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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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/* */
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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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/* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT */
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/* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; */
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/* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) */
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/* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN */
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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 _EXPM1F4_H_
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#define _EXPM1F4_H_ 1
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#include <spu_intrinsics.h>
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#include "expf4.h"
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#include "divf4.h"
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#define EXPM1F4_P0 0.0000000000000000000000000e-00
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#define EXPM1F4_P1 9.9999999999999988897769754e-01
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#define EXPM1F4_P2 -6.5597409827762467697531701e-04
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#define EXPM1F4_P3 2.3800889637330315679042414e-02
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#define EXPM1F4_P4 -1.0914929910143700584950963e-05
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#define EXPM1F4_Q0 1.0000000000000000000000000e-00
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#define EXPM1F4_Q1 -5.0065597410018825019761834e-01
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#define EXPM1F4_Q2 1.0746220997195164714721471e-01
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#define EXPM1F4_Q3 -1.1966024153043854083566799e-02
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#define EXPM1F4_Q4 5.9997727954467768105711878e-04
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/*
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* FUNCTION
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* vector float _expm1f4(vector float x)
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*
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* _expm1d2 computes the exponential - 1 for each element
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* of the input vector x.
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*
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* This function is intended to return accurate values, even
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* where exp(x) - 1 would normally produce bad results due to
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* floating-point cancellation errors.
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*
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*/
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static __inline vector float _expm1f4(vector float x)
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{
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vector float onef = spu_splats(1.0f);
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vector float rangelo = spu_splats(-0.4f);
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vector float rangehi = spu_splats(0.35f);
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vector unsigned int use_exp;
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vector float pr, qr;
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vector float eresult;
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vector float rresult;
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vector float result;
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use_exp = spu_or(spu_cmpgt(x, rangehi), spu_cmpgt(rangelo, x));
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/*
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* Calculate directly using exp(x) - 1
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*/
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eresult = spu_sub(_expf4(x), onef);
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/*
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* For x in [-0.5,0.5], use a rational approximation.
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* The madd's are interleaved to reduce dependency stalls. Looks
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* like gcc is smart enough to do this on it's own... but why
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* take the chance.
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*/
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pr = spu_madd(x, spu_splats((float)EXPM1F4_P4), spu_splats((float)EXPM1F4_P3));
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qr = spu_madd(x, spu_splats((float)EXPM1F4_Q4), spu_splats((float)EXPM1F4_Q3));
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pr = spu_madd(pr, x, spu_splats((float)EXPM1F4_P2));
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qr = spu_madd(qr, x, spu_splats((float)EXPM1F4_Q2));
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pr = spu_madd(pr, x, spu_splats((float)EXPM1F4_P1));
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qr = spu_madd(qr, x, spu_splats((float)EXPM1F4_Q1));
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pr = spu_madd(pr, x, spu_splats((float)EXPM1F4_P0));
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qr = spu_madd(qr, x, spu_splats((float)EXPM1F4_Q0));
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rresult = _divf4(pr, qr);
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/*
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* Select either direct calculation or rational approximation.
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*/
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result = spu_sel(rresult, eresult, use_exp);
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return result;
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}
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#endif /* _EXPM1F4_H_ */
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#endif /* __SPU__ */
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