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/* Single-precision vector (Advanced SIMD) cos function.
Copyright (C) 2023-2024 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library; if not, see
<https://www.gnu.org/licenses/>. */
#include "v_math.h"
static const struct data
{
float32x4_t poly[4];
float32x4_t range_val, inv_pi, pi_1, pi_2, pi_3;
} data = {
/* 1.886 ulp error. */
.poly = { V4 (-0x1.555548p-3f), V4 (0x1.110df4p-7f), V4 (-0x1.9f42eap-13f),
V4 (0x1.5b2e76p-19f) },
.pi_1 = V4 (0x1.921fb6p+1f),
.pi_2 = V4 (-0x1.777a5cp-24f),
.pi_3 = V4 (-0x1.ee59dap-49f),
.inv_pi = V4 (0x1.45f306p-2f),
.range_val = V4 (0x1p20f)
};
#define C(i) d->poly[i]
static float32x4_t VPCS_ATTR NOINLINE
special_case (float32x4_t x, float32x4_t y, uint32x4_t odd, uint32x4_t cmp)
{
/* Fall back to scalar code. */
y = vreinterpretq_f32_u32 (veorq_u32 (vreinterpretq_u32_f32 (y), odd));
return v_call_f32 (cosf, x, y, cmp);
}
float32x4_t VPCS_ATTR NOINLINE V_NAME_F1 (cos) (float32x4_t x)
{
const struct data *d = ptr_barrier (&data);
float32x4_t n, r, r2, r3, y;
uint32x4_t odd, cmp;
#if WANT_SIMD_EXCEPT
r = vabsq_f32 (x);
cmp = vcgeq_u32 (vreinterpretq_u32_f32 (r),
vreinterpretq_u32_f32 (d->range_val));
if (__glibc_unlikely (v_any_u32 (cmp)))
/* If fenv exceptions are to be triggered correctly, set any special lanes
to 1 (which is neutral w.r.t. fenv). These lanes will be fixed by
special-case handler later. */
r = vbslq_f32 (cmp, v_f32 (1.0f), r);
#else
cmp = vcageq_f32 (x, d->range_val);
r = x;
#endif
/* n = rint((|x|+pi/2)/pi) - 0.5. */
n = vrndaq_f32 (vfmaq_f32 (v_f32 (0.5), r, d->inv_pi));
odd = vshlq_n_u32 (vreinterpretq_u32_s32 (vcvtq_s32_f32 (n)), 31);
n = vsubq_f32 (n, v_f32 (0.5f));
/* r = |x| - n*pi (range reduction into -pi/2 .. pi/2). */
r = vfmsq_f32 (r, d->pi_1, n);
r = vfmsq_f32 (r, d->pi_2, n);
r = vfmsq_f32 (r, d->pi_3, n);
/* y = sin(r). */
r2 = vmulq_f32 (r, r);
r3 = vmulq_f32 (r2, r);
y = vfmaq_f32 (C (2), C (3), r2);
y = vfmaq_f32 (C (1), y, r2);
y = vfmaq_f32 (C (0), y, r2);
y = vfmaq_f32 (r, y, r3);
if (__glibc_unlikely (v_any_u32 (cmp)))
return special_case (x, y, odd, cmp);
return vreinterpretq_f32_u32 (veorq_u32 (vreinterpretq_u32_f32 (y), odd));
}
libmvec_hidden_def (V_NAME_F1 (cos))
HALF_WIDTH_ALIAS_F1 (cos)
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