我有个现成的库单元。提供了三种CRC校验的方法。可以进行优化.pas 单元代码如下：告诉我邮件地址，我可以MAIL给你例程！
{ This unit provides three speed-optimized functions to }
{ compute (or continue computation of) a Cyclic Redundency }
{ Check (CRC). Applicable to XModem protocol (16-bit CRC), }
{ SEA's "ARC" utility, PKZip (32-bit CRC) and many others }
{ compatible software. }
{ Please see TESTCRC.DPR for example. }
{*************************************************************}
{ Each function takes three parameters: }
{ }
{ InitCRC - The initial CRC value. This may be the }
{ recommended initialization value if this is the first or }
{ only block to be checked, or this may be a previously }
{ computed CRC value if this is a continuation. }
{ XModem and ARC usually starts with zero (0), 32 bit crc }
{ starts with all bits on ($FFFFFFFF). }
{ }
{ Buffer - An untyped parameter (Pointer^) specifying the }
{ beginning of the memory area to be checked. }
{ }
{ Length - A word indicating the length of the memory area to }
{ be checked. If Length is zero, the function returns the }
{ value of InitCRC. }
{ }
{ The function result is the updated CRC. }
{*************************************************************}
unit CRC;
interface
function UpdateCRC16(InitCRC: Word; var Buffer;
Length: {$IFDEF Win32} LongInt {$ELSE} Word {$ENDIF}): Word;
{ I believe this is the CRC used by the XModem protocol.
The transmitting end should initialize with zero, UpdateCRC16 for
the block, Continue the UpdateCRC16 for two nulls, and append the
result (hi order byte first) to the transmitted block. The receiver
should initialize with zero and UpdateCRC16 for the received block
including the two byte CRC. The result will be zero (why?) if there
were no transmission errors. (I have not tested this function with
an actual XModem implementation, though I did verify the behavior
just described. See TESTCRC.DPR.) }
function UpdateCRCArc(InitCRC: Word; var Buffer;
Length: {$IFDEF Win32} LongInt {$ELSE} Word {$ENDIF}): Word;
{ This function computes the CRC used by SEA's ARC utility.
Initialize with zero.}
function UpdateCRC32(InitCRC: LongInt; var Buffer;
{$IFDEF Win32} Length: LongInt {$ELSE} Length: Word {$ENDIF}): LongInt;
{ This function computes the CRC used by PKZIP and Forsberg's ZModem.
Initialize with high-values ($FFFFFFFF), and finish by inverting
allbits (Not). }
function FileCRC16(FileName: String; var CRC16: Word): Boolean; { Return True if ok }
function FileCRCArc(FileName: String; var CRCArc: Word): Boolean; { Return True if ok }
function FileCRC32(FileName: String; var CRC32: LongInt): Boolean; { Return True if ok }
implementation
const
CrcArcTab: Array[0..$FF] of Word =
($00000, $0C0C1, $0C181, $00140, $0C301, $003C0, $00280, $0C241,
$0C601, $006C0, $00780, $0C741, $00500, $0C5C1, $0C481, $00440,
$0CC01, $00CC0, $00D80, $0CD41, $00F00, $0CFC1, $0CE81, $00E40,
$00A00, $0CAC1, $0CB81, $00B40, $0C901, $009C0, $00880, $0C841,
$0D801, $018C0, $01980, $0D941, $01B00, $0DBC1, $0DA81, $01A40,
$01E00, $0DEC1, $0DF81, $01F40, $0DD01, $01DC0, $01C80, $0DC41,
$01400, $0D4C1, $0D581, $01540, $0D701, $017C0, $01680, $0D641,
$0D201, $012C0, $01380, $0D341, $01100, $0D1C1, $0D081, $01040,
$0F001, $030C0, $03180, $0F141, $03300, $0F3C1, $0F281, $03240,
$03600, $0F6C1, $0F781, $03740, $0F501, $035C0, $03480, $0F441,
$03C00, $0FCC1, $0FD81, $03D40, $0FF01, $03FC0, $03E80, $0FE41,
$0FA01, $03AC0, $03B80, $0FB41, $03900, $0F9C1, $0F881, $03840,
$02800, $0E8C1, $0E981, $02940, $0EB01, $02BC0, $02A80, $0EA41,
$0EE01, $02EC0, $02F80, $0EF41, $02D00, $0EDC1, $0EC81, $02C40,
$0E401, $024C0, $02580, $0E541, $02700, $0E7C1, $0E681, $02640,
$02200, $0E2C1, $0E381, $02340, $0E101, $021C0, $02080, $0E041,
$0A001, $060C0, $06180, $0A141, $06300, $0A3C1, $0A281, $06240,
$06600, $0A6C1, $0A781, $06740, $0A501, $065C0, $06480, $0A441,
$06C00, $0ACC1, $0AD81, $06D40, $0AF01, $06FC0, $06E80, $0AE41,
$0AA01, $06AC0, $06B80, $0AB41, $06900, $0A9C1, $0A881, $06840,
$07800, $0B8C1, $0B981, $07940, $0BB01, $07BC0, $07A80, $0BA41,
$0BE01, $07EC0, $07F80, $0BF41, $07D00, $0BDC1, $0BC81, $07C40,
$0B401, $074C0, $07580, $0B541, $07700, $0B7C1, $0B681, $07640,
$07200, $0B2C1, $0B381, $07340, $0B101, $071C0, $07080, $0B041,
$05000, $090C1, $09181, $05140, $09301, $053C0, $05280, $09241,
$09601, $056C0, $05780, $09741, $05500, $095C1, $09481, $05440,
$09C01, $05CC0, $05D80, $09D41, $05F00, $09FC1, $09E81, $05E40,
$05A00, $09AC1, $09B81, $05B40, $09901, $059C0, $05880, $09841,
$08801, $048C0, $04980, $08941, $04B00, $08BC1, $08A81, $04A40,
$04E00, $08EC1, $08F81, $04F40, $08D01, $04DC0, $04C80, $08C41,
$04400, $084C1, $08581, $04540, $08701, $047C0, $04680, $08641,
$08201, $042C0, $04380, $08341, $04100, $081C1, $08081, $04040);
Crc16Tab: Array[0..$FF] of Word =
($00000, $01021, $02042, $03063, $04084, $050a5, $060c6, $070e7,
$08108, $09129, $0a14a, $0b16b, $0c18c, $0d1ad, $0e1ce, $0f1ef,
$01231, $00210, $03273, $02252, $052b5, $04294, $072f7, $062d6,
$09339, $08318, $0b37b, $0a35a, $0d3bd, $0c39c, $0f3ff, $0e3de,
$02462, $03443, $00420, $01401, $064e6, $074c7, $044a4, $05485,
$0a56a, $0b54b, $08528, $09509, $0e5ee, $0f5cf, $0c5ac, $0d58d,
$03653, $02672, $01611, $00630, $076d7, $066f6, $05695, $046b4,
$0b75b, $0a77a, $09719, $08738, $0f7df, $0e7fe, $0d79d, $0c7bc,
$048c4, $058e5, $06886, $078a7, $00840, $01861, $02802, $03823,
$0c9cc, $0d9ed, $0e98e, $0f9af, $08948, $09969, $0a90a, $0b92b,
$05af5, $04ad4, $07ab7, $06a96, $01a71, $00a50, $03a33, $02a12,
$0dbfd, $0cbdc, $0fbbf, $0eb9e, $09b79, $08b58, $0bb3b, $0ab1a,
$06ca6, $07c87, $04ce4, $05cc5, $02c22, $03c03, $00c60, $01c41,
$0edae, $0fd8f, $0cdec, $0ddcd, $0ad2a, $0bd0b, $08d68, $09d49,
$07e97, $06eb6, $05ed5, $04ef4, $03e13, $02e32, $01e51, $00e70,
$0ff9f, $0efbe, $0dfdd, $0cffc, $0bf1b, $0af3a, $09f59, $08f78,
$09188, $081a9, $0b1ca, $0a1eb, $0d10c, $0c12d, $0f14e, $0e16f,
$01080, $000a1, $030c2, $020e3, $05004, $04025, $07046, $06067,
$083b9, $09398, $0a3fb, $0b3da, $0c33d, $0d31c, $0e37f, $0f35e,
$002b1, $01290, $022f3, $032d2, $04235, $05214, $06277, $07256,
$0b5ea, $0a5cb, $095a8, $08589, $0f56e, $0e54f, $0d52c, $0c50d,
$034e2, $024c3, $014a0, $00481, $07466, $06447, $05424, $04405,
$0a7db, $0b7fa, $08799, $097b8, $0e75f, $0f77e, $0c71d, $0d73c,
$026d3, $036f2, $00691, $016b0, $06657, $07676, $04615, $05634,
$0d94c, $0c96d, $0f90e, $0e92f, $099c8, $089e9, $0b98a, $0a9ab,
$05844, $04865, $07806, $06827, $018c0, $008e1, $03882, $028a3,
$0cb7d, $0db5c, $0eb3f, $0fb1e, $08bf9, $09bd8, $0abbb, $0bb9a,
$04a75, $05a54, $06a37, $07a16, $00af1, $01ad0, $02ab3, $03a92,
$0fd2e, $0ed0f, $0dd6c, $0cd4d, $0bdaa, $0ad8b, $09de8, $08dc9,
$07c26, $06c07, $05c64, $04c45, $03ca2, $02c83, $01ce0, $00cc1,
$0ef1f, $0ff3e, $0cf5d, $0df7c, $0af9b, $0bfba, $08fd9, $09ff8,
$06e17, $07e36, $04e55, $05e74, $02e93, $03eb2, $00ed1, $01ef0);
Crc32Tab: Array[0..$FF] 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, $2d02ef8d);
function UpdateCRC16(InitCRC: Word; var Buffer;
Length: {$IFDEF Win32} LongInt {$ELSE} Word {$ENDIF}): Word;
begin
asm
{$IFDEF Win32}
push esi
push edi
push eax
push ebx
push ecx
push edx
lea edi, Crc16Tab
mov esi, Buffer
mov ax, InitCrc
mov ecx, Length
or ecx, ecx
jz @@done
@@loop:
xor ebx, ebx
mov bl, ah
mov ah, al
lodsb
shl bx, 1
add ebx, edi
xor ax, [ebx]
loop @@loop
@@done:
mov Result, ax
pop edx
pop ecx
pop ebx
pop eax
pop edi
pop esi
{$ELSE}
lea di, Crc16Tab
push ds
pop es
push ds
lds si, Buffer
mov ax, InitCrc
mov cx, Length
or cx, cx
jz @@done
@@loop:
xor bx, bx
mov bl, ah
mov ah, al
lodsb
shl bx, 1
xor ax, es:[di + bx]
loop @@loop
pop ds
@@done:
mov Result, ax
{$ENDIF}
end;
end;
function UpdateCRCArc(InitCRC: Word; var Buffer;
Length: {$IFDEF Win32} LongInt {$ELSE} Word {$ENDIF}): Word;
begin
asm
{$IFDEF Win32}
push esi
push edi
push eax
push ebx
push ecx
push edx
lea edi, CrcArcTab
mov esi, Buffer
mov ax, InitCrc
mov ecx, Length
or ecx, ecx
jz @@done
@@loop:
xor ebx, ebx
mov bl, al
lodsb
xor bl, al
shl bx, 1
add ebx, edi
mov bx, [ebx]
xor bl, ah
mov ax, bx
loop @@loop
@@done:
mov Result, ax
pop edx
pop ecx
pop ebx
pop eax
pop edi
pop esi
{$ELSE}
lea di, CrcArcTab
push ds
pop es
push ds
lds si, Buffer
mov ax, InitCrc
mov cx, Length
or cx, cx
jz @@done
@@loop:
xor bx, bx
mov bl, al
lodsb
xor bl, al
shl bx, 1
mov bx, es:[di + bx]
xor bl, ah
mov ax, bx
loop @@loop
pop ds
@@done:
mov Result, ax
{$ENDIF}
end;
end;
function UpdateCRC32(InitCRC: LongInt; var Buffer;
{$IFDEF Win32} Length: LongInt {$ELSE} Length: Word {$ENDIF}): LongInt;
begin
asm
{$IFDEF Win32}
push esi
push edi
push eax
push ebx
push ecx
push edx
lea edi, Crc32Tab
mov esi, Buffer
mov ax, word ptr InitCRC
mov dx, word ptr InitCRC + 2
mov ecx, Length
or ecx, ecx
jz @@done
@@loop:
xor ebx, ebx
mov bl, al
lodsb
xor bl, al
mov al, ah
mov ah, dl
mov dl, dh
xor dh, dh
shl bx, 1
shl bx, 1
add ebx, edi
xor ax, [ebx]
xor dx, [ebx + 2]
loop @@loop
@@done:
mov word ptr Result, ax
mov word ptr Result + 2, dx
pop edx
pop ecx
pop ebx
pop eax
pop edi
pop esi
{$ELSE}
push ds
pop es
push ds
lea di, CRC32Tab
lds si, Buffer
mov ax, word ptr InitCRC
mov dx, word ptr InitCRC + 2
mov cx, Length
or cx, cx
jz @@done
@@loop:
xor bh, bh
mov bl, al
lodsb
xor bl, al
mov al, ah
mov ah, dl
mov dl, dh
xor dh, dh
shl bx, 1
shl bx, 1
xor ax, es:[di + bx]
xor dx, es:[di + bx + 2]
loop @@loop
@@done:
pop ds
mov word ptr Result, ax
mov word ptr Result + 2, dx
{$ENDIF}
end;
end;
function FileCRC16(FileName: String; var CRC16: Word): Boolean; { Return True if ok }
var
f: File;
p: Pointer;
FSize: LongInt;
{$IFNDEF Win32}
tmp: Word;
{$ENDIF}
begin
{$I+}
