mirror of git://sourceware.org/git/glibc.git
62 lines
2.2 KiB
C
62 lines
2.2 KiB
C
/* Double-precision (SVE) sinpi 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 "sv_math.h"
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#include "poly_sve_f64.h"
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static const struct data
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{
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double poly[10], range_val;
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} data = {
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/* Polynomial coefficients generated using Remez algorithm,
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see sinpi.sollya for details. */
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.poly = { 0x1.921fb54442d184p1, -0x1.4abbce625be53p2, 0x1.466bc6775ab16p1,
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-0x1.32d2cce62dc33p-1, 0x1.507834891188ep-4, -0x1.e30750a28c88ep-8,
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0x1.e8f48308acda4p-12, -0x1.6fc0032b3c29fp-16,
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0x1.af86ae521260bp-21, -0x1.012a9870eeb7dp-25 },
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.range_val = 0x1p63,
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};
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/* A fast SVE implementation of sinpi.
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Maximum error 3.10 ULP:
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_ZGVsMxv_sinpi(0x1.df1a14f1b235p-2) got 0x1.fd64f541606cp-1
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want 0x1.fd64f541606c3p-1. */
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svfloat64_t SV_NAME_D1 (sinpi) (svfloat64_t x, const svbool_t pg)
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{
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const struct data *d = ptr_barrier (&data);
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/* range reduction into -1/2 .. 1/2)
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with n = rint(x) and r = r - n. */
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svfloat64_t n = svrinta_x (pg, x);
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svfloat64_t r = svsub_x (pg, x, n);
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/* Result should be negated based on if n is odd or not. */
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svbool_t cmp = svaclt (pg, x, d->range_val);
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svuint64_t intn = svreinterpret_u64 (svcvt_s64_z (pg, n));
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svuint64_t sign = svlsl_z (cmp, intn, 63);
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/* y = sin(r). */
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svfloat64_t r2 = svmul_x (pg, r, r);
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svfloat64_t r4 = svmul_x (pg, r2, r2);
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svfloat64_t y = sv_pw_horner_9_f64_x (pg, r2, r4, d->poly);
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y = svmul_x (pg, y, r);
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return svreinterpret_f64 (sveor_x (pg, svreinterpret_u64 (y), sign));
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}
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