Fast Z80 Bit Reversal

For years I’ve been using the following simple code to reverse the bits in the A register by rotating the bits left out of one register and right into another:

; reverse bits in A
; 8 bytes / 206 cycles

  ld b,8
  ld l,a
REVLOOP:
  rl l
  rra
  djnz REVLOOP

Recently I wondered if it’s possible to save a few cycles.

read more…

thank to JM @ http://www.retroprogramming.com/