Signed Integers || two’s complement in Assembly language

2’s complement in Assembly language
In mathematics, the additive inverse of a number n is the value, when added to n, produces zero. Here are a few examples, expressed in decimal:
6 + –6 = 0
0 + 0 = 0
–1 + 1 = 0
Programs often include both subtraction and addition operations, but internally, the CPU really only performs addition. To get around this restriction,
the computer uses the additive inverse. When subtracting A – B, the CPU instead performs A + (–B). For example, to simulate the subtraction of 4
from 6, the CPU adds –4 to 6:
6 + –4 = 2

Binary Two’s Complement

When working with binary numbers, we use the term two’s complement to refer to a number’s additive inverse. The two’s complement of a number
n is formed by reversing n’s bits and adding 1. Here, for example, n equals the 4-bit number 0001:
N: 0001
Reverse N: 1110
Add 1: 1111
The two’s complement of n, when added to n, produces zero:
0001 + 1111 = 0000
It doesn't matter how many bits are used by n. The two’s complement is formed using the same method:
N = 1 00000001
Reverse N: 11111110
Add 1: 11111111
N = 1 0000000000000001
Reverse N: 1111111111111110
Add 1: 1111111111111111

Here are some examples of 8-bit two’s complements:

n(decimal)                            n(binary)                               NEG(n)                                  (decimal)
+2                                       00000010                             11111110                                   –2
+16                                     00010000                             11110000                                   –16
+127                                    01111111                            10000001                                   –127