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authorRoland McGrath <roland@gnu.org>1995-02-18 01:27:10 +0000
committerRoland McGrath <roland@gnu.org>1995-02-18 01:27:10 +0000
commit28f540f45bbacd939bfd07f213bcad2bf730b1bf (patch)
tree15f07c4c43d635959c6afee96bde71fb1b3614ee /stdlib/bsearch.c
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initial import
Diffstat (limited to 'stdlib/bsearch.c')
-rw-r--r--stdlib/bsearch.c51
1 files changed, 51 insertions, 0 deletions
diff --git a/stdlib/bsearch.c b/stdlib/bsearch.c
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+++ b/stdlib/bsearch.c
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+/* Copyright (C) 1991, 1992 Free Software Foundation, Inc.
+This file is part of the GNU C Library.
+
+The GNU C Library is free software; you can redistribute it and/or
+modify it under the terms of the GNU Library General Public License as
+published by the Free Software Foundation; either version 2 of the
+License, or (at your option) any later version.
+
+The GNU C Library 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
+Library General Public License for more details.
+
+You should have received a copy of the GNU Library General Public
+License along with the GNU C Library; see the file COPYING.LIB. If
+not, write to the Free Software Foundation, Inc., 675 Mass Ave,
+Cambridge, MA 02139, USA. */
+
+#include <ansidecl.h>
+#include <stdlib.h>
+
+
+/* Perform a binary search for KEY in BASE which has NMEMB elements
+ of SIZE bytes each. The comparisons are done by (*COMPAR)(). */
+PTR
+DEFUN(bsearch, (key, base, nmemb, size, compar),
+ register CONST PTR key AND register CONST PTR base AND
+ size_t nmemb AND register size_t size AND
+ register int EXFUN((*compar), (CONST PTR, CONST PTR)))
+{
+ register size_t l, u, idx;
+ register CONST PTR p;
+ register int comparison;
+
+ l = 0;
+ u = nmemb;
+ while (l < u)
+ {
+ idx = (l + u) / 2;
+ p = (PTR) (((CONST char *) base) + (idx * size));
+ comparison = (*compar)(key, p);
+ if (comparison < 0)
+ u = idx;
+ else if (comparison > 0)
+ l = idx + 1;
+ else
+ return (PTR) p;
+ }
+
+ return NULL;
+}