主题：[求助]求CRC16 校验码算法例子

#include<stdio.h>

unsigned int calccrc(unsigned char crcbuf,unsigned int crc)
{
 unsigned char i;
 crc=crc ^ crcbuf;
 for(i=0;i<8;i++)
 {
  unsigned char chk;
  chk=crc&1;
  crc=crc>>1;
  crc=crc&0x7fff;
  if (chk==1)
  crc=crc^0xa001;
  crc=crc&0xffff;
 }
 return crc;

}

unsigned int chkcrc(unsigned char *buf,unsigned char len)
{
 unsigned char hi,lo;
 unsigned int i;
 unsigned int crc;
 crc=0xFFFF;
 for (i=0;i<len;i++)
 {
  crc=calccrc(*buf,crc);
  buf++;
 }
 hi=crc%256;
 lo=crc/256;
 crc=(hi<<8)|lo;
 return crc;
}

void main()
{
 //char buf[8]={0x01,0x03,0x00,0x00,0x00,0x02};
 char buf[8]={0x01,0x04,0x00,0x00,0x00,0x0a};
 int modbus,i;

 //memset(buf,0,sizeof(buf));
 //for(i=0;i<8;i++)
 {
 // buf[i]=40+i;
 }

 modbus = chkcrc(buf,sizeof(buf)-2);
 printf("----modbus=%x\n",modbus);
}

这个是  VC的算法，这个经过测试，结果是正确的！

全局代码

Public Function calccrc(crcbuf As Uinteger, crc As Uinteger) As Uinteger
Dim i As Uinteger
crc = crc Xor crcbuf
For i = 0 To 7
 Dim chk As Uinteger
 chk = crc And 1
 crc = crc >> 1
 crc = crc And &H7fff
 If chk = 1 Then
  crc = crc Xor &Ha001
 End If
 crc = crc And &Hffff
Next
Return crc
End Function

Public Function chkcrc(buf As Uinteger(),len As Uinteger) As Uinteger
Dim hi As Uinteger, lo As Uinteger
Dim i As Uinteger
Dim crc As Uinteger
crc = &Hffff
For i = 0 To len - 1
 crc = calccrc(buf(i), crc)
Next
hi = crc Mod 256
lo = crc / 256
crc = (hi << 8) Or lo
Return crc
End Function

调用代码

Dim aaff As uInteger() = {&H01, &H04, &H00, &H00, &H00, &H0a}
Dim aa As Integer = chkcrc(aaff, aaff.Length)
Dim bb As String = Convert.ToString(aa, 16).ToUpper()
msgbox(bb)

算法有问题，换一种算法

Public Function crc_16(Array As UInteger(), Len As UInteger) As UInteger
 Dim IX As UInteger, IY As UInteger, CRC As UInteger
        Dim Rcvbuf(1) As UInteger
 CRC = &Hffff
 'set all 1
 If Len <= 0 Then
  CRC = 0
 Else
  Len -= 1
  

  For IX = 0 To Len
   CRC = CRC Xor (Array(IX))
   For IY = 0 To 7
    If (CRC And 1) <> 0 Then
     CRC = (CRC >> 1) Xor &Ha001
    Else
     CRC = CRC >> 1
     '
    End If
   Next

  Next
 End If
 Rcvbuf(0) = (CRC And &Hff00) >> 8
 '高位置
 Rcvbuf(1) = (CRC And &Hff)
 '低位置
 CRC = Rcvbuf(0) << 8
 CRC += Rcvbuf(1)
 Return CRC
End Function

----------------

Dim aaff As uInteger() = {&H55, &H05, &H01}
Dim aa As Integer = crc_16(aaff, aaff.Length)
Dim bb As String = Convert.ToString(aa, 16).ToUpper()
msgbox(bb)