Added fragment calculations (untested).

writer_fragment.go

@@ -16,6 +16,54 @@ func (f *fragment) SizeLeft() uint32 {
 
 func (f *fragment) AddFragment(fil *fileHolder) {
 	//SizeLeft should already be checked
+	fil.fragOffset = len(f.files)
 	f.files = append(f.files, fil)
 	f.sizes = append(f.sizes, fil.blockSizes[len(fil.blockSizes)-1])
 }
+
+func (w *Writer) addToFragments(fil *fileHolder) {
+	fragSize := fil.blockSizes[len(fil.blockSizes)-1]
+	//only fragment if the final block is less then 80% of a full block or AlwaysFragment
+	if w.Flags.AlwaysFragment || fragSize < uint32(float32(w.BlockSize)*0.8) {
+		var possibleFrags []int
+		for i := range w.frags {
+			left := w.frags[i].SizeLeft()
+			if left == fragSize {
+				fil.fragIndex = i
+				w.frags[i].AddFragment(fil)
+				return
+			} else if left > fragSize {
+				possibleFrags = append(possibleFrags, i)
+			}
+		}
+		if len(possibleFrags) > 0 {
+			fil.fragIndex = possibleFrags[0]
+		} else {
+			fil.fragIndex = len(w.frags)
+			w.frags = append(w.frags, fragment{
+				w:     w,
+				files: []*fileHolder{fil},
+				sizes: []uint32{fragSize},
+			})
+		}
+	}
+}
+
+func (w *Writer) calculateFragsAndBlockSizes() {
+	for _, files := range w.structure {
+		for i := range files {
+			files[i].fragIndex = -1
+			files[i].blockSizes = make([]uint32, files[i].size/uint64(w.BlockSize))
+			for j := range files[i].blockSizes {
+				files[i].blockSizes[j] = w.BlockSize
+			}
+			fragSize := uint32(files[i].size % uint64(w.BlockSize))
+			if fragSize > 0 {
+				files[i].blockSizes = append(files[i].blockSizes, fragSize)
+				if !w.Flags.NoFragments {
+					w.addToFragments(files[i])
+				}
+			}
+		}
+	}
+}