NEG -- Two's Complement Negation

NEG -- Two's Complement Negation Opcode Instruction Clocks Description F6 /3 NEG r/m8 2/6 Two's complement negate r/m byte F7 /3 NEG r/m16 2/6 Two's complement negate r/m word F7 /3 NEG r/m32 2/6 Two's complement negate r/m dword Operation IF r/m = 0 THEN CF = 0 ELSE CF = 1; FI; r/m = - r/m; Description NEG replaces the value of a register or memory operand with its two's complement. The operand is subtracted from zero, and the result is placed in the operand. The carry flag is set to 1, unless the operand is zero, in which case the carry flag is cleared to 0. Flags Affected CF as described above; OF, SF, ZF, and PF as described in Appendix C Protected Mode Exceptions #GP(0) if the result is in a nonwritable segment; #GP(0) for an illegal memory operand effective address in the CS, DS, ES, FS, or GS segments; #SS(0) for an illegal address in the SS segment; #PF(fault-code) for a page fault Real Address Mode Exceptions Interrupt 13 if any part of the operand would lie outside of the effective address space from 0 to 0FFFFH Virtual 8086 Mode Exceptions Same exceptions as in real-address mode; #PF(fault-code) for a page fault