/*
 * Single-precision SVE sin(x) function.
 *
 * Copyright (c) 2019-2023, Arm Limited.
 * SPDX-License-Identifier: MIT OR Apache-2.0 WITH LLVM-exception
 */

#include "sv_math.h"
#include "pl_sig.h"
#include "pl_test.h"

static const struct data
{
  float poly[4];
  /* Pi-related values to be loaded as one quad-word and used with
     svmla_lane.  */
  float negpi1, negpi2, negpi3, invpi;
  float shift;
} data = {
  .poly = {
    /* Non-zero coefficients from the degree 9 Taylor series expansion of
       sin.  */
    -0x1.555548p-3f, 0x1.110df4p-7f, -0x1.9f42eap-13f, 0x1.5b2e76p-19f
  },
  .negpi1 = -0x1.921fb6p+1f,
  .negpi2 = 0x1.777a5cp-24f,
  .negpi3 = 0x1.ee59dap-49f,
  .invpi = 0x1.45f306p-2f,
  .shift = 0x1.8p+23f
};

#define RangeVal 0x49800000 /* asuint32 (0x1p20f).  */
#define C(i) sv_f32 (d->poly[i])

static svfloat32_t NOINLINE
special_case (svfloat32_t x, svfloat32_t y, svbool_t cmp)
{
  return sv_call_f32 (sinf, x, y, cmp);
}

/* A fast SVE implementation of sinf.
   Maximum error: 1.89 ULPs.
   This maximum error is achieved at multiple values in [-2^18, 2^18]
   but one example is:
   SV_NAME_F1 (sin)(0x1.9247a4p+0) got 0x1.fffff6p-1 want 0x1.fffffap-1.  */
svfloat32_t SV_NAME_F1 (sin) (svfloat32_t x, const svbool_t pg)
{
  const struct data *d = ptr_barrier (&data);

  svfloat32_t ax = svabs_x (pg, x);
  svuint32_t sign
      = sveor_x (pg, svreinterpret_u32 (x), svreinterpret_u32 (ax));
  svbool_t cmp = svcmpge (pg, svreinterpret_u32 (ax), RangeVal);

  /* pi_vals are a quad-word of helper values - the first 3 elements contain
     -pi in extended precision, the last contains 1 / pi.  */
  svfloat32_t pi_vals = svld1rq (svptrue_b32 (), &d->negpi1);

  /* n = rint(|x|/pi).  */
  svfloat32_t n = svmla_lane (sv_f32 (d->shift), ax, pi_vals, 3);
  svuint32_t odd = svlsl_x (pg, svreinterpret_u32 (n), 31);
  n = svsub_x (pg, n, d->shift);

  /* r = |x| - n*pi  (range reduction into -pi/2 .. pi/2).  */
  svfloat32_t r;
  r = svmla_lane (ax, n, pi_vals, 0);
  r = svmla_lane (r, n, pi_vals, 1);
  r = svmla_lane (r, n, pi_vals, 2);

  /* sin(r) approx using a degree 9 polynomial from the Taylor series
     expansion. Note that only the odd terms of this are non-zero.  */
  svfloat32_t r2 = svmul_x (pg, r, r);
  svfloat32_t y;
  y = svmla_x (pg, C (2), r2, C (3));
  y = svmla_x (pg, C (1), r2, y);
  y = svmla_x (pg, C (0), r2, y);
  y = svmla_x (pg, r, r, svmul_x (pg, y, r2));

  /* sign = y^sign^odd.  */
  sign = sveor_x (pg, sign, odd);

  if (unlikely (svptest_any (pg, cmp)))
    return special_case (x,
			 svreinterpret_f32 (sveor_x (
			     svnot_z (pg, cmp), svreinterpret_u32 (y), sign)),
			 cmp);
  return svreinterpret_f32 (sveor_x (pg, svreinterpret_u32 (y), sign));
}

PL_SIG (SV, F, 1, sin, -3.1, 3.1)
PL_TEST_ULP (SV_NAME_F1 (sin), 1.40)
PL_TEST_SYM_INTERVAL (SV_NAME_F1 (sin), 0, 0x1p23, 1000000)
PL_TEST_SYM_INTERVAL (SV_NAME_F1 (sin), 0x1p23, inf, 10000)