#include <stdio.h>
#include <stdlib.h>
#include <dos.h>

struct list_entry {
    struct list_entry *next;
    int    data;
};
volatile struct list_entry *ListHead = NULL;
volatile struct list_entry *ListTail = NULL;

void insert( struct list_entry *new_entry )
  {
    /* insert new_entry at end of linked list */
    new_entry->next = NULL;
    _disable();       /* disable interrupts */
    if( ListTail == NULL ) {
      ListHead = new_entry;
    } else {
      ListTail->next = new_entry;
    }
    ListTail = new_entry;
    _enable();	      /* enable interrupts now */
  }

void main()
  {
    struct list_entry *p;
    int i;

    for( i = 1; i <= 10; i++ ) {
      p = (struct list_entry *)
	  malloc( sizeof( struct list_entry ) );
      if( p == NULL ) break;
      p->data = i;
      insert( p );
    }
  }
