Page 386 - Programming Microcontrollers in C

The Monitor Program 371

file and certain lines of the file will be included or excluded depending
on the definition of this parameter.
It is intended to store the data in a linked list in memory. The
linked list will have a node called an Entry. An Entry contains two
characters that will be indices into the data array. The first member is
the index to the data in the data array. The second member is an index
to the next Entry for the next data entry. An array of 35 Entrys will
be stored in EEPROM along with an array of 698 (=768–35*2) chars
to store the nonvolatile data. There are 768 bytes of EEPROM on the
particular M68HC912B32 chip that we are using here.
A structure type named Epro is created to hold the collections
of Entrys and the remaining data for the data storage area. This
structure will be forced to the address 0xd00 at link time. It will
also be identified as EEPROM so that assignments to this memory
area will compile to storage to EEPROM rather than writes to normal
data memory. The first three entries in the data[] array are devoted
to special uses. data[0] contains the next open index into the
data[] array, data[1] contains an index to the beginning of the
list and data[2] contains the number of entries in the list. To
simplify both the code writing and remembering of the uses of these
memory locations, I used macros to define useful names for these
locations. Also included here is an old favorite, the FOREVER loop.
#define DOS
#ifndef PHONE_H
#define PHONE_H

#ifdef DOS
#include <stdio.h>
typedef unsigned int WORD;
enum Bool{FALSE,TRUE};
#define FOREVER while(TRUE)
#endif

#include <stdlib.h>
#include <string.h>

typedef struct {
unsigned dataindex;