/// <summary>Initializes a new instance of the CRC class.</summary>
/// <param name="parameters">The parameters to utilize in the CRC calculation.</param>
/// <exception cref="ArgumentNullException">When the specified parameters are null.</exception>
public Crc(CrcParameters parameters) : base()
{
lock (syncLock) {
if (parameters == null)
{
throw new ArgumentNullException("parameters", Hasher.Properties.Resources.paramCantBeNull);
}
this.parameters = parameters;
HashSizeValue = this.parameters.Order;
Crc.BuildLookup(this.parameters);
lookup = (long[])lookupTables[this.parameters];
if (this.parameters.Order == 64)
{
registerMask = 0x00FFFFFFFFFFFFFF;
}
else
{
registerMask = (long)(Math.Pow(2, (this.parameters.Order - 8)) - 1);
}
checksum = this.parameters.InitialValue;
if (this.parameters.ReflectInput)
{
checksum = Reflect(checksum, this.parameters.Order);
}
}
}
/// <summary>Initializes a new instance of the XUM32 class.</summary>
public Xum32() : base()
{
lock (syncLock) {
HashSizeValue = 32;
crcHash = new Crc(CrcParameters.GetParameters(CrcStandard.Crc32Bit));
elfHash = new ElfHash();
}
}
/// <summary>Build the CRC lookup table for a given polynomial.</summary>
static private void BuildLookup(CrcParameters param)
{
if (lookupTables.Contains(param))
{
// No sense in creating the table twice.
return;
}
long[] table = new long[256];
long topBit = (long)1 << (param.Order - 1);
long widthMask = (((1 << (param.Order - 1)) - 1) << 1) | 1;
// Build the table.
for (int i = 0; i < table.Length; i++)
{
table[i] = i;
if (param.ReflectInput)
{
table[i] = Reflect((long)i, 8);
}
table[i] = table[i] << (param.Order - 8);
for (int j = 0; j < 8; j++)
{
if ((table[i] & topBit) != 0)
{
table[i] = (table[i] << 1) ^ param.Polynomial;
}
else
{
table[i] <<= 1;
}
}
if (param.ReflectInput)
{
table[i] = Reflect(table[i], param.Order);
}
table[i] &= widthMask;
}
// Add the new lookup table.
lookupTables.Add(param, table);
}
/// <summary>Retrieves a standard set of CRC parameters.</summary>
/// <param name="standard">The name of the standard parameter set to retrieve.</param>
/// <returns>The CRC Parameters for the given standard.</returns>
public static CrcParameters GetParameters(CrcStandard standard)
{
CrcParameters param = null;
switch (standard)
{
case CrcStandard.Crc8Bit: param = new CrcParameters(8, 0x07, 0, 0, false); break;
case CrcStandard.Crc8BitIcode: param = new CrcParameters(8, 0x1D, 0xFD, 0, false); break;
case CrcStandard.Crc8BitItu: param = new CrcParameters(8, 0x07, 0, 0x55, false); break;
case CrcStandard.Crc8BitMaxim: param = new CrcParameters(8, 0x31, 0, 0, true); break;
case CrcStandard.Crc8BitWcdma: param = new CrcParameters(8, 0x9B, 0, 0, true); break;
case CrcStandard.Crc16Bit: param = new CrcParameters(16, 0x8005, 0, 0, true); break;
case CrcStandard.Crc16BitArc: goto case CrcStandard.Crc16Bit;
case CrcStandard.Crc16BitIbm: goto case CrcStandard.Crc16Bit;
case CrcStandard.Crc16BitLha: goto case CrcStandard.Crc16Bit;
case CrcStandard.Crc16BitCcitt: param = new CrcParameters(16, 0x1021, 0, 0, true); break;
case CrcStandard.Crc16BitKermit: goto case CrcStandard.Crc16BitCcitt;
case CrcStandard.Crc16BitCcittFalse: param = new CrcParameters(16, 0x1021, 0xFFFF, 0, false); break;
case CrcStandard.Crc16BitMaxim: param = new CrcParameters(16, 0x8005, 0, 0xFFFF, true); break;
case CrcStandard.Crc16BitUsb: param = new CrcParameters(16, 0x8005, 0xFFFF, 0xFFFF, true); break;
case CrcStandard.Crc16BitX25: param = new CrcParameters(16, 0x1021, 0xFFFF, 0xFFFF, true); break;
case CrcStandard.Crc16BitXmodem: param = new CrcParameters(16, 0x1021, 0, 0, false); break;
case CrcStandard.Crc16BitZmodem: goto case CrcStandard.Crc16BitXmodem;
case CrcStandard.Crc16BitXkermit: param = new CrcParameters(16, 0x8408, 0, 0, true); break;
case CrcStandard.Crc24Bit: param = new CrcParameters(24, 0x864CFB, 0xB704CE, 0, false); break;
case CrcStandard.Crc24BitOpenPgp: goto case CrcStandard.Crc24Bit;
case CrcStandard.Crc32Bit: param = new CrcParameters(32, 0x04C11DB7, 0xFFFFFFFF, 0xFFFFFFFF, true); break;
case CrcStandard.Crc32BitPkzip: goto case CrcStandard.Crc32Bit;
case CrcStandard.Crc32BitItu: goto case CrcStandard.Crc32Bit;
case CrcStandard.Crc32BitBzip2: param = new CrcParameters(32, 0x04C11DB7, 0xFFFFFFFF, 0xFFFFFFFF, false); break;
case CrcStandard.Crc32BitIscsi: param = new CrcParameters(32, 0x1EDC6F41, 0xFFFFFFFF, 0xFFFFFFFF, true); break;
case CrcStandard.Crc32BitJam: param = new CrcParameters(32, 0x04C11DB7, 0xFFFFFFFF, 0, true); break;
case CrcStandard.Crc32BitPosix: param = new CrcParameters(32, 0x04C11DB7, 0, 0xFFFFFFFF, false); break;
case CrcStandard.Crc32BitCksum: goto case CrcStandard.Crc32BitPosix;
case CrcStandard.Crc32BitMpeg2: param = new CrcParameters(32, 0x04C11DB7, 0xFFFFFFFF, 0, false); break;
case CrcStandard.Crc64Bit: param = new CrcParameters(64, 0x42F0E1EBA9EA3693, 0, 0, false); break;
case CrcStandard.Crc64BitWE: param = new CrcParameters(64, (long)0x42F0E1EBA9EA3693, -1, -1, false); break;
case CrcStandard.Crc64BitIso: param = new CrcParameters(64, 0x000000000000001B, 0, 0, true); break;
case CrcStandard.Crc64BitJones: param = new CrcParameters(64, unchecked ((long)0xAD93D23594C935A9), 0, 0, true); break;
}
return(param);
}
/// <summary>Initializes a new instance of the Cksum class.</summary>
public Cksum() : base(CrcParameters.GetParameters(CrcStandard.Crc32BitCksum)) { }
// Pre-build the more popular lookup tables.
static Crc()
{
lookupTables = new Hashtable();
BuildLookup(CrcParameters.GetParameters(CrcStandard.Crc32Bit));
}
/// <summary>Initializes a new instance of the CRC class.</summary>
/// <remarks>This constructor implements the default parameters of Crc32Bit.</remarks>
public Crc() : this(CrcParameters.GetParameters(CrcStandard.Crc32Bit))
{
}
// Pre-build the more popular lookup tables.
static Crc()
{
lookupTables = new Dictionary <CrcParameters, long[]>();
BuildLookup(CrcParameters.GetParameters(CrcStandard.Crc32Bit));
}
