1/* Copyright (C) 1997-2024 Free Software Foundation, Inc.
2 This file is part of the GNU C Library.
3
4 The GNU C Library is free software; you can redistribute it and/or
5 modify it under the terms of the GNU Lesser General Public
6 License as published by the Free Software Foundation; either
7 version 2.1 of the License, or (at your option) any later version.
8
9 The GNU C Library is distributed in the hope that it will be useful,
10 but WITHOUT ANY WARRANTY; without even the implied warranty of
11 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
12 Lesser General Public License for more details.
13
14 You should have received a copy of the GNU Lesser General Public
15 License along with the GNU C Library. If not, see
16 <https://www.gnu.org/licenses/>. */
17
18#include <math.h>
19#include <math_private.h>
20#include "mathimpl.h"
21#include <libm-alias-finite.h>
22
23#ifndef SUFF
24#define SUFF
25#endif
26#ifndef float_type
27#define float_type double
28#endif
29
30#define CONCATX(a,b) __CONCAT(a,b)
31#define s(name) CONCATX(name,SUFF)
32#define m81(func) __m81_u(s(func))
33
34float_type
35s(__ieee754_atan2) (float_type y, float_type x)
36{
37 float_type pi, pi_2, z;
38 unsigned long y_cond, x_cond;
39
40 __asm ("fmovecr%.x %#0, %0" : "=f" (pi));
41 __asm ("fscale%.w %#-1, %0" : "=f" (pi_2) : "0" (pi));
42 y_cond = __m81_test (val: y);
43 x_cond = __m81_test (val: x);
44
45 if ((x_cond | y_cond) & __M81_COND_NAN)
46 z = x + y;
47 else if (y_cond & __M81_COND_ZERO)
48 {
49 if (x_cond & __M81_COND_NEG)
50 z = y_cond & __M81_COND_NEG ? -pi : pi;
51 else
52 z = y;
53 }
54 else if (x_cond & __M81_COND_INF)
55 {
56 if (y_cond & __M81_COND_INF)
57 {
58 float_type pi_4;
59 __asm ("fscale%.w %#-2, %0" : "=f" (pi_4) : "0" (pi));
60 z = x_cond & __M81_COND_NEG ? 3 * pi_4 : pi_4;
61 }
62 else
63 z = x_cond & __M81_COND_NEG ? pi : 0;
64 if (y_cond & __M81_COND_NEG)
65 z = -z;
66 }
67 else if (y_cond & __M81_COND_INF)
68 z = y_cond & __M81_COND_NEG ? -pi_2 : pi_2;
69 else if (x_cond & __M81_COND_NEG)
70 {
71 if (y_cond & __M81_COND_NEG)
72 {
73 if (-x > -y)
74 z = -pi + m81(__atan) (mathop_x: y / x);
75 else
76 z = -pi_2 - m81(__atan) (mathop_x: x / y);
77 }
78 else
79 {
80 if (-x > y)
81 z = pi + m81(__atan) (mathop_x: y / x);
82 else
83 z = pi_2 - m81(__atan) (mathop_x: x / y);
84 }
85 }
86 else
87 {
88 if (y_cond & __M81_COND_NEG)
89 {
90 if (x > -y)
91 z = m81(__atan) (mathop_x: y / x);
92 else
93 z = -pi_2 - m81(__atan) (mathop_x: x / y);
94 }
95 else
96 {
97 if (x > y)
98 z = m81(__atan) (mathop_x: y / x);
99 else
100 z = pi_2 - m81(__atan) (mathop_x: x / y);
101 }
102 }
103 return z;
104}
105libm_alias_finite (s(__ieee754_atan2), s (__atan2))
106

source code of glibc/sysdeps/m68k/m680x0/fpu/e_atan2.c