Two's Complement Negation (neg)

neg{bwl} 	r/m[8|16|32]

Operation

two's-complement r/m[8|16|32] -> r/m[8|16|32]

Description

Replace the value of the byte, word, or long with its two's complement; that is, neg subtracts the byte, word, or long value from 0, and puts the result in the byte, word, or long respectively.

neg sets the carry flag to 1, unless initial value of the byte, word, or long is 0. In this case neg clears the carry flag to 0.

Example

Replace the 8-bit contents of the effective address (addressed by the ESI register plus an offset of 1) with its two's complement:

negb 1(%esi)

Replace the 16-bit contents of the effective address (addressed by the EDI register plus an offset of 4) with its two's complement:

negw 4(%edi)

Replace the 32-bit contents of the effective address (addressed by the EDI register plus an offset of 4) with its two's complement:

negl 4(%edi)