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CRCUNIT.PAS
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Wrap
Pascal/Delphi Source File
|
1997-08-16
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5KB
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144 lines
{
▀▀▀▀▀▀▀▀ ▀▀▀▀▀▀ ▀▀ ▀▀
▀▀ ▀▀ ▀▀ ▀▀ ▀▀
▀▀ ▀▀ ▀▀▀ ▀▀▀▀▀ The DoorKit!
▀▀ ▀▀ ▀▀ ▀▀ ▀▀
▀▀ ▀▀▀▀▀▀ ▀▀ ▀▀
The BBS Door Development Kit By The People - For The People!
Feel free to modify or optimize this code at will. All I ask is that if
find a better way to do things (and you will), please send me a copy of
your modifications. Thanks in advance!....Larry L. Athey....
This unit is used for calculating the 32 Bit CRC value of strings and
files. This is especially handy for creating resource files for MAX
compatible doors with unique names. Using the CRC32 value of a file
for its file name prevents the possibility of display errors and also
prevents two identical files with different file names. }
{$A+,B-,D+,E+,F+,G+,I-,L+,N-,O+,P-,Q-,R-,S-,T-,V+,X+}
UNIT CRCUNIT;
INTERFACE
FUNCTION FileToCRC(FName : STRING) : STRING;
FUNCTION StringToCRC(InStr : STRING) : STRING;
IMPLEMENTATION
CONST Crc_32_Tab: 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
);
FUNCTION UpdC32(Octet : BYTE ; Crc : LONGINT) : LONGINT;
BEGIN
UpdC32 := Crc_32_Tab[BYTE(Crc XOR LONGINT(Octet))] XOR ((Crc SHR 8) AND $00FFFFFF);
END;
FUNCTION CrcString(I : LONGINT) : STRING; Assembler;
asm
jmp @1
@0 :
db '0123456789abcdef'
@1 :
cld
les di, @result
mov ax, 0008h
stosb
mov cx, 4
mov si, 3
@2 :
mov al, BYTE [I + si]
DEC si
push si
mov bl, al
mov dl, bl
AND bx, 00f0h
SHR bx, 4
AND dx, 000fh
mov si, bx
mov al, BYTE [cs : @0 + si]
stosb
mov si, dx
mov al, BYTE [cs : @0 + si]
stosb
pop si
loop @2
END;
FUNCTION StringCRC(InStr : STRING) : LONGINT;
VAR
CrcVal : LONGINT;
A : WORD;
BEGIN
CrcVal := $FFFFFFFF;
FOR A := 1 TO LENGTH(InStr) DO CrcVal := UpdC32(ORD(InStr[A]),CrcVal);
StringCRC := CrcVal;
END;
FUNCTION CrcEnd(Crc : LONGINT) : LONGINT;
BEGIN
CrcEnd := Crc XOR $ffffffff;
END;
FUNCTION FileToCRC(FName : STRING) : STRING;
VAR
Crc : LONGINT;
F : FILE;
Buf : ARRAY[1..1024] OF BYTE;
Nr,N : WORD;
BEGIN
ASSIGN(F,FName);
RESET(F,1);
IF IORESULT = 0 THEN BEGIN
Crc := $ffffffff;
REPEAT
BLOCKREAD(F,Buf,SIZEOF(Buf),Nr);
FOR N := 1 TO Nr DO Crc := UpdC32(Buf[N],Crc);
UNTIL Nr = 0;
CLOSE(F);
Crc := CrcEnd(Crc);
FileToCRC := CrcString(Crc);
END ELSE FileToCRC := '';
END;
FUNCTION StringToCRC(InStr : STRING) : STRING;
BEGIN
StringToCRC := CrcString(StringCrc(InStr));
END;
END.