PAGESIZE 4096
DATASTART (char *)&etext;

typedef struct dlist {
  struct dlist *flink;
  struct dlist *blink;
  char *addr;
  char *stop;
  unsigned long size;
} *Dlist;

Dlist curptr, endptr; ( Dlist is a structure to create a link list)
  int no_chunks=0, pn;
  long size;
  caddr_t stop, addr;

  if(incremental){       /*-- variable used to check if incremental checkpointing on? --*/
    endptr = inc_list->main->flink;
 
    /*-- for each included chunk of the heap --*/
    for(curptr = inc_list->main->blink->blink;
        curptr != endptr; curptr = curptr->blink){

      /*-- write out the last page in the included chunk --*/
      stop = curptr->addr;
      pn = ((long)curptr->stop - (long)DATASTART) / PAGESIZE;

      if(isdirty(pn)){ /* function to check if the segment has been modified*/ 
        addr = (caddr_t)max((long)curptr->addr,
                            (long)((pn * PAGESIZE) + DATASTART));
        size = (long)curptr->stop - (long)addr;

        debug(stderr, "DEBUG: Writing heap from 0x%x to 0x%x, pn = %d\n",
                                                   addr, addr+size, pn);
        if(write_chunk(addr, size, map_fd, data_fd) == -1){ /* function to write a chunk to a file */
          return -1;
        }
        no_chunks++;
      }

      /*-- write out all the whole pages in the middle of the chunk --*/
      for(pn--; pn * PAGESIZE + DATASTART >= stop; pn--){
        if(isdirty(pn)){
          addr = (caddr_t)((pn * PAGESIZE) + DATASTART);
          debug(stderr, "DEBUG: Writing heap from 0x%x to 0x%x, pn = %d\n",
                                                 addr, addr+PAGESIZE, pn);
          if(write_chunk(addr, PAGESIZE, map_fd, data_fd) == -1){
            return -1;
          }
         
          }
          no_chunks++;
        }
      }

      /*-- write out the first page in the included chunk --*/
      addr = curptr->addr;
      size = ((pn+1) * PAGESIZE + DATASTART) - addr;

      if(size > 0 && (isdirty(pn))){
        debug(stderr, "DEBUG: Writing heap from 0x%x to 0x%x\n", addr, addr+size);
        if(write_chunk(addr, size, map_fd, data_fd) == -1){
          return -1;
        }

        
        }
        no_chunks++;
      }
    }
  }
  else{  /*-- incremental checkpointing off! --*/
    endptr = inc_list->main->blink;

    /*-- for each included chunk of the heap --*/
    for(curptr = inc_list->main->flink->flink;
        curptr != endptr; curptr = curptr->flink){
      debug(stderr, "DEBUG: saving memory from 0x%x to 0x%x\n", 
                         curptr->addr, curptr->addr+curptr->size);

      if(write_chunk(curptr->addr, curptr->size, map_fd, data_fd) == -1){
        return -1;
      }
  
      }
      no_chunks++;
    }
  }

  return no_chunks;