move score to /var/games, games to /usr/share/games

[unix-history] / usr / src / games / atc / list.c

/*
* Copyright (c) 1987 by Ed James, UC Berkeley.  All rights reserved.
*
* Copy permission is hereby granted provided that this notice is
* retained on all partial or complete copies.
*
* For more info on this and all of my stuff, mail edjames@berkeley.edu.
*/

#include "include.h"

PLANE   *
newplane()
{
       return ((PLANE *) calloc(1, sizeof (PLANE)));
}

append(l, p)
       LIST    *l;
       PLANE   *p;
{
       PLANE   *q = NULL, *r = NULL;

       if (l->head == NULL) {
               p->next = p->prev = NULL;
               l->head = l->tail = p;
       } else {
               q = l -> head;

               while (q != NULL && q->plane_no < p->plane_no) {
                       r = q;
                       q = q -> next;
               }

               if (q) {
                       if (r) {
                               p->prev = r;
                               r->next = p;
                               p->next = q;
                               q->prev = p;
                       } else {
                               p->next = q;
                               p->prev = NULL;
                               q->prev = p;
                               l->head = p;
                       }
               } else {
                       l->tail->next = p;
                       p->next = NULL;
                       p->prev = l->tail;
                       l->tail = p;
               }
       }
}

delete(l, p)
       LIST    *l;
       PLANE   *p;
{
       if (l->head == NULL)
               loser(p, "deleted a non-existant plane! Get help!");
       
       if (l->head == p && l->tail == p)
               l->head = l->tail = NULL;
       else if (l->head == p) {
               l->head = p->next;
               l->head->prev = NULL;
       } else if (l->tail == p) {
               l->tail = p->prev;
               l->tail->next = NULL;
       } else {
               p->prev->next = p->next;
               p->next->prev = p->prev;
       }
}