Save 3 more cycles in drunkwalk.

1 files changed, 8 insertions, 6 deletions

diff --git a/dla.s b/dla.s
index 68a13ba..5a0932b 100644
--- a/dla.s
+++ b/dla.s
@@ -551,10 +551,10 @@ checkneigh:
  ; check neighbors. used to be a subroutine, inlined it.
  ; also inlined plotsetup here.
  sty part_y           ; 3
- lda lineaddrs_l,y
- sta pixptr
- lda lineaddrs_h,y
- sta pixptr+1
+ lda lineaddrs_l,y    ; 5
+ sta pixptr           ; 3
+ lda lineaddrs_h,y    ; 5
+ sta pixptr+1         ; 3
 
  ; 3/4 of the time, we can use a faster code path, check
  ; (-1,0) and (1,0) at the same time. this happens only when
@@ -601,8 +601,10 @@ pp1ok:
  tay
  lda (pixptr),y
  and pixmask
- bne stick
- jmp dwloop ; too far for branch. X *still* holds (maybe modified) part_x
+ beq dwloop ; ...or fall through to stick.
+ ; note that if we add much more code to drunkwalk, the beq will
+ ; have to become a jmp, which takes 3 extra cycles. so any code
+ ; added above had better save more than 3 cycles!
 
 stick: ; we always get here with Z flag clear
  stx part_x ; only update part_x at exit.