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[/] [openrisc/] [trunk/] [gnu-src/] [newlib-1.18.0/] [newlib/] [libm/] [machine/] [spu/] [headers/] [erfd2.h] - Blame information for rev 207

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1 207 jeremybenn
/* --------------------------------------------------------------  */
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/* (C)Copyright 2007,2008,                                         */
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/* International Business Machines Corporation                     */
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/* All Rights Reserved.                                            */
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/* Redistribution and use in source and binary forms, with or      */
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/* without modification, are permitted provided that the           */
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/* following conditions are met:                                   */
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/*                                                                 */
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/* - Redistributions of source code must retain the above copyright*/
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/*   notice, this list of conditions and the following disclaimer. */
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/*                                                                 */
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/* - Redistributions in binary form must reproduce the above       */
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/*   copyright notice, this list of conditions and the following   */
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/*   disclaimer in the documentation and/or other materials        */
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/*   provided with the distribution.                               */
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/*                                                                 */
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/* - Neither the name of IBM Corporation nor the names of its      */
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/*   contributors may be used to endorse or promote products       */
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/*   derived from this software without specific prior written     */
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/*   permission.                                                   */
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/*                                                                 */
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/* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND          */
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/* CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES,     */
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/* INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF        */
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/* MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE        */
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/* DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR            */
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/* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,    */
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/* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;    */
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/* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR    */
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/* OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE,  */
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/* EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.              */
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/* --------------------------------------------------------------  */
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/* PROLOG END TAG zYx                                              */
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#ifdef __SPU__
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#ifndef _ERFD2_H_
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#define _ERFD2_H_       1
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#include <spu_intrinsics.h>
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#include "expd2.h"
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#include "recipd2.h"
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#include "divd2.h"
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#include "erf_utils.h"
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/*
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 * FUNCTION
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 *  vector double _erfd2(vector double x)
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 *
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 * DESCRIPTION
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 *  The erfd2 function computes the error function of each element of x.
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 *
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 *  C99 Special Cases:
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 *  - erf(+0) returns +0
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 *  - erf(-0) returns -0
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 *  - erf(+infinite) returns +1
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 *  - erf(-infinite) returns -1
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 *
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 *  Other Cases:
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 *  - erf(Nan) returns Nan
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 *
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 */
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static __inline vector double _erfd2(vector double x)
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{
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  vec_uchar16 dup_even  = ((vec_uchar16) { 0,1,2,3, 0,1,2,3,  8, 9,10,11,  8, 9,10,11 });
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  vec_double2 onehalfd  = spu_splats(0.5);
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  vec_double2 oned      = spu_splats(1.0);
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  vec_double2 sign_mask = spu_splats(-0.0);
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  /* This is where we switch from Taylor Series to Continued Fraction approximation */
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  vec_float4 approx_point = spu_splats(1.77f);
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  vec_double2 xabs, xsqu, xsign;
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  vec_double2 tresult, presult, result;
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  xsign = spu_and(x, sign_mask);
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  xabs = spu_andc(x, sign_mask);
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  xsqu = spu_mul(x, x);
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  /*
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   * Taylor Series Expansion near Zero
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   */
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  TAYLOR_ERF(xabs, xsqu, tresult);
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  /*
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   * Continued Fraction Approximation of Erfc().
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   * erf = 1 - erfc
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   */
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  CONTFRAC_ERFC(xabs, xsqu, presult);
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  presult = spu_sub(oned, presult);
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  /*
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   * Select the appropriate approximation.
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   */
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  vec_float4 xf = spu_roundtf(xabs);
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  xf = spu_shuffle(xf, xf, dup_even);
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  result = spu_sel(tresult, presult, (vec_ullong2)spu_cmpgt(xf, approx_point));
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  /*
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   * Special cases/errors.
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   */
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  /* x = +/- infinite, return +/-1 */
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  /* x = nan, return x */
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  result = spu_sel(result, oned, spu_testsv(x, SPU_SV_NEG_INFINITY | SPU_SV_POS_INFINITY));
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  result = spu_sel(result,    x, spu_testsv(x, SPU_SV_NEG_DENORM   | SPU_SV_POS_DENORM));
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  /*
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   * Preserve sign in result, since erf(-x) = -erf(x)
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   */
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  result = spu_or(result, xsign);
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  return result;
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}
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#endif /* _ERFD2_H_ */
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#endif /* __SPU__ */

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