谁有crc算法及例程，给小弟一份，不胜感激！！！ (50分)

yanglibo兄，能不能把
http://www.delphibbs.com/delphibbs/dispq.asp?lid=130441
的crc例程给我一份？谢谢！

crc有好几种呢

CRC校验程序我倒是有一个，32位，
生成多项式0x04c11db7，用了很多次没有问题。
算法原理不明，想要留个mail

sjzzhyong@yeah.net
谢谢！

关注！

function CRC16_std(InitCrc: Word; Buffer: PChar; Length: Integer): Word;
const
Crc16Table: array[0..$FF] of Word =
(
$0000, $C0C1, $C181, $0140, $C301, $03C0, $0280, $C241,
$C601, $06C0, $0780, $C741, $0500, $C5C1, $C481, $0440,
$CC01, $0CC0, $0D80, $CD41, $0F00, $CFC1, $CE81, $0E40,
$0A00, $CAC1, $CB81, $0B40, $C901, $09C0, $0880, $C841,
$D801, $18C0, $1980, $D941, $1B00, $DBC1, $DA81, $1A40,
$1E00, $DEC1, $DF81, $1F40, $DD01, $1DC0, $1C80, $DC41,
$1400, $D4C1, $D581, $1540, $D701, $17C0, $1680, $D641,
$D201, $12C0, $1380, $D341, $1100, $D1C1, $D081, $1040,
$F001, $30C0, $3180, $F141, $3300, $F3C1, $F281, $3240,
$3600, $F6C1, $F781, $3740, $F501, $35C0, $3480, $F441,
$3C00, $FCC1, $FD81, $3D40, $FF01, $3FC0, $3E80, $FE41,
$FA01, $3AC0, $3B80, $FB41, $3900, $F9C1, $F881, $3840,
$2800, $E8C1, $E981, $2940, $EB01, $2BC0, $2A80, $EA41,
$EE01, $2EC0, $2F80, $EF41, $2D00, $EDC1, $EC81, $2C40,
$E401, $24C0, $2580, $E541, $2700, $E7C1, $E681, $2640,
$2200, $E2C1, $E381, $2340, $E101, $21C0, $2080, $E041,
$A001, $60C0, $6180, $A141, $6300, $A3C1, $A281, $6240,
$6600, $A6C1, $A781, $6740, $A501, $65C0, $6480, $A441,
$6C00, $ACC1, $AD81, $6D40, $AF01, $6FC0, $6E80, $AE41,
$AA01, $6AC0, $6B80, $AB41, $6900, $A9C1, $A881, $6840,
$7800, $B8C1, $B981, $7940, $BB01, $7BC0, $7A80, $BA41,
$BE01, $7EC0, $7F80, $BF41, $7D00, $BDC1, $BC81, $7C40,
$B401, $74C0, $7580, $B541, $7700, $B7C1, $B681, $7640,
$7200, $B2C1, $B381, $7340, $B101, $71C0, $7080, $B041,
$5000, $90C1, $9181, $5140, $9301, $53C0, $5280, $9241,
$9601, $56C0, $5780, $9741, $5500, $95C1, $9481, $5440,
$9C01, $5CC0, $5D80, $9D41, $5F00, $9FC1, $9E81, $5E40,
$5A00, $9AC1, $9B81, $5B40, $9901, $59C0, $5880, $9841,
$8801, $48C0, $4980, $8941, $4B00, $8BC1, $8A81, $4A40,
$4E00, $8EC1, $8F81, $4F40, $8D01, $4DC0, $4C80, $8C41,
$4400, $84C1, $8581, $4540, $8701, $47C0, $4680, $8641,
$8201, $42C0, $4380, $8341, $4100, $81C1, $8081, $4040
);

var
Crc: Word;
begin
Crc := 0;
while Length > 0 do
begin
Crc := (Crc shr 8) xor CRC16Table[(Crc xor (Byte(Buffer^))) and $00FF];
Inc(Buffer);
Dec(Length);
end;
Result := Crc;
end;

function CRCInfo(const asInfo: string): string;
var
wdCRC: Word;
bytLow, bytHi: Byte;
M: PChar;
i: Integer;
begin
M := PChar(asInfo);
i := StrLen(M);
wdCRC := CRC16_std($FFFF, M, I);
bytLow := Lo(wdCRC);
bytHi := Hi(wdCRC);
Result := Chr(bytLow) + Chr(bytHi);
end;

我在TNPP协议中用到的，16位CRC校验，没问题的。

unit Crc32 ;
interface
uses
Windows, Messages, stdctrls,SysUtils,
Classes, Graphics, Controls, Forms, Dialogs,ThdTimer;

PROCEDURE CalcCRC32 (p: pointer; nbyte: WORD; VAR CRCvalue: LongInt) ;

implementation
CONST table: ARRAY[0..255] OF LongInt =
($00000000, $77073096, $EE0E612C, $990951BA,
$076DC419, $706AF48F, $E963A535, $9E6495A3,
$0EDB8832, $79DCB8A4, $E0D5E91E, $97D2D988,
$09B64C2B, $7EB17CBD, $E7B82D07, $90BF1D91,
$1DB71064, $6AB020F2, $F3B97148, $84BE41DE,
$1ADAD47D, $6DDDE4EB, $F4D4B551, $83D385C7,
$136C9856, $646BA8C0, $FD62F97A, $8A65C9EC,
$14015C4F, $63066CD9, $FA0F3D63, $8D080DF5,
$3B6E20C8, $4C69105E, $D56041E4, $A2677172,
$3C03E4D1, $4B04D447, $D20D85FD, $A50AB56B,
$35B5A8FA, $42B2986C, $DBBBC9D6, $ACBCF940,
$32D86CE3, $45DF5C75, $DCD60DCF, $ABD13D59,
$26D930AC, $51DE003A, $C8D75180, $BFD06116,
$21B4F4B5, $56B3C423, $CFBA9599, $B8BDA50F,
$2802B89E, $5F058808, $C60CD9B2, $B10BE924,
$2F6F7C87, $58684C11, $C1611DAB, $B6662D3D,

$76DC4190, $01DB7106, $98D220BC, $EFD5102A,
$71B18589, $06B6B51F, $9FBFE4A5, $E8B8D433,
$7807C9A2, $0F00F934, $9609A88E, $E10E9818,
$7F6A0DBB, $086D3D2D, $91646C97, $E6635C01,
$6B6B51F4, $1C6C6162, $856530D8, $F262004E,
$6C0695ED, $1B01A57B, $8208F4C1, $F50FC457,
$65B0D9C6, $12B7E950, $8BBEB8EA, $FCB9887C,
$62DD1DDF, $15DA2D49, $8CD37CF3, $FBD44C65,
$4DB26158, $3AB551CE, $A3BC0074, $D4BB30E2,
$4ADFA541, $3DD895D7, $A4D1C46D, $D3D6F4FB,
$4369E96A, $346ED9FC, $AD678846, $DA60B8D0,
$44042D73, $33031DE5, $AA0A4C5F, $DD0D7CC9,
$5005713C, $270241AA, $BE0B1010, $C90C2086,
$5768B525, $206F85B3, $B966D409, $CE61E49F,
$5EDEF90E, $29D9C998, $B0D09822, $C7D7A8B4,
$59B33D17, $2EB40D81, $B7BD5C3B, $C0BA6CAD,

$EDB88320, $9ABFB3B6, $03B6E20C, $74B1D29A,
$EAD54739, $9DD277AF, $04DB2615, $73DC1683,
$E3630B12, $94643B84, $0D6D6A3E, $7A6A5AA8,
$E40ECF0B, $9309FF9D, $0A00AE27, $7D079EB1,
$F00F9344, $8708A3D2, $1E01F268, $6906C2FE,
$F762575D, $806567CB, $196C3671, $6E6B06E7,
$FED41B76, $89D32BE0, $10DA7A5A, $67DD4ACC,
$F9B9DF6F, $8EBEEFF9, $17B7BE43, $60B08ED5,
$D6D6A3E8, $A1D1937E, $38D8C2C4, $4FDFF252,
$D1BB67F1, $A6BC5767, $3FB506DD, $48B2364B,
$D80D2BDA, $AF0A1B4C, $36034AF6, $41047A60,
$DF60EFC3, $A867DF55, $316E8EEF, $4669BE79,
$CB61B38C, $BC66831A, $256FD2A0, $5268E236,
$CC0C7795, $BB0B4703, $220216B9, $5505262F,
$C5BA3BBE, $B2BD0B28, $2BB45A92, $5CB36A04,
$C2D7FFA7, $B5D0CF31, $2CD99E8B, $5BDEAE1D,

$9B64C2B0, $EC63F226, $756AA39C, $026D930A,
$9C0906A9, $EB0E363F, $72076785, $05005713,
$95BF4A82, $E2B87A14, $7BB12BAE, $0CB61B38,
$92D28E9B, $E5D5BE0D, $7CDCEFB7, $0BDBDF21,
$86D3D2D4, $F1D4E242, $68DDB3F8, $1FDA836E,
$81BE16CD, $F6B9265B, $6FB077E1, $18B74777,
$88085AE6, $FF0F6A70, $66063BCA, $11010B5C,
$8F659EFF, $F862AE69, $616BFFD3, $166CCF45,
$A00AE278, $D70DD2EE, $4E048354, $3903B3C2,
$A7672661, $D06016F7, $4969474D, $3E6E77DB,
$AED16A4A, $D9D65ADC, $40DF0B66, $37D83BF0,
$A9BCAE53, $DEBB9EC5, $47B2CF7F, $30B5FFE9,
$BDBDF21C, $CABAC28A, $53B39330, $24B4A3A6,
$BAD03605, $CDD70693, $54DE5729, $23D967BF,
$B3667A2E, $C4614AB8, $5D681B02, $2A6F2B94,
$B40BBE37, $C30C8EA1, $5A05DF1B, $2D02EF8D);


TYPE
buffer = ARRAY[1..65521] OF BYTE; {largest buffer that can be}
{allocated on heap }
VAR
i: WORD;
q: ^buffer;

PROCEDURE CalcCRC32 (p: pointer; nbyte: WORD; VAR CRCvalue: LongInt);
{The following is a little cryptic (but executes very quickly).
The algorithm is as follows:
1. exclusive-or the input byte with the low-order portion of
the CRC register to get an INDEX
2. shift the CRC register eight bits to the right
3. exclusive-or the CRC register with the contents of
Table[INDEX]
4. repeat steps 1 through 3 for all bytes}
BEGIN
q := p;
FOR i := 1 TO nBYTE DO
CRCvalue := (CRCvalue SHR 8) XOR
Table[ q^ XOR (CRCvalue AND $000000FF) ]
END {CalcCRC32};


PROCEDURE CalcFileCRC32 (FromName: STRING; VAR CRCvalue: LongInt;
VAR IOBuffer: pointer; BufferSize: WORD; VAR TotalBytes: LongInt;
VAR error: WORD);
VAR
BytesRead: WORD;
FromFile : FILE;
i : WORD;
BEGIN
FileMode := 0; {Turbo default is 2 for R/W; 0 is for R/O}
CRCValue := $FFFFFFFF;
ASSIGN (FromFile,FromName);
{$I-} RESET (FromFile,1); {$I+}
error := IOResult;
IF error = 0
THEN BEGIN
TotalBytes := 0;

REPEAT
//BlockRead (FromFile,pchar(IOBuffer)^,BufferSize,BytesRead);
CalcCRC32 (IOBuffer,BytesRead,CRCvalue);
INC (TotalBytes, BytesRead)
UNTIL BytesRead = 0;
CLOSE (FromFile)
END;
CRCvalue := NOT CRCvalue
END ;{CalcFileCRC32}
end .

多人接受答案了。