1/* Single-precision vector (Advanced SIMD) cos function.
2
3 Copyright (C) 2023-2024 Free Software Foundation, Inc.
4 This file is part of the GNU C Library.
5
6 The GNU C Library is free software; you can redistribute it and/or
7 modify it under the terms of the GNU Lesser General Public
8 License as published by the Free Software Foundation; either
9 version 2.1 of the License, or (at your option) any later version.
10
11 The GNU C Library is distributed in the hope that it will be useful,
12 but WITHOUT ANY WARRANTY; without even the implied warranty of
13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14 Lesser General Public License for more details.
15
16 You should have received a copy of the GNU Lesser General Public
17 License along with the GNU C Library; if not, see
18 <https://www.gnu.org/licenses/>. */
19
20#include "v_math.h"
21
22static const struct data
23{
24 float32x4_t poly[4];
25 float32x4_t range_val, inv_pi, pi_1, pi_2, pi_3;
26} data = {
27 /* 1.886 ulp error. */
28 .poly = { V4 (-0x1.555548p-3f), V4 (0x1.110df4p-7f), V4 (-0x1.9f42eap-13f),
29 V4 (0x1.5b2e76p-19f) },
30
31 .pi_1 = V4 (0x1.921fb6p+1f),
32 .pi_2 = V4 (-0x1.777a5cp-24f),
33 .pi_3 = V4 (-0x1.ee59dap-49f),
34
35 .inv_pi = V4 (0x1.45f306p-2f),
36 .range_val = V4 (0x1p20f)
37};
38
39#define C(i) d->poly[i]
40
41static float32x4_t VPCS_ATTR NOINLINE
42special_case (float32x4_t x, float32x4_t y, uint32x4_t odd, uint32x4_t cmp)
43{
44 /* Fall back to scalar code. */
45 y = vreinterpretq_f32_u32 (veorq_u32 (vreinterpretq_u32_f32 (y), odd));
46 return v_call_f32 (cosf, x, y, cmp);
47}
48
49float32x4_t VPCS_ATTR NOINLINE V_NAME_F1 (cos) (float32x4_t x)
50{
51 const struct data *d = ptr_barrier (&data);
52 float32x4_t n, r, r2, r3, y;
53 uint32x4_t odd, cmp;
54
55#if WANT_SIMD_EXCEPT
56 r = vabsq_f32 (x);
57 cmp = vcgeq_u32 (vreinterpretq_u32_f32 (r),
58 vreinterpretq_u32_f32 (d->range_val));
59 if (__glibc_unlikely (v_any_u32 (cmp)))
60 /* If fenv exceptions are to be triggered correctly, set any special lanes
61 to 1 (which is neutral w.r.t. fenv). These lanes will be fixed by
62 special-case handler later. */
63 r = vbslq_f32 (cmp, v_f32 (1.0f), r);
64#else
65 cmp = vcageq_f32 (x, d->range_val);
66 r = x;
67#endif
68
69 /* n = rint((|x|+pi/2)/pi) - 0.5. */
70 n = vrndaq_f32 (vfmaq_f32 (v_f32 (0.5), r, d->inv_pi));
71 odd = vshlq_n_u32 (vreinterpretq_u32_s32 (vcvtq_s32_f32 (n)), 31);
72 n = vsubq_f32 (n, v_f32 (0.5f));
73
74 /* r = |x| - n*pi (range reduction into -pi/2 .. pi/2). */
75 r = vfmsq_f32 (r, d->pi_1, n);
76 r = vfmsq_f32 (r, d->pi_2, n);
77 r = vfmsq_f32 (r, d->pi_3, n);
78
79 /* y = sin(r). */
80 r2 = vmulq_f32 (r, r);
81 r3 = vmulq_f32 (r2, r);
82 y = vfmaq_f32 (C (2), C (3), r2);
83 y = vfmaq_f32 (C (1), y, r2);
84 y = vfmaq_f32 (C (0), y, r2);
85 y = vfmaq_f32 (r, y, r3);
86
87 if (__glibc_unlikely (v_any_u32 (cmp)))
88 return special_case (x, y, odd, cmp);
89 return vreinterpretq_f32_u32 (veorq_u32 (vreinterpretq_u32_f32 (y), odd));
90}
91libmvec_hidden_def (V_NAME_F1 (cos))
92HALF_WIDTH_ALIAS_F1 (cos)
93

source code of glibc/sysdeps/aarch64/fpu/cosf_advsimd.c