1 /*
2 * SPDX-License-Identifier: BSD-2-Clause
3 *
4 * Copyright (c) 2004 David Schultz <das@FreeBSD.ORG>
5 * Copyright (c) 2026 Jesús Blázquez <jesuscblazquez@gmail.com>
6 * 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 <float.h>
31 #include <math.h>
32 #include <stdbool.h>
33
34 #include "fpmath.h"
35
36 #ifdef USE_BUILTIN_FMAXIMUM_MAG_NUM
37 double
fmaximum_mag_num(double x,double y)38 fmaximum_mag_num(double x, double y)
39 {
40 return (__builtin_fmaximum_mag_num(x, y));
41 }
42 #else
43 double
fmaximum_mag_num(double x,double y)44 fmaximum_mag_num(double x, double y)
45 {
46 union IEEEd2bits u[2];
47 bool nan_x, nan_y;
48
49 u[0].d = x;
50 u[1].d = y;
51
52 nan_x = isnan(x);
53 nan_y = isnan(y);
54
55 if (nan_x || nan_y) {
56 /* If both are NaN, adding returns qNaN */
57 if (nan_x && nan_y)
58 return (x + y);
59
60 /* force_except makes sure sNaN's raise exceptions */
61 volatile double force_except = x + y;
62 force_except;
63
64 if (nan_x)
65 return (y);
66 else
67 return (x);
68 }
69
70 double ax = fabs(x);
71 double ay = fabs(y);
72
73 if (ay > ax)
74 return (y);
75 if (ax > ay)
76 return (x);
77
78 /* If magnitudes are equal, we break the tie with the sign */
79 if (u[0].bits.sign != u[1].bits.sign)
80 return (u[u[0].bits.sign].d);
81
82 return (x);
83 }
84 #endif
85
86 #if (LDBL_MANT_DIG == 53)
87 __weak_reference(fmaximum_mag_num, fmaximum_mag_numl);
88 #endif
89