mirror of
https://github.com/autc04/Retro68.git
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125 lines
5.1 KiB
C
125 lines
5.1 KiB
C
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/* -------------------------------------------------------------- */
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/* (C)Copyright 2001,2008, */
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/* International Business Machines Corporation, */
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/* Sony Computer Entertainment, Incorporated, */
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/* Toshiba Corporation, */
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/* */
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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 _ATANF4_H_
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#define _ATANF4_H_ 1
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#include <spu_intrinsics.h>
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#include "simdmath.h"
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#include "recipf4.h"
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/*
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* FUNCTION
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* vector float _atanf4(vector float x)
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*
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* DESCRIPTION
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* The _atanf4 function computes the arc tangent of a vector of values x;
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* that is the values whose tangent is x.
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*
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* The _atanf4 function returns the arc tangents in radians and the value
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* is mathematically defined to be in the range -PI/2 to PI/2.
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*
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* The arc tangent function is computed using a polynomial approximation
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* (B. Carlson, M. Goldstein, Los Alamos Scientific Laboratory, 1955).
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* __8__
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* \
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* \
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* atan(x) = / Ci*x^(2*i+1)
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* /____
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* i=0
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*
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* for x in the range -1 to 1. The remaining regions are defined to be:
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*
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* [1, infinity] : PI/2 + atanf(-1/x)
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* [-infinity, -1] : -PI/2 + atanf(-1/x)
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*
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*/
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static __inline vector float _atanf4(vector float x)
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{
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vector float bias;
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vector float x2, x3, x4, x8, x9;
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vector float hi, lo;
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vector float result;
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vector float inv_x;
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vector unsigned int sign;
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vector unsigned int select;
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sign = spu_sl(spu_rlmask((vector unsigned int)x, -31), 31);
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inv_x = _recipf4(x);
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inv_x = (vector float)spu_xor((vector unsigned int)inv_x, spu_splats(0x80000000));
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select = (vector unsigned int)spu_cmpabsgt(x, spu_splats(1.0f));
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bias = (vector float)spu_or(sign, (vector unsigned int)(spu_splats((float)SM_PI_2)));
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bias = (vector float)spu_and((vector unsigned int)bias, select);
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x = spu_sel(x, inv_x, select);
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/* Instruction counts can be reduced if the polynomial was
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* computed entirely from nested (dependent) fma's. However,
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* to reduce the number of pipeline stalls, the polygon is evaluated
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* in two halves(hi and lo).
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*/
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bias = spu_add(bias, x);
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x2 = spu_mul(x, x);
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x3 = spu_mul(x2, x);
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x4 = spu_mul(x2, x2);
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x8 = spu_mul(x4, x4);
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x9 = spu_mul(x8, x);
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hi = spu_madd(spu_splats(0.0028662257f), x2, spu_splats(-0.0161657367f));
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hi = spu_madd(hi, x2, spu_splats(0.0429096138f));
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hi = spu_madd(hi, x2, spu_splats(-0.0752896400f));
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hi = spu_madd(hi, x2, spu_splats(0.1065626393f));
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lo = spu_madd(spu_splats(-0.1420889944f), x2, spu_splats(0.1999355085f));
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lo = spu_madd(lo, x2, spu_splats(-0.3333314528f));
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lo = spu_madd(lo, x3, bias);
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result = spu_madd(hi, x9, lo);
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return (result);
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}
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#endif /* _ATANF4_H_ */
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#endif /* __SPU__ */
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