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 <math.h>
31 #include <stdbool.h>
32
33 #include "fpmath.h"
34
35 long double
fmaximum_mag_numl(long double x,long double y)36 fmaximum_mag_numl(long double x, long double y)
37 {
38 union IEEEl2bits u[2];
39 bool nan_x, nan_y;
40
41 u[0].e = x;
42 mask_nbit_l(u[0]);
43 u[1].e = y;
44 mask_nbit_l(u[1]);
45
46 nan_x = isnan(x);
47 nan_y = isnan(y);
48
49 if (nan_x || nan_y) {
50 /* If both are NaN, adding returns qNaN */
51 if (nan_x && nan_y)
52 return (x + y);
53
54 /* force_except makes sure sNaN's raise exceptions */
55 volatile long double force_except = x + y;
56 force_except;
57
58 if (nan_x)
59 return (y);
60 else
61 return (x);
62 }
63
64 long double ax = fabsl(x);
65 long double ay = fabsl(y);
66
67 if (ay > ax)
68 return (y);
69 if (ax > ay)
70 return (x);
71
72 /* If magnitudes are equal, we break the tie with the sign */
73 if (u[0].bits.sign != u[1].bits.sign)
74 return (u[0].bits.sign ? y : x);
75
76 return (x);
77 }
78