x86 Instruction Set Reference



Opcode Mnemonic Description
2C ib SUB AL,imm8 Subtract imm8 from AL.
2D iw SUB AX,imm16 Subtract imm16 from AX.
2D id SUB EAX,imm32 Subtract imm32 from EAX.
80 /5 ib SUB r/m8,imm8 Subtract imm8 from r/m8.
81 /5 iw SUB r/m16,imm16 Subtract imm16 from r/m16.
81 /5 id SUB r/m32,imm32 Subtract imm32 from r/m32.
83 /5 ib SUB r/m16,imm8 Subtract sign-extended imm8 from r/m16.
83 /5 ib SUB r/m32,imm8 Subtract sign-extended imm8 from r/m32.
28 /r SUB r/m8,r8 Subtract r8 from r/m8.
29 /r SUB r/m16,r16 Subtract r16 from r/m16.
29 /r SUB r/m32,r32 Subtract r32 from r/m32.
2A /r SUB r8,r/m8 Subtract r/m8 from r8.
2B /r SUB r16,r/m16 Subtract r/m16 from r16.
2B /r SUB r32,r/m32 Subtract r/m32 from r32.

Subtracts the second operand (source operand) from the first operand (destination 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, register, or 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 SUB instruction performs integer subtraction. It evaluates the result for both signed and unsigned integer operands and sets the OF and CF flags to indicate an 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.

Destination = Destination - Source;
Flags affected

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

Instruction Latency Throughput Execution Unit