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

cde/lib/tt/mini_isam/isbsearch.c

@@ -0,0 +1,62 @@
+/*%%  (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. 				 */
+/*%%  $XConsortium: isbsearch.c /main/3 1995/10/23 11:35:44 rswiston $ 			 				 */
+#ifndef lint
+static char sccsid[] = "@(#)isbsearch.c 1.3 89/07/17 Copyr 1988 Sun Micro";
+#endif
+
+/*
+ * Copyright (c) 1988 by Sun Microsystems, Inc.
+ */
+
+/*
+ * isbsearch.c
+ *
+ * Description:
+ *	Binary search function.
+ *	If differs from bsearch(3) in that if an exact match is not found,
+ *	the next lower key is returned. If key is lower than any key in table,
+ *	NULL value is returned.
+ *	
+ */
+
+
+char *_isbsearch (key,table,nelems,keylen,cmpf)
+    char *key;
+    char *table;
+    int nelems;
+    int keylen;
+    int (*cmpf) ();
+{
+    register int len,l1,result;		     /* current length of array to search */
+    register char *p,*low;
+    
+    if (nelems <= 0) return (char *) 0;
+
+    /* Check if key is lower than any key in the table. */
+    result = (*cmpf) (key,table);
+    if (result < 0 ) return (char *) 0;	     /* Key is lower */
+    else if (result == 0) return table;	     /* Exact match */
+    
+    for (low = table,len = nelems; len > 0;) {
+	l1 = len >> 1;
+	p = low + keylen * l1;
+	if ((result = (*cmpf) (key,p)) == 0)    /* Exact match found */
+	    return p;
+	
+	if (result > 0 )	{		     /* Key is in higher half */
+	    len -= l1 + 1;
+	    low = p + keylen;
+	}
+	else   {			     /* Key is in lower half */
+	    len = l1 ;
+	}
+    }
+
+    /* No matching key found, return next lower key */
+    return (result>0)?p:(p-keylen);		     
+}
+
+