source: trunk/libs/newlib/src/newlib/libm/machine/spu/headers/cosf4.h @ 444

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/* PROLOG END TAG zYx                                              */
#ifdef __SPU__

#ifndef _COSF4_H_
#define _COSF4_H_       1


#include <spu_intrinsics.h>

#include "cos_sin.h"

/*
 * FUNCTION
 *      vector float _cosf4(vector float angle)
 *
 * DESCRIPTION
 *      The _cosf4 function computes the cosine of a vector of angles 
 *      (expressed in radians) to an accuracy of single precision floating
 *       point.
 *
 */
static __inline vector float _cosf4(vector float angle)
{
  vec_int4   octant;
  vec_uint4  select;
  vec_float4 cos, sin;
  vec_float4 toggle_sign, answer;

  /* Range reduce the input angle x into the range -PI/4 to PI/4
   * by performing simple modulus.
   */
  MOD_PI_OVER_FOUR_F(angle, octant);

  /* Compute the cosine and sine of the range reduced input.
   */
  COMPUTE_COS_SIN_F(angle, cos, sin);

  /* For each SIMD element, select which result (cos or sin) to use
   * with a sign correction depending upon the octant of the original
   * angle (Maclaurin series).
   *
   *   octants      angles     select  sign toggle 
   *   -------   ------------  ------  -----------
   *     0          0 to 45     cos        no      
   *    1,2        45 to 135    sin        yes
   *    3,4       135 to 225    cos        yes
   *    5,6       225 to 315    sin        no
   *     7        315 to 360    cos        no
   */ 
  toggle_sign = (vec_float4)spu_sl(spu_and(spu_add(octant, 2), 4), 29);
  select = spu_cmpeq(spu_and(octant, 2), 0);

  answer = spu_xor(spu_sel(sin, cos, select), toggle_sign);

  return (answer);

}

#endif /* _COSF4_H_ */
#endif /* __SPU__ */