/// <summary>
/// Updates the tag instance's state from a block of tag data.
/// </summary>
/// <param name="data">The tag data.</param>
/// <param name="dataOffset">The offset of the tag data relative to the tag instance's header.</param>
internal void Update(CachedTagData data, uint dataOffset)
{
Group = data.Group;
DefinitionOffset = data.MainStructOffset + dataOffset;
Dependencies = new ReadOnlySet <int>(new HashSet <int>(data.Dependencies));
_pointerOffsets = data.PointerFixups.Select(fixup => fixup.WriteOffset + dataOffset).ToList();
_resourceOffsets = data.ResourcePointerOffsets.Select(offset => offset + dataOffset).ToList();
}
/// <summary>
/// Builds a description for a tag's data without extracting anything.
/// </summary>
/// <param name="stream">The stream to read from.</param>
/// <param name="tag">The tag to read.</param>
/// <param name="dataOffset">On return, this will contain the offset of the tag's data relative to its header.</param>
/// <returns>The description that was built. </returns>
private static CachedTagData BuildTagData(Stream stream, CachedTagInstance tag, out uint dataOffset)
{
var data = new CachedTagData
{
Group = tag.Group,
MainStructOffset = tag.DefinitionOffset,
};
foreach (var dependency in tag.Dependencies)
{
data.Dependencies.Add(dependency);
}
// Read pointer fixups
var reader = new BinaryReader(stream);
foreach (var pointerOffset in tag.PointerOffsets)
{
reader.BaseStream.Position = tag.HeaderOffset + pointerOffset;
data.PointerFixups.Add(new CachedTagData.PointerFixup
{
WriteOffset = pointerOffset,
TargetOffset = tag.PointerToOffset(reader.ReadUInt32()),
});
}
// Find the start of the tag's data by finding the offset of the first block which is pointed to by something
// We CAN'T just calculate a header size here because we don't know for sure if there's padding and how big it is
var startOffset = tag.DefinitionOffset;
foreach (var fixup in data.PointerFixups)
{
startOffset = Math.Min(startOffset, Math.Min(fixup.WriteOffset, fixup.TargetOffset));
}
// Now convert all offsets into relative ones
foreach (var fixup in data.PointerFixups)
{
fixup.WriteOffset -= startOffset;
fixup.TargetOffset -= startOffset;
}
data.ResourcePointerOffsets.AddRange(tag.ResourcePointerOffsets.Select(offset => offset - startOffset));
data.TagReferenceOffsets.AddRange(tag.TagReferenceOffsets.Select(offset => offset - startOffset));
data.MainStructOffset -= startOffset;
dataOffset = startOffset;
return(data);
}
/// <summary>
/// Overwrites a tag's data.
/// </summary>
/// <param name="stream">The stream to write to.</param>
/// <param name="tag">The tag to overwrite.</param>
/// <param name="data">The data to store.</param>
public void SetTagData(Stream stream, CachedTagInstance tag, CachedTagData data)
{
if (tag == null)
{
throw new ArgumentNullException(nameof(tag));
}
else if (data == null)
{
throw new ArgumentNullException(nameof(data));
}
else if (data.Group == TagGroup.None)
{
throw new ArgumentException("Cannot assign a tag to a null tag group");
}
else if (data.Data == null)
{
throw new ArgumentException("The tag data buffer is null");
}
// Ensure the data fits
var headerSize = CachedTagInstance.CalculateHeaderSize(data);
var alignedHeaderSize = (uint)((headerSize + 0xF) & ~0xF);
if (tag.HeaderOffset < 0)
{
tag.HeaderOffset = GetNewTagOffset(tag.Index);
}
var alignedLength = (data.Data.Length + 0xF) & ~0xF;
ResizeBlock(stream, tag, tag.HeaderOffset, tag.TotalSize, alignedHeaderSize + alignedLength);
tag.TotalSize = alignedHeaderSize + alignedLength;
tag.Update(data, alignedHeaderSize);
// Write in the new header and data
stream.Position = tag.HeaderOffset;
var writer = new BinaryWriter(stream);
tag.WriteHeader(writer);
StreamUtil.Fill(stream, 0, (int)(alignedHeaderSize - headerSize));
stream.Write(data.Data, 0, data.Data.Length);
StreamUtil.Fill(stream, 0, alignedLength - data.Data.Length);
// Correct pointers
foreach (var fixup in data.PointerFixups)
{
writer.BaseStream.Position = tag.HeaderOffset + alignedHeaderSize + fixup.WriteOffset;
writer.Write(tag.OffsetToPointer(alignedHeaderSize + fixup.TargetOffset));
}
UpdateTagOffsets(writer);
}
/// <summary>
/// Calculates the header size that would be needed for a given block of tag data.
/// </summary>
/// <param name="data">The descriptor to use.</param>
/// <returns>The size of the tag's header.</returns>
internal static uint CalculateHeaderSize(CachedTagData data) =>
(uint)(TagHeaderSize +
data.Dependencies.Count * 4 +
data.PointerFixups.Count * 4 +
data.ResourcePointerOffsets.Count * 4 +
data.TagReferenceOffsets.Count * 4);