Android Question CRC16A problrem

[Olaan]

I would like the experts to help me about the code ,I have VB6.0 code is

Function CRC16A(buffer() As Byte) As Long

Dim i As Long
Dim Temp As Long
Dim crc As Long
Dim j As Integer
    crc = &HFFFF&
    For i = LBound(buffer) To UBound(buffer)
        Temp = buffer(i) * &H100&
        crc = crc Xor Temp
           
           For j = 0 To 7
                If (crc And &H8000&) Then
                    crc = ((crc * 2) Xor &H1021&) And &HFFFF&
                Else
                    crc = (crc * 2) And &HFFFF&
                End If
            Next j
Next i
CRC16A = crc And &HFFFF
    
End Function

and

...
...
Dim m As String
m = IIf(Val(Text5.Text) = 0, QRCodePromptPayPart1 & QRCodePromptPayPart3, QRCodePromptPayPart1 & QRCodePromptPayPart2 & QRCodePromptPayPart3)
Dim aBuf() As Byte
    
    Dim crc As Long
    
    aBuf = StrConv(m, vbFromUnicode)

    
     crc = CRC16A(aBuf)
    
    
    QRCodePromptPayIs = m & Hex(crc)
...
...

I would like to use in B4A ,I don't know how to code these line as belows

    aBuf = StrConv(m, vbFromUnicode)

and

  QRCodePromptPayIs = m & Hex(crc)

I have coded function CRC() is belows

Private Sub CRC16A(Buffer() As Byte) As Long

Dim i As Long
Dim Temp As Long
Dim crc As Long
Dim j As Int
    crc = 0xHFFFF
    'For i = LBound(Buffer) To UBound(Buffer)
    For i = 0 To Buffer.Length - 1
        Temp = Buffer(i) * 0xH100
        'crc = crc Bit.Xor Temp
        crc = Bit.Xor (crc ,Temp)
           
           For j = 0 To 7
                'If (crc Bit.And 0xH8000) Then
            If  Bit.And(crc, 0xH8000) Then
                   ' crc = ((crc * 2) Bit.Xor 0xH1021) And 0xHFFFF
                crc = Bit.And( Bit.Xor((crc * 2), 0xH1021), 0xHFFFF)
                Else
                    'crc = (crc * 2) Bit.And 0xHFFFF
                crc =  Bit.And( (crc * 2), 0xHFFFF)
                End If
           Next 
   Next 


    Return  Bit.And( crc,0xHFFFF)

End Sub

 

[aeric]

There are several threads on CRC

Modbus CRC16 calculation

Hello, I have to calculate the CRC16 of a MODBUS string. Unfortunately I have no idea how can I do that. I have found a code for Visual Basic, how I can convert it for Basic4Android? Public Function CRC(buf() As Byte, lbuf As Integer) As Integer...

www.b4x.com

 

[Olaan]

There are several threads on CRC

Modbus CRC16 calculation

Hello, I have to calculate the CRC16 of a MODBUS string. Unfortunately I have no idea how can I do that. I have found a code for Visual Basic, how I can convert it for Basic4Android? Public Function CRC(buf() As Byte, lbuf As Integer) As Integer...

www.b4x.com

I have read it.But.I don't know how tocode these 2 lines.(strconv(), hex())

aBuf = StrConv(m, vbFromUnicode)

And

QRCodePromptPayIs = m & Hex(crc)

 

[Olaan]

The lastest ,I have the code

    Dim m As String=sf2.iif(sf2.Val(Label10.Text)=0,cs.Append(content1).Append(content3),cs.Append(content1).Append(content2).Append(content3))
    Dim aBuf() As Byte
    'Dim crc As Long
    Dim crc As Int
    Dim ByteConv As ByteConverter
    'aBuf=ByteConv.StringToBytes(m,"UTF8")
    aBuf=m.GetBytes("UTF8")
    crc=CRC16A(aBuf)
    Log(crc)
    Dim tmp2 As String=crc
    Dim tmp3 As String=Bit.ToHexString(ByteConv.HexFromBytes(tmp2.GetBytes("UTF8")))
     cs= m & tmp3

  cs= m & tmp3

,But I can't code,it has error "Types do not match" ( cs as StringBuilder)

 

[Olaan]

Okay, It's my mistake. I must use .append() instead of it.

 

[Olaan]

I have eror code

An error has occurred in sub:chkinguest_crc16a(java line:749) java.lang.RuntimeException: Cannot parse:32768 as boolean continue?

my code is belows

Private Sub CRC16A(Buffer() As Byte) As Long
    Dim Temp As Long
    Dim crc1 As Long
    crc1 = 0xFFFF
    
    
    'For i = LBound(Buffer) To UBound(Buffer)
    For i = 0 To Buffer.Length - 1
        
        Temp = Buffer(i) * 0x0100
        
        crc1 = Bit.Xor (crc1 ,Temp)
           
        For j = 0 To 7
            
            If  Bit.And(crc1, 0x8000) Then
                
                crc1 = Bit.And( Bit.Xor((crc1 * 2), 0x1021), 0xFFFF)
            Else
                
                crc1 =  Bit.And( (crc1 * 2), 0xFFFF)
            End If
        Next
    Next
    
    crc1=Bit.And( crc1,0xFFFF)
    Return  crc1
End Sub

I can't solve it ,please help me.

 

[aeric]

where is your sample project?

 

[Olaan]

where is your sample project?

My project is about promptpay.I can'tsend all of the code. But.It used crc16A() function for checksum. I have tried to compare between Erel's code and mine.

 

[aeric]

My project is about promptpay.I can'tsend all of the code. But.It used crc16A() function for checksum. I have tried to compare between Erel's code and mine.

As I said, sample project, not actual project. You need to provide sample input and expected output resulted from the function.

 

[Olaan]

I have test Erel's crc() instead of mine, program can run, but.my crc16A() can't.

 

[aeric]

I am not expert in this topic but there are many CRC algorithms and depend on your input data type (string text, number, hex, bytes).

Online CRC-8 CRC-16 CRC-32 Calculator

Calculate CRC-8, CRC-16, CRC-32 checksums online

crccalc.com

 

[Olaan]

My.original.source code vb6.0.is post#1

 

[emexes]

I have error code

Cannot parse:32768 as boolean continue?

If  Bit.And(crc1, 0x8000) Then

I can't solve it ,please help me.

Try:

            '''If Bit.And(crc1, 0x8000) Then    'Bit.And returns signed 32-bit Int, not Boolean
            If Bit.And(crc1, 0x8000) <> 0 Then

 

[emexes]

I feel things will go better for you with this too:

    For i = 0 To Buffer.Length - 1
        '''Temp = Buffer(i) * 0x0100
        Temp = Bit.And(Buffer(i), 0xFF) * 0x0100    'convert B4X signed Byte -128..127 to unsigned 0..255

and tbh that multiplication should really be a left-shift but on the other hand it ain't broke so let's leave it be ? for now ?

 

[emexes]

I would like to use in B4A ,I don't know how to code these line

It would be super-useful if you had sample CRC16A input bytes and corresponding output long, to confirm that your ported B4X function is generating the same results as the original VB6 function.

 

[MicroDrie]

It would be super-useful if you had sample CRC16A sample input bytes and corresponding output long, to confirm that your ported B4X function is generating the same results as the original VB6 function.

Be aware that the CRC16 calculation takes place over the byte value that applies to an ASCII character. The original ASCII character has an 8 bit value in one byte. In Windows you may have to deal with an extended two-byte charter code for a character code. Without a known test string and the expected result, a CRC16 calculation says nothing about the correctness of the calculation.

 

[emexes]

Be aware that the CRC16 calculation takes place over the byte value that applies to an ASCII character. The original ASCII character has an 8 bit value in one byte. In Windows you may have to deal with an extended two-byte charter code for a character code. Without a known test string and the expected result, a CRC16 calculation says nothing about the correctness of the calculation.

I do not understand what this has to do with my posts about getting the CRC16A routine working.

But I cheerfully agree I had not considered that the VB6 CRC16A code's Bytes would be any size other than 8-bits.

 

[Olaan]

After I have test.My poblem is rather to the line, I will try to code.

If  Bit.And(crc1, 0x8000) Then

 

[Olaan]

This is my the small code.

 

[Olaan]

In VB6.0 is

'Must cut comma  all from the cost at cashmoney
QRCodePromptPayPart2 = Trim("54") & Format$(str(Len(StrCutCommaAll(cashmoney))), "00") & Trim(StrCutCommaAll(cashmoney))

In B4A is (I'm not sure that it 's correct?)

    Dim tmp As String=sf2.Len(NumberFormat2(cashmoney,1,0,0,False))
    'Log(tmp)
    Dim content2 As String=sf2.Trim("54")&NumberFormat(tmp,2,0)
    'Log(content2)