mirror of
https://github.com/cc65/cc65.git
synced 2024-10-03 12:55:56 +00:00
51 lines
1.1 KiB
ArmAsm
51 lines
1.1 KiB
ArmAsm
|
;
|
||
|
; Ullrich von Bassewitz, 2010-11-03
|
||
|
;
|
||
|
; CC65 runtime: 16x16 => 32 signed multiplication
|
||
|
;
|
||
|
|
||
|
.export imul16x16r32, _cc65_imul16x16r32
|
||
|
.import popax, negax, umul16x16r32m, negeax
|
||
|
.importzp ptr1, ptr3, tmp1
|
||
|
|
||
|
|
||
|
;---------------------------------------------------------------------------
|
||
|
; 16x16 => 32 signed multiplication routine.
|
||
|
;
|
||
|
; lhs rhs result result also in
|
||
|
; -------------------------------------------------------------
|
||
|
; ptr1 ax ax:sreg
|
||
|
;
|
||
|
; There is probably a faster way to do this.
|
||
|
;
|
||
|
|
||
|
|
||
|
_cc65_imul16x16r32:
|
||
|
sta ptr1
|
||
|
stx ptr1+1
|
||
|
jsr popax
|
||
|
|
||
|
imul16x16r32:
|
||
|
stx tmp1
|
||
|
cpx #0
|
||
|
bpl @L1
|
||
|
jsr negax
|
||
|
@L1: sta ptr3
|
||
|
stx ptr3+1
|
||
|
|
||
|
lda ptr1+1
|
||
|
eor tmp1
|
||
|
sta tmp1
|
||
|
lda ptr1
|
||
|
ldx ptr1+1
|
||
|
bpl @L2
|
||
|
jsr negax
|
||
|
sta ptr1
|
||
|
stx ptr1+1
|
||
|
@L2: jsr umul16x16r32m
|
||
|
ldy tmp1
|
||
|
bpl @L3
|
||
|
jmp negeax
|
||
|
@L3: rts
|
||
|
|