Compilers: Principles and Practice by Pearson

458 Appendix C

C.4.2 Relocating Loader

Here, the load addresses given in the program file are relative addresses only, generally with

respect to the program beginning address of 0. The operating system will allocate a load address

to the loader and the loader will load the program instructions and data at places in memory with

this load address as beginning. In order that the program is still valid at the actual load address,

all position-dependent addresses must be modified by the loader. For example, consider a small

program segment:

in program file in memory

0000 JMP 0020 1000 JMP 1020

0010 0100 1010 1100

0014 Y 1014 Y