Split 8 bit byte.

Question

So Say I have an array of bytes that is 16 long, with each 8 bits representing my data and an array that is 8 long with each 4 bits (so 2 per byte) representing my data.

If I wanted to loop over these and get the values, what would be the easiest way of doing so?

My poor attempt would be something like this, but this doesn't appear to be working as I expect.

for(int i = 0; i < bigByteArray.Length; i++) 
{
    byte BigByteInfo = bigByteArray[i];
    byte SmallByteInfo;
    if(i % 2 == 0)
    {
        SmallByteInfo = smallByteArray[i / 2] % 16;
    }
    else
    {
        SmallByteInfo = smallByteArray[i / 2] / 16;
    }

    //Use of data Here.
}

Answer 1

If I understand right (bigByteArray is 16 long, smallByteArray is 8 long, packed):

for(int i = 0; i < bigByteArray.Length; i++)
{
    bigByteArray[i] = (byte)((smallByteArray[i / 2] >> (i % 2 == 0 ? 4 : 0)) & 0xF);
}

Answer 2

you can use this class as helper class

public class FoutBitsArrayEnumerator : IEnumeable<byte>
{
  FoutBitsArrayEnumerator(byte[] array)
  {
    this.array = array;
  }
  public IEnumerator<byte> GetEnumerator
  {
    foreach (byte i in array)
    {
        yield return i & 15;
        yield return (i >> 4) & 15;
    }
  }

  byte[] array;
}