/// <summary>
/// Calculate CRC32 for PRG and CHR fields and store it into PCKx and CCKx fields
/// </summary>
public void CalculateAndStoreCRCs()
{
foreach (var key in Fields.Keys.Where(k => k.StartsWith("PRG")))
{
var num = key[3];
var crc32 = Crc32Calculator.CalculateCRC32(Fields[key]);
Fields[$"PCK{num}"] = new byte[] {
(byte)(crc32 & 0xFF),
(byte)((crc32 >> 8) & 0xFF),
(byte)((crc32 >> 16) & 0xFF),
(byte)((crc32 >> 24) & 0xFF)
};
}
foreach (var key in Fields.Keys.Where(k => k.StartsWith("CHR")))
{
var num = key[3];
var crc32 = Crc32Calculator.CalculateCRC32(Fields[key]);
Fields[$"CCK{num}"] = new byte[] {
(byte)(crc32 & 0xFF),
(byte)((crc32 >> 8) & 0xFF),
(byte)((crc32 >> 16) & 0xFF),
(byte)((crc32 >> 24) & 0xFF)
};
}
}
/// <summary>
/// Calculate overall CRC32
/// </summary>
/// <returns></returns>
public uint CalculateCRC32()
=> Crc32Calculator.CalculateCRC32(
Enumerable.Concat(Fields.Where(k => k.Key.StartsWith("PRG")).OrderBy(k => k.Key).SelectMany(i => i.Value),
Fields.Where(k => k.Key.StartsWith("CHR")).OrderBy(k => k.Key).SelectMany(i => i.Value)).ToArray()
);
