Subversion Repositories openrisc_2011-10-31

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/* PROLOG END TAG zYx                                              */

#ifdef __SPU__

#ifndef _EXPM1D2_H_

#define _EXPM1D2_H_     1

#include <spu_intrinsics.h>

#include "expd2.h"

#include "divd2.h"

#define EXPM1_P0 0.0000000000000000000000000e+00

#define EXPM1_P1 1.0000000000000000000000000e+00

#define EXPM1_P2 9.7234232565378004697204117e-04

#define EXPM1_P3 3.3328278237299953368211192e-02

#define EXPM1_P4 3.1156225044634678993365345e-05

#define EXPM1_P5 2.1352206553343212164751408e-04

#define EXPM1_P6 1.6975135794626144795757452e-07

#define EXPM1_P7 2.7686287801334994383131629e-07

#define EXPM1_P8 1.1186114936216450015354379e-10

#define EXPM1_Q0 1.0000000000000000000000000e+00

#define EXPM1_Q1 -4.9902765767434620336473472e-01

#define EXPM1_Q2 1.1617544040780639069687652e-01

#define EXPM1_Q3 -1.6551954366467523660499950e-02

#define EXPM1_Q4 1.5864115838972218334307351e-03

#define EXPM1_Q5 -1.0534540477401370666288988e-04

#define EXPM1_Q6 4.7650003993592160620959043e-06

#define EXPM1_Q7 -1.3529198871087017840776265e-07

#define EXPM1_Q8 1.8635779407675460757658020e-09

/*

 * FUNCTION

 *      vector double _expm1d2(vector double x)

 *

 * DESCRIPTION

 *      _expm1d2 computes the exponential - 1 for each element

 *      of the input vector x.

 *

 *      This function is intended to return accurate values, even

 *      where exp(x) - 1 would normally produce bad results due to

 *      floating-point cancellation errors.

 *

 */

static __inline vector double _expm1d2(vector double x)

{

  vector double oned  = spu_splats(1.0);

  vector double range = spu_splats(1.0625);

  vector unsigned long long use_exp;

  vector double pr, qr;

  vector double eresult;

  vector double rresult;

  vector double result;

  /* Compiler Bug. Replace xbug with x when spu_cmp*() doesn't

   * modify it's arguments! */

  volatile vector double xbug = x;

  use_exp = spu_cmpabsgt(xbug, range);

  /*

   * Calculate directly using exp(x) - 1

   */

  eresult = spu_sub(_expd2(x), oned);

  /*

   * For x in [-1.0625,1.0625], use a rational approximation.

   * The madd's are interleaved to reduce dependency stalls. Looks

   * like gcc is smart enough to do this on it's own... but why

   * take the chance.

   */

  pr = spu_madd(x, spu_splats(EXPM1_P8), spu_splats(EXPM1_P7));

  qr = spu_madd(x, spu_splats(EXPM1_Q8), spu_splats(EXPM1_Q7));

  pr = spu_madd(pr, x, spu_splats(EXPM1_P6));

  qr = spu_madd(qr, x, spu_splats(EXPM1_Q6));

  pr = spu_madd(pr, x, spu_splats(EXPM1_P5));

  qr = spu_madd(qr, x, spu_splats(EXPM1_Q5));

  pr = spu_madd(pr, x, spu_splats(EXPM1_P4));

  qr = spu_madd(qr, x, spu_splats(EXPM1_Q4));

  pr = spu_madd(pr, x, spu_splats(EXPM1_P3));

  qr = spu_madd(qr, x, spu_splats(EXPM1_Q3));

  pr = spu_madd(pr, x, spu_splats(EXPM1_P2));

  qr = spu_madd(qr, x, spu_splats(EXPM1_Q2));

  pr = spu_madd(pr, x, spu_splats(EXPM1_P1));

  qr = spu_madd(qr, x, spu_splats(EXPM1_Q1));

  pr = spu_madd(pr, x, spu_splats(EXPM1_P0));

  qr = spu_madd(qr, x, spu_splats(EXPM1_Q0));

  rresult = _divd2(pr, qr);

  /*

   * Select either direct calculation or rational approximation.

   */

  result = spu_sel(rresult, eresult, use_exp);

  return result;

}

#endif /* _EXPM1D2_H_ */

#endif /* __SPU__ */