Click here to Skip to main content
Click here to Skip to main content

ZIP CRC32 Static Method and Values

, 30 Jun 2008
Rate this:
Please Sign up or sign in to vote.
A static C# method and values for a small footprint paste into your C# code

Introduction

What! Another Crc32 routine? Well, I like small, fast, and lightweight solutions ... especially the kind having a quick copy and paste solution.

Using the Code

Copy and paste the following into your class or struct... and add overloads as you wish. I've put some overloads into the download code.

//*****************************************************************************
#region Crc32 ESSENTIAL STATIC METHOD AND POLYVALS (where all THE WORK IS DONE)
    internal static uint Crc32  // The only moving part (method) 
        ( uint theStartingCRC
        , byte[] theBytes
        , int theStartingIndex
        , int forCount
        )
    {
        uint iCursor = ~theStartingCRC;
        int iTop = theStartingIndex + forCount;
        for (int i = theStartingIndex; i < iTop; i++)
        {
            iCursor = (((uint)(iCursor / 256)) & 0xFFFFFF)
                ^ Crc32_PolyVals[(int)((iCursor ^ theBytes[i]) & 0xFF)]; 
        }
        return ~iCursor;
    }
    // NOTE: No PolyVals dynamic build! 
    // Weighing dynamic generation code bytes=<whatever> 
    // versus 1024 static bytes, we suggest the savings(if any) of dynamic generation 
    // are not significant and static storage never has to be 
    // dynamically generated (grin).
    // We consider less heap motion (allocation/collection) a good thing.
    private static readonly uint[] Crc32_PolyVals = 
    {
<small>        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,</small>
     };

#endregion Crc32 ESSENTIAL STATIC METHOD AND POLYVALS

History

  • 27th December, 2007: Initial post
  • 27th June, 2008: Corrected the "stream overload" example in the download file

License

This article, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

Share

About the Author

G.Franklin

United States United States
No Biography provided

Comments and Discussions

 
QuestionCan you code a dynamic hash function? PinmemberTushar Arora20-Aug-10 8:19 
GeneralMy vote of 1 PinmemberDizZ5-May-10 5:31 
QuestionBug in stream implementation? PinmemberSteve Pritchard27-Jun-08 0:10 
Hi,
 
I think there's a bug in the stream implementation in the commented out code. It seems to have a redundant for loop. I think the code should look like this:
 
            uint iCrc = 0;
            byte[] xBuf = (theOptionalReusableBuffer != null)
                ? theOptionalReusableBuffer : new byte[1024];
            int iRead;
            while ( 0 < (iRead = theStream.Read(xBuf, 0, xBuf.Length)))
            {
                iCrc = Crc32(iCrc, xBuf, 0, iRead);
            }
            theStream.Dispose(); 
rather than like this:
 
            uint iCrc = 0;
            byte[] xBuf = (theOptionalReusableBuffer != null)
                ? theOptionalReusableBuffer : new byte[1024];
            int iRead;
            while (0 < (iRead = theStream.Read(xBuf, 0, xBuf.Length)))
            {
                for (int i = 0; i < iRead; i++)
                    iCrc = Crc32(iCrc, xBuf, 0, iRead);
            }
            theStream.Dispose(); 
 
Cheers,
 
Steve.
AnswerRe: Bug in stream implementation? Pinmemberg.CoderCat27-Jun-08 6:49 
QuestionWhat is your polynomial generator? PinmemberMember 122027-Dec-07 21:06 
AnswerRe: What is your polynomial generator? Pinmemberg.CoderCat29-Feb-08 7:16 
GeneralRe: What is your polynomial generator? PinmemberTobiasP9-Jul-08 1:38 
GeneralRe: What is your polynomial generator? Pinmemberg.CoderCat9-Jul-08 10:35 
GeneralSuggestions... PinmemberMichael Moreno27-Dec-07 19:36 
GeneralRe: Suggestions... Pinmemberg.CoderCat29-Feb-08 7:33 

General General    News News    Suggestion Suggestion    Question Question    Bug Bug    Answer Answer    Joke Joke    Rant Rant    Admin Admin   

Use Ctrl+Left/Right to switch messages, Ctrl+Up/Down to switch threads, Ctrl+Shift+Left/Right to switch pages.

| Advertise | Privacy | Mobile
Web01 | 2.8.140827.1 | Last Updated 30 Jun 2008
Article Copyright 2007 by G.Franklin
Everything else Copyright © CodeProject, 1999-2014
Terms of Service
Layout: fixed | fluid