sinf4.h

Newlib 嵌入式 C库 标准实现代码

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/* PROLOG END TAG zYx                                              */
#ifdef __SPU__
#ifndef _SINF4_H_
#define _SINF4_H_	1

#include <spu_intrinsics.h>

#include "cos_sin.h"

/*
 * FUNCTION
 *	vector float _sind2(vector float angle)
 *
 * DESCRIPTION
 *	The _sinf4 function computes the sine of a vector of angles (expressed 
 *	in radians) to an accuracy of a single precision floating point.
 *
 */
static __inline vector float _sinf4(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     sin        no      
   *    1,2        45 to 135    cos        no
   *    3,4       135 to 225    sin        yes
   *    5,6       225 to 315    cos        yes
   *     7        315 to 360    sin        no
   */ 
  toggle_sign = (vec_float4)spu_sl(spu_and(octant, 4), 29);
  select = spu_cmpeq(spu_and(octant, 2), 0);

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

  return (answer);
}

#endif /* _SINF4_H_ */
#endif /* __SPU__ */