Addressing mode

Question

Self reallocating code  required for displacement addressing mode.How ?Please someone explain this concept.

Answer 1

There is a base register exist for displacement addressing mode.

Base register contains a pointer to a memory location. An integer ( or constant) is also referred to as a displacement. The address of the operand is obtained by adding the contents of the base register plus the constant. 

a self-relocating program is a program that relocates its own address-dependent instructions and data when run, and is therefore capable of being loaded into memory at any address.

So self relocating means self modifying .

Comments

@Bikram Sir it means it is "modifying the address only ".  Then in this case can I  say self-relocating code also required for indirect addressing mode ?

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Self reallocating code  required for displacement addressing mode

It simply means it can calculate it's own effective address by itself , by adding that integer constant to base register address.

In indirect addressing mode we have register or memory location that contains the address of the operand is directly used in instruction .

 But in case of displacement mode  we add a constant value , in case of indirect mode , that integer constant is not added.

so both are not same . and in case of displacement self relocating code can be used only .