Page 393 - Programming Microcontrollers in C

378 Chapter 7 Advanced Topics

for(j=0;j<nl;i++,j++) /* at NEXT_OPEN */
epro->data[i]=number[j];
epro-
>header[LIST_ENTRIES++].dataindex=NEXT_OPEN;
NEXT_OPEN+=sl+nl;

if(LIST_ENTRIES>=1) /* no entries in list never 0 */
epro->header[LIST_ENTRIES-1].next=LIST_ENTRIES;
}

Listing 7-13: The saveit() Function
If there is enough room in the EEPROM array to store the new
data, the encoded name and the encoded number are both written
into the array at the appropriate location. Recall that the encode
routines return the lengths of the encoded data. NEXT_OPEN is the
next unused entry in the array. After the data are written to the array,
the new value for NEXT_OPEN is calculated by adding the length
of the two encoded arrays to the old value.
Finally, if there is more than one entry in the array the index for
the new entry, LIST_ENTRIES, will be put in the next location of
the previous entry, epro->header[LIST_ENTRIES-1].next.

The printout() and the printafter() Functions
These two functions are almost the same. Therefore, they will be
discussed together. In both cases, control is returned to the calling
program if there are no data to be printed out. The printout()
routine starts at the beginning of the list and prints the entire contents
of the EEPROM. Prior to the printout, the contents are decoded.
Both decode routines return a new line character at the end of the
data stream along with a null character to indicate the end of the line.
Notice in the printout() function, the data starts at the start of
the list and cycles through all of the contents of the list.
#include “phone.h”

void printout(Epro *epro)