/// <summary>
/// Decode the volume resource map.
/// </summary>
/// <param name="data">Resource map data.</param>
/// <param name="startOffset">Start offset in resource map data.</param>
/// <param name="length">Length of resource map data (in bytes).</param>
/// <param name="resourceMapEntries">Resource map entry collection to add decoded entries to.</param>
internal static void ReadResourceMap(byte[] data, int startOffset, int length, VolumeResourceMapEntryCollection resourceMapEntries)
{
int count = length / 3;
if (count > 255)
{
// There can't be more than 255 resources for a particular type of resource
// If the resource map is longer than that, it is probably padded with junk
count = 255;
}
for (int index = 0; index < count; index++)
{
int dataOffset = startOffset + (index * 3);
byte b0 = data[dataOffset + 0];
byte b1 = data[dataOffset + 1];
byte b2 = data[dataOffset + 2];
// [0][1][2] = volume file number and position in that volume file
// [0] = 76543210 [1] = 76543210 [2] = 76543210
// [0] = VVVVPPPP [1] = PPPPPPPP [2] = PPPPPPPP
// When all three bytes are 0xff it means the resource doesn't exist
if (!(b0 == 0xff && b1 == 0xff && b2 == 0xff))
{
int volume = (b0 & 0xf0) >> 4;
int resOffset = ((b0 & 0x0f) * 0x10000) + (b1 * 0x100) + b2;
var entry = new VolumeResourceMapEntry((byte)index, (byte)volume, resOffset);
resourceMapEntries.Add(entry);
}
}
}
private static void LoadResourceMapFile(byte[] data, VolumeResourceMapEntryCollection resourceMapEntries)
{
VolumeDecoder.ReadResourceMap(data, 0, data.Length, resourceMapEntries);
}
