Michael,

I do agree that swapping bits in C is less econimical than doing it in assembly; the code I presented was not intended to be as economical as possible, it was merely intended as to demonstrate how it could be done using less RAM memory. Using a look-up table may not always be possible, especially in the smaller controllers.

Here's a somewhat more economical piece of code in assembly (16 bytes):

;R0 holds the byte to be manipulated.
;Result is returned in R1

swap_bits:	mov	R2,#9
nxt_shift:	djnz	R2,shift
		jmp	end_shift
shift:		mov	A,R0
		rrc	A
		mov	R0,A
		mov	A,R1
		rlc	A
		mov	R1,A
		jmp	nxt_shift
end_shift:      ret