Add two 16 bit BCD numbers
Objective
In this post we will assembly language code for Add Two 16 Bit BCD Numbers Code which we will be running using TASM on windows. So First we are going to initialize memory for storing two numbers which will be loaded into AX and BX registers respectively.
Add Two 16 Bit BCD Numbers Algorithm
Step I : Initialize the data memory.
Step II : Load the first number into AX register.
Step III : Load the second number into BX register.
Step IV : Add two lower digits.
Step V : Adjust result to valid BCD number.
Step VI : Store the result in BL.
Step VII : Add the two upper digits with carry.
Step VIII : Adjust result to valid BCD number.
Step IX : Store the result in BH.
Step X : Display the result.
Step XI : Stop.
16 Bit BCD Numbers Program
.model small
.data
a dw 3629H
b dw 4738H
.code
mov ax, @data ; Initialize data section
mov ds, ax
mov ax, a ; Load number1 in ax
mov bx, b ; Load number2 in bx
add al, bl ; add lower two digits. Result in al
daa ; adjust result to valid bcd
mov bl, al ; store result in bl
adc ah, bh ; add upper two digits. Result in ah
mov al, ah ; al=ah as daa works on al only
daa ; adjust result to valid BCD
mov bh, al ; store result in bh
mov ch, 04h ; Count of digits to be displayed
mov cl, 04h ; Count to roll by 4 bits
rol bx, cl ; roll bl so that msb comes to lsb
mov dl, bl ; load dl with data to be displayed
and dl, 0fH ; get only lsb
cmp dl, 09 ; check if digit is 0-9 or letter A-F
jbe l4
add dl, 07 ; if letter add 37H else only add 30H
add dl, 30H
mov ah, 02 ; Function 2 under INT 21H (Display character)
int 21H
dec ch ; Decrement Count
jnz l2
mov ah, 4cH ; Terminate Program
int 21H
end
Find more assembly language codes here.
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