先看java代碼實作方法：
/**CRC值*/
private int value = 0xffff;
private static int CRC16_TABLE[] = {
0x0000, 0x1189, 0x2312, 0x329b, 0x4624, 0x57ad, 0x6536, 0x74bf,
0x8c48, 0x9dc1, 0xaf5a, 0xbed3, 0xca6c, 0xdbe5, 0xe97e, 0xf8f7,
0x1081, 0x0108, 0x3393, 0x221a, 0x56a5, 0x472c, 0x75b7, 0x643e,
0x9cc9, 0x8d40, 0xbfdb, 0xae52, 0xdaed, 0xcb64, 0xf9ff, 0xe876,
0x2102, 0x308b, 0x0210, 0x1399, 0x6726, 0x76af, 0x4434, 0x55bd,
0xad4a, 0xbcc3, 0x8e58, 0x9fd1, 0xeb6e, 0xfae7, 0xc87c, 0xd9f5,
0x3183, 0x200a, 0x1291, 0x0318, 0x77a7, 0x662e, 0x54b5, 0x453c,
0xbdcb, 0xac42, 0x9ed9, 0x8f50, 0xfbef, 0xea66, 0xd8fd, 0xc974,
0x4204, 0x538d, 0x6116, 0x709f, 0x0420, 0x15a9, 0x2732, 0x36bb,
0xce4c, 0xdfc5, 0xed5e, 0xfcd7, 0x8868, 0x99e1, 0xab7a, 0xbaf3,
0x5285, 0x430c, 0x7197, 0x601e, 0x14a1, 0x0528, 0x37b3, 0x263a,
0xdecd, 0xcf44, 0xfddf, 0xec56, 0x98e9, 0x8960, 0xbbfb, 0xaa72,
0x6306, 0x728f, 0x4014, 0x519d, 0x2522, 0x34ab, 0x0630, 0x17b9,
0xef4e, 0xfec7, 0xcc5c, 0xddd5, 0xa96a, 0xb8e3, 0x8a78, 0x9bf1,
0x7387, 0x620e, 0x5095, 0x411c, 0x35a3, 0x242a, 0x16b1, 0x0738,
0xffcf, 0xee46, 0xdcdd, 0xcd54, 0xb9eb, 0xa862, 0x9af9, 0x8b70,
0x8408, 0x9581, 0xa71a, 0xb693, 0xc22c, 0xd3a5, 0xe13e, 0xf0b7,
0x0840, 0x19c9, 0x2b52, 0x3adb, 0x4e64, 0x5fed, 0x6d76, 0x7cff,
0x9489, 0x8500, 0xb79b, 0xa612, 0xd2ad, 0xc324, 0xf1bf, 0xe036,
0x18c1, 0x0948, 0x3bd3, 0x2a5a, 0x5ee5, 0x4f6c, 0x7df7, 0x6c7e,
0xa50a, 0xb483, 0x8618, 0x9791, 0xe32e, 0xf2a7, 0xc03c, 0xd1b5,
0x2942, 0x38cb, 0x0a50, 0x1bd9, 0x6f66, 0x7eef, 0x4c74, 0x5dfd,
0xb58b, 0xa402, 0x9699, 0x8710, 0xf3af, 0xe226, 0xd0bd, 0xc134,
0x39c3, 0x284a, 0x1ad1, 0x0b58, 0x7fe7, 0x6e6e, 0x5cf5, 0x4d7c,
0xc60c, 0xd785, 0xe51e, 0xf497, 0x8028, 0x91a1, 0xa33a, 0xb2b3,
0x4a44, 0x5bcd, 0x6956, 0x78df, 0x0c60, 0x1de9, 0x2f72, 0x3efb,
0xd68d, 0xc704, 0xf59f, 0xe416, 0x90a9, 0x8120, 0xb3bb, 0xa232,
0x5ac5, 0x4b4c, 0x79d7, 0x685e, 0x1ce1, 0x0d68, 0x3ff3, 0x2e7a,
0xe70e, 0xf687, 0xc41c, 0xd595, 0xa12a, 0xb0a3, 0x8238, 0x93b1,
0x6b46, 0x7acf, 0x4854, 0x59dd, 0x2d62, 0x3ceb, 0x0e70, 0x1ff9,
0xf78f, 0xe606, 0xd49d, 0xc514, 0xb1ab, 0xa022, 0x92b9, 0x8330,
0x7bc7, 0x6a4e, 0x58d5, 0x495c, 0x3de3, 0x2c6a, 0x1ef1, 0x0f78
};
/**
* 計算一個位元組陣列的CRC值 注意：這個位元組陣列是由16進制字串轉換成byte陣列的
* @param data
*/
public void update(byte[] data) {
//int fcs = 0xffff;
for (int i = 0; i < data.length; i++) {
// 1.value 右移8位(相當于除以256)
// 2.value與進來的資料進行異或運算后再與0xFF進行與運算
// 得到一個索引index，然后查找CRC16_TABLE表相應索引的資料
// 1和2得到的資料再進行異或運算。
value = (value >> 8) ^ CRC16_TABLE[(value ^ data[i]) & 0xff];
}
// 取反
//return ~fcs;
}
以上代碼想要在 delphi 7 下實作，希望老師幫忙；
比如：
十六進制：0D0108651200000054700002 可以得到CRC：E1CC
0D0108651200000054700003 可以得到CRC：F045
或者
十六進制：0D01303836353132303030303030353437300002 可以得到CRC：E1CC
0D01303836353132303030303030353437300003 可以得到CRC：F045
我的代碼如下：(CRC值對不上)
function Build_CRC(const szData:String):String;
var
Bdata:array of byte;
lv_i,lv_j,fcs:Integer;
begin
lv_i := Trunc(Length(szData)/2);
SetLength(Bdata, lv_i);
fcs := $FFFF;
for lv_j := 0 to lv_i -1 do
begin
Bdata[lv_j] := StrToInt('$' + szData[lv_j * 2 + 1] + szData[lv_j * 2 + 2]);
//showmessage(char(Bdata[lv_j]));
fcs := (fcs shr 8) xor CRCTable16[(fcs xor Bdata[lv_j]) and $FF];
end;
showmessage(IntToHex(fcs,4));
end;
uj5u.com熱心網友回復：
非查表法的一個實作：unit unCRC16;
interface
function CalCRC16(AData:array of Byte; AStart,AEnd:Integer): Word;
implementation
function CalCRC16(AData:array of Byte; AStart,AEnd:Integer): Word;
const
GENP = $A001;
var
crc:Word;
i:Integer;
tmp:Byte;
procedure CalOneByte(AByte:Byte);
var
j:Integer;
begin
crc:=crc xor AByte;
for j := 0 to 7 do
begin
tmp:=crc and 1;
crc:=crc shr 1;
crc:= crc and $7FFF;
if tmp = 1 then
crc:= crc xor GENP;
crc:=crc and $FFFF;
end;
end;
begin
crc:=$FFFF;
for i := AStart to AEnd do
CalOneByte(AData[i]);
Result:=crc;
end;
end.
如果生成多項式不一樣，則GENP = $A001;這個值不一樣，比如：$1021
網上也可以找到好多的CRC代碼
uj5u.com熱心網友回復：
function Build_CRC(const szData:String):String;var
Bdata:array of byte;
lv_i,lv_j,fcs:Integer;
pword:Word;
begin
lv_i := Trunc(Length(szData)/2);
SetLength(Bdata, lv_i);
//fcs := $FFFF;
for lv_j := 0 to lv_i -1 do
begin
Bdata[lv_j] := StrToInt('$' + szData[lv_j * 2 + 1] + szData[lv_j * 2 + 2]);
//showmessage(char(Bdata[lv_j]));
//fcs := (fcs shr 8) xor CRCTable16[(fcs xor Bdata[lv_j]) and $FF];
end;
pword := CalCRC16(Bdata,1,Length(Bdata));
showmessage(PChar(pword));
end;
Edit1.Text := '0D01303836353132303030303030353437300002';
Build_CRC(trim(Edit1.Text));
老師 運行會報錯呢
uj5u.com熱心網友回復：
我按查表法算了下，結果也符合，你這個是CCITT16的反轉校驗，是按這個演算法沒錯的//fcs := (fcs shr 8) xor CRCTable16[(fcs xor Bdata[lv_j]) and $FF];
結果不對，就不知道你要的那個結果是怎么算的了
轉載請註明出處，本文鏈接：https://www.uj5u.com/houduan/77534.html
標籤：語言基礎/算法/系統設計