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freebsd
GitHub Repository: freebsd/freebsd-src
 Path: blob/main/contrib/arm-optimized-routines/math/aarch64/sve/cospi.c
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/*

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 * Double-precision SVE cospi(x) function.

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 *

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 * Copyright (c) 2023-2024, Arm Limited.

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 * SPDX-License-Identifier: MIT OR Apache-2.0 WITH LLVM-exception

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 */

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#include "sv_math.h"

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#include "mathlib.h"

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#include "test_sig.h"

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#include "test_defs.h"

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#include "sv_poly_f64.h"

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static const struct data

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{

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  double poly[10];

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  double 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 = 0x1p53,

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};

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/* A fast SVE implementation of cospi.

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   Maximum error 3.20 ULP:

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   _ZGVsMxv_cospi(0x1.f18ba32c63159p-6) got 0x1.fdabf595f9763p-1

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				       want 0x1.fdabf595f9766p-1.  */

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svfloat64_t SV_NAME_D1 (cospi) (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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  /* Using cospi(x) = sinpi(0.5 - x)

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     range reduction and offset into sinpi range -1/2 .. 1/2

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     r = 0.5 - |x - rint(x)|.  */

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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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  r = svsub_x (pg, sv_f64 (0.5), svabs_x (pg, r));

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  /* Result should be negated based on if n is odd or not.

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     If ax >= 2^53, the result will always be positive.  */

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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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#if WANT_TRIGPI_TESTS

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TEST_ULP (SV_NAME_D1 (cospi), 2.71)

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TEST_DISABLE_FENV (SV_NAME_D1 (cospi))

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TEST_SYM_INTERVAL (SV_NAME_D1 (cospi), 0, 0x1p-63, 5000)

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TEST_SYM_INTERVAL (SV_NAME_D1 (cospi), 0x1p-63, 0.5, 10000)

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TEST_SYM_INTERVAL (SV_NAME_D1 (cospi), 0.5, 0x1p51, 10000)

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TEST_SYM_INTERVAL (SV_NAME_D1 (cospi), 0x1p51, inf, 100000)

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#endif

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CLOSE_SVE_ATTR

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