment, int ignoreJumpAtEnd, int firstPat) {
+  loopOrder=0;
+  loopRow=0;
+  loopEnd=-1;
+  int nextOrder=-1;
+  int nextRow=0;
+  int effectVal=0;
+  int lastSuspectedLoopEnd=-1;
+  DivPattern* subPat[DIV_MAX_CHANS];
+  unsigned char wsWalked[8192];
+  memset(wsWalked,0,8192);
+  if (firstPat>0) {
+    memset(wsWalked,255,32*firstPat);
+  }
+  for (int i=firstPat; i<ordersLen; i++) {
+    for (int j=0; j<chans; j++) {
+      subPat[j]=pat[j].getPattern(orders.ord[j][i],false);
+    }
+    if (i>lastSuspectedLoopEnd) {
+      lastSuspectedLoopEnd=i;
+    }
+    for (int j=nextRow; j<patLen; j++) {
+      nextRow=0;
+      bool changingOrder=false;
+      bool jumpingOrder=false;
+      if (wsWalked[((i<<5)+(j>>3))&8191]&(1<<(j&7))) {
+        loopOrder=i;
+        loopRow=j;
+        loopEnd=lastSuspectedLoopEnd;
+        return true;
+      }
+      for (int k=0; k<chans; k++) {
+        for (int l=0; l<pat[k].effectCols; l++) {
+          effectVal=subPat[k]->data[j][5+(l<<1)];
+          if (effectVal<0) effectVal=0;
+          if (subPat[k]->data[j][4+(l<<1)]==0x0d) {
+            if (jumpTreatment==2) {
+              if ((i<ordersLen-1 || !ignoreJumpAtEnd)) {
+                nextOrder=i+1;
+                nextRow=effectVal;
+                jumpingOrder=true;
+              }
+            } else if (jumpTreatment==1) {
+              if (nextOrder==-1 && (i<ordersLen-1 || !ignoreJumpAtEnd)) {
+                nextOrder=i+1;
+                nextRow=effectVal;
+                jumpingOrder=true;
+              }
+            } else {
+              if ((i<ordersLen-1 || !ignoreJumpAtEnd)) {
+                if (!changingOrder) {
+                  nextOrder=i+1;
+                }
+                jumpingOrder=true;
+                nextRow=effectVal;
+              }
+            }
+          } else if (subPat[k]->data[j][4+(l<<1)]==0x0b) {
+            if (nextOrder==-1 || jumpTreatment==0) {
+              nextOrder=effectVal;
+              if (jumpTreatment==1 || jumpTreatment==2 || !jumpingOrder) {
+                nextRow=0;
+              }
+              changingOrder=true;
+            }
+          }
+        }
+      }
+
+      wsWalked[((i<<5)+(j>>3))&8191]|=1<<(j&7);
+      
+      if (nextOrder!=-1) {
+        i=nextOrder-1;
+        nextOrder=-1;
+        break;
+      }
+    }
+  }
+  return false;
+}
+
 void DivSubSong::clearData() {
   for (int i=0; i<DIV_MAX_CHANS; i++) {
     pat[i].wipePatterns();
@@ -128,7 +210,122 @@ void DivSubSong::makePatUnique() {
   }
 }
 
-void DivSong::findSubSongs() {
+void DivSong::findSubSongs(int chans) {
+  std::vector<DivSubSong*> newSubSongs;
+  for (DivSubSong* i: subsong) {
+    std::vector<int> subSongStart;
+    std::vector<int> subSongEnd;
+    int loopOrder=0;
+    int loopRow=0;
+    int loopEnd=-1;
+    int curStart=-1;
+
+    // find possible subsongs
+    logD("finding subsongs...");
+    while (++curStart<i->ordersLen) {
+      if (!i->walk(loopOrder,loopRow,loopEnd,chans,jumpTreatment,ignoreJumpAtEnd,curStart)) break;
+      
+      // make sure we don't pick the same range twice
+      if (!subSongEnd.empty()) {
+        if (subSongEnd.back()==loopEnd) continue;
+      }
+
+      logV("found a subsong: %d-%d",curStart,loopEnd);
+      subSongStart.push_back(curStart);
+      subSongEnd.push_back(loopEnd);
+    }
+
+    // if this is the only song, quit
+    if (subSongStart.size()<2) {
+      subSongStart.clear();
+      subSongEnd.clear();
+      newSubSongs.clear();
+      continue;
+    }
+
+    // now copy the song
+    bool isTouched[DIV_MAX_CHANS][DIV_MAX_PATTERNS];
+    memset(isTouched,0,DIV_MAX_CHANS*DIV_MAX_PATTERNS*sizeof(bool));
+    for (size_t j=1; j<subSongStart.size(); j++) {
+      bool isUsed[DIV_MAX_CHANS][DIV_MAX_PATTERNS];
+      int start=subSongStart[j];
+      int end=subSongEnd[j];
+
+      DivSubSong* theCopy=new DivSubSong;
+
+      theCopy->name=i->name;
+      theCopy->notes=i->notes;
+      theCopy->hilightA=i->hilightA;
+      theCopy->hilightB=i->hilightB;
+      theCopy->timeBase=i->timeBase;
+      theCopy->arpLen=i->arpLen;
+      theCopy->speeds=i->speeds;
+      theCopy->virtualTempoN=i->virtualTempoN;
+      theCopy->virtualTempoD=i->virtualTempoD;
+      theCopy->hz=i->hz;
+      theCopy->patLen=i->patLen;
+
+      // copy orders
+      memset(isUsed,0,DIV_MAX_CHANS*DIV_MAX_PATTERNS*sizeof(bool));
+      for (int k=start, kIndex=0; k<=end; k++, kIndex++) {
+        for (int l=0; l<DIV_MAX_CHANS; l++) {
+          theCopy->orders.ord[l][kIndex]=i->orders.ord[l][k];
+          isUsed[l][i->orders.ord[l][k]]=true;
+          isTouched[l][i->orders.ord[l][k]]=true;
+        }
+      }
+      theCopy->ordersLen=end-start+1;
+      
+      memcpy(theCopy->chanShow,i->chanShow,DIV_MAX_CHANS*sizeof(bool));
+      memcpy(theCopy->chanShowChanOsc,i->chanShowChanOsc,DIV_MAX_CHANS*sizeof(bool));
+      memcpy(theCopy->chanCollapse,i->chanCollapse,DIV_MAX_CHANS);
+
+      for (int k=0; k<DIV_MAX_CHANS; k++) {
+        theCopy->chanName[k]=i->chanName[k];
+        theCopy->chanShortName[j]=i->chanShortName[k];
+
+        theCopy->pat[k].effectCols=i->pat[k].effectCols;
+
+        for (int l=0; l<DIV_MAX_PATTERNS; l++) {
+          if (i->pat[k].data[l]==NULL) continue;
+          if (!isUsed[k][l]) continue;
+          DivPattern* origPat=i->pat[k].getPattern(l,false);
+          DivPattern* copyPat=theCopy->pat[k].getPattern(l,true);
+          origPat->copyOn(copyPat);
+        }
+      }
+
+      newSubSongs.push_back(theCopy);
+    }
+
+    // and cut this one
+    i->ordersLen=subSongEnd[0]+1;
+
+    // remove taken patterns as well, as long as they're not used in the original subsong
+    // first unmark patterns which are used
+    for (int j=subSongStart[0]; j<=subSongEnd[0]; j++) {
+      for (int k=0; k<DIV_MAX_CHANS; k++) {
+        isTouched[k][i->orders.ord[k][j]]=false;
+      }
+    }
+
+    // then remove the rest
+    for (int j=0; j<DIV_MAX_CHANS; j++) {
+      for (int k=0; k<DIV_MAX_PATTERNS; k++) {
+        if (isTouched[j][k]) {
+          if (i->pat[j].data[k]!=NULL) {
+            delete i->pat[j].data[k];
+            i->pat[j].data[k]=NULL;
+          }
+        }
+      }
+    }
+  }
+
+  // append every subsong we found
+  for (DivSubSong* i: newSubSongs) {
+    subsong.push_back(i);
+  }
 
 }
 
diff --git a/src/engine/song.h b/src/engine/song.h
index f9e9bc740..8912ec4a1 100644
--- a/src/engine/song.h
+++ b/src/engine/song.h
@@ -178,6 +178,11 @@ struct DivSubSong {
   String chanName[DIV_MAX_CHANS];
   String chanShortName[DIV_MAX_CHANS];
 
+  /**
+   * walk through the song and determine loop position.
+   */
+  bool walk(int& loopOrder, int& loopRow, int& loopEnd, int chans, int jumpTreatment, int ignoreJumpAtEnd, int firstPat=0);
+
   void clearData();
   void optimizePatterns();
   void rearrangePatterns();
@@ -356,7 +361,7 @@ struct DivSong {
   /**
    * find data past 0Bxx effects and place that into new sub-songs.
    */
-  void findSubSongs();
+  void findSubSongs(int chans);
 
   /**
    * clear orders and patterns.