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/* Double-precision vector (Advanced SIMD) acosh 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/>. */
#define WANT_V_LOG1P_K0_SHORTCUT 1
#include "v_log1p_inline.h"
const static struct data
{
struct v_log1p_data log1p_consts;
uint64x2_t one, thresh;
} data = {
.log1p_consts = V_LOG1P_CONSTANTS_TABLE,
.one = V2 (0x3ff0000000000000),
.thresh = V2 (0x1ff0000000000000) /* asuint64(0x1p511) - asuint64(1). */
};
static float64x2_t NOINLINE VPCS_ATTR
special_case (float64x2_t x, float64x2_t y, uint64x2_t special,
const struct v_log1p_data *d)
{
return v_call_f64 (acosh, x, log1p_inline (y, d), special);
}
/* Vector approximation for double-precision acosh, based on log1p.
The largest observed error is 3.02 ULP in the region where the
argument to log1p falls in the k=0 interval, i.e. x close to 1:
_ZGVnN2v_acosh(0x1.00798aaf80739p+0) got 0x1.f2d6d823bc9dfp-5
want 0x1.f2d6d823bc9e2p-5. */
VPCS_ATTR float64x2_t V_NAME_D1 (acosh) (float64x2_t x)
{
const struct data *d = ptr_barrier (&data);
uint64x2_t special
= vcgeq_u64 (vsubq_u64 (vreinterpretq_u64_f64 (x), d->one), d->thresh);
float64x2_t special_arg = x;
#if WANT_SIMD_EXCEPT
if (__glibc_unlikely (v_any_u64 (special)))
x = vbslq_f64 (special, vreinterpretq_f64_u64 (d->one), x);
#endif
float64x2_t xm1 = vsubq_f64 (x, v_f64 (1));
float64x2_t y;
y = vaddq_f64 (x, v_f64 (1));
y = vmulq_f64 (y, xm1);
y = vsqrtq_f64 (y);
y = vaddq_f64 (xm1, y);
if (__glibc_unlikely (v_any_u64 (special)))
return special_case (special_arg, y, special, &d->log1p_consts);
return log1p_inline (y, &d->log1p_consts);
}
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