1 /* $OpenBSD: s_lrintf.c,v 1.5 2011/04/20 21:32:59 martynas Exp $ */
2 /* $NetBSD: lrintf.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 <math.h>
33 #include <ieeefp.h>
34 #include <machine/ieee.h>
35 #include "math_private.h"
36
37 #ifndef LRINTNAME
38 #define LRINTNAME lrintf
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
46 static const float
47 TWO23[2]={
48 8.3886080000e+06, /* 0x4b000000 */
49 -8.3886080000e+06, /* 0xcb000000 */
50 };
51
52 RESTYPE
LRINTNAME(float x)53 LRINTNAME(float x)
54 {
55 u_int32_t i0;
56 int e, s, shift;
57 RESTYPE res;
58
59 GET_FLOAT_WORD(i0, x);
60 e = i0 >> SNG_FRACBITS;
61 s = e >> SNG_EXPBITS;
62 e = (e & 0xff) - SNG_EXP_BIAS;
63
64 /* 1.0 x 2^31 (or 2^63) is already too large */
65 if (e >= (int)RESTYPE_BITS - 1)
66 return (s ? RESTYPE_MIN : RESTYPE_MAX); /* ??? unspecified */
67
68 /* >= 2^23 is already an exact integer */
69 if (e < SNG_FRACBITS) {
70 volatile float t = x; /* clip extra precision */
71 /* round, using current direction */
72 t += TWO23[s];
73 t -= TWO23[s];
74 x = t;
75 }
76
77 GET_FLOAT_WORD(i0, x);
78 e = ((i0 >> SNG_FRACBITS) & 0xff) - SNG_EXP_BIAS;
79 i0 &= 0x7fffff;
80 i0 |= (1 << SNG_FRACBITS);
81
82 if (e < 0)
83 return (0);
84
85 shift = e - SNG_FRACBITS;
86 if (shift >=0)
87 res = (shift < RESTYPE_BITS ? (RESTYPE)i0 << shift : 0);
88 else
89 res = (shift > -RESTYPE_BITS ? (RESTYPE)i0 >> -shift : 0);
90
91 return (s ? -res : res);
92 }
93