Save the size of each block in a Furnace module

papers/format.md

@@ -130,7 +130,7 @@ size | description
 size | description
 -----|------------------------------------
   4  | "INFO" block ID
-  4  | reserved
+  4  | size of the block excluding the ID and this field
   1  | time base (of first song)
   1  | speed 1 (of first song)
   1  | speed 2 (of first song)
@@ -332,7 +332,7 @@ the way it's currently done is really weird, but it provides for some backwards
 size | description
 -----|------------------------------------
   4  | "SONG" block ID
-  4  | reserved
+  4  | size of the block excluding the ID and this field
   1  | time base
   1  | speed 1
   1  | speed 2
@@ -386,7 +386,7 @@ notes:
 size | description
 -----|------------------------------------
   4  | "INST" block ID
-  4  | reserved
+  4  | size of the block excluding the ID and this field
   2  | format version (see header)
   1  | instrument type
      | - 0: standard
@@ -795,7 +795,7 @@ size | description
 size | description
 -----|------------------------------------
   4  | "WAVE" block ID
-  4  | reserved
+  4  | size of the block excluding the ID and this field
  STR | wavetable name
   4  | wavetable size
   4  | wavetable min
@@ -809,7 +809,7 @@ size | description
 size | description
 -----|------------------------------------
   4  | "SMPL" block ID
-  4  | reserved
+  4  | size of the block excluding the ID and this field
  STR | sample name
   4  | length
   4  | rate
@@ -841,7 +841,7 @@ size | description
 size | description
 -----|------------------------------------
   4  | "PATR" block ID
-  4  | reserved
+  4  | size of the block excluding the ID and this field
   2  | channel
   2  | pattern index
   2  | subsong (>=95) or reserved

src/engine/fileOps.cpp

@@ -2696,7 +2696,7 @@ SafeWriter* DivEngine::saveFur(bool notPrimary) {
   std::vector<int> wavePtr;
   std::vector<int> samplePtr;
   std::vector<int> patPtr;
-  size_t ptrSeek, subSongPtrSeek;
+  size_t ptrSeek, subSongPtrSeek, blockStartSeek, blockEndSeek;
   size_t subSongIndex=0;
   DivSubSong* subSong=song.subsong[subSongIndex];
   warnings="";
@@ -2775,6 +2775,7 @@ SafeWriter* DivEngine::saveFur(bool notPrimary) {
 
   /// SONG INFO
   w->write("INFO",4);
+  blockStartSeek=w->tell();
   w->writeI(0);
 
   w->writeC(subSong->timeBase);
@@ -2932,11 +2933,17 @@ SafeWriter* DivEngine::saveFur(bool notPrimary) {
     w->writeI(0);
   }
 
+  blockEndSeek=w->tell();
+  w->seek(blockStartSeek,SEEK_SET);
+  w->writeI(blockEndSeek-blockStartSeek-4);
+  w->seek(0,SEEK_END);
+
   /// SUBSONGS
   for (subSongIndex=1; subSongIndex<song.subsong.size(); subSongIndex++) {
     subSong=song.subsong[subSongIndex];
     subSongPtr.push_back(w->tell());
     w->write("SONG",4);
+    blockStartSeek=w->tell();
     w->writeI(0);
 
     w->writeC(subSong->timeBase);
@@ -2979,6 +2986,11 @@ SafeWriter* DivEngine::saveFur(bool notPrimary) {
     for (int i=0; i<chans; i++) {
       w->writeString(subSong->chanShortName[i],false);
     }
+
+    blockEndSeek=w->tell();
+    w->seek(blockStartSeek,SEEK_SET);
+    w->writeI(blockEndSeek-blockStartSeek-4);
+    w->seek(0,SEEK_END);
   }
 
   /// INSTRUMENT
@@ -3000,6 +3012,7 @@ SafeWriter* DivEngine::saveFur(bool notPrimary) {
     DivSample* sample=song.sample[i];
     samplePtr.push_back(w->tell());
     w->write("SMPL",4);
+    blockStartSeek=w->tell();
     w->writeI(0);
 
     w->writeString(sample->name,false);
@@ -3012,6 +3025,11 @@ SafeWriter* DivEngine::saveFur(bool notPrimary) {
     w->writeI(sample->loopStart);
 
     w->write(sample->getCurBuf(),sample->getCurBufLen());
+
+    blockEndSeek=w->tell();
+    w->seek(blockStartSeek,SEEK_SET);
+    w->writeI(blockEndSeek-blockStartSeek-4);
+    w->seek(0,SEEK_END);
   }
 
   /// PATTERN
@@ -3019,6 +3037,7 @@ SafeWriter* DivEngine::saveFur(bool notPrimary) {
     DivPattern* pat=song.subsong[i.subsong]->pat[i.chan].getPattern(i.pat,false);
     patPtr.push_back(w->tell());
     w->write("PATR",4);
+    blockStartSeek=w->tell();
     w->writeI(0);
 
     w->writeS(i.chan);
@@ -3036,6 +3055,11 @@ SafeWriter* DivEngine::saveFur(bool notPrimary) {
     }
 
     w->writeString(pat->name,false);
+
+    blockEndSeek=w->tell();
+    w->seek(blockStartSeek,SEEK_SET);
+    w->writeI(blockEndSeek-blockStartSeek-4);
+    w->seek(0,SEEK_END);
   }
 
   /// POINTERS

src/engine/instrument.cpp

@@ -24,7 +24,10 @@
 #include "../fileutils.h"
 
 void DivInstrument::putInsData(SafeWriter* w) {
+  size_t blockStartSeek, blockEndSeek;
+
   w->write("INST",4);
+  blockStartSeek=w->tell();
   w->writeI(0);
 
   w->writeS(DIV_ENGINE_VERSION);
@@ -520,6 +523,11 @@ void DivInstrument::putInsData(SafeWriter* w) {
   for (int j=0; j<23; j++) { // reserved
     w->writeC(0);
   }
+
+  blockEndSeek=w->tell();
+  w->seek(blockStartSeek,SEEK_SET);
+  w->writeI(blockEndSeek-blockStartSeek-4);
+  w->seek(0,SEEK_END);
 }
 
 DivDataErrors DivInstrument::readInsData(SafeReader& reader, short version) {

src/engine/wavetable.cpp

@@ -24,7 +24,10 @@
 #include "../fileutils.h"
 
 void DivWavetable::putWaveData(SafeWriter* w) {
+  size_t blockStartSeek, blockEndSeek;
+
   w->write("WAVE",4);
+  blockStartSeek=w->tell();
   w->writeI(0);
 
   w->writeC(0); // name
@@ -34,6 +37,11 @@ void DivWavetable::putWaveData(SafeWriter* w) {
   for (int j=0; j<len; j++) {
     w->writeI(data[j]);
   }
+
+  blockEndSeek=w->tell();
+  w->seek(blockStartSeek,SEEK_SET);
+  w->writeI(blockEndSeek-blockStartSeek-4);
+  w->seek(0,SEEK_END);
 }
 
 DivDataErrors DivWavetable::readWaveData(SafeReader& reader, short version) {