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Need to separate 16 bit binary to 4bit and 12 bit binary values

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Join Date: Jul 2008

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praksk

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Need to separate 16 bit binary to 4bit and 12 bit binary values

Jul 25th, 2008

I am relatively new to visual basic. I need to take two 8 bit byte values, join them to makea 16 bit binary value and then separate the 4 msb as a 4bit binary vale and the 12 lsb as a 12 bit binary value.

Thanks in advance for helping me out.

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QVeen72

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Re: Need to separate 16 bit binary to 4bit and 12 bit binary values

Jul 25th, 2008

Hi,

Post Some Sample Data here..
For What Input , What is the Output you want...?

Regards
Veena

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Teropod

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Re: Need to separate 16 bit binary to 4bit and 12 bit binary values

Jul 25th, 2008

Do you have

high byte__________low byte
l1l1l1l1l1l1l1l1l____l1l1l1l1l1l1l1l1l

Or you have two bytes like
high byte=255
low byte=255?

Those are example numbers.

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dmf1978

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Re: Need to separate 16 bit binary to 4bit and 12 bit binary values

Jul 25th, 2008

Hi,
Try this

 Help with Code Tags 
 VB Syntax (Toggle Plain Text) 
      Dim byteA As Long
      Dim byteB As Long
      Dim sumBytes As Long
      Dim fourBits As Long
      Dim twelveBits As Long
 
      byteA = 32 ' 00100000b = 32d
      byteB = 64 ' 01000000b = 64d
 
      ' Adding the two bytes to get a Word
      ' sumBytes = 0010000001000000b = 2048b
      sumBytes = byteA * 255 + byteB
 
      ' Take the four higher bits
      ' using this mask 1111000000000000b = 61440d
      fourBits = sumBytes And 61440
 
      ' Take the next twelve bits
      ' using this mask 0000111111111111b = 4095d
      twelveBits = sumBytes And 4095
 
      MsgBox fourBits
      MsgBox twelveBits
      Dim byteA As Long
      Dim byteB As Long
      Dim sumBytes As Long
      Dim fourBits As Long
      Dim twelveBits As Long
      
      byteA = 32 ' 00100000b = 32d
      byteB = 64 ' 01000000b = 64d
      
      ' Adding the two bytes to get a Word
      ' sumBytes = 0010000001000000b = 2048b
      sumBytes = byteA * 255 + byteB
      
      ' Take the four higher bits
      ' using this mask 1111000000000000b = 61440d
      fourBits = sumBytes And 61440
  
      ' Take the next twelve bits
      ' using this mask 0000111111111111b = 4095d
      twelveBits = sumBytes And 4095
  
      MsgBox fourBits
      MsgBox twelveBits

Just change the values of byteA and byteB.

Hope it helps

Last edited by dmf1978; Jul 25th, 2008 at 10:30 am.

-- Martín

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praksk

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Re: Need to separate 16 bit binary to 4bit and 12 bit binary values

Jul 25th, 2008

Hi Veena,Terapod, dmf1978

Thanks for your replies.

I see light in dmf1978's code. Using the code I am able to get the 12 bit integer as I need it, however, The 4 bits when separated are to be a nibble with values from 0 to 15.

Dim byteA As Byte
Dim byteB As Byte

byteA = 65 '01000001b = 65d
byteB = 32 '00100000b = 32d

( On joining the two bytes we get 0100000100100000 , and on masking the 4 bits (MSB) we get 000100100000 = 288d . Now I need to get the 4 bit nibble 0100 = 4d )

Best Regards,
praksk

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dmf1978

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Re: Need to separate 16 bit binary to 4bit and 12 bit binary values

Jul 25th, 2008

Hi,
Well, I guess you have to shift right the variable fourBits 12 positions.
Try this (I am not really sure it will work, because I have not VB here)

 Help with Code Tags 
 VB Syntax (Toggle Plain Text) 
      Dim byteA As Long
      Dim byteB As Long
      Dim sumBytes As Long
      Dim fourBits As Long
      Dim twelveBits As Long
 
      byteA = 32 ' 00100000b = 32d
      byteB = 64 ' 01000000b = 64d
 
      ' Adding the two bytes to get a Word
      ' sumBytes = 0010000001000000b = 2048b
      sumBytes = byteA * 255 + byteB
 
      ' Take the four higher bits
      ' using this mask 1111000000000000b = 61440d
      fourBits = sumBytes And 61440
 
      ' Shift right twelve positions
      fourBits = fourBits / 2 ^ 12
 
      ' Take the next twelve bits
      ' using this mask 0000111111111111b = 4095d
      twelveBits = sumBytes And 4095
 
      MsgBox fourBits
      MsgBox twelveBits
      Dim byteA As Long
      Dim byteB As Long
      Dim sumBytes As Long
      Dim fourBits As Long
      Dim twelveBits As Long
      
      byteA = 32 ' 00100000b = 32d
      byteB = 64 ' 01000000b = 64d
      
      ' Adding the two bytes to get a Word
      ' sumBytes = 0010000001000000b = 2048b
      sumBytes = byteA * 255 + byteB
      
      ' Take the four higher bits
      ' using this mask 1111000000000000b = 61440d
      fourBits = sumBytes And 61440

      ' Shift right twelve positions
      fourBits = fourBits / 2 ^ 12
  
      ' Take the next twelve bits
      ' using this mask 0000111111111111b = 4095d
      twelveBits = sumBytes And 4095
  
      MsgBox fourBits
      MsgBox twelveBits

Last edited by dmf1978; Jul 25th, 2008 at 1:26 pm.

-- Martín

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Teropod

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Re: Need to separate 16 bit binary to 4bit and 12 bit binary values

Jul 25th, 2008

Thats all nice but when i make code in vb i usually try to make it more universal so if i need it i can easy use it on other application and or if i need change output value i can do it much easier by changing input values

For example make conversion from numbering systems vb don't have binary numeric format as much as i know.

I just hope that you wont have too many combination for those binary numbers.
Just make simple function that will convert string witch have "binary value" and convert it to long value. that should be max 10 lines of code for any binary value you put in there.

Just copy and paste these function in your module.
Use it and you wont have to worry how much is 1100101 in dec?

 Help with Code Tags 
 Visual Basic 4 / 5 / 6 Syntax (Toggle Plain Text) 
Function BinToDec(strBin As String) As Long
'If return value is -1 please check strBin value!
 
Dim lonBinLenght As Long
Dim lonDecMirror As Long
 
    On Error GoTo Errorhandler
 
    lonBinLenght = Len(strBin)
 
    For i = 0 To lonBinLenght - 1
        If (Mid(strBin, lonBinLenght - i, 1)) > 1 Then GoTo Errorhandler
 
        lonDecMirror = lonDecMirror + (Mid(strBin, lonBinLenght - i, 1) * 2 ^ i)
 
    Next
 
    BinToDec = lonDecMirror
 
Exit Function
Errorhandler:
    strBin = -1
End Function
Function BinToDec(strBin As String) As Long
'If return value is -1 please check strBin value!

Dim lonBinLenght As Long
Dim lonDecMirror As Long
    
    On Error GoTo Errorhandler
    
    lonBinLenght = Len(strBin)
    
    For i = 0 To lonBinLenght - 1
        If (Mid(strBin, lonBinLenght - i, 1)) > 1 Then GoTo Errorhandler
        
        lonDecMirror = lonDecMirror + (Mid(strBin, lonBinLenght - i, 1) * 2 ^ i)
    
    Next
    
    BinToDec = lonDecMirror

Exit Function
Errorhandler:
    strBin = -1
End Function

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dmf1978

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Re: Need to separate 16 bit binary to 4bit and 12 bit binary values

Jul 25th, 2008

•

Originally Posted by Teropod

Just make simple function that will convert string witch have "binary value" and convert it to long value. that should be max 10 lines of code for any binary value you put in there.

And it is nice too, but as he say, he don't have string binary values. All that I know is the existence of two bytes. I've coded taking account of these.
As you said... Have fun

-- Martín

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Teropod

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Re: Need to separate 16 bit binary to 4bit and 12 bit binary values

Jul 25th, 2008

Then he can just use these function.

Its also simple.

 Help with Code Tags 
 Visual Basic 4 / 5 / 6 Syntax (Toggle Plain Text) 
Function DecToBin(lonDec As Long, lonNumberOfBits As Long) As String
Dim strBinMirror As String
Dim intBit As Integer
Dim lonDecMirror As Long
 
    lonDecMirror = lonDec
 
    Do While lonDecMirror > 0
        intBit = lonDecMirror Mod 2
        lonDecMirror = Fix(lonDecMirror / 2)
        strBinMirror = intBit & strBinMirror
    Loop
 
    If Len(strBinMirror) < lonNumberOfBits Then
        For i = 1 To lonNumberOfBits - Len(strBinMirror)
            strBinMirror = "0" & strBinMirror
        Next
    End If
 
    DecToBin = strBinMirror
End Function
Function DecToBin(lonDec As Long, lonNumberOfBits As Long) As String
Dim strBinMirror As String
Dim intBit As Integer
Dim lonDecMirror As Long
    
    lonDecMirror = lonDec
    
    Do While lonDecMirror > 0
        intBit = lonDecMirror Mod 2
        lonDecMirror = Fix(lonDecMirror / 2)
        strBinMirror = intBit & strBinMirror
    Loop

    If Len(strBinMirror) < lonNumberOfBits Then
        For i = 1 To lonNumberOfBits - Len(strBinMirror)
            strBinMirror = "0" & strBinMirror
        Next
    End If
            
    DecToBin = strBinMirror
End Function

Hope these two functions will help!

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dmf1978

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Re: Need to separate 16 bit binary to 4bit and 12 bit binary values

#10

Jul 25th, 2008

HI,
I see your point. But what he need is to separate some bits from a word. To do this, the easy way is to use masks. The mask thing is not an invention of mine.

Take a look here: http://en.wikipedia.org/wiki/Mask_(computing)
It is the more straightforward way to do that. And it uses less code too.

Sure, I am with you that he must code this inside a function, passing the original word, start_bit, end_bit, etc.

Regards

Last edited by dmf1978; Jul 25th, 2008 at 7:30 pm.

-- Martín