x86 Jump

There are 2 categories of conditional jump. The problem arises because NASM can generate a binary opcode in different way. A jump target that lies within 127 bytes of the conditional jump instruction is called short jump. A jump that is farther than 127 bytes but within the code segment is called near jump. A near jump can be as far as 2GB away. A far jump go out of a segment which mean specifying both segment and offset. This is quite uncommon.

A short jump generates a short and compact opcode which is always 2 bytes in size. Near jump generates a opcode of either 4 bytes or 6 bytes. NASM generates short jump by default as this is most commonly use in programs. To generate near jump, one must explicitly specify

jne loop ;short jump
jne near loop ;near jump

The above does not apply to unconditional jump.