1 /* $OpenBSD: s_lrint.c,v 1.10 2013/07/03 04:46:36 espie Exp $ */
2 /* $NetBSD: lrint.c,v 1.3 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 <sys/types.h>
31 #include <sys/limits.h>
32 #include <float.h>
33 #include <math.h>
34 #include <ieeefp.h>
35 #include <machine/ieee.h>
36
37 #include "math_private.h"
38
39 #ifndef LRINTNAME
40 #define LRINTNAME lrint
41 #define RESTYPE long int
42 #define RESTYPE_MIN LONG_MIN
43 #define RESTYPE_MAX LONG_MAX
44 #endif
45
46 #define RESTYPE_BITS (sizeof(RESTYPE) * 8)
47
48 static const double
49 TWO52[2]={
50 4.50359962737049600000e+15, /* 0x43300000, 0x00000000 */
51 -4.50359962737049600000e+15, /* 0xC3300000, 0x00000000 */
52 };
53
54 RESTYPE
LRINTNAME(double x)55 LRINTNAME(double x)
56 {
57 u_int32_t i0, i1;
58 int e, s, shift;
59 RESTYPE res;
60
61 GET_HIGH_WORD(i0, x);
62 e = i0 >> DBL_FRACHBITS;
63 s = e >> DBL_EXPBITS;
64 e = (e & 0x7ff) - DBL_EXP_BIAS;
65
66 /* 1.0 x 2^31 (or 2^63) is already too large */
67 if (e >= (int)RESTYPE_BITS - 1)
68 return (s ? RESTYPE_MIN : RESTYPE_MAX); /* ??? unspecified */
69
70 /* >= 2^52 is already an exact integer */
71 if (e < DBL_FRACBITS) {
72 volatile double t = x; /* clip extra precision */
73 /* round, using current direction */
74 t += TWO52[s];
75 t -= TWO52[s];
76 x = t;
77 }
78
79 EXTRACT_WORDS(i0, i1, x);
80 e = ((i0 >> DBL_FRACHBITS) & 0x7ff) - DBL_EXP_BIAS;
81 i0 &= 0xfffff;
82 i0 |= (1 << DBL_FRACHBITS);
83
84 if (e < 0)
85 return (0);
86
87 shift = e - DBL_FRACBITS;
88 if (shift >=0)
89 res = (shift < RESTYPE_BITS ? (RESTYPE)i1 << shift : 0);
90 else
91 res = (shift > -RESTYPE_BITS ? (RESTYPE)i1 >> -shift : 0);
92 shift += 32;
93 if (shift >=0)
94 res |= (shift < RESTYPE_BITS ? (RESTYPE)i0 << shift : 0);
95 else
96 res |= (shift > -RESTYPE_BITS ? (RESTYPE)i0 >> -shift : 0);
97
98 return (s ? -res : res);
99 }
100
101 #if LDBL_MANT_DIG == DBL_MANT_DIG
102 __strong_alias(lrintl, lrint);
103 #endif /* LDBL_MANT_DIG == DBL_MANT_DIG */
104