public PIFFListItem(PIFFEntry entry, IffFile target)
{
Entry = entry;
if (entry.ChunkLabel != "")
{
Name = entry.ChunkLabel;
}
else
{
//try find the original to get name
var chunks = target.SilentListAll();
Replaced = chunks.FirstOrDefault(chunk => chunk.ChunkType == entry.Type && chunk.OriginalID == entry.ChunkID);
if (Replaced == null)
{
Name = "UNKNOWN";
}
else
{
Name = Replaced.OriginalLabel;
}
}
}
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);
}
