CODEWITHSUNDEEP
vb.nettype-conversionhexbytebit
Gforse
Gforse

Reputation: 373

Get first three bits from a byte

My question is simple, i need to convert the first three bits of a byte to a integer (Enum) value. However the things i try i always get a 0 back. This is wat the document says:

Bit 0-3: These bits indicate the connection state.

Value 0 to 14 indicate the connection state. Value 3 = Connected

Now the response i get (from a serial device) is a encoded byte stream of ASCII hex values, so i first need to convert it from a hex string to byte array and then get the bits from it. This is my code so far:

Dim strResonse As String = "0C03" 'This should result in a connection state value of 3

Dim ConState(2) As Byte
ConState = HexStringToByteArray(strResonse)
Dim int As Integer = ConState(1) << 1 And ConState(1) << 2 And ConState(1) << 3
Debug.Print(int.ToString)


Private Function HexStringToByteArray(ByVal shex As String) As Byte()
    Dim B As Byte() = Enumerable.Range(0, shex.Length).Where(Function(x) x Mod 2 = 0).[Select](Function(x) Convert.ToByte(shex.Substring(x, 2), 16)).ToArray()
    Return Enumerable.Range(0, shex.Length).Where(Function(x) x Mod 2 = 0).[Select](Function(x) Convert.ToByte(shex.Substring(x, 2), 16)).ToArray()
End Function

Upvotes: 0

Views: 988

Answers (1)

the_lotus
the_lotus

Reputation: 12748

It would be easier to use bit operation

Dim connectionState As Integer
Dim response As Integer = &HC03

' Get the first 4 bits. 15 in binary is 1111
connectionState = response And 15

If your input is really a string, there a built-in way to convert to integer.

Dim response As Integer = Convert.ToInt32("C03", 16)

If you really want to get an array, I suggest you use the built in method.

Dim allBits As Byte() = BitConverter.GetBytes(response)

There also the BitArray class that can be handy.

Upvotes: 2

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