Compilers: Principles and Practice by Pearson

Linkers and Loaders 451

C.1.2 Tasks Performed by a Linker

Each module starting address is 0, each is to be allocated a separate load address.

For the example modules in Fig. C.2, assuming that the O/S resident part takes 100 units, then the

load addresses are as shown in Table C.1.

Obviously, the Linker will have to:

c

adjust the Jump addresses;

c

adjust address of local references;

c

find location of the external symbols and insert their addresses.

Table C.1

Example: modules to be linked

Module Length Starting or Load address

A 300 100

B 600 400

C 400 1000

D 300 1400

C.1.3 An Object Module

What information should be there? See Fig. C.3.

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