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NEG

Negates the value of the destination operand by calculating the two's complement (subtracts the operand from zero).

The following table covers the supported source and destination operands:

DO NOT support LOCK

The instruction is available in 16-bit, 32-bit, and 64-bit operand sizes. It operates on rN or mN where N is 8, 16, 32, or 64.

The CF flag is set to 1 if the operand is not zero; if the operand is zero, CF is cleared to 0. The SF flag is set if the result is negative. The OF flag is set if the operand is the minimum representable signed integer for the given size (e.g., 0x80 for 8-bit), as the result cannot be represented in two's complement.

When using NEG on the minimum signed value (e.g., -128 for i8), the result is the same as the input value, and the OF flag WILL be set. This is a critical edge case for arithmetic logic.