Initial import of the CDE 2.1.30 sources from the Open Group.

cde/lib/tt/mini_isam/isdlink.c

@@ -0,0 +1,103 @@
+/*%%  (c) Copyright 1993, 1994 Hewlett-Packard Company			 */
+/*%%  (c) Copyright 1993, 1994 International Business Machines Corp.	 */
+/*%%  (c) Copyright 1993, 1994 Sun Microsystems, Inc.			 */
+/*%%  (c) Copyright 1993, 1994 Novell, Inc. 				 */
+/*%%  $TOG: isdlink.c /main/4 1999/09/29 15:03:15 mgreess $ 			 				 */
+#ifndef lint
+	static char sccsid[] = "@(#)isdlink.c 1.4 89/09/01 Copyr 1988 Sun Micro";
+#endif
+
+/*
+ * Copyright (c) 1988 by Sun Microsystems, Inc.
+ */
+
+/*
+ * isdlink.c
+ *
+ * Description:
+ *	Double link list functions
+ */
+
+#include "isam_impl.h"
+
+/* _isdln_base_insert () - Insert element into list (at the front) -----------*/
+void _isdln_base_insert (base,l,e)
+	register char		*base;
+	register struct dlink	*l,*e;
+{
+	e->dln_forward = l->dln_forward;
+	l->dln_forward = (char *)e - base;
+	
+	e->dln_backward = (char *)l - base;
+	((struct dlink *)(base + e->dln_forward))->dln_backward = (char *)e - base;
+}
+
+/* _isdln_base_append () - Append element to list (at the end) -------------*/
+void _isdln_base_append (base,l,e)
+	register char		*base;
+	register struct dlink	*l,*e;
+{
+	e->dln_backward = l->dln_backward;
+	l->dln_backward = (char *)e - base;
+	
+	e->dln_forward = (char *)l - base;
+	((struct dlink *)(base + e->dln_backward))->dln_forward = (char *)e - base;
+}
+
+/* _isdln_base_remove () - Remove element from list -------------------------*/
+void _isdln_base_remove (base,e)
+	register char		*base;
+	register struct dlink	*e;
+{
+	((struct dlink *)(base + e->dln_backward))->dln_forward = e->dln_forward;
+	((struct dlink *)(base + e->dln_forward))->dln_backward = e->dln_backward;
+}
+
+/* _isdln_base_first () - Return first element of the list -------------------*/
+struct dlink * _isdln_base_first(base,l)
+	register char		*base;
+	register struct dlink    	*l;
+{
+	struct dlink *val = (struct dlink *)(base + l->dln_forward);
+
+	if (val == NULL) {
+		if (NULL == (struct dlink *)(base + l->dln_forward) &&
+		    NULL == (struct dlink *)(base + l->dln_backward))
+			_isdln_base_makeempty(base, l);
+		val = l;
+	}
+	return(val);
+}
+
+/* _isdln_base_next () - Return next element in the list --------------------*/
+struct dlink * _isdln_base_next(base,l)
+	register char		*base;
+	register struct dlink    	*l;
+{
+	return (((struct dlink *)(base + l->dln_forward))); 
+}
+
+/* _isdln_base_prev () - Return previous element in the list ----------------*/
+struct dlink * _isdln_base_prev(base,l)
+	register char		*base;
+	register struct dlink    	*l;
+{
+	return  (((struct dlink *)(base + l->dln_backward))); 
+}
+
+/* _isdln_base_makeempty () - Make head of empty list -----------------------*/
+void _isdln_base_makeempty(base,l)
+	register char		*base;
+	register struct dlink    	*l;
+{
+	l->dln_forward = l->dln_backward = (char *)l - base;
+}
+
+/* _isdln_base_isempty () - Test if list is empty---------------------------*/
+int _isdln_base_isempty(base,l)
+	register char		*base;
+	register struct dlink    	*l;
+{
+	return (l->dln_forward == (char *)l - base &&
+		l->dln_backward == (char *)l - base);
+}