long pointer into byte data stream

[eaton]

I have a stream of 8 bit values coming in. after capturing these 10 bytes in a buffer I want to assign a long pointer to the 2 bytes of interest and interpret them as a 16 bit value. This works fine except for the fact that the 2 bytes are reversed. i.e 0x3c 0x04 coming in is seen as 0x043c. Is there an easy way to reverse this. What I do now is reverse the 2 bytes in the buffer and assign the long pointer in the normal manner. But it is slow and kind of clunky. I'm using memcpy to move the message from the rx buffer into a temporary holding buffer. Perhaps there is some way to modify memcpy.

[Mark]

Why not load the incoming data in reverse order?

[ckielstra]

[Ttelmah]

I have to agree that swapping the bytes on the way in, or first, is the 'best' solution to this. I like Ckielstra's byte swap routine, a real example of 'lateral thinking'. The same basic trick, can though be used to do the byte swap on the input!. If you simply 'XOR' the byte counter with 1, and use this as the index to write into the array, all the alternate bytes will be swapped, and probably just about as efficiently as possible. :-)

Best Wishes

[Guest]

Thanks for your help guys. The Byte swap module is pretty slick