public override void Read(IffFile iff, Stream stream)
{
using (var io = IoBuffer.FromStream(stream, ByteOrder.LITTLE_ENDIAN))
{
Version = io.ReadUInt16();
SourceIff = io.ReadVariableLengthPascalString();
if (Version > 1)
{
Comment = io.ReadVariableLengthPascalString();
}
Entries = new PIFFEntry[io.ReadUInt16()];
for (int i = 0; i < Entries.Length; i++)
{
var e = new PIFFEntry();
e.Type = io.ReadCString(4);
e.ChunkID = io.ReadUInt16();
if (Version > 1)
{
e.Comment = io.ReadVariableLengthPascalString();
}
e.EntryType = (PIFFEntryType)io.ReadByte();
if (e.EntryType == PIFFEntryType.Patch)
{
e.ChunkLabel = io.ReadVariableLengthPascalString();
e.ChunkFlags = io.ReadUInt16();
if (Version > 0)
{
e.NewChunkID = io.ReadUInt16();
}
else
{
e.NewChunkID = e.ChunkID;
}
e.NewDataSize = io.ReadUInt32();
var size = io.ReadUInt32();
e.Patches = new PIFFPatch[size];
uint lastOff = 0;
for (int j = 0; j < e.Patches.Length; j++)
{
var p = new PIFFPatch();
p.Offset = lastOff + io.ReadVarLen();
lastOff = p.Offset;
p.Size = io.ReadVarLen();
p.Mode = (PIFFPatchMode)io.ReadByte();
if (p.Mode == PIFFPatchMode.Add)
{
p.Data = io.ReadBytes(p.Size);
}
e.Patches[j] = p;
}
}
Entries[i] = e;
}
}
}
public override void Read(IffFile iff, Stream stream)
{
using (var io = IoBuffer.FromStream(stream, ByteOrder.LITTLE_ENDIAN))
{
Version = io.ReadUInt16();
SourceIff = io.ReadVariableLengthPascalString();
Entries = new PIFFEntry[io.ReadUInt16()];
for (int i=0; i<Entries.Length; i++)
{
var e = new PIFFEntry();
e.Type = io.ReadCString(4);
e.ChunkID = io.ReadUInt16();
e.Delete = io.ReadByte()>0;
if (!e.Delete)
{
e.ChunkLabel = io.ReadVariableLengthPascalString();
e.ChunkFlags = io.ReadUInt16();
if (Version > 0) e.NewChunkID = io.ReadUInt16();
else e.NewChunkID = e.ChunkID;
e.NewDataSize = io.ReadUInt32();
var size = io.ReadUInt32();
e.Patches = new PIFFPatch[size];
uint lastOff = 0;
for (int j=0; j<e.Patches.Length; j++)
{
var p = new PIFFPatch();
p.Offset = lastOff + io.ReadVarLen();
lastOff = p.Offset;
p.Size = io.ReadVarLen();
p.Mode = (PIFFPatchMode)io.ReadByte();
if (p.Mode == PIFFPatchMode.Add) p.Data = io.ReadBytes(p.Size);
e.Patches[j] = p;
}
}
Entries[i] = e;
}
}
}
public static PIFFEntry MakeChunkDiff(IffChunk chk)
{
var e = new PIFFEntry { Type = chk.ChunkType, ChunkID = chk.OriginalID, NewChunkID = chk.ChunkID };
if (chk == null)
{
e.Delete = true;
return e;
}
byte[] newData = null;
using (var stream = new MemoryStream())
{
if (!chk.Write(chk.ChunkParent, stream))
{
return null; //use original
}
newData = stream.ToArray();
}
e.ChunkLabel = (chk.OriginalLabel==chk.ChunkLabel)?"":chk.ChunkLabel;
e.ChunkFlags = chk.ChunkFlags;
e.NewDataSize = (uint)newData.Length;
//encode difference as sequence of changes
var oldData = chk.OriginalData;
var patches = new List<PIFFPatch>();
int i;
for (i=0; i<newData.Length; i += 1000)
{
if (i >= oldData.Length)
{
//no more comparisons, just add the remainder
var remain = new byte[newData.Length-i];
Array.Copy(newData, i, remain, 0, remain.Length);
patches.Add(new PIFFPatch
{
Mode = PIFFPatchMode.Add,
Data = remain,
Offset = (uint)i,
Size = (uint)remain.Length
});
break;
}
//dynamic programming matrix.
int m = Math.Min(1000, Math.Max(0, newData.Length - i))+1;
int n = Math.Min(1000, Math.Max(0, oldData.Length - i))+1;
ushort[,] comp = new ushort[m, n];
for (int x=1; x<m; x++)
{
for (int y=1; y<n; y++)
{
if (newData[i+x-1] == oldData[i + y -1]) comp[x, y] = (ushort)(comp[x - 1, y - 1] + 1);
else comp[x, y] = Math.Max(comp[x, y - 1], comp[x - 1, y]);
}
}
var changes = new Stack<byte>();
//backtrack through compare
{
int x = m-1, y = n-1;
while (true)
{
if (x>0 && y>0 && newData[i + x -1] == oldData[i + y -1])
{
x--; y--; changes.Push(0); //no change
} else if (y>0 && (x==0 || comp[x,y-1] >= comp[x-1,y]))
{
y--; changes.Push(2); //remove
} else if (x>0 && (y==0 || comp[x,y-1] < comp[x-1,y]))
{
x--; changes.Push(1); //add
} else
{
break;
}
}
}
byte lastC = 0;
PIFFPatch curr = null;
List<byte> addArray = null;
int ptr = 0;
foreach (var c in changes)
{
if (c != lastC && curr != null)
{
if (lastC == 1) curr.Data = addArray.ToArray();
patches.Add(curr);
curr = null;
}
if (c == 0) ptr++;
else if (c == 1)
{
if (lastC != 1)
{
curr = new PIFFPatch { Mode = PIFFPatchMode.Add, Offset = (uint)(i + ptr), Size = 1 };
addArray = new List<byte>();
addArray.Add(newData[i + ptr]);
}
else
{
curr.Size++;
addArray.Add(newData[i + ptr]);
}
ptr++;
}
else
{
if (lastC != 2)
curr = new PIFFPatch { Mode = PIFFPatchMode.Remove, Offset = (uint)(i + ptr), Size = 1 };
else
curr.Size++;
}
lastC = c;
}
if (curr != null)
{
if (lastC == 1) curr.Data = addArray.ToArray();
patches.Add(curr);
}
if (m < n)
{
//remainder on src to be removed
patches.Add(new PIFFPatch { Mode = PIFFPatchMode.Remove, Offset = (uint)(i+ptr), Size = (uint)(n-m) });
}
/*else if (m != n)
{
//remainder on dest to be added
var remain = new byte[m-n];
Array.Copy(newData, i+ptr, remain, 0, remain.Length);
patches.Add(new PIFFPatch
{
Mode = PIFFPatchMode.Add,
Data = remain,
Offset = (uint)(i+ ptr),
Size = (uint)remain.Length
});
}*/
}
if (oldData.Length > i)
{
//ran out of new data, but old is still going. Remove the remainder.
patches.Add(new PIFFPatch
{
Mode = PIFFPatchMode.Remove,
Offset = (uint)newData.Length,
Size = (uint)(oldData.Length - i)
});
}
e.Patches = patches.ToArray();
return e;
}