; ( n1 n2 -- rem quot) Arithmetics
; R( -- )
; signed division n1/n2 with remainder
VE_SLASHMOD:
.db $04, "/mod",0
.dw VE_HEAD
.set VE_HEAD = VE_SLASHMOD
XT_SLASHMOD:
.dw PFA_SLASHMOD
PFA_SLASHMOD:
movw temp2, tosl
ld temp0, Y+
ld temp1, Y+
mov temp6,temp1 ;move dividend High to sign register
eor temp6,temp3 ;xor divisor High with sign register
sbrs temp1,7 ;if MSB in dividend set
rjmp PFA_SLASHMOD_1
com temp1 ; change sign of dividend
com temp0
subi temp0,low(-1)
sbci temp1,high(-1)
PFA_SLASHMOD_1:
sbrs temp3,7 ;if MSB in divisor set
rjmp PFA_SLASHMOD_2
com temp3 ; change sign of divisor
com temp2
subi temp2,low(-1)
sbci temp3,high(-1)
PFA_SLASHMOD_2: clr temp4 ;clear remainder Low byte
sub temp5,temp5;clear remainder High byte and carry
ldi temp7,17 ;init loop counter
PFA_SLASHMOD_3: rol temp0 ;shift left dividend
rol temp1
dec temp7 ;decrement counter
brne PFA_SLASHMOD_5 ;if done
sbrs temp6,7 ; if MSB in sign register set
rjmp PFA_SLASHMOD_4
com temp1 ; change sign of result
com temp0
subi temp0,low(-1)
sbci temp1,high(-1)
PFA_SLASHMOD_4: rjmp PFA_SLASHMODmod_done ; return
PFA_SLASHMOD_5: rol temp4 ;shift dividend into remainder
rol temp5
sub temp4,temp2 ;remainder = remainder - divisor
sbc temp5,temp3 ;
brcc PFA_SLASHMOD_6 ;if result negative
add temp4,temp2 ; restore remainder
adc temp5,temp3
clc ; clear carry to be shifted into result
rjmp PFA_SLASHMOD_3 ;else
PFA_SLASHMOD_6: sec ; set carry to be shifted into result
rjmp PFA_SLASHMOD_3
PFA_SLASHMODmod_done:
; put remainder on stack
st -Y,temp5
st -Y,temp4
; put quotient on stack
movw tosl, temp0
jmp_ DO_NEXT