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Speed up crc32 calculations subclassing crcproxy #319

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996357c
Implemented a faster CRC32 calculcation
KarsVeltman Feb 8, 2019
8d64d03
renamed lookupvalue to index
KarsVeltman Feb 8, 2019
5c1ec5e
fixing codacy issues
KarsVeltman Aug 27, 2019
eace3a3
updated Microsoft.SourceLink.GitHub package reference
KarsVeltman Aug 27, 2019
a170360
Merge pull request #1 from icsharpcode/master
decipherer Aug 27, 2019
d3030a4
Merge with master
KarsVeltman Aug 27, 2019
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3 changes: 3 additions & 0 deletions src/ICSharpCode.SharpZipLib/AssemblyInfo.cs
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using System.Runtime.CompilerServices;

[assembly: InternalsVisibleTo("ICSharpCode.SharpZipLib.Tests, PublicKey = 0024000004800000940000000602000000240000525341310004000001000100b9a14ea8fc9d7599e0e82a1292a23103f0210e2f928a0f466963af23fffadba59dcc8c9e26ecd114d7c0b4179e4bc93b1656b7ee2d4a67dd7c1992653e0d9cc534f7914b6f583b022e0a7aa8a430f407932f9a6806f0fc64d61e78d5ae01aa8f8233196719d44da2c50a2d1cfa3f7abb7487b3567a4f0456aa6667154c6749b1")]
180 changes: 4 additions & 176 deletions src/ICSharpCode.SharpZipLib/Checksum/BZip2Crc.cs
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using ICSharpCode.SharpZipLib.Checksum.Proxy;
using System;

namespace ICSharpCode.SharpZipLib.Checksum
{
/// <summary>
/// CRC-32 with unreversed data and reversed output
/// </summary>
/// <remarks>
/// Generate a table for a byte-wise 32-bit CRC calculation on the polynomial:
/// x^32+x^26+x^23+x^22+x^16+x^12+x^11+x^10+x^8+x^7+x^5+x^4+x^2+x^1+x^0.
///
/// Polynomials over GF(2) are represented in binary, one bit per coefficient,
/// with the lowest powers in the most significant bit. Then adding polynomials
/// is just exclusive-or, and multiplying a polynomial by x is a right shift by
/// one. If we call the above polynomial p, and represent a byte as the
/// polynomial q, also with the lowest power in the most significant bit (so the
/// byte 0xb1 is the polynomial x^7+x^3+x+1), then the CRC is (q*x^32) mod p,
/// where a mod b means the remainder after dividing a by b.
///
/// This calculation is done using the shift-register method of multiplying and
/// taking the remainder. The register is initialized to zero, and for each
/// incoming bit, x^32 is added mod p to the register if the bit is a one (where
/// x^32 mod p is p+x^32 = x^26+...+1), and the register is multiplied mod p by
/// x (which is shifting right by one and adding x^32 mod p if the bit shifted
/// out is a one). We start with the highest power (least significant bit) of
/// q and repeat for all eight bits of q.
///
/// The table is simply the CRC of all possible eight bit values. This is all
/// the information needed to generate CRC's on data a byte at a time for all
/// combinations of CRC register values and incoming bytes.
/// </remarks>
public sealed class BZip2Crc : IChecksum
public sealed class BZip2Crc : Crc32Base
{
#region Instance Fields
private static readonly NormalCrc32Proxy _proxy = new NormalCrc32Proxy();

private const uint crcInit = 0xFFFFFFFF;
//const uint crcXor = 0x00000000;

private static readonly uint[] crcTable = {
0X00000000, 0X04C11DB7, 0X09823B6E, 0X0D4326D9,
0X130476DC, 0X17C56B6B, 0X1A864DB2, 0X1E475005,
0X2608EDB8, 0X22C9F00F, 0X2F8AD6D6, 0X2B4BCB61,
0X350C9B64, 0X31CD86D3, 0X3C8EA00A, 0X384FBDBD,
0X4C11DB70, 0X48D0C6C7, 0X4593E01E, 0X4152FDA9,
0X5F15ADAC, 0X5BD4B01B, 0X569796C2, 0X52568B75,
0X6A1936C8, 0X6ED82B7F, 0X639B0DA6, 0X675A1011,
0X791D4014, 0X7DDC5DA3, 0X709F7B7A, 0X745E66CD,
0X9823B6E0, 0X9CE2AB57, 0X91A18D8E, 0X95609039,
0X8B27C03C, 0X8FE6DD8B, 0X82A5FB52, 0X8664E6E5,
0XBE2B5B58, 0XBAEA46EF, 0XB7A96036, 0XB3687D81,
0XAD2F2D84, 0XA9EE3033, 0XA4AD16EA, 0XA06C0B5D,
0XD4326D90, 0XD0F37027, 0XDDB056FE, 0XD9714B49,
0XC7361B4C, 0XC3F706FB, 0XCEB42022, 0XCA753D95,
0XF23A8028, 0XF6FB9D9F, 0XFBB8BB46, 0XFF79A6F1,
0XE13EF6F4, 0XE5FFEB43, 0XE8BCCD9A, 0XEC7DD02D,
0X34867077, 0X30476DC0, 0X3D044B19, 0X39C556AE,
0X278206AB, 0X23431B1C, 0X2E003DC5, 0X2AC12072,
0X128E9DCF, 0X164F8078, 0X1B0CA6A1, 0X1FCDBB16,
0X018AEB13, 0X054BF6A4, 0X0808D07D, 0X0CC9CDCA,
0X7897AB07, 0X7C56B6B0, 0X71159069, 0X75D48DDE,
0X6B93DDDB, 0X6F52C06C, 0X6211E6B5, 0X66D0FB02,
0X5E9F46BF, 0X5A5E5B08, 0X571D7DD1, 0X53DC6066,
0X4D9B3063, 0X495A2DD4, 0X44190B0D, 0X40D816BA,
0XACA5C697, 0XA864DB20, 0XA527FDF9, 0XA1E6E04E,
0XBFA1B04B, 0XBB60ADFC, 0XB6238B25, 0XB2E29692,
0X8AAD2B2F, 0X8E6C3698, 0X832F1041, 0X87EE0DF6,
0X99A95DF3, 0X9D684044, 0X902B669D, 0X94EA7B2A,
0XE0B41DE7, 0XE4750050, 0XE9362689, 0XEDF73B3E,
0XF3B06B3B, 0XF771768C, 0XFA325055, 0XFEF34DE2,
0XC6BCF05F, 0XC27DEDE8, 0XCF3ECB31, 0XCBFFD686,
0XD5B88683, 0XD1799B34, 0XDC3ABDED, 0XD8FBA05A,
0X690CE0EE, 0X6DCDFD59, 0X608EDB80, 0X644FC637,
0X7A089632, 0X7EC98B85, 0X738AAD5C, 0X774BB0EB,
0X4F040D56, 0X4BC510E1, 0X46863638, 0X42472B8F,
0X5C007B8A, 0X58C1663D, 0X558240E4, 0X51435D53,
0X251D3B9E, 0X21DC2629, 0X2C9F00F0, 0X285E1D47,
0X36194D42, 0X32D850F5, 0X3F9B762C, 0X3B5A6B9B,
0X0315D626, 0X07D4CB91, 0X0A97ED48, 0X0E56F0FF,
0X1011A0FA, 0X14D0BD4D, 0X19939B94, 0X1D528623,
0XF12F560E, 0XF5EE4BB9, 0XF8AD6D60, 0XFC6C70D7,
0XE22B20D2, 0XE6EA3D65, 0XEBA91BBC, 0XEF68060B,
0XD727BBB6, 0XD3E6A601, 0XDEA580D8, 0XDA649D6F,
0XC423CD6A, 0XC0E2D0DD, 0XCDA1F604, 0XC960EBB3,
0XBD3E8D7E, 0XB9FF90C9, 0XB4BCB610, 0XB07DABA7,
0XAE3AFBA2, 0XAAFBE615, 0XA7B8C0CC, 0XA379DD7B,
0X9B3660C6, 0X9FF77D71, 0X92B45BA8, 0X9675461F,
0X8832161A, 0X8CF30BAD, 0X81B02D74, 0X857130C3,
0X5D8A9099, 0X594B8D2E, 0X5408ABF7, 0X50C9B640,
0X4E8EE645, 0X4A4FFBF2, 0X470CDD2B, 0X43CDC09C,
0X7B827D21, 0X7F436096, 0X7200464F, 0X76C15BF8,
0X68860BFD, 0X6C47164A, 0X61043093, 0X65C52D24,
0X119B4BE9, 0X155A565E, 0X18197087, 0X1CD86D30,
0X029F3D35, 0X065E2082, 0X0B1D065B, 0X0FDC1BEC,
0X3793A651, 0X3352BBE6, 0X3E119D3F, 0X3AD08088,
0X2497D08D, 0X2056CD3A, 0X2D15EBE3, 0X29D4F654,
0XC5A92679, 0XC1683BCE, 0XCC2B1D17, 0XC8EA00A0,
0XD6AD50A5, 0XD26C4D12, 0XDF2F6BCB, 0XDBEE767C,
0XE3A1CBC1, 0XE760D676, 0XEA23F0AF, 0XEEE2ED18,
0XF0A5BD1D, 0XF464A0AA, 0XF9278673, 0XFDE69BC4,
0X89B8FD09, 0X8D79E0BE, 0X803AC667, 0X84FBDBD0,
0X9ABC8BD5, 0X9E7D9662, 0X933EB0BB, 0X97FFAD0C,
0XAFB010B1, 0XAB710D06, 0XA6322BDF, 0XA2F33668,
0XBCB4666D, 0XB8757BDA, 0XB5365D03, 0XB1F740B4
};

/// <summary>
/// The CRC data checksum so far.
/// </summary>
private uint checkValue;

#endregion Instance Fields

/// <summary>
/// Initialise a default instance of <see cref="BZip2Crc"></see>
/// </summary>
public BZip2Crc()
{
Reset();
}

/// <summary>
/// Resets the CRC data checksum as if no update was ever called.
/// </summary>
public void Reset()
{
checkValue = crcInit;
}

/// <summary>
/// Returns the CRC data checksum computed so far.
/// </summary>
/// <remarks>Reversed Out = true</remarks>
public long Value
{
get
{
// Tehcnically, the output should be:
//return (long)(~checkValue ^ crcXor);
// but x ^ 0 = x, so there is no point in adding
// the XOR operation
return (long)(~checkValue);
}
}

/// <summary>
/// Updates the checksum with the int bval.
/// </summary>
/// <param name = "bval">
/// the byte is taken as the lower 8 bits of bval
/// </param>
/// <remarks>Reversed Data = false</remarks>
public void Update(int bval)
{
checkValue = unchecked(crcTable[(byte)(((checkValue >> 24) & 0xFF) ^ bval)] ^ (checkValue << 8));
}

/// <summary>
/// Updates the CRC data checksum with the bytes taken from
/// a block of data.
/// </summary>
/// <param name="buffer">Contains the data to update the CRC with.</param>
public void Update(byte[] buffer)
{
if (buffer == null)
{
throw new ArgumentNullException(nameof(buffer));
}

Update(new ArraySegment<byte>(buffer, 0, buffer.Length));
}

/// <summary>
/// Update CRC data checksum based on a portion of a block of data
/// </summary>
/// <param name = "segment">
/// The chunk of data to add
/// </param>
public void Update(ArraySegment<byte> segment)
{
var count = segment.Count;
var offset = segment.Offset;

while (--count >= 0)
Update(segment.Array[offset++]);
}
internal override Crc32ProxyBase Proxy => _proxy;
}
}
165 changes: 6 additions & 159 deletions src/ICSharpCode.SharpZipLib/Checksum/Crc32.cs
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using ICSharpCode.SharpZipLib.Checksum.Proxy;
using System;

namespace ICSharpCode.SharpZipLib.Checksum
{
/// <summary>
/// CRC-32 with reversed data and unreversed output
/// </summary>
/// <remarks>
/// Generate a table for a byte-wise 32-bit CRC calculation on the polynomial:
/// x^32+x^26+x^23+x^22+x^16+x^12+x^11+x^10+x^8+x^7+x^5+x^4+x^2+x^1+x^0.
///
/// Polynomials over GF(2) are represented in binary, one bit per coefficient,
/// with the lowest powers in the most significant bit. Then adding polynomials
/// is just exclusive-or, and multiplying a polynomial by x is a right shift by
/// one. If we call the above polynomial p, and represent a byte as the
/// polynomial q, also with the lowest power in the most significant bit (so the
/// byte 0xb1 is the polynomial x^7+x^3+x+1), then the CRC is (q*x^32) mod p,
/// where a mod b means the remainder after dividing a by b.
///
/// This calculation is done using the shift-register method of multiplying and
/// taking the remainder. The register is initialized to zero, and for each
/// incoming bit, x^32 is added mod p to the register if the bit is a one (where
/// x^32 mod p is p+x^32 = x^26+...+1), and the register is multiplied mod p by
/// x (which is shifting right by one and adding x^32 mod p if the bit shifted
/// out is a one). We start with the highest power (least significant bit) of
/// q and repeat for all eight bits of q.
///
/// The table is simply the CRC of all possible eight bit values. This is all
/// the information needed to generate CRC's on data a byte at a time for all
/// combinations of CRC register values and incoming bytes.
/// </remarks>
public sealed class Crc32 : IChecksum
public sealed class Crc32 : Crc32Base
{
#region Instance Fields
private static readonly ReflectedCrc32Proxy _proxy = new ReflectedCrc32Proxy();

internal override Crc32ProxyBase Proxy => _proxy;

private static readonly uint crcInit = 0xFFFFFFFF;
private static readonly uint crcXor = 0xFFFFFFFF;

private static readonly uint[] crcTable = {
0x00000000, 0x77073096, 0xEE0E612C, 0x990951BA, 0x076DC419,
0x706AF48F, 0xE963A535, 0x9E6495A3, 0x0EDB8832, 0x79DCB8A4,
0xE0D5E91E, 0x97D2D988, 0x09B64C2B, 0x7EB17CBD, 0xE7B82D07,
0x90BF1D91, 0x1DB71064, 0x6AB020F2, 0xF3B97148, 0x84BE41DE,
0x1ADAD47D, 0x6DDDE4EB, 0xF4D4B551, 0x83D385C7, 0x136C9856,
0x646BA8C0, 0xFD62F97A, 0x8A65C9EC, 0x14015C4F, 0x63066CD9,
0xFA0F3D63, 0x8D080DF5, 0x3B6E20C8, 0x4C69105E, 0xD56041E4,
0xA2677172, 0x3C03E4D1, 0x4B04D447, 0xD20D85FD, 0xA50AB56B,
0x35B5A8FA, 0x42B2986C, 0xDBBBC9D6, 0xACBCF940, 0x32D86CE3,
0x45DF5C75, 0xDCD60DCF, 0xABD13D59, 0x26D930AC, 0x51DE003A,
0xC8D75180, 0xBFD06116, 0x21B4F4B5, 0x56B3C423, 0xCFBA9599,
0xB8BDA50F, 0x2802B89E, 0x5F058808, 0xC60CD9B2, 0xB10BE924,
0x2F6F7C87, 0x58684C11, 0xC1611DAB, 0xB6662D3D, 0x76DC4190,
0x01DB7106, 0x98D220BC, 0xEFD5102A, 0x71B18589, 0x06B6B51F,
0x9FBFE4A5, 0xE8B8D433, 0x7807C9A2, 0x0F00F934, 0x9609A88E,
0xE10E9818, 0x7F6A0DBB, 0x086D3D2D, 0x91646C97, 0xE6635C01,
0x6B6B51F4, 0x1C6C6162, 0x856530D8, 0xF262004E, 0x6C0695ED,
0x1B01A57B, 0x8208F4C1, 0xF50FC457, 0x65B0D9C6, 0x12B7E950,
0x8BBEB8EA, 0xFCB9887C, 0x62DD1DDF, 0x15DA2D49, 0x8CD37CF3,
0xFBD44C65, 0x4DB26158, 0x3AB551CE, 0xA3BC0074, 0xD4BB30E2,
0x4ADFA541, 0x3DD895D7, 0xA4D1C46D, 0xD3D6F4FB, 0x4369E96A,
0x346ED9FC, 0xAD678846, 0xDA60B8D0, 0x44042D73, 0x33031DE5,
0xAA0A4C5F, 0xDD0D7CC9, 0x5005713C, 0x270241AA, 0xBE0B1010,
0xC90C2086, 0x5768B525, 0x206F85B3, 0xB966D409, 0xCE61E49F,
0x5EDEF90E, 0x29D9C998, 0xB0D09822, 0xC7D7A8B4, 0x59B33D17,
0x2EB40D81, 0xB7BD5C3B, 0xC0BA6CAD, 0xEDB88320, 0x9ABFB3B6,
0x03B6E20C, 0x74B1D29A, 0xEAD54739, 0x9DD277AF, 0x04DB2615,
0x73DC1683, 0xE3630B12, 0x94643B84, 0x0D6D6A3E, 0x7A6A5AA8,
0xE40ECF0B, 0x9309FF9D, 0x0A00AE27, 0x7D079EB1, 0xF00F9344,
0x8708A3D2, 0x1E01F268, 0x6906C2FE, 0xF762575D, 0x806567CB,
0x196C3671, 0x6E6B06E7, 0xFED41B76, 0x89D32BE0, 0x10DA7A5A,
0x67DD4ACC, 0xF9B9DF6F, 0x8EBEEFF9, 0x17B7BE43, 0x60B08ED5,
0xD6D6A3E8, 0xA1D1937E, 0x38D8C2C4, 0x4FDFF252, 0xD1BB67F1,
0xA6BC5767, 0x3FB506DD, 0x48B2364B, 0xD80D2BDA, 0xAF0A1B4C,
0x36034AF6, 0x41047A60, 0xDF60EFC3, 0xA867DF55, 0x316E8EEF,
0x4669BE79, 0xCB61B38C, 0xBC66831A, 0x256FD2A0, 0x5268E236,
0xCC0C7795, 0xBB0B4703, 0x220216B9, 0x5505262F, 0xC5BA3BBE,
0xB2BD0B28, 0x2BB45A92, 0x5CB36A04, 0xC2D7FFA7, 0xB5D0CF31,
0x2CD99E8B, 0x5BDEAE1D, 0x9B64C2B0, 0xEC63F226, 0x756AA39C,
0x026D930A, 0x9C0906A9, 0xEB0E363F, 0x72076785, 0x05005713,
0x95BF4A82, 0xE2B87A14, 0x7BB12BAE, 0x0CB61B38, 0x92D28E9B,
0xE5D5BE0D, 0x7CDCEFB7, 0x0BDBDF21, 0x86D3D2D4, 0xF1D4E242,
0x68DDB3F8, 0x1FDA836E, 0x81BE16CD, 0xF6B9265B, 0x6FB077E1,
0x18B74777, 0x88085AE6, 0xFF0F6A70, 0x66063BCA, 0x11010B5C,
0x8F659EFF, 0xF862AE69, 0x616BFFD3, 0x166CCF45, 0xA00AE278,
0xD70DD2EE, 0x4E048354, 0x3903B3C2, 0xA7672661, 0xD06016F7,
0x4969474D, 0x3E6E77DB, 0xAED16A4A, 0xD9D65ADC, 0x40DF0B66,
0x37D83BF0, 0xA9BCAE53, 0xDEBB9EC5, 0x47B2CF7F, 0x30B5FFE9,
0xBDBDF21C, 0xCABAC28A, 0x53B39330, 0x24B4A3A6, 0xBAD03605,
0xCDD70693, 0x54DE5729, 0x23D967BF, 0xB3667A2E, 0xC4614AB8,
0x5D681B02, 0x2A6F2B94, 0xB40BBE37, 0xC30C8EA1, 0x5A05DF1B,
0x2D02EF8D
};

/// <summary>
/// The CRC data checksum so far.
/// </summary>
private uint checkValue;

#endregion Instance Fields

internal static uint ComputeCrc32(uint oldCrc, byte bval)
{
return (uint)(Crc32.crcTable[(oldCrc ^ bval) & 0xFF] ^ (oldCrc >> 8));
}

/// <summary>
/// Initialise a default instance of <see cref="Crc32"></see>
/// </summary>
public Crc32()
{
Reset();
return ~_proxy.Append(~oldCrc, new [] { bval }, 0, 1);
}

/// <summary>
/// Resets the CRC data checksum as if no update was ever called.
/// </summary>
public void Reset()
{
checkValue = crcInit;
}

/// <summary>
/// Returns the CRC data checksum computed so far.
/// </summary>
/// <remarks>Reversed Out = false</remarks>
public long Value
{
get
{
return (long)(checkValue ^ crcXor);
}
}

/// <summary>
/// Updates the checksum with the int bval.
/// </summary>
/// <param name = "bval">
/// the byte is taken as the lower 8 bits of bval
/// </param>
/// <remarks>Reversed Data = true</remarks>
public void Update(int bval)
{
checkValue = unchecked(crcTable[(checkValue ^ bval) & 0xFF] ^ (checkValue >> 8));
}

/// <summary>
/// Updates the CRC data checksum with the bytes taken from
/// a block of data.
/// </summary>
/// <param name="buffer">Contains the data to update the CRC with.</param>
public void Update(byte[] buffer)
{
if (buffer == null)
{
throw new ArgumentNullException(nameof(buffer));
}

Update(new ArraySegment<byte>(buffer, 0, buffer.Length));
}

/// <summary>
/// Update CRC data checksum based on a portion of a block of data
/// </summary>
/// <param name = "segment">
/// The chunk of data to add
/// </param>
public void Update(ArraySegment<byte> segment)
{
var count = segment.Count;
var offset = segment.Offset;

while (--count >= 0)
Update(segment.Array[offset++]);
}
}
}
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