Arithmetic and Logic Instructions

Unary Arithmetic Instructions

Unary arithmetic instructions are those that operate on a single operand. These instructions perform arithmetic operations directly on the operand without requiring a second operand.

1 Neg (Negation)

The Neg instruction negates (changes the sign of) the operand. It computes the two's complement of the operand, effectively multiplying it by -1.

Syntax:

Intel Syntax:

neg operand

mov eax, 10   ; Load 10 into EAX
neg eax       ; Negate the value of EAX (result: -10)

AT&T Syntax:

neg destination

movl $10, %eax  # Load 10 into EAX
negl %eax       # Negate the value of EAX (resulting in -10)

2 INC (Increment)

The inc instruction increments the value of the operand by 1.

Syntax:

Intel Syntax:

inc operand

mov ebx, 5    ; Load 5 into EBX
inc ebx       ; Increment the value of EBX by 1 (result: 6)

AT&T Syntax:

inc destination

movl $10, %eax  # Load 10 into EAX
incl %eax       # Increment the value of EAX by 1

3 DEC (Decrement)

This instruction decrements the value of the operand by 1.

Syntax:

Intel Syntax:

dec operand

mov ecx, 8    ; Load 8 into ECX
dec ecx       ; Decrement the value of ECX by 1 (result: 7)

AT&T Syntax:

dec destination

movl $20, %ebx  # Load 20 into EBX
decl %ebx       # Decrement the value of EBX by 1

Binary Arithmetic Instructions

These instructions allow for the manipulation of numerical data, performing operations such as addition, subtraction, multiplication, and division.

1 Add (Addition)

Adds the value of the source operand to the destination operand and stores the result in the destination.

Syntax:

Intel Syntax:

add rax, rbx   ; Add the contents of RBX to RAX and store the result in RAX

2 Sub (Subtraction)

Subtracts the value of the source operand from the destination operand and stores the result in the destination.

Syntax:

Intel Syntax:

sub rdx, rcx   ; Subtract the contents of RCX from RDX and store the result in RDX

3 IMul(Signed multiplication)

Performs signed multiplication of the destination and source operands and stores the result in the destination.

Syntax:

Intel Syntax:

imul rsi, rdi ; Multiply the contents of RDI by RSI and store the result in RSI

4 IDIV (Signed Division)

Performs signed division of the DX:AX register pair (RDX:RAX for 64-bit division) by the operand, storing the quotient in AX register (or RAX for 64-bit division) and the remainder in DX register (or RDX for 64-bit division).

Syntax:

Intel Syntax:

mov rax, 100   ; Load 100 into RAX
idiv rcx       ; Divide RDX:RAX by RCX

5 Mul (Unsigned Multiplication)

Performs unsigned multiplication of the AX register (EAX register for 32-bit, RAX for 64-bit) by the source operand, storing the results in AX register (EAX for 32-bit, ). The operand can be a register or a memory location.

6 Div (Unsigned Division)

Performs unsigned division of the DX:AX register pair by the operand, storing the quotient in AX and the remainder in DX.