Assembly language provides low-level instructions for performing arithmetic operations. These operations are fundamental for manipulating data and performing calculations in assembly programs.

Basic Arithmetic Instructions

Assembly offers several instructions for basic arithmetic operations:

ADD: Addition
SUB: Subtraction
MUL: Unsigned multiplication
IMUL: Signed multiplication
DIV: Unsigned division
IDIV: Signed division

Addition and Subtraction

Addition and subtraction are straightforward operations in assembly. They typically involve two operands: a destination and a source.

; Addition
ADD AX, BX   ; AX = AX + BX

; Subtraction
SUB CX, DX   ; CX = CX - DX

Multiplication

Multiplication in assembly can be performed using the MUL (unsigned) or IMUL (signed) instructions. The result is often stored in multiple registers due to potential overflow.

; Unsigned multiplication
MOV AX, 5
MOV BX, 10
MUL BX       ; Result in DX:AX

; Signed multiplication
MOV AX, -5
MOV BX, 10
IMUL BX      ; Result in DX:AX

Division

Division operations use the DIV (unsigned) or IDIV (signed) instructions. The dividend is typically stored in the AX or DX:AX registers, depending on the size of the operands.

; Unsigned division
MOV AX, 100
MOV BL, 10
DIV BL       ; Quotient in AL, Remainder in AH

; Signed division
MOV AX, -100
MOV BL, 10
IDIV BL      ; Quotient in AL, Remainder in AH

Considerations

Be aware of register sizes when performing arithmetic operations.
Handle potential overflow situations, especially in multiplication and division.
Use appropriate signed or unsigned instructions based on your data types.
Consider using Assembly Floating-Point Operations for decimal calculations.

Advanced Arithmetic

For more complex calculations, you may need to combine multiple instructions or use specialized instructions provided by specific CPU architectures. Understanding Assembly CPU Architecture can help optimize your arithmetic operations.

Optimization Techniques

To improve performance, consider these optimization techniques:

Use shift operations instead of multiplication or division by powers of 2.
Utilize Assembly SIMD Instructions for parallel arithmetic operations on multiple data elements.
Implement Assembly Code Optimization strategies to reduce instruction count and improve execution speed.

Mastering arithmetic operations in assembly is crucial for efficient low-level programming. As you become more comfortable with these basic operations, you'll be better equipped to tackle more complex assembly programming tasks.