/// <inheritdoc />
protected override async Task<byte[]> ComputeHashAsyncInternal(UnifiedData data)
{
UInt32 hash = 0;
await data.ForEachReadAsync((dataBytes, position, length) => {
ProcessBytes(ref hash, dataBytes, position, length);
}).ConfigureAwait(false);
return BitConverter.GetBytes(hash);
}
/// <inheritdoc />
protected override async Task<byte[]> ComputeHashAsyncInternal(UnifiedData data)
{
// Use 64-bit variable regardless of CRC bit length
UInt64 hash = Settings.InitialValue;
// Reflect InitialValue if processing as big endian
if (Settings.ReflectIn)
hash = hash.ReflectBits(HashSize);
// Store table reference in local variable to lower overhead.
var crcTable = Settings.DataDivisionTable;
// How much hash must be right-shifted to get the most significant byte (HashSize >= 8) or bit (HashSize < 8)
int mostSignificantShift = HashSize - 8;
if (HashSize < 8)
mostSignificantShift = HashSize - 1;
await data.ForEachReadAsync((dataBytes, position, length) => {
ProcessBytes(ref hash, crcTable, mostSignificantShift, dataBytes, position, length);
}).ConfigureAwait(false);
// Account for mixed-endianness
if (Settings.ReflectIn ^ Settings.ReflectOut)
hash = hash.ReflectBits(HashSize);
hash ^= Settings.XOrOut;
return hash.ToBytes(HashSize);
}
/// <inheritdoc />
protected override async Task<byte[]> ComputeHashAsyncInternal(UnifiedData data)
{
var prime = HashParameters[HashSize].Prime;
var offset = HashParameters[HashSize].Offset;
// Handle 32-bit and 64-bit cases in a strongly-typed manner for performance
if (HashSize == 32)
{
var hash = offset[0];
await data.ForEachReadAsync(
(dataBytes, position, length) => {
ProcessBytes32(ref hash, prime[0], dataBytes, position, length);
}).ConfigureAwait(false);
return BitConverter.GetBytes(hash);
} else if (HashSize == 64) {
var hash = ((UInt64) offset[1] << 32) | offset[0];
var prime64 = ((UInt64) prime[1] << 32) | prime[0];
await data.ForEachReadAsync(
(dataBytes, position, length) => {
ProcessBytes64(ref hash, prime64, dataBytes, position, length);
}).ConfigureAwait(false);
return BitConverter.GetBytes(hash);
}
// Process extended-sized FNV.
{
var hash = offset.ToArray();
await data.ForEachReadAsync(
(dataBytes, position, length) => {
ProcessBytes(ref hash, prime, dataBytes, position, length);
}).ConfigureAwait(false);
return hash.ToBytes()
.ToArray();
}
}