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/* -------------------------------------------------------------- */
/* (C)Copyright 2001,2008, */
/* International Business Machines Corporation, */
/* Sony Computer Entertainment, Incorporated, */
/* Toshiba Corporation, */
/* */
/* All Rights Reserved. */
/* */
/* Redistribution and use in source and binary forms, with or */
/* without modification, are permitted provided that the */
/* following conditions are met: */
/* */
/* - Redistributions of source code must retain the above copyright*/
/* notice, this list of conditions and the following disclaimer. */
/* */
/* - Redistributions in binary form must reproduce the above */
/* copyright notice, this list of conditions and the following */
/* disclaimer in the documentation and/or other materials */
/* provided with the distribution. */
/* */
/* - Neither the name of IBM Corporation nor the names of its */
/* contributors may be used to endorse or promote products */
/* derived from this software without specific prior written */
/* permission. */
/* */
/* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND */
/* CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, */
/* INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF */
/* MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE */
/* DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR */
/* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, */
/* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT */
/* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; */
/* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) */
/* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN */
/* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR */
/* OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, */
/* EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. */
/* -------------------------------------------------------------- */
/* PROLOG END TAG zYx */
#ifdef __SPU__
#ifndef _ATANF4_H_
#define _ATANF4_H_ 1
#include <spu_intrinsics.h>
#include "simdmath.h"
#include "recipf4.h"
/*
* FUNCTION
* vector float _atanf4(vector float x)
*
* DESCRIPTION
* The _atanf4 function computes the arc tangent of a vector of values x;
* that is the values whose tangent is x.
*
* The _atanf4 function returns the arc tangents in radians and the value
* is mathematically defined to be in the range -PI/2 to PI/2.
*
* The arc tangent function is computed using a polynomial approximation
* (B. Carlson, M. Goldstein, Los Alamos Scientific Laboratory, 1955).
* __8__
* \
* \
* atan(x) = / Ci*x^(2*i+1)
* /____
* i=0
*
* for x in the range -1 to 1. The remaining regions are defined to be:
*
* [1, infinity] : PI/2 + atanf(-1/x)
* [-infinity, -1] : -PI/2 + atanf(-1/x)
*
*/
static __inline vector float _atanf4(vector float x)
{
vector float bias;
vector float x2, x3, x4, x8, x9;
vector float hi, lo;
vector float result;
vector float inv_x;
vector unsigned int sign;
vector unsigned int select;
sign = spu_sl(spu_rlmask((vector unsigned int)x, -31), 31);
inv_x = _recipf4(x);
inv_x = (vector float)spu_xor((vector unsigned int)inv_x, spu_splats(0x80000000));
select = (vector unsigned int)spu_cmpabsgt(x, spu_splats(1.0f));
bias = (vector float)spu_or(sign, (vector unsigned int)(spu_splats((float)SM_PI_2)));
bias = (vector float)spu_and((vector unsigned int)bias, select);
x = spu_sel(x, inv_x, select);
/* Instruction counts can be reduced if the polynomial was
* computed entirely from nested (dependent) fma's. However,
* to reduce the number of pipeline stalls, the polygon is evaluated
* in two halves(hi and lo).
*/
bias = spu_add(bias, x);
x2 = spu_mul(x, x);
x3 = spu_mul(x2, x);
x4 = spu_mul(x2, x2);
x8 = spu_mul(x4, x4);
x9 = spu_mul(x8, x);
hi = spu_madd(spu_splats(0.0028662257f), x2, spu_splats(-0.0161657367f));
hi = spu_madd(hi, x2, spu_splats(0.0429096138f));
hi = spu_madd(hi, x2, spu_splats(-0.0752896400f));
hi = spu_madd(hi, x2, spu_splats(0.1065626393f));
lo = spu_madd(spu_splats(-0.1420889944f), x2, spu_splats(0.1999355085f));
lo = spu_madd(lo, x2, spu_splats(-0.3333314528f));
lo = spu_madd(lo, x3, bias);
result = spu_madd(hi, x9, lo);
return (result);
}
#endif /* _ATANF4_H_ */
#endif /* __SPU__ */
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