1/*	$OpenBSD: s_lroundf.c,v 1.2 2011/04/17 13:59:54 martynas Exp $	*/
2/* $NetBSD: lroundf.c,v 1.2 2004/10/13 15:18:32 drochner Exp $ */
3
4/*-
5 * Copyright (c) 2004
6 *	Matthias Drochner. All rights reserved.
7 *
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
10 * are met:
11 * 1. Redistributions of source code must retain the above copyright
12 *    notice, this list of conditions and the following disclaimer.
13 * 2. Redistributions in binary form must reproduce the above copyright
14 *    notice, this list of conditions and the following disclaimer in the
15 *    documentation and/or other materials provided with the distribution.
16 *
17 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
18 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
20 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
21 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
22 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
23 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
24 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
25 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
26 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
27 * SUCH DAMAGE.
28 */
29
30#include <math.h>
31#include <sys/types.h>
32#include <sys/limits.h>
33#include <ieeefp.h>
34#include <machine/ieee.h>
35#include "math_private.h"
36
37#ifndef LROUNDNAME
38#define LROUNDNAME lroundf
39#define RESTYPE long int
40#define RESTYPE_MIN LONG_MIN
41#define RESTYPE_MAX LONG_MAX
42#endif
43
44#define RESTYPE_BITS (sizeof(RESTYPE) * 8)
45
46RESTYPE
47LROUNDNAME(float x)
48{
49	u_int32_t i0;
50	int e, s, shift;
51	RESTYPE res;
52
53	GET_FLOAT_WORD(i0, x);
54	e = i0 >> SNG_FRACBITS;
55	s = e >> SNG_EXPBITS;
56	e = (e & 0xff) - SNG_EXP_BIAS;
57
58	/* 1.0 x 2^-1 is the smallest number which can be rounded to 1 */
59	if (e < -1)
60		return (0);
61	/* 1.0 x 2^31 (or 2^63) is already too large */
62	if (e >= (int)RESTYPE_BITS - 1)
63		return (s ? RESTYPE_MIN : RESTYPE_MAX); /* ??? unspecified */
64
65	/* >= 2^23 is already an exact integer */
66	if (e < SNG_FRACBITS) {
67		/* add 0.5, extraction below will truncate */
68		x += (s ? -0.5 : 0.5);
69	}
70
71	GET_FLOAT_WORD(i0, x);
72	e = ((i0 >> SNG_FRACBITS) & 0xff) - SNG_EXP_BIAS;
73	i0 &= 0x7fffff;
74	i0 |= (1 << SNG_FRACBITS);
75
76	shift = e - SNG_FRACBITS;
77	if (shift >=0)
78		res = (shift < RESTYPE_BITS ? (RESTYPE)i0 << shift : 0);
79	else
80		res = (shift > -RESTYPE_BITS ? (RESTYPE)i0 >> -shift : 0);
81
82	return (s ? -res : res);
83}
84