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/* Single-precision (SVE) sinpi 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 "sv_math.h"
#include "poly_sve_f32.h"
static const struct data
{
float poly[6], range_val;
} data = {
/* Taylor series coefficents for sin(pi * x). */
.poly = { 0x1.921fb6p1f, -0x1.4abbcep2f, 0x1.466bc6p1f, -0x1.32d2ccp-1f,
0x1.50783p-4f, -0x1.e30750p-8f },
.range_val = 0x1p31,
};
/* A fast SVE implementation of sinpif.
Maximum error 2.48 ULP:
_ZGVsMxv_sinpif(0x1.d062b6p-2) got 0x1.fa8c06p-1
want 0x1.fa8c02p-1. */
svfloat32_t SV_NAME_F1 (sinpi) (svfloat32_t x, const svbool_t pg)
{
const struct data *d = ptr_barrier (&data);
/* range reduction into -1/2 .. 1/2
with n = rint(x) and r = r - n. */
svfloat32_t n = svrinta_x (pg, x);
svfloat32_t r = svsub_x (pg, x, n);
/* Result should be negated based on if n is odd or not. */
svbool_t cmp = svaclt (pg, x, d->range_val);
svuint32_t intn = svreinterpret_u32 (svcvt_s32_z (pg, n));
svuint32_t sign = svlsl_z (cmp, intn, 31);
/* y = sin(r). */
svfloat32_t r2 = svmul_x (pg, r, r);
svfloat32_t y = sv_horner_5_f32_x (pg, r2, d->poly);
y = svmul_x (pg, y, r);
return svreinterpret_f32 (sveor_x (pg, svreinterpret_u32 (y), sign));
}
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