bit_blit or memmove for DCPU

gistfile1.txt

; ----- blit from B (len X) into C -- preserves A Y Z
:blit
  ifl b, c
    bra blit.backward.extern
:blit.forward.extern
  set i, b
  set j, c
  add x, b
; blit from [I, X) forward into J
:blit.forward
  set b, x
  sub b, 8
:.1
  ifl b, i
    bra .3
:.2
  sti [j], [i]
  sti [j], [i]
  sti [j], [i]
  sti [j], [i]
  sti [j], [i]
  sti [j], [i]
  sti [j], [i]
  sti [j], [i]
  ifg b, i
    bra .2
:.3
  ifl i, x
:.4
    sti [j], [i]
  ifl i, x
    bra .4
  ret
:blit.backward.extern
  set j, c
  add j, x
  sub j, 1
  set i, b
  add i, x
  sub i, 1
  set x, b
  sub x, 1
; blit from (X, I] backward into J
:blit.backward
  set b, x
  add b, 8
:.1
  ifg b, i
    bra .3
:.2
  std [j], [i]
  std [j], [i]
  std [j], [i]
  std [j], [i]
  std [j], [i]
  std [j], [i]
  std [j], [i]
  std [j], [i]
  ifl b, i
    bra .2
:.3
  ifg i, x
:.4
    std [j], [i]
  ifg i, x
    bra .4
  ret