Convert VB6 yDecoder to B4a

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potman100

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Hi

I have a ydecoder function that I use in VB6, I need to convert it to run under b4a, I think its fairly straight forward, just need to change a couple of string replace lines, but there is 1 part I have no idea on, so hope somebody can help.

This is the VB6 Function
B4X: 
Public Function yDecode(sString As String) As String

    Dim bOut() As Byte, bIn() As Byte, bTest As Byte, bEscaped As Boolean, lPos As Long, lChar As Long

    sString = Replace(sString, vbCr, vbNullString)      'Get rid of the vbCrLfs.  These could be in...
    sString = Replace(sString, vbLf, vbNullString)      'either order.

    bIn = StrConv(sString, vbFromUnicode)               'Load the input byte array.
    ReDim bOut(UBound(bIn))                             'There is no case where the output will be larger.
    
    For lChar = 0 To UBound(bIn)
        If bIn(lChar) <> 61 Then
            bTest = ((bIn(lChar) + 256) - 42) Mod 256
            If bEscaped Then
                bTest = ((bTest + 256) - 64) Mod 256
                bEscaped = False
            End If
            bOut(lPos) = bTest
            lPos = lPos + 1
        Else
            bEscaped = True
        End If
    Next lChar

    ReDim Preserve bOut(lPos - 1)                       'Truncate the unused portion of the buffer.
    yDecode = StrConv(bOut, vbUnicode)                  'Convert back to a string and return.

End Function

And this is what I have so far with b4a

B4X: 
Sub ydecoder(iData As String) As String 
Dim bIn() As Byte, bTest As Byte, bEscaped As Boolean, lPos As Long, lChar As Long

   iData = iData.Replace(Chr(10),Null)
   iData = iData.Replace(Chr(13),Null)
   
   bIn = iData.GetBytes("UTF-8")

Dim bOut(bIn.Length) As Byte


'*********** NOT SURE IF THIS WILL WORK, BUT I THINK IT WILL ************

    For lChar = 0 To bIn.Length 
        If bIn(lChar) <> 61 Then
            bTest = ((bIn(lChar) + 256) - 42) Mod 256
            If bEscaped Then
                bTest = ((bTest + 256) - 64) Mod 256
                bEscaped = False
            End If
            bOut(lPos) = bTest
            lPos = lPos + 1
        Else
            bEscaped = True
        End If
    Next lChar

'*********** NOT SURE IF THIS WILL WORK, BUT I THINK IT WILL ************




End Sub

Im unsure about the last 2 lines :

B4X: 
ReDim Preserve bOut(lPos - 1)                       'Truncate the unused portion of the buffer.
yDecode = StrConv(bOut, vbUnicode)                  'Convert back to a string and return.

Thanks in advance for any help.

Regards

Potman100
 
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potman100

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Hi

yEnc is an encoding method which offers efficient and proper transmission for binaries on Usenet.

99% of Usenet binaries use this method of encoding when uploading to Usenet.

Im playing with an Nntp program.

Regards

Potman100
 
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potman100

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Hi nfordbscndrd

Thanks for the info, I did not know about this post, Ill have a look and see if I can convert it.

Regards

Potma100
 
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klaus

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For the last lines try these:
B4X: 
  Next

  Dim bc as ByteConverter
  Dim yDecode as String
  yDecode = bc.StringFromBytes(bOut, "UTF-8")
  Return yDecode
End Sub
No iteration variable after Next !
Uses the ByteConverter library.

Best regards.
 
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potman100

Active Member
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Longtime User
Hi Klaus,

Firstly thanks for the reply

Sorry this is a bit long but wanted to give you the whole picture.

I compile the data from an AsyncStreams, when I recieve data on the stream
I convert is from a byte array to a string :

Dim msg As String
msg = BytesToString(buffer, 0, buffer.Length, "UTF-8")

There can be multi packets of data to create the final raw data so I add the
msg data to a string :

nBuffer = nBuffer & msg

when the data is complete I pass it to the ydecoder sub, there is a bit of cleaning
required, removing chr(10) & chr(13) from the string data, then its converted in to
a byte array for decoding :

bIn = iData.GetBytes("UTF-8")


Vb Source :



Vb Decoded data :



B4a Source :


B4a Decoded data :


I think its something to do with Character Sets ?

Any Idea's ?

Regards

Potman100
 
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potman100

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Longtime User
Hi Klaus

I found one, not exactly sure how it works !

When reading the asyncstream I found that using :

msg = BytesToString(buffer, 0, buffer.Length, "WINDOWS-1252")

created the same data as in VB6, but there was still an issue in the decoding
of the data, so I passed the WINDOWS-1252" encoded buffer to the decoder as a string
and then converted it to a byte array :

bIn = iData.GetBytes("WINDOWS-1252")

all appeared to work until I tried to convert it back to a string, and then the data was all messed up.

The soloution was not to convert it to a string, but use a RandomAccessFile to write the bytes to the
output file and it works 100%.

Thanks for your time and help.

Regards

Potman
 
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