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/* Double-precision AdvSIMD log1p
Copyright (C) 2023-2025 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 0
#include "v_log1p_inline.h"
const static struct data
{
struct v_log1p_data d;
uint64x2_t inf, minus_one;
} data = { .d = V_LOG1P_CONSTANTS_TABLE,
.inf = V2 (0x7ff0000000000000),
.minus_one = V2 (0xbff0000000000000) };
#define BottomMask v_u64 (0xffffffff)
static float64x2_t NOINLINE VPCS_ATTR
special_case (float64x2_t x, uint64x2_t cmp, const struct data *d)
{
/* Side-step special lanes so fenv exceptions are not triggered
inadvertently. */
float64x2_t x_nospecial = v_zerofy_f64 (x, cmp);
return v_call_f64 (log1p, x, log1p_inline (x_nospecial, &d->d), cmp);
}
/* Vector log1p approximation using polynomial on reduced interval. Routine is
a modification of the algorithm used in scalar log1p, with no shortcut for
k=0 and no narrowing for f and k. Maximum observed error is 2.45 ULP:
_ZGVnN2v_log1p(0x1.658f7035c4014p+11) got 0x1.fd61d0727429dp+2
want 0x1.fd61d0727429fp+2 . */
VPCS_ATTR float64x2_t V_NAME_D1 (log1p) (float64x2_t x)
{
const struct data *d = ptr_barrier (&data);
uint64x2_t ix = vreinterpretq_u64_f64 (x);
uint64x2_t ia = vreinterpretq_u64_f64 (vabsq_f64 (x));
uint64x2_t special_cases
= vorrq_u64 (vcgeq_u64 (ia, d->inf), vcgeq_u64 (ix, d->minus_one));
if (__glibc_unlikely (v_any_u64 (special_cases)))
return special_case (x, special_cases, d);
return log1p_inline (x, &d->d);
}
strong_alias (V_NAME_D1 (log1p), V_NAME_D1 (logp1))
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