.export tosumula0, tosmula0
.export mul8x16, mul8x16a
- .import popsreg
- .importzp sreg, ptr4
+ .import popptr1
+ .importzp ptr1, ptr4
;---------------------------------------------------------------------------
tosmula0:
tosumula0:
sta ptr4
-mul8x16:jsr popsreg ; Get left operand
+mul8x16:jsr popptr1 ; Get left operand (Y=0 by popptr1)
- lda #0 ; Clear byte 1
+ tya ; Clear byte 1
ldy #8 ; Number of bits
- ldx sreg+1 ; Get into register for speed
+ ldx ptr1+1 ; check if lhs is 8 bit only
beq mul8x8 ; Do 8x8 multiplication if high byte zero
mul8x16a:
sta ptr4+1 ; Clear byte 2
@L0: bcc @L1
clc
- adc sreg
- pha
- txa ; hi byte of left op
+ adc ptr1
+ tax
+ lda ptr1+1 ; hi byte of left op
adc ptr4+1
sta ptr4+1
- pla
+ txa
@L1: ror ptr4+1
ror a
lsr ptr4 ; Get first bit into carry
@L0: bcc @L1
clc
- adc sreg
+ adc ptr1
@L1: ror
ror ptr4
dey