O D I T S Z A P C OF: Overflow flag TF: Trap flag AF: Aux carry F F F F F F F F F DF: Direction flag SF: Sign flag PF: Parity flag * * * * * * IF: Interrupt flag ZF: Zero flag CF: Carry flag
CMP r8,r8 CMP m8,r8 CMP r8,m8 CMP r16,r16 CMP m16,r16 CMP r16,16 CMP r32,r32 386+ CMP m32,r32 386+ CMP r32,m32 386+ CMP r8,i8 CMP m8,i8 CMP r16,i16 CMP m16,i16 CMP r32,i32 386+ CMP m32,i32 386+ CMP r16,i8 CMP m16,i8 CMP r32,i8 386+ CMP m32,i8 386+ CMP AL,i8 CMP AX,i16 CMP EAX,i32 386+
CMP BX,DI CMP EAX,5 CMP AX,0FFFFH ;Uses single-byte opcode CMP AL,42H ;Uses single-byte opcode CMP BP,17H CMP WORD [BX+SI+Inset],5 CMP WORD ES:[BX],0B800H
CMP compares its two operations, and sets the flags to indicate the results of the comparison. The destination operand is not affected. The operation itself is identical to subtraction of the source from the destination without borrow (SUB), save that the result does not replace the destination. Typically, CMP is followed by one of the conditional jump instructions; that is, JE to jump if the operands were equal; JNE if they were unequal; and so forth.
r8 = AL AH BL BH CL CH DL DH r16 = AX BX CX DX BP SP SI DI sr = CS DS SS ES FS GS r32 = EAX EBX ECX EDX EBP ESP ESI EDI m8 = 8-bit memory data m16 = 16-bit memory data m32 = 32-bit memory data i8 = 8-bit immediate data i16 = 16-bit immediate data i32 = 32-bit immediate data d8 = 8-bit signed displacement d16 = 16-bit signed displacement d32 = 32-bit unsigned displacement