52 lines
1.6 KiB
C
52 lines
1.6 KiB
C
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/* Copyright (C) 1991, 1992 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Library General Public License as
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published by the Free Software Foundation; either version 2 of the
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License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Library General Public License for more details.
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You should have received a copy of the GNU Library General Public
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License along with the GNU C Library; see the file COPYING.LIB. If
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not, write to the Free Software Foundation, Inc., 675 Mass Ave,
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Cambridge, MA 02139, USA. */
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#include <ansidecl.h>
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#include <stdlib.h>
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/* Perform a binary search for KEY in BASE which has NMEMB elements
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of SIZE bytes each. The comparisons are done by (*COMPAR)(). */
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PTR
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DEFUN(bsearch, (key, base, nmemb, size, compar),
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register CONST PTR key AND register CONST PTR base AND
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size_t nmemb AND register size_t size AND
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register int EXFUN((*compar), (CONST PTR, CONST PTR)))
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{
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register size_t l, u, idx;
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register CONST PTR p;
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register int comparison;
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l = 0;
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u = nmemb;
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while (l < u)
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{
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idx = (l + u) / 2;
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p = (PTR) (((CONST char *) base) + (idx * size));
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comparison = (*compar)(key, p);
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if (comparison < 0)
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u = idx;
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else if (comparison > 0)
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l = idx + 1;
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else
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return (PTR) p;
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}
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return NULL;
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}
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