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t_round.c revision 1.3 
      1 /* $NetBSD: t_round.c,v 1.3 2011/09/13 08:58:41 jruoho Exp $ */
      2 
      3 /*-
      4  * Copyright (c) 2011 The NetBSD Foundation, Inc.
      5  * All rights reserved.
      6  *
      7  * Redistribution and use in source and binary forms, with or without
      8  * modification, are permitted provided that the following conditions
      9  * are met:
     10  * 1. Redistributions of source code must retain the above copyright
     11  *    notice, this list of conditions and the following disclaimer.
     12  * 2. Redistributions in binary form must reproduce the above copyright
     13  *    notice, this list of conditions and the following disclaimer in the
     14  *    documentation and/or other materials provided with the distribution.
     15  *
     16  * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
     17  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
     18  * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
     19  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
     20  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
     21  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
     22  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
     23  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
     24  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
     25  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
     26  * POSSIBILITY OF SUCH DAMAGE.
     27  */
     28 
     29 #include <atf-c.h>
     30 #include <math.h>
     31 
     32 /*
     33  * This tests for a bug in the initial implementation where
     34  * precision was lost in an internal substraction, leading to
     35  * rounding into the wrong direction.
     36  */
     37 
     38 /* 0.5 - EPSILON */
     39 #define VAL	0x0.7ffffffffffffcp0
     40 #define VALF	0x0.7fffff8p0
     41 
     42 #ifdef __vax__
     43 #define SMALL_NUM	1.0e-38
     44 #else
     45 #define SMALL_NUM	1.0e-40
     46 #endif
     47 
     48 ATF_TC(round_dir);
     49 ATF_TC_HEAD(round_dir, tc)
     50 {
     51 	atf_tc_set_md_var(tc, "descr","Check for rounding in wrong direction");
     52 }
     53 
     54 ATF_TC_BODY(round_dir, tc)
     55 {
     56 	double a = VAL, b, c;
     57 	float af = VALF, bf, cf;
     58 
     59 	b = round(a);
     60 	bf = roundf(af);
     61 
     62 	ATF_CHECK(fabs(b) < SMALL_NUM);
     63 	ATF_CHECK(fabsf(bf) < SMALL_NUM);
     64 
     65 	c = round(-a);
     66 	cf = roundf(-af);
     67 
     68 	ATF_CHECK(fabs(c) < SMALL_NUM);
     69 	ATF_CHECK(fabsf(cf) < SMALL_NUM);
     70 }
     71 
     72 ATF_TP_ADD_TCS(tp)
     73 {
     74 
     75 	ATF_TP_ADD_TC(tp, round_dir);
     76 
     77 	return atf_no_error();
     78 }
     79