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/* Single-precision vector (Advanced SIMD) atanh function
Copyright (C) 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"
#include "v_log1pf_inline.h"
const static struct data
{
struct v_log1pf_data log1pf_consts;
uint32x4_t one;
#if WANT_SIMD_EXCEPT
uint32x4_t tiny_bound;
#endif
} data = {
.log1pf_consts = V_LOG1PF_CONSTANTS_TABLE,
.one = V4 (0x3f800000),
#if WANT_SIMD_EXCEPT
/* 0x1p-12, below which atanhf(x) rounds to x. */
.tiny_bound = V4 (0x39800000),
#endif
};
#define AbsMask v_u32 (0x7fffffff)
#define Half v_u32 (0x3f000000)
static float32x4_t NOINLINE VPCS_ATTR
special_case (float32x4_t x, float32x4_t y, uint32x4_t special)
{
return v_call_f32 (atanhf, x, y, special);
}
/* Approximation for vector single-precision atanh(x) using modified log1p.
The maximum error is 3.08 ULP:
__v_atanhf(0x1.ff215p-5) got 0x1.ffcb7cp-5
want 0x1.ffcb82p-5. */
VPCS_ATTR float32x4_t NOINLINE V_NAME_F1 (atanh) (float32x4_t x)
{
const struct data *d = ptr_barrier (&data);
float32x4_t halfsign = vbslq_f32 (AbsMask, v_f32 (0.5), x);
float32x4_t ax = vabsq_f32 (x);
uint32x4_t iax = vreinterpretq_u32_f32 (ax);
#if WANT_SIMD_EXCEPT
uint32x4_t special
= vorrq_u32 (vcgeq_u32 (iax, d->one), vcltq_u32 (iax, d->tiny_bound));
/* Side-step special cases by setting those lanes to 0, which will trigger no
exceptions. These will be fixed up later. */
if (__glibc_unlikely (v_any_u32 (special)))
ax = v_zerofy_f32 (ax, special);
#else
uint32x4_t special = vcgeq_u32 (iax, d->one);
#endif
float32x4_t y = vdivq_f32 (vaddq_f32 (ax, ax), vsubq_f32 (v_f32 (1), ax));
y = log1pf_inline (y, d->log1pf_consts);
if (__glibc_unlikely (v_any_u32 (special)))
return special_case (x, vmulq_f32 (halfsign, y), special);
return vmulq_f32 (halfsign, y);
}
libmvec_hidden_def (V_NAME_F1 (atanh))
HALF_WIDTH_ALIAS_F1 (atanh)
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