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85 lines
2.9 KiB
C
85 lines
2.9 KiB
C
/* Single-precision vector (AdvSIMD) cosh function
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Copyright (C) 2024 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library; if not, see
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<https://www.gnu.org/licenses/>. */
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#include "v_expf_inline.h"
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#include "v_math.h"
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static const struct data
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{
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struct v_expf_data expf_consts;
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uint32x4_t tiny_bound, special_bound;
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} data = {
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.expf_consts = V_EXPF_DATA,
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.tiny_bound = V4 (0x20000000), /* 0x1p-63: Round to 1 below this. */
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/* 0x1.5a92d8p+6: expf overflows above this, so have to use special case. */
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.special_bound = V4 (0x42ad496c),
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};
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#if !WANT_SIMD_EXCEPT
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static float32x4_t NOINLINE VPCS_ATTR
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special_case (float32x4_t x, float32x4_t y, uint32x4_t special)
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{
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return v_call_f32 (coshf, x, y, special);
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}
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#endif
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/* Single-precision vector cosh, using vector expf.
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Maximum error is 2.38 ULP:
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_ZGVnN4v_coshf (0x1.e8001ep+1) got 0x1.6a491ep+4
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want 0x1.6a4922p+4. */
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float32x4_t VPCS_ATTR V_NAME_F1 (cosh) (float32x4_t x)
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{
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const struct data *d = ptr_barrier (&data);
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float32x4_t ax = vabsq_f32 (x);
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uint32x4_t iax = vreinterpretq_u32_f32 (ax);
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uint32x4_t special = vcgeq_u32 (iax, d->special_bound);
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#if WANT_SIMD_EXCEPT
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/* If fp exceptions are to be triggered correctly, fall back to the scalar
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variant for all inputs if any input is a special value or above the bound
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at which expf overflows. */
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if (__glibc_unlikely (v_any_u32 (special)))
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return v_call_f32 (coshf, x, x, v_u32 (-1));
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uint32x4_t tiny = vcleq_u32 (iax, d->tiny_bound);
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/* If any input is tiny, avoid underflow exception by fixing tiny lanes of
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input to 0, which will generate no exceptions. */
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if (__glibc_unlikely (v_any_u32 (tiny)))
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ax = v_zerofy_f32 (ax, tiny);
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#endif
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/* Calculate cosh by exp(x) / 2 + exp(-x) / 2. */
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float32x4_t t = v_expf_inline (ax, &d->expf_consts);
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float32x4_t half_t = vmulq_n_f32 (t, 0.5);
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float32x4_t half_over_t = vdivq_f32 (v_f32 (0.5), t);
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#if WANT_SIMD_EXCEPT
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if (__glibc_unlikely (v_any_u32 (tiny)))
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return vbslq_f32 (tiny, v_f32 (1), vaddq_f32 (half_t, half_over_t));
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#else
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if (__glibc_unlikely (v_any_u32 (special)))
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return special_case (x, vaddq_f32 (half_t, half_over_t), special);
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#endif
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return vaddq_f32 (half_t, half_over_t);
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}
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libmvec_hidden_def (V_NAME_F1 (cosh))
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HALF_WIDTH_ALIAS_F1 (cosh)
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