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65 lines
2.2 KiB
C
65 lines
2.2 KiB
C
/* Double-precision vector (Advanced SIMD) atanh 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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#define WANT_V_LOG1P_K0_SHORTCUT 0
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#include "v_log1p_inline.h"
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const static struct data
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{
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struct v_log1p_data log1p_consts;
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uint64x2_t one, half;
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} data = { .log1p_consts = V_LOG1P_CONSTANTS_TABLE,
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.one = V2 (0x3ff0000000000000),
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.half = V2 (0x3fe0000000000000) };
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static float64x2_t VPCS_ATTR NOINLINE
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special_case (float64x2_t x, float64x2_t y, uint64x2_t special)
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{
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return v_call_f64 (atanh, x, y, special);
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}
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/* Approximation for vector double-precision atanh(x) using modified log1p.
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The greatest observed error is 3.31 ULP:
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_ZGVnN2v_atanh(0x1.ffae6288b601p-6) got 0x1.ffd8ff31b5019p-6
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want 0x1.ffd8ff31b501cp-6. */
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VPCS_ATTR
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float64x2_t V_NAME_D1 (atanh) (float64x2_t x)
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{
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const struct data *d = ptr_barrier (&data);
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float64x2_t ax = vabsq_f64 (x);
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uint64x2_t ia = vreinterpretq_u64_f64 (ax);
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uint64x2_t sign = veorq_u64 (vreinterpretq_u64_f64 (x), ia);
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uint64x2_t special = vcgeq_u64 (ia, d->one);
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float64x2_t halfsign = vreinterpretq_f64_u64 (vorrq_u64 (sign, d->half));
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#if WANT_SIMD_EXCEPT
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ax = v_zerofy_f64 (ax, special);
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#endif
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float64x2_t y;
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y = vaddq_f64 (ax, ax);
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y = vdivq_f64 (y, vsubq_f64 (v_f64 (1), ax));
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y = log1p_inline (y, &d->log1p_consts);
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if (__glibc_unlikely (v_any_u64 (special)))
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return special_case (x, vmulq_f64 (y, halfsign), special);
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return vmulq_f64 (y, halfsign);
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}
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