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/* Single-precision vector (AdvSIMD) cosh 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_expf_inline.h"
#include "v_math.h"
static const struct data
{
struct v_expf_data expf_consts;
uint32x4_t tiny_bound, special_bound;
} data = {
.expf_consts = V_EXPF_DATA,
.tiny_bound = V4 (0x20000000), /* 0x1p-63: Round to 1 below this. */
/* 0x1.5a92d8p+6: expf overflows above this, so have to use special case. */
.special_bound = V4 (0x42ad496c),
};
#if !WANT_SIMD_EXCEPT
static float32x4_t NOINLINE VPCS_ATTR
special_case (float32x4_t x, float32x4_t y, uint32x4_t special)
{
return v_call_f32 (coshf, x, y, special);
}
#endif
/* Single-precision vector cosh, using vector expf.
Maximum error is 2.38 ULP:
_ZGVnN4v_coshf (0x1.e8001ep+1) got 0x1.6a491ep+4
want 0x1.6a4922p+4. */
float32x4_t VPCS_ATTR V_NAME_F1 (cosh) (float32x4_t x)
{
const struct data *d = ptr_barrier (&data);
float32x4_t ax = vabsq_f32 (x);
uint32x4_t iax = vreinterpretq_u32_f32 (ax);
uint32x4_t special = vcgeq_u32 (iax, d->special_bound);
#if WANT_SIMD_EXCEPT
/* If fp exceptions are to be triggered correctly, fall back to the scalar
variant for all inputs if any input is a special value or above the bound
at which expf overflows. */
if (__glibc_unlikely (v_any_u32 (special)))
return v_call_f32 (coshf, x, x, v_u32 (-1));
uint32x4_t tiny = vcleq_u32 (iax, d->tiny_bound);
/* If any input is tiny, avoid underflow exception by fixing tiny lanes of
input to 0, which will generate no exceptions. */
if (__glibc_unlikely (v_any_u32 (tiny)))
ax = v_zerofy_f32 (ax, tiny);
#endif
/* Calculate cosh by exp(x) / 2 + exp(-x) / 2. */
float32x4_t t = v_expf_inline (ax, &d->expf_consts);
float32x4_t half_t = vmulq_n_f32 (t, 0.5);
float32x4_t half_over_t = vdivq_f32 (v_f32 (0.5), t);
#if WANT_SIMD_EXCEPT
if (__glibc_unlikely (v_any_u32 (tiny)))
return vbslq_f32 (tiny, v_f32 (1), vaddq_f32 (half_t, half_over_t));
#else
if (__glibc_unlikely (v_any_u32 (special)))
return special_case (x, vaddq_f32 (half_t, half_over_t), special);
#endif
return vaddq_f32 (half_t, half_over_t);
}
libmvec_hidden_def (V_NAME_F1 (cosh))
HALF_WIDTH_ALIAS_F1 (cosh)
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