Chapter 4: Arithmetic and Logical Operations in Assembly Language

 

Introduction:

Importance of arithmetic and logical operations in assembly language programming

Overview of common arithmetic and logical instructions in MASM

Arithmetic Operations:

Addition, subtraction, multiplication, and division operations in MASM

Understanding the different operand types (registers, memory, immediate values)

Handling signed and unsigned numbers in arithmetic operations

Logical Operations:

Bitwise logical operations (AND, OR, XOR) in MASM

Bit shifting operations (left shift, right shift) in MASM

Using logical operations for data manipulation and flag manipulation

Example:

assembly

Copy code

.model small

.stack 100h

.data

    value1 dw 10

    value2 dw 5

    result dw ?

.code

main proc

    mov ax, @data

    mov ds, ax

    ; Arithmetic operations

    mov ax, value1

    add ax, value2 ; ax = ax + value2

    mov result, ax

    ; Logical operations

    mov ax, value1

    and ax, value2 ; ax = ax & value2

    or ax, value2  ; ax = ax | value2

    xor ax, value2 ; ax = ax ^ value2

    mov ah, 4Ch

    int 21h

main endp

end main

In this example, we demonstrate arithmetic and logical operations in MASM. We have two word-sized variables, value1 and value2, and a result variable called result.

For arithmetic operations, we use the add instruction to add the value of value2 to the ax register (which holds the value of value1). The result is then stored in the result variable.

For logical operations, we use the and, or, and xor instructions to perform bitwise logical operations between the ax register and the value of value2. The results are stored back in the ax register.

By understanding arithmetic and logical operations in MASM, readers can perform various calculations and manipulate data in their assembly language programs. They learn how to use instructions like add, and, or, and xor to perform arithmetic calculations and logical manipulations on data. This knowledge enables them to write more complex algorithms and implement various computational tasks in assembly language.