Convert bitarray to string without using ChrW function - string

Question

I need to convert bitarray to unicode string (default encoding in vb.net for string type).
For example, let's say the 000000000100000100000000010000100000000001000011 is the bit string representation for 3 x 16bit unicode characters, respectively A = 65; B = 66 and C = 67 (codePoints resulted in conversion of those bits to Integer).
Now, those bits are stored in bitarray. Is there a way to convert the bitarray to string without using the build-in ChrW function?
I need this because since I already have the bits ordered as encoding would do, so I try to avoid a double conversion to gain some performance.

Answer 1

Use Byte() and System.Text.Encoding...
'BIN: 00000000 01000001 00000000 01000010 00000000 01000011
'HEX: 0 0 4 1 0 0 4 2 0 0 4 3
Dim s1 As String = "ABC"
Console.WriteLine("Original string:" & s1)
Dim b1 As Byte() = System.Text.Encoding.BigEndianUnicode.GetBytes(s1)
Console.WriteLine("Big-endian UTF-16 (Hex):" & BitConverter.ToString(b1))
b1(1) = b1(1) Or CByte(&H4) 'change byte 1 from 01000001 to 01000101
Dim s2 As String = System.Text.Encoding.BigEndianUnicode.GetString(b1)
Console.WriteLine("Modified string:" & s2)
Console.ReadKey()

Answer 2

I don't know if this'll actually be faster than using ChrW(), and it's probably not the prettiest solution either ;), but I here's how I did it:
To do what you ask I did these steps:
Reverse the bit array (since .NET interprets them from left to right, rather than right to left)
Create a byte array of the bits. The size of the array should be the amount of bits divided by 8 (8 bits = 1 byte) rounded up to the nearest integer (see Math.Ceiling()).
Use Encoding.Unicode to decode the byte array into a string.
Convert the string into an array of chars, reverse it, and convert the new char array back into a string.
I've put this together in a function:
Public Function BitArrayToString(ByVal Bits As BitArray) As String
'Reverse the bits (I didn't have access to a compiler tha supports Linq, please don't hate).
Dim ReversedValues As Boolean() = New Boolean(Bits.Count - 1) {}
For x As Integer = 0 To Bits.Count - 1
ReversedValues((ReversedValues.Length - 1) - x) = Bits(x)
Next
'Put the reversed bits into a new bit array.
Dim ReversedBits As New BitArray(ReversedValues)
'Declare a byte array to 1/8th of the bit array's size, rounded up to the nearest integer.
Dim Bytes As Byte() = New Byte(Math.Ceiling(ReversedBits.Length / 8) - 1) {}
ReversedBits.CopyTo(Bytes, 0)
'Decode the byte array into a string.
Dim Result As String = System.Text.Encoding.Unicode.GetString(Bytes)
'Get the string as a char array and reverse it.
Dim Chars As Char() = Result.ToCharArray()
Array.Reverse(Chars)
'Return the resulting string from our reversed chars.
Return New String(Chars)
End Function
Online test: https://ideone.com/SUTWlJ