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;
; Ullrich von Bassewitz, 13.08.1998
; Christian Krueger, 11-Mar-2017, added 65SC02 optimization
;
; CC65 runtime: multiplication for long (unsigned) ints
;
.export tosumul0ax, tosumuleax, tosmul0ax, tosmuleax
.import addysp1
.importzp sp, sreg, tmp1, tmp2, tmp3, tmp4, ptr1, ptr3, ptr4
.macpack cpu
tosmul0ax:
tosumul0ax:
.if (.cpu .bitand ::CPU_ISET_65SC02)
stz sreg
stz sreg+1
.else
ldy #$00
sty sreg
sty sreg+1
.endif
tosmuleax:
tosumuleax:
mul32: sta ptr1
stx ptr1+1 ; op2 now in ptr1/sreg
.if (.cpu .bitand ::CPU_ISET_65SC02)
lda (sp)
ldy #1
.else
ldy #0
lda (sp),y
iny
.endif
sta ptr3
lda (sp),y
sta ptr3+1
iny
lda (sp),y
sta ptr4
iny
lda (sp),y
sta ptr4+1 ; op1 in pre3/ptr4
jsr addysp1 ; Drop TOS
; Do (ptr1:sreg)*(ptr3:ptr4) --> EAX.
lda #0
sta tmp4
sta tmp3
sta tmp2
ldy #32
L0: lsr tmp4
ror tmp3
ror tmp2
ror a
ror sreg+1
ror sreg
ror ptr1+1
ror ptr1
bcc L1
clc
adc ptr3
pha
lda ptr3+1
adc tmp2
sta tmp2
lda ptr4
adc tmp3
sta tmp3
lda ptr4+1
adc tmp4
sta tmp4
pla
L1: dey
bpl L0
lda ptr1 ; Load the low result word
ldx ptr1+1
rts
|
