A description of positions [left, right] is appropriate more for C code than for Assembly code. (A description of timing [first argument, second argument] is more appropriate for the way that Assembly code is written.)
;
.export _cc65_umul8x8r16
- .import umul8x8r16, popa
-
- .include "zeropage.inc"
+ .import umul8x8r16, popa, ptr1:zp
;---------------------------------------------------------------------------
;---------------------------------------------------------------------------
; 16x16 => 32 signed multiplication routine.
;
-; lhs rhs result result also in
+; LHS RHS result result also in
; -------------------------------------------------------------
-; ptr1 ax ax:sreg
+; ax ptr1 ax:sreg
;
; There is probably a faster way to do this.
;
;---------------------------------------------------------------------------
; 16x16 => 32 unsigned multiplication routine. Because the overhead for a
; 16x16 => 16 unsigned multiplication routine is small, we will tag it with
-; the matching labels as well.
+; the matching labels, as well.
;
-; routine lhs rhs result result also in
+; routine LHS RHS result result also in
; -----------------------------------------------------------------------
-; umul16x16r32 ptr1 ax ax:sreg ptr1:sreg
-; umul16x16r32m ptr1 ptr3 ax:sreg ptr1:sreg
-; umul16x16r16 ptr1 ax ax ptr1
-; umul16x16r16m ptr1 ptr3 ax ptr1
+; umul16x16r32 ax ptr1 ax:sreg ptr1:sreg
+; umul16x16r32m ptr3 ptr1 ax:sreg ptr1:sreg
+; umul16x16r16 ax ptr1 ax ptr1
+; umul16x16r16m ptr3 ptr1 ax ptr1
;
; ptr3 is left intact by the routine.
;
;---------------------------------------------------------------------------
; 8x16 => 24 unsigned multiplication routine. Because the overhead for a
; 8x16 => 16 unsigned multiplication routine is small, we will tag it with
-; the matching labels as well.
+; the matching labels, as well.
;
-; routine lhs rhs result result also in
+; routine LHS RHS result result also in
; -----------------------------------------------------------------------
-; umul8x16r24 ptr1-lo ax ax:sreg-lo ptr1:sreg-lo
-; umul8x16r24m ptr1-lo ptr3 ax:sreg-lo ptr1:sreg-lo
+; umul8x16r24 ax ptr1-low ax:sreg-low ptr1:sreg-low
+; umul8x16r24m ptr3 ptr1-low ax:sreg-low ptr1:sreg-low
;
-; ptr3 ist left intact by the routine.
+; ptr3 is left intact by the routine.
;
umul8x16r24:
;
; Ullrich von Bassewitz, 2010-11-02
;
-; CC65 runtime: 8x8 => 16 multiplication
+; CC65 runtime: 8x8 => 16 unsigned multiplication
;
.export umul8x8r16, umul8x8r16m
;---------------------------------------------------------------------------
-; 8x8 => 16 multiplication routine.
+; 8x8 => 16 unsigned multiplication routine.
;
-; lhs rhs result result also in
+; LHS RHS result result in also
; -------------------------------------------------------------
-; ptr1-lo ptr3-lo ax ptr1
+; .A (ptr3-low) ptr1-low .XA ptr1
;
umul8x8r16:
umul8x8r16m:
lda #0 ; Clear byte 1
ldy #8 ; Number of bits
- lsr ptr1 ; Get first bit of lhs into carry
+ lsr ptr1 ; Get first bit of RHS into carry
@L0: bcc @L1
clc
adc ptr3
dey
bne @L0
tax
- stx ptr1+1 ; Result in a/x and ptr1
+ stx ptr1+1 ; Result in .XA and ptr1
lda ptr1 ; Load the result
rts ; Done
-
-