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一段C++算法请高手帮忙编辑成Pascal

发布时间: 2012-04-03 12:38:19 作者: rapoo

一段C++算法,请高手帮忙编辑成Pascal,谢谢!
#include <stdio.h>

#define SLIDE_ID_LEN 11// Length of slide ID

// This function computes and returns the CRC associated with the slideIDString input
// argument.
//
unsigned char computeCrc(char *slideIdString)
{
unsigned char Local8BitPoly = 0x025;
unsigned char crcTable[256];
int i,j;
unsigned char crc = 0;

// Generate CRC table
unsigned char crc_accum;
for(i=0; i <256; i++)
{
crc_accum = (unsigned char) i;

for(j=0; j <8; j++)
{ // If lead 1 then XOR to divide else move on.
if(crc_accum & 0x80)
crc_accum = (crc_accum < < 1) ^ Local8BitPoly;
else
crc_accum = (crc_accum < < 1);
}
crcTable[i] = crc_accum; // Update next item in table
}


// calculate the CRC
for(j=0; j < SLIDE_ID_LEN; j++)
{
i = ((crc) ^ slideIdString[j]) & 0xff;
crc = (crc < < 8) ^ crcTable[i];
}

return crc;
}


// This main program provides an example of how to use the computeCrc function.
// In this example, the CRC 's are computed and displayed for a range of 25 ID 's starting
// with the ID value of "140180001 ".
//
int main(int argc, char* argv[])
{
long id = 140180001;
char idstring[SLIDE_ID_LEN+1];
int i;

// Generate CRC for 25 values
for (i=0; i < 25; i++, id++)
{
sprintf(idstring, "%011d ", id);
printf( "%s %03d\n ", idstring, computeCrc(idstring));
}

return 0;
}


[解决办法]
program Project2;

{$APPTYPE CONSOLE}

uses
SysUtils;

const
SLIDE_ID_LEN = 11; // Length of slide ID

function computeCrc(slideIdString: PChar): Byte;
var
Local8BitPoly: Byte;
crcTable: array[0..255] of Byte;
i, j: Integer;
crc_accum: Byte;
begin
Result := 0;
Local8BitPoly := $025;
// Generate CRC table
for i := 0 to 255 do
begin
crc_accum := Byte(i);
for j := 0 to 7 do
begin
// If lead 1 then XOR to divide else move on.
if crc_accum and $80 <> 0 then
crc_accum := Byte((crc_accum shl 1) xor Local8BitPoly)
else crc_accum := (crc_accum shl 1);
end;
crcTable[i] := crc_accum; // Update next item in table
end;


// calculate the CRC
for j := 0 to SLIDE_ID_LEN - 1 do
begin
i := (Result xor Byte(slideIdString[j])) and $ff;
Result := Byte((Result shl 8) xor crcTable[i]);
end;
end;

var
id: Longint = 140180001;
idstring: array [0..SLIDE_ID_LEN - 1] of Char;
i: Integer;

begin
// Generate CRC for 25 values
for i := 0 to 24 do
begin
SysUtils.FormatBuf(idstring[0], SizeOf(idstring), '%.11d ', 5, [id]);
Writeln(Format( '%s %.3d ', [idstring, computeCrc(idstring)]));
Inc(id);
end;
Readln;
end.

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