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