crc32.cpp

来自「非常好用的五子棋游戏源码」· C++ 代码 · 共 71 行

// Created:09-25-98
// By Jeff Connelly

// CRC-32 calculation

// The polynomial for CRC-32 is...
// 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
// Note that any number except 0 to the 0th power will result in 1, so x^0=1

#include "stdafx.h"
#define EXPORTING
#include "comprlib.h"

static unsigned long crc_32_table[0x100] =
    {           // Polymonial 0xEDB88320
    0x000000000L, 0x077073096L, 0x0EE0E612CL, 0x0990951BAL, 0x0076DC419L, 0x0706AF48FL, 0x0E963A535L, 0x09E6495A3L,
    0x00EDB8832L, 0x079DCB8A4L, 0x0E0D5E91EL, 0x097D2D988L, 0x009B64C2BL, 0x07EB17CBDL, 0x0E7B82D07L, 0x090BF1D91L,
    0x01DB71064L, 0x06AB020F2L, 0x0F3B97148L, 0x084BE41DEL, 0x01ADAD47DL, 0x06DDDE4EBL, 0x0F4D4B551L, 0x083D385C7L,
    0x0136C9856L, 0x0646BA8C0L, 0x0FD62F97AL, 0x08A65C9ECL, 0x014015C4FL, 0x063066CD9L, 0x0FA0F3D63L, 0x08D080DF5L,
    0x03B6E20C8L, 0x04C69105EL, 0x0D56041E4L, 0x0A2677172L, 0x03C03E4D1L, 0x04B04D447L, 0x0D20D85FDL, 0x0A50AB56BL,
    0x035B5A8FAL, 0x042B2986CL, 0x0DBBBC9D6L, 0x0ACBCF940L, 0x032D86CE3L, 0x045DF5C75L, 0x0DCD60DCFL, 0x0ABD13D59L,
    0x026D930ACL, 0x051DE003AL, 0x0C8D75180L, 0x0BFD06116L, 0x021B4F4B5L, 0x056B3C423L, 0x0CFBA9599L, 0x0B8BDA50FL,
    0x02802B89EL, 0x05F058808L, 0x0C60CD9B2L, 0x0B10BE924L, 0x02F6F7C87L, 0x058684C11L, 0x0C1611DABL, 0x0B6662D3DL,
    0x076DC4190L, 0x001DB7106L, 0x098D220BCL, 0x0EFD5102AL, 0x071B18589L, 0x006B6B51FL, 0x09FBFE4A5L, 0x0E8B8D433L,
    0x07807C9A2L, 0x00F00F934L, 0x09609A88EL, 0x0E10E9818L, 0x07F6A0DBBL, 0x0086D3D2DL, 0x091646C97L, 0x0E6635C01L,
    0x06B6B51F4L, 0x01C6C6162L, 0x0856530D8L, 0x0F262004EL, 0x06C0695EDL, 0x01B01A57BL, 0x08208F4C1L, 0x0F50FC457L,
    0x065B0D9C6L, 0x012B7E950L, 0x08BBEB8EAL, 0x0FCB9887CL, 0x062DD1DDFL, 0x015DA2D49L, 0x08CD37CF3L, 0x0FBD44C65L,
    0x04DB26158L, 0x03AB551CEL, 0x0A3BC0074L, 0x0D4BB30E2L, 0x04ADFA541L, 0x03DD895D7L, 0x0A4D1C46DL, 0x0D3D6F4FBL,
    0x04369E96AL, 0x0346ED9FCL, 0x0AD678846L, 0x0DA60B8D0L, 0x044042D73L, 0x033031DE5L, 0x0AA0A4C5FL, 0x0DD0D7CC9L,
    0x05005713CL, 0x0270241AAL, 0x0BE0B1010L, 0x0C90C2086L, 0x05768B525L, 0x0206F85B3L, 0x0B966D409L, 0x0CE61E49FL,
    0x05EDEF90EL, 0x029D9C998L, 0x0B0D09822L, 0x0C7D7A8B4L, 0x059B33D17L, 0x02EB40D81L, 0x0B7BD5C3BL, 0x0C0BA6CADL,
    0x0EDB88320L, 0x09ABFB3B6L, 0x003B6E20CL, 0x074B1D29AL, 0x0EAD54739L, 0x09DD277AFL, 0x004DB2615L, 0x073DC1683L,
    0x0E3630B12L, 0x094643B84L, 0x00D6D6A3EL, 0x07A6A5AA8L, 0x0E40ECF0BL, 0x09309FF9DL, 0x00A00AE27L, 0x07D079EB1L,
    0x0F00F9344L, 0x08708A3D2L, 0x01E01F268L, 0x06906C2FEL, 0x0F762575DL, 0x0806567CBL, 0x0196C3671L, 0x06E6B06E7L,
    0x0FED41B76L, 0x089D32BE0L, 0x010DA7A5AL, 0x067DD4ACCL, 0x0F9B9DF6FL, 0x08EBEEFF9L, 0x017B7BE43L, 0x060B08ED5L,
    0x0D6D6A3E8L, 0x0A1D1937EL, 0x038D8C2C4L, 0x04FDFF252L, 0x0D1BB67F1L, 0x0A6BC5767L, 0x03FB506DDL, 0x048B2364BL,
    0x0D80D2BDAL, 0x0AF0A1B4CL, 0x036034AF6L, 0x041047A60L, 0x0DF60EFC3L, 0x0A867DF55L, 0x0316E8EEFL, 0x04669BE79L,
    0x0CB61B38CL, 0x0BC66831AL, 0x0256FD2A0L, 0x05268E236L, 0x0CC0C7795L, 0x0BB0B4703L, 0x0220216B9L, 0x05505262FL,
    0x0C5BA3BBEL, 0x0B2BD0B28L, 0x02BB45A92L, 0x05CB36A04L, 0x0C2D7FFA7L, 0x0B5D0CF31L, 0x02CD99E8BL, 0x05BDEAE1DL,
    0x09B64C2B0L, 0x0EC63F226L, 0x0756AA39CL, 0x0026D930AL, 0x09C0906A9L, 0x0EB0E363FL, 0x072076785L, 0x005005713L,
    0x095BF4A82L, 0x0E2B87A14L, 0x07BB12BAEL, 0x00CB61B38L, 0x092D28E9BL, 0x0E5D5BE0DL, 0x07CDCEFB7L, 0x00BDBDF21L,
    0x086D3D2D4L, 0x0F1D4E242L, 0x068DDB3F8L, 0x01FDA836EL, 0x081BE16CDL, 0x0F6B9265BL, 0x06FB077E1L, 0x018B74777L,
    0x088085AE6L, 0x0FF0F6A70L, 0x066063BCAL, 0x011010B5CL, 0x08F659EFFL, 0x0F862AE69L, 0x0616BFFD3L, 0x0166CCF45L,
    0x0A00AE278L, 0x0D70DD2EEL, 0x04E048354L, 0x03903B3C2L, 0x0A7672661L, 0x0D06016F7L, 0x04969474DL, 0x03E6E77DBL,
    0x0AED16A4AL, 0x0D9D65ADCL, 0x040DF0B66L, 0x037D83BF0L, 0x0A9BCAE53L, 0x0DEBB9EC5L, 0x047B2CF7FL, 0x030B5FFE9L,
    0x0BDBDF21CL, 0x0CABAC28AL, 0x053B39330L, 0x024B4A3A6L, 0x0BAD03605L, 0x0CDD70693L, 0x054DE5729L, 0x023D967BFL,
    0x0B3667A2EL, 0x0C4614AB8L, 0x05D681B02L, 0x02A6F2B94L, 0x0B40BBE37L, 0x0C30C8EA1L, 0x05A05DF1BL, 0x02D02EF8DL
    };


// Updates the CRC pointed to by 'crc' with character 'c'
void EXPORT crc32(unsigned char c, unsigned long* crc)
{
    c ^= *(unsigned char*)crc;      // apply current crc to current character
    *crc >>= 8;                     // shift old value down
    *crc ^= crc_32_table[c];        // xor in new value
}

// Generates a CRC for the whole input file, output file untouched
unsigned long EXPORT crc32()
{
    register unsigned long crc = 0;

    while (!end_of_data())
    {
        crc32 (read_byte(), &crc);
    }
    return crc;
}