What's a time efficient algorithm to copy unaligned bit arrays?

Question

I\'ve had to do this many times in the past, and I\'ve never been satisfied with the results.

Can anyone suggest a fast way of copying a contiguous bit array fro

Answer 1

Your inner loop takes pieces of two bytes and moves them to a destination byte. That's almost optimal. Here are a few more hints in no particular order:

• There's no need to limit yourself to a byte at a time. Use the largest integer size your platform will let you get away with. This of course will complicate your starting and trailing logic.
• If you use unsigned chars or integers, you may not need to mask the second piece of the source after it's shifted right. This will depend on your compiler.
• If you do need the mask, make sure your compiler is moving the table lookup outside of the loop. If it isn't, copy it to a temporary variable and use that.