form1.frm

crc校验

VERSION 5.00
Begin VB.Form Form1 
   Caption         =   "Form1"
   ClientHeight    =   3150
   ClientLeft      =   180
   ClientTop       =   360
   ClientWidth     =   4680
   LinkTopic       =   "Form1"
   ScaleHeight     =   3150
   ScaleWidth      =   4680
   StartUpPosition =   3  '窗口缺省
   Begin VB.CommandButton Command1 
      Caption         =   "Command1"
      Height          =   495
      Left            =   1680
      TabIndex        =   0
      Top             =   960
      Width           =   1215
   End
End
Attribute VB_Name = "Form1"
Attribute VB_GlobalNameSpace = False
Attribute VB_Creatable = False
Attribute VB_PredeclaredId = True
Attribute VB_Exposed = False
Private Sub Command1_Click()
Dim CRC() As Byte
      Dim d() As Byte '待传输数据
      ReDim d(2) As Byte
      d(0) = 123
      d(1) = 112
      d(2) = 135
      CRC = CRC16(d) '调用CRC16计算函数
      Print Hex(CRC(0))
      Print Hex(CRC(1))
      'CRC(0)为高位
      'CRC(1)为低位
End Sub
Function CRC16(data() As Byte) As String
      Dim CRC16Lo As Byte, CRC16Hi As Byte      'CRC寄存器
      Dim CL As Byte, CH As Byte                '多项式码&HA001
      Dim SaveHi As Byte, SaveLo As Byte
      Dim i As Integer
      Dim Flag As Integer
      CRC16Lo = &HFF
      CRC16Hi = &HFF
      CL = &H1
      CH = &HA0
      For i = 0 To UBound(data)
        CRC16Lo = CRC16Lo Xor data(i) '每一个数据与CRC寄存器进行异或
        For Flag = 0 To 7
          SaveHi = CRC16Hi
          SaveLo = CRC16Lo
          CRC16Hi = CRC16Hi \ 2            '高位右移一位
          CRC16Lo = CRC16Lo \ 2            '低位右移一位
          If ((SaveHi And &H1) = &H1) Then '如果高位字节最后一位为1
            CRC16Lo = CRC16Lo Or &H80      '则低位字节右移后前面补1
          End If                           '否则自动补0
          If ((SaveLo And &H1) = &H1) Then '如果LSB为1，则与多项式码进行异或
            CRC16Hi = CRC16Hi Xor CH
            CRC16Lo = CRC16Lo Xor CL
          End If
        Next Flag
      Next i
      Dim ReturnData(1) As Byte
      ReturnData(0) = CRC16Hi              'CRC高位
      ReturnData(1) = CRC16Lo              'CRC低位
      CRC16 = ReturnData
    End Function