mehrmann wb extensions

[xboard.git] / winboard-dm-beta4 / lists.c

diff --git a/winboard-dm-beta4/lists.c b/winboard-dm-beta4/lists.c
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+++ b/winboard-dm-beta4/lists.c
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+/*
+ * lists.c -- Functions to implement a double linked list
+ * XBoard $Id$
+ *
+ * Copyright 1995 Free Software Foundation, Inc.
+ *
+ * ------------------------------------------------------------------------
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111 USA.
+ * ------------------------------------------------------------------------
+ *
+ * This file could well be a part of backend.c, but I prefer it this
+ * way.
+ */
+
+#include "config.h"
+
+#include <stdio.h>
+#if STDC_HEADERS
+# include <stdlib.h>
+#endif /* not STDC_HEADERS */
+
+#include "common.h"
+#include "lists.h"
+
+
+
+/* Check, if List l is empty; returns TRUE, if it is, FALSE
+ * otherwise.
+ */
+int ListEmpty(l)
+    List *l;
+{
+    return(l->head == (ListNode *) &l->tail);
+}
+
+
+/* Initialize a list. Must be executed before list is used.
+ */
+void ListNew(l)
+    List *l;
+{
+    l->head = (ListNode *) &l->tail;
+    l->tail = NULL;
+    l->tailPred = (ListNode *) l;
+}
+
+
+/* Remove node n from the list it is inside.
+ */
+void ListRemove(n)
+    ListNode *n;
+{
+    if (n->succ != NULL) {  /*  Be safe  */
+       n->pred->succ = n->succ;
+       n->succ->pred = n->pred;
+       n->succ = NULL;     /*  Mark node as no longer being member */
+       n->pred = NULL;     /*  of a list.                          */
+    }
+}
+
+
+/* Delete node n.
+ */
+void ListNodeFree(n)
+    ListNode *n;
+{
+    if (n) {
+       ListRemove(n);
+       free(n);
+    }
+}
+
+
+/* Create a list node with size s. Returns NULL, if out of memory.
+ */
+ListNode *ListNodeCreate(s)
+    size_t s;
+{
+    ListNode *n;
+
+    if ((n = (ListNode*) malloc(s))) {
+       n->succ = NULL; /*  Mark node as not being member of a list.    */
+       n->pred = NULL;
+    }
+    return(n);
+}
+
+
+/* Insert node n into the list of node m after m.
+ */
+void ListInsert(m, n)
+    ListNode *m, *n;
+{
+    n->succ = m->succ;
+    n->pred = m;
+    m->succ = n;
+    n->succ->pred = n;
+}
+
+
+/* Add node n to the head of list l.
+ */
+void ListAddHead(l, n)
+    List *l;
+    ListNode *n;
+{
+    ListInsert((ListNode *) &l->head, n);
+}
+
+
+/* Add node n to the tail of list l.
+ */
+void ListAddTail(l, n)
+    List *l;
+    ListNode *n;
+{
+    ListInsert((ListNode *) l->tailPred, n);
+}
+
+
+/* Return element with number n of list l. (NULL, if n doesn't exist.)
+ * Counting starts with 0.
+ */
+ListNode *ListElem(l, n)
+    List *l;
+    int n;
+{
+    ListNode *ln;
+
+    for (ln = l->head;  ln->succ;  ln = ln->succ) {
+       if (!n--) {
+           return (ln);
+       }
+    }
+
+    return(NULL);
+}