x86 Instruction Set Reference

# ADD

# Add

Opcode Mnemonic Description
04 ib ADD AL, imm8 Add imm8 to AL
05 iw ADD AX, imm16 Add imm16 to AX
05 id ADD EAX, imm32 Add imm32 to EAX
80 /0 ib ADD r/m8, imm8 Add imm8 to r/m8
81 /0 iw ADD r/m16, imm16 Add imm16 to r/m16
81 /0 id ADD r/m32, imm32 Add imm32 to r/m32
83 /0 ib ADD r/m16, imm8 Add sign-extended imm8 to r/m16
83 /0 ib ADD r/m32, imm8 Add sign-extended imm8 to r/m32
00 /r ADD r/m8, r8 Add r8 to r/m8
01 /r ADD r/m16, r16 Add r16 to r/m16
01 /r ADD r/m32, r32 Add r32 to r/m32
02 /r ADD r8, r/m8 Add r/m8 to r8
03 /r ADD r16, r/m16 Add r/m16 to r16
03 /r ADD r32, r/m32 Add r/m32 to r32

# Description

Adds the first operand (destination operand) and the second operand (source operand) and stores the result in the destination operand. The destination operand can be a register or a memory location; the source operand can be an immediate, a register, or a memory location. (However, two memory operands cannot be used in one instruction.) When an immediate value is used as an operand, it is sign-extended to the length of the destination operand format.

The ADD instruction performs integer addition. It evaluates the result for both signed and unsigned integer operands and sets the OF and CF flags to indicate a carry (overflow) in the signed or unsigned result, respectively. The SF flag indicates the sign of the signed result.

This instruction can be used with a LOCK prefix to allow the instruction to be executed atomically.

# Operation

Destination = Destination + Source;
1
2

# Flags affected

The OF, SF, ZF, AF, CF, and PF flags are set according to the result.

# Protected Mode Exceptions
#GP(0) If the destination is located in a non-writable segment. If a memory operand effective address is outside the CS, DS, ES, FS, or GS segment limit. If the DS, ES, FS, or GS register is used to access memory and it contains a null segment selector.
#GP(0) If the destination is located in a non-writable segment. If a memory operand effective address is outside the CS, DS, ES, FS, or GS segment limit. If the DS, ES, FS, or GS register is used to access memory and it contains a null segment selector.
#SS(0) If a memory operand effective address is outside the SS segment limit.
#PF(fault-code) If a page fault occurs.

# Real-Address Mode Exceptions
#GP If a memory operand effective address is outside the CS, DS, ES, FS, or GS segment limit.
#GP If a memory operand effective address is outside the CS, DS, ES, FS, or GS segment limit.

# Virtual-8086 Mode Exceptions
#GP(0) If a memory operand effective address is outside the CS, DS, ES, FS, or GS segment limit.
#GP(0) If a memory operand effective address is outside the CS, DS, ES, FS, or GS segment limit.
#SS(0) If a memory operand effective address is outside the SS segment limit.
#PF(fault-code) If a page fault occurs.
Instruction Latency Throughput Execution Unit
CPUID 0F3n/0F2n 0F3n/0F2n 0F2n
ADD 1/0.5 0.5/0.5 ALU

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