Hi guys, I had been testing the 32-bit routine provided by Dr. Marshall in the code library section. I had been testing fixed values, but I kept getting incorrect values for my results from the division, and I found a pattern. For some reason, the quotient result is multiplied by 256 and that is the result given. For instance, I tested out 130,560/510. The correct answer is 256, but for some reason, it is giving me 256*256 = 65,536. I tried out simpler numbers like 2/1. The correct answer is 2, but it gave me 2*256 = 512. It keeps following the same pattern. I am posting the division code as well as my display routine below. Please give me advice if you can figure out where the problem is coming from, because I haven't been able to so far. The quotient should be in r0-r3 and the remainder in r4-r7. Thanks for the help.

Here is the code, I know it's long, but please bear with me:

Start:
;registers r0-r3 are the dividend and equal 130,560
mov r0, #00h
mov r1, #01h
mov r2, #0FEh
mov r3, #00h

;register r4 & r5 are the divisor and equal 510
mov r4, #01h
mov r5, #0FEh
lcall UDIV32

mov num, #0 ;variable to track leading zeros since i don't want them displayed
lcall BilConv ;this is the display routine
ljmp 0

;this part below is the 32-bit division routine

UDIV32: push 08 ; Save Register Bank 1
push 09
push 0AH
push 0BH
push 0CH
push 0DH
push 0EH
push 0FH
push dpl
push dph
push B
setb RS0 ;Select Register Bank 1
mov r7, #0 ;clear partial remainder
mov r6, #0
mov r5, #0
mov r4, #0
mov B, #32 ; set loop count

div_lp32: clr RS0 ; Select Register Bank 0
clr C ; clear carry flag
mov a, r0
rlc a
mov r0, a
mov a, r1
rlc a
mov r1, a
mov a, r2
rlc a
mov r2, a
mov a, r3
rlc a
mov r3, a
setb RS0 ;Select Register Bank 1
mov a, r4 ;the lowest bit of the
rlc a ; partial remainder
mov r4, a
mov a, r5
rlc a
mov r5, a
mov a, r6
rlc a
mov r6, a
mov a, r7
rlc a
mov r7, a
mov a, r4 ;trial subtract divisor
clr C ;from partial remainder
subb a, 04
mov dpl, a
mov a, r5
subb a, 05
mov dph, a
mov a, r6
subb a, #0
mov 06, a
mov a, r7
subb a, #0
mov 07, a
cpl C
jnc div_321
mov r7, 07
mov r6, 06
mov r5, dph
mov r4, dpl
div_321: mov a, r0
rlc a
mov r0, a
mov a, r1
rlc a
mov r1, a
mov a, r2
rlc a
mov r2, a
mov a, r3
rlc a
mov r3, a
djnz B, div_lp32

mov 07, r7
mov 06, r6
mov 05, r5
mov 04, r4
;put remainder, saved before the last subtraction, in bank 0, and put quotient in bank 0

mov 03, r3
mov 02, r2
mov 01, r1
mov 00, r0
clr RS0
pop B
pop dph
pop dpl
pop 0FH ; Retrieve Register Bank 1
pop 0EH
pop 0DH
pop 0CH
pop 0BH
pop 0AH
pop 09
pop 08

ret
;-----------------------------------------------------

;this part below is my display routine

BilConv: clr c
mov counter, #0

BilLoop: MOV A,R3 ;how many time we can subtract 1,000,000,000 without carry (3B9ACA00h)
SUBB A,#00H
MOV R3,A
MOV A,R2
SUBB A,#0CAH
MOV R2,A
MOV A,R1
SUBB A,#9AH
MOV R1,A
mov a, r0
subb a, #3Bh
mov r0, a
JC BilSkip
INC counter
mov num, #1
LJMP BilLoop

BilSkip: mov a, counter
mov save, a
mov a, num
cjne a, #1, continue
mov a, save
acall toASCII

continue: mov a, r3
add a, #00h
mov r3, a
mov a, r2
addc a, #0CAh
mov r2, a
mov a, r1
addc a, #9Ah
mov r1, a
mov a, r0
addc a, #3Bh
mov r0, a
;-----------------------------------------
clr c
mov counter, #0

HunMilLoop: MOV A,R3 ;how many time we can subtract 100,000,000 without carry (5F5E100h)
SUBB A,#00H
MOV R3,A
MOV A,R2
SUBB A,#0E1H
MOV R2,A
MOV A,R1
SUBB A,#0F5H
MOV R1,A
mov a, r0
subb a, #05h
mov r0, a
JC HunMilSkip
INC counter
mov num, #1
LJMP HunMilLoop

HunMilSkip: mov a, counter
mov save, a
mov a, num
cjne a, #1, continue2
mov a, save
acall toASCII

continue2: mov a, r3
add a, #00h
mov r3, a
mov a, r2
addc a, #0E1h
mov r2, a
mov a, r1
addc a, #0F5h
mov r1, a
mov a, r0
addc a, #05h
mov r0, a

;----------------------------------------------
clr C
mov counter, #0

Hex3DecLoop1: MOV A,R3 ;how many time we can subtract 10,000,000 without carry (989680H)
SUBB A,#80H
MOV R3,A
MOV A,R2
SUBB A,#96H
MOV R2,A
MOV A,R1
SUBB A,#98H
MOV R1,A
mov a, r0
subb a, #00h
mov r0, a
JC Hex3DecSkip1
INC counter
mov num, #1
LJMP Hex3DecLoop1

Hex3DecSkip1: mov a, counter
mov save, a
mov a, num
cjne a, #1, continue3
mov a, save
acall toASCII

continue3: mov a, r3
add a, #80h
mov r3, a
mov a, r2
addc a, #96h
mov r2, a
mov a, r1
addc a, #98h
mov r1, a
mov a, r0
addc a, #00h
mov r0, a
;------------------------------------------------------------
clr c
mov counter, #0

Hex3DecLoop2: MOV A,R3 ;how many times we can subtract 1,000,000 (F4240H) without carry
SUBB A,#40H
MOV R3,A
MOV A,R2
SUBB A,#42H
MOV R2,A
MOV A,R1
SUBB A,#0FH
MOV R1,A
mov a, r0
subb a, #00h
mov r0, a
JC Hex3DecSkip2
INC counter
mov num, #1
LJMP Hex3DecLoop2

Hex3DecSkip2: mov a, counter
mov save, a
mov a, num
cjne a, #1, continue4
mov a, save
acall toASCII

continue4: MOV A,R3 ;how many times we can subtract 1,000,000 (F4240H) without carry
add A,#40H
MOV R3,A
MOV A,R2
addc A,#42H
MOV R2,A
MOV A,R1
addc A,#0FH
MOV R1,A
mov a, r0
addc a, #00h
mov r0, a
;------------------------------------------------------------
CLR C
MOV counter, #0


Hex3DecLoop3: MOV A,R3 ;100000 (186A0H)?
SUBB A,#0A0H
MOV R3,A
MOV A,R2
SUBB A,#86H
MOV R2,A
MOV A,R1
SUBB A,#01H
MOV R1,A
mov a, r0
subb a, #00h
mov r0, a
JC Hex3DecSkip3
INC counter
mov num, #1
LJMP Hex3DecLoop3


Hex3DecSkip3: mov a, counter
mov save, a
mov a, num
cjne a, #1, continue5
mov a, save
acall toASCII

continue5: MOV A,R3
ADD A,#0A0H
MOV R3,A
MOV A,R2
ADDC A,#86H
MOV R2,A
MOV A,R1
ADDC A,#01H
MOV R1,A
mov a, r0
addc a, #00h
mov r0, a

;------------------------------------------------------------
CLR C
MOV counter, #0

Hex2DecLoop1: MOV A,R3 ;10000 (2710h)?
SUBB A,#010H
MOV R3,A
MOV A,R2
SUBB A,#27H
MOV R2,A
MOV A,R1
SUBB A,#0
MOV R1,A
mov a, r0
subb a, #00h
mov r0, a
JC Hex2DecSkip1
INC counter
mov num, #1
LJMP Hex2DecLoop1



Hex2DecSkip1: mov a, counter
mov save, a
mov a, num
cjne a, #1, continue6
mov a, save
acall toASCII

continue6: MOV A,R3
ADD A,#010H
MOV R3,A
MOV A,R2
ADDC A,#27H
MOV R2,A
mov a, r1
addc a, #00h
mov r1, a
mov a, r0
addc a, #00h
mov r0, a

;------------------------------------------------------------
CLR C
MOV counter,#0

Hex2DecLoop2: MOV A,R3 ;1000 (3E8h)?
SUBB A,#0E8H
MOV R3,A
MOV A,R2
SUBB A,#03H
MOV R2,A
JC Hex2DecSkip2
INC counter
mov num, #1
LJMP Hex2DecLoop2

Hex2DecSkip2: mov a, counter
mov save, a
mov a, num
cjne a, #1, continue7
mov a, save
acall toASCII

continue7: MOV A,R3
ADD A,#0E8H
MOV R3,A
MOV A,R2
ADDC A,#03H
MOV R2,A

;------------------------------------------------------------
CLR C
MOV counter,#0

Hex2DecLoop3: MOV A,R3 ;100 (64h)?
SUBB A,#064H
MOV R3,A
MOV A,R2
SUBB A,#0H
MOV R2,A
JC Hex2DecSkip3
INC counter
mov num, #1
LJMP Hex2DecLoop3

Hex2DecSkip3: mov a, counter
mov save, a
mov a, num
cjne a, #1, continue8
mov a, save
acall toASCII

continue8: MOV A,R3
ADD A,#064H
MOV R3,A
MOV A,R2
ADDC A,#0H
MOV R2,A

;------------------------------------------------------------
CLR C
MOV counter,#0

Hex2DecLoop4: MOV A,R3 ;10 (0Ah)?
SUBB A,#0AH
MOV R3,A
JC Hex2DecSkip4
INC counter
mov num, #1
LJMP Hex2DecLoop4

Hex2DecSkip4: mov a, counter
mov save, a
mov a, num
cjne a, #1, continue9
mov a, save
acall toASCII

continue9: MOV A,R3 ADD A,#0AH
acall toASCII
;ljmp 0

RET






toASCII: mov b, #30h
add a, b
lcall lcd_cout
ret