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<h1> words/slashmod.asm </h1> |
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<pre> |
; ( 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 |
</pre> |
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