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CP/M Plus (CP/M® Version 3) Operating System Programmer's Guide

 

Appendix B

PRL File Generation

B.1

PRL Format

A Page Relocatable Program has an origin offset of 100H bytes that is stored on disk as a file of type PRL. The format is shown in Table B-1.

Table B-1. PRL File Format

Address
Contents
0001-0002H
Program size
0004-0005H
Minimum buffer requirements (additional memory)
0006-00FFH
Currently unused, reserved for future allocation
0100 + Program size = Start of bit map

The bit map is a string of bits identifying those bytes in the source code that require relocation. There is one byte in the bit map for every 8 bytes of source code.

The most significant bit, bit 7, of the first byte of the bit map indicates whether or not the first byte of the source code requires relocation. If the bit is on, it indicates that relocation is required. The next bit, bit 6, of the first byte corresponds to the second byte of the source code, and so forth.

B.2

Generating a PRL

The preferred technique for generating a PRL file is to use the CP/M LINK-80, which can generate a PRL file from a REL relocatable object file. This technique is described in the Programmer's Utilities Guide for The CP/M Family of Operating Systems. A sample link command is shown below.

A>Iink dump[op]

End of Appendix B

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