/* Single-precision vector (Advanced SIMD) cos function.

   Copyright (C) 2023-2026 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 "v_math.h"

static const struct data
{
  float32x4_t poly[4];
  float32x4_t range_val, inv_pi, pi_1, pi_2, pi_3;
} data = {
  /* 1.886 ulp error.  */
  .poly = { V4 (-0x1.555548p-3f), V4 (0x1.110df4p-7f), V4 (-0x1.9f42eap-13f),
	    V4 (0x1.5b2e76p-19f) },

  .pi_1 = V4 (0x1.921fb6p+1f),
  .pi_2 = V4 (-0x1.777a5cp-24f),
  .pi_3 = V4 (-0x1.ee59dap-49f),

  .inv_pi = V4 (0x1.45f306p-2f),
  .range_val = V4 (0x1p20f)
};

#define C(i) d->poly[i]

static float32x4_t VPCS_ATTR NOINLINE
special_case (float32x4_t x, float32x4_t y, uint32x4_t odd, uint32x4_t cmp)
{
  /* Fall back to scalar code.  */
  y = vreinterpretq_f32_u32 (veorq_u32 (vreinterpretq_u32_f32 (y), odd));
  return v_call_f32 (cosf, x, y, cmp);
}

float32x4_t VPCS_ATTR NOINLINE V_NAME_F1 (cos) (float32x4_t x)
{
  const struct data *d = ptr_barrier (&data);
  float32x4_t n, r, r2, r3, y;
  uint32x4_t odd, cmp;

  cmp = vcageq_f32 (x, d->range_val);

  /* n = rint((|x|+pi/2)/pi) - 0.5.  */
  n = vrndaq_f32 (vfmaq_f32 (v_f32 (0.5), x, d->inv_pi));
  odd = vshlq_n_u32 (vreinterpretq_u32_s32 (vcvtq_s32_f32 (n)), 31);
  n = vsubq_f32 (n, v_f32 (0.5f));

  /* r = |x| - n*pi  (range reduction into -pi/2 .. pi/2).  */
  r = vfmsq_f32 (x, d->pi_1, n);
  r = vfmsq_f32 (r, d->pi_2, n);
  r = vfmsq_f32 (r, d->pi_3, n);

  /* y = sin(r).  */
  r2 = vmulq_f32 (r, r);
  r3 = vmulq_f32 (r2, r);
  y = vfmaq_f32 (C (2), C (3), r2);
  y = vfmaq_f32 (C (1), y, r2);
  y = vfmaq_f32 (C (0), y, r2);
  y = vfmaq_f32 (r, y, r3);

  if (__glibc_unlikely (v_any_u32 (cmp)))
    return special_case (x, y, odd, cmp);
  return vreinterpretq_f32_u32 (veorq_u32 (vreinterpretq_u32_f32 (y), odd));
}
libmvec_hidden_def (V_NAME_F1 (cos))
HALF_WIDTH_ALIAS_F1 (cos)
