Addtion of two digits - HELP, I dont know what the problem of my program is; my program is all about addition of two numbers

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manjaru

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Posts: 1
Member No.: 32159
Joined: 20-February 10

hello.. i dont know what the problem of my program..
my program is all about addition of two numbers..

here is my program in fasm:

CODE

org 100h

start:

mov ax,03h
int 10h

mov dx, message
mov ah,9
int 21h

xor ah,ah
int 16h
mov bh,al
;push bx

xor ah,ah
int 16h
mov bl,al
push bx

mov ah,9
int 21h

xor ah,ah
int 16h
mov ch,al

xor ah,ah
int 16h
mov cl,al

mov dx, result
mov ah,9
int 21h

add bl,cl
sub bl,30h

cmp bl,0ah
jae label_x

add bh,ch
sub bh,30h

;mov dl,bl
;mov dx, result
;mov ah,9
;int 21h

mov dl,bl
mov ah,2
int 21h

mov dh,bh
mov ah,2
int 21h
int 20h

label_x:
add bl,06h
pop cx
push cx
;shl bl,4

;mov dx,result
;mov ah,9
;int 21h

;add bl,30
;mov dl,bl
;mov ah,3
;int 21h

message: db 13,10,"enter 2 digit numbers: $"
result: db 13,10, "sum: $"

hope this prog. will be solved.. godbless.. thanks

shoorick

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Group: Admins
Posts: 2301
Member No.: 160
Joined: 22-June 04

you should run your code under debugger first to see what you do in real. i see you try to provide BCD addition, but you are adding ASCII codes and only then substructing 30h: it's wrong. you have to substract 30h from both codes first, or substract 60h after.
next: if your bl is more then 10, you are jupming forvard and skipping adding higher bytes, then add-ing 6, etc. etc.

it would be better to do something like this:

CODE

org 100h

start:

mov ax,03h
int 10h

mov dx, message
mov ah,9
int 21h

xor ah,ah
int 16h
mov bh,al

xor ah,ah
int 16h
mov bl,al

mov ah,9
int 21h

xor ah,ah
int 16h
mov ch,al

xor ah,ah
int 16h
mov cl,al

mov dx, result
mov ah,9
int 21h

; prepare numbers

and cx,0F0Fh
and bx,0F0Fh

; add parts

add bh,ch
add bl,cl

; lower to higher part carry

cmp bl,10
jb label1

sub bl,10
inc bh

label1:

; higher part correction an print leading "1" if need

cmp bh,10
jb label2

sub bh,10
mov dl,"1"
mov ah,2
int 21h

label2:

or bx, 3030h

mov dl,bh
mov ah,2
int 21h

mov dl,bl
mov ah,2
int 21h

xor ah,ah
int 16h

int 20h

message: db 13,10,"enter 2 digit numbers: $"
result: db 13,10, "sum: $"

of course, it is just "academic" way to understand asm basic things

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