;
-; Piotr Fusik, 07.03.2018
+; Piotr Fusik, 09.03.2018
; originally by Ullrich von Bassewitz
;
; CC65 runtime: Decrement eax by value in Y
sec
sbc tmp1
bcs @L9
-; borrow from X
+
+; Borrow from X.
+
dex
- cpx #$ff
+ cpx #$FF
bne @L9
-; X wrapped from zero to $ff, borrow from sreg
+
+; X wrapped from zero to $FF, borrow from sreg.
+
dec sreg
cpx sreg
bne @L9
-; sreg wrapped from zero to $ff, borrow from sreg+1
+
+; sreg wrapped from zero to $FF, borrow from sreg+1.
+
dec sreg+1
+
+; Done.
+
@L9: rts