form1.frm

使用VB程序编写的一个简单实用的CRC校验器

VERSION 5.00
Begin VB.Form Form1 
   Caption         =   "Form1"
   ClientHeight    =   3090
   ClientLeft      =   60
   ClientTop       =   450
   ClientWidth     =   5190
   LinkTopic       =   "Form1"
   ScaleHeight     =   3090
   ScaleWidth      =   5190
   StartUpPosition =   3  '窗口缺省
   Begin VB.TextBox Text4 
      Height          =   1095
      Left            =   6240
      TabIndex        =   6
      Text            =   "Text4"
      Top             =   2040
      Width           =   3255
   End
   Begin VB.TextBox Text3 
      Height          =   855
      Left            =   6240
      TabIndex        =   5
      Text            =   "Text3"
      Top             =   720
      Width           =   2895
   End
   Begin VB.TextBox Text2 
      Height          =   615
      Left            =   1800
      TabIndex        =   2
      Text            =   "Text2"
      Top             =   1440
      Width           =   2775
   End
   Begin VB.TextBox Text1 
      Height          =   495
      Left            =   1680
      TabIndex        =   1
      Text            =   "Text1"
      Top             =   600
      Width           =   2775
   End
   Begin VB.CommandButton Command1 
      Caption         =   "计算"
      Height          =   615
      Left            =   1440
      TabIndex        =   0
      Top             =   2280
      Width           =   1455
   End
   Begin VB.Label Label2 
      Caption         =   "计算结果"
      Height          =   495
      Left            =   120
      TabIndex        =   4
      Top             =   1440
      Width           =   1455
   End
   Begin VB.Label Label1 
      Caption         =   "要校验的数据"
      Height          =   495
      Left            =   240
      TabIndex        =   3
      Top             =   600
      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()
     Text2.Text = CRC(Text1.Text)       '调用CRC16计算函数
End Sub
  '取得CRC校验码
Public Function CRC(STR1 As String) As String
Dim CRCREG As Long            '定义CRC寄存器
Dim MVAL As Long
Dim R As Integer


CRCREG = 65535                '把寄存器各位都置为1

If (Len(STR1) Mod 2 = 1) Then
STR1 = "0" & STR1             '当输入的数字串不是偶个数时，在前面补0
End If

For R = 1 To Len(STR1) Step 2
MVAL = Val("&H" + Mid(STR1, R, 2))     '提取输入的数的前两位，转换为十六进制的

CRCREG = CRCREG Xor MVAL
'CRCREG = CRCREG And 65535


For T = 1 To 8 Step 1
If (CRCREG And &H1) Then
CRCREG = (CRCREG \ 2) Xor &HA001
CRCREG = CRCREG And 65535
Else
CRCREG = CRCREG \ 2
'CRCREG = CRCREG And 65535
End If
Next

Next

Dim A As Long
Dim B As Long
A = CRCREG And 255          '取低八位
B = CRCREG And 65280        '取高八位
A = A * 256                 '低八位变成高八位
B = B / 256                 '高八位变成低八位
If (A + B) < 16 Then
CRC = "000" + Hex(A + B)
ElseIf (A + B) < 256 Then
CRC = "00" + Hex(A + B)
ElseIf (A + B) < 4096 Then
CRC = "0" + Hex(A + B)
Else
CRC = Hex(A + B)
End If

End Function

Private Sub Form_Load()
 Text1.Text = ""
  Text2.Text = ""
End Sub