Page 392 - Programming Microcontrollers in C

The SAVEIT() Routine 377

which then sends the information to this function,
saveit(). The data that arrives is in the form of
two binary strings. The first string, the name, is
Huffman encoded and the second string, the phone
number, is bcd encoded. These data are to be
stored in the EEPROM. A linked list that uses
indicies rather than pointers is used. The EEPROM
is broken into two fields. The first field is an
array of the type Entry. This array is DLEN long.
The next field is an array that contains the re­
mainder of the EEPROM. This array is an array of
type unsigned. It will mostly contain data that
has been encoded. The first three entries in the
array are special. The first field contains the
index to the next unused entry in the array. The
second field is the index to the start of the list
and the final field contains the number of entries
in the list.
************************************************************************/
#include “phone.h”

void saveit(char *s,char *n,Epro *epro)
{
int i,j,sl,nl;
unsigned name[ALEN];
unsigned number[NLEN];

sl=encode(s,name,ALEN);/* encode both the name and */
nl=numbdup(n,number,NLEN);/* the number */
/* store encoded data on the end of the array */
if(NEXT_OPEN+sl+nl>DATAPROM)/* do not overwrite the array */
{
puts(“***buffer full***\n”);
return;
}
for(i=NEXT_OPEN,j=0;j<sl;i++,j++)
epro->data[i]=name[j]; /* save the name then the number */