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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 _ATAND2_H_
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#define _ATAND2_H_ 1
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#include <spu_intrinsics.h>
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#include "simdmath.h"
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#include "recipd2.h"
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#include "logd2.h"
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#include "acosd2.h"
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#include "asind2.h"
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#include "sqrtd2.h"
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/*
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* FUNCTION
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* vector double _atand2(vector double x)
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*
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* DESCRIPTION
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* The _atand2 function computes the arc tangent of a vector of values x.
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*
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* The arc tangent function is computed using the following relations:
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* [0, 1] : arcsin(x1/sqrt(spu_add(x1squ + 1 )));
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* (1, infinity] : PI/2 + atanf(-1/x)
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* [-infinity, 0) : -arcsin(|x|)
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*
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*/
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static __inline vector double _atand2(vector double x)
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{
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vector double signbit = spu_splats(-0.0);
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vector double oned = spu_splats(1.0);
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vector double pi2 = spu_splats(SM_PI_2);
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vector double xabs, x1;
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vector double result;
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vector unsigned long long gt1;
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xabs = spu_andc(x, signbit);
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gt1 = spu_cmpgt(xabs, oned);
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/*
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* For x > 1, use the relation:
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* atan(x) = pi/2 - atan(1/x), x>1
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*/
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x1 = spu_sel(xabs, _recipd2(xabs), gt1);
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vector double x1squ = spu_mul(x1, x1);
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result = _asind2(_divd2(x1, _sqrtd2(spu_add(x1squ, oned))));
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/*
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* For x > 1, use the relation: atan(x) = pi/2 - atan(1/x), x>1
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*/
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result = spu_sel(result, spu_sub(pi2, result), gt1);
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/*
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* Antisymmetric function - preserve sign of x in result.
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*/
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result = spu_sel(result, x, (vec_ullong2)signbit);
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return (result);
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}
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#endif /* _ATAND2_H_ */
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#endif /* __SPU__ */
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