mirror of
https://github.com/autc04/Retro68.git
synced 2024-11-06 11:08:43 +00:00
136 lines
4.9 KiB
C
136 lines
4.9 KiB
C
/* -------------------------------------------------------------- */
|
|
/* (C)Copyright 2007,2008, */
|
|
/* International Business Machines 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 _TANHF4_H_
|
|
#define _TANHF4_H_ 1
|
|
|
|
#include <spu_intrinsics.h>
|
|
|
|
#include "expf4.h"
|
|
#include "divf4.h"
|
|
|
|
#include "tanhd2.h"
|
|
|
|
/*
|
|
* FUNCTION
|
|
* vector float _tanhf4(vector float x)
|
|
*
|
|
* DESCRIPTION
|
|
* The _tanhf4 function computes the hyperbolic tangent for each
|
|
* element of the input vector.
|
|
*
|
|
* We use the following to approximate tanh:
|
|
*
|
|
* |x| <= .25: Taylor Series
|
|
* |x| > .25: tanh(x) = (exp(2x) - 1)/(exp(2x) + 1)
|
|
*
|
|
*
|
|
* SPECIAL CASES:
|
|
* - tanh(+/- 0) = +/-0
|
|
* - tanh(+/- infinity) = +/- 1
|
|
*
|
|
*/
|
|
|
|
static __inline vector float _tanhf4(vector float x)
|
|
{
|
|
vector float signbit = spu_splats(-0.0f);
|
|
vector float onef = spu_splats(1.0f);
|
|
vector float twof = spu_splats(2.0f);
|
|
vector float xabs;
|
|
vector float x2;
|
|
vector unsigned int gttaylor;
|
|
vector float e;
|
|
vector float tresult;
|
|
vector float eresult;
|
|
vector float result;
|
|
|
|
xabs = spu_andc(x, signbit);
|
|
|
|
/*
|
|
* This is where we switch from Taylor Series
|
|
* to exponential formula.
|
|
*/
|
|
gttaylor = spu_cmpgt(xabs, spu_splats(0.25f));
|
|
|
|
|
|
/*
|
|
* Taylor Series Approximation
|
|
*/
|
|
x2 = spu_mul(x,x);
|
|
tresult = spu_madd(x2, spu_splats((float)TANH_TAY06), spu_splats((float)TANH_TAY05));
|
|
tresult = spu_madd(x2, tresult, spu_splats((float)TANH_TAY04));
|
|
tresult = spu_madd(x2, tresult, spu_splats((float)TANH_TAY03));
|
|
tresult = spu_madd(x2, tresult, spu_splats((float)TANH_TAY02));
|
|
tresult = spu_madd(x2, tresult, spu_splats((float)TANH_TAY01));
|
|
tresult = spu_mul(xabs, tresult);
|
|
|
|
|
|
/*
|
|
* Exponential Formula
|
|
* Our expf4 function gives a more accurate result in general
|
|
* with xabs instead of x for x<0. We correct for sign later.
|
|
*/
|
|
e = _expf4(spu_mul(xabs, twof));
|
|
eresult = _divf4(spu_sub(e, onef), spu_add(e, onef));
|
|
|
|
|
|
/*
|
|
* Select Taylor or exp result.
|
|
*/
|
|
result = spu_sel(tresult, eresult, gttaylor);
|
|
|
|
/*
|
|
* Correct for accumulated truncation error when
|
|
* tanh(x) should return 1.
|
|
* Note that this also handles the special case of
|
|
* x = +/- infinity.
|
|
*/
|
|
result = spu_sel(result, onef, spu_cmpgt(xabs, spu_splats(9.125f)));
|
|
|
|
/*
|
|
* Antisymmetric function - preserve sign bit of x
|
|
* in the result.
|
|
*/
|
|
result = spu_sel(result, x, (vec_uint4)signbit);
|
|
|
|
return result;
|
|
}
|
|
|
|
#endif /* _TANHF4_H_ */
|
|
#endif /* __SPU__ */
|