How to cram two bytes into a short?

Question

Hi all,
I have some byte[] data that I am receiving, and I need to put two bytes into one short (or int, or whatever), as the byte[] will form a two bytes-per-pixel image. I've been working with 8-bit data (this is 12-bits, NOT packed), which is much easier to manipulate.
I currently have this method to convert a byte[] of 8-bit data into a short (I do this because Java does not support signed types and I need that 8th bit):
private short[] convertBytesToShorts(byte[] data) {
     short[] convertedData = new short[data.length];
     for (int i = 0; i < data.length; i++) {
          convertedData[i] = (short)((short)data[i] & 0xff);
     return convertedData;
}Is there a way to modify this to place two bytes into one short? Is it possible to just AND two bytes with 0xff and add them together to create one short? Surely it cannot be that simple. Also, remember that I must treat the values as unsigned.
Furthermore, the two bytes look like this:
| xxxx xxxx | xxxx 0000 |So the last four bits in the second byte are 0s.
Any advice is appreciated.
Message was edited by:
Djaunl

Answer 1

I've been working with 8-bit
data (this is 12-bits, NOT packed), Obviously that is contradictory.
I currently have this method to convert a byte[] of
8-bit data into a short (I do this because Java does
not support signed types and I need that 8th bit):
Yes it does. The fact that it displays a byte as and integer and the conversion in that process produces a negative display value has nothing at all to do with the bits.
Is there a way to modify this to place two bytes into
one short? short s = (short)(((b1 << 8) & 0x0ff) | (b2 & 0x0ff))
Of course you still have to deal with getting the order correct.
(You can probably get rid of that first mask but you would need to test that.)