/* origin: FreeBSD /usr/src/lib/msun/src/s_cosf.c */
/*
 * Conversion to float by Ian Lance Taylor, Cygnus Support, ian@cygnus.com.
 * Optimized by Bruce D. Evans.
 */
/*
 * ====================================================
 * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
 *
 * Developed at SunPro, a Sun Microsystems, Inc. business.
 * Permission to use, copy, modify, and distribute this
 * software is freely granted, provided that this notice
 * is preserved.
 * ====================================================
 */

#include "libm.h"

/* Small multiples of pi/2 rounded to double precision. */
static const double c1pio2 = 1 * M_PI_2, /* 0x3FF921FB, 0x54442D18 */
    c2pio2 = 2 * M_PI_2,                 /* 0x400921FB, 0x54442D18 */
    c3pio2 = 3 * M_PI_2,                 /* 0x4012D97C, 0x7F3321D2 */
    c4pio2 = 4 * M_PI_2;                 /* 0x401921FB, 0x54442D18 */

float cosf(float x) {
  double y;
  uint32_t ix;
  unsigned n, sign;

  GET_FLOAT_WORD(ix, x);
  sign = ix >> 31;
  ix &= 0x7fffffff;

  if (ix <= 0x3f490fda) {  /* |x| ~<= pi/4 */
    if (ix < 0x39800000) { /* |x| < 2**-12 */
      /* raise inexact if x != 0 */
      FORCE_EVAL(x + 0x1p120f);
      return 1.0f;
    }
    return __cosdf(x);
  }
  if (ix <= 0x407b53d1) { /* |x| ~<= 5*pi/4 */
    if (ix > 0x4016cbe3)  /* |x|  ~> 3*pi/4 */
      return -__cosdf(sign ? x + c2pio2 : x - c2pio2);
    else {
      if (sign)
        return __sindf(x + c1pio2);
      else
        return __sindf(c1pio2 - x);
    }
  }
  if (ix <= 0x40e231d5) { /* |x| ~<= 9*pi/4 */
    if (ix > 0x40afeddf)  /* |x| ~> 7*pi/4 */
      return __cosdf(sign ? x + c4pio2 : x - c4pio2);
    else {
      if (sign)
        return __sindf(-x - c3pio2);
      else
        return __sindf(x - c3pio2);
    }
  }

  /* cos(Inf or NaN) is NaN */
  if (ix >= 0x7f800000)
    return x - x;

  /* general argument reduction needed */
  n = __rem_pio2f(x, &y);
  switch (n & 3) {
    case 0:
      return __cosdf(y);
    case 1:
      return __sindf(-y);
    case 2:
      return -__cosdf(y);
    default:
      return __sindf(y);
  }
}