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/* -------------------------------------------------------------- */
/* (C)Copyright 2006,2007, */
/* 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. */
/* 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 _LOG2D2_H_
#define _LOG2D2_H_ 1
#include <spu_intrinsics.h>
/*
* FUNCTION
* vector double _log2d2(vector double x)
*
* DESCRIPTION
* The function _log2d2 computes log base 2 of the input x for each
* of the double word elements of x. The log2 is decomposed
* into two parts, log2 of the exponent and log2 of the
* fraction. The log2 of the fraction is approximated
* using a 21st order polynomial of the form:
*
* __20_
* \
* log(x) = x * (1 + \ (Ci * x^i))
* /
* /____
* i=0
*
* for x in the range 0-1.
*/
#define LOG_C00
#define LOG_C01
#define LOG_C02
static __inline vector double _log2d2(vector double vx)
{
vec_int4 addval;
vec_ullong2 exp_mask = spu_splats(0x7FF0000000000000ULL);
vec_double2 vy, vxw;
vec_double2 v1 = spu_splats(1.0);
vec_double2 x2, x4, x8, x10, p1, p2;
/* Extract the fraction component of input by forcing
* its exponent so that input is in the range [1.0, 2.0)
* and then subtract 1.0 to force it in the range
* [0.0, 1.0).
*/
vxw = spu_sub(spu_sel(vx, v1, exp_mask), v1);
/* Compute the log2 of the exponent as exp - 1023.
*/
addval = spu_add(spu_rlmask((vec_int4)vx, -20), -1023);
/* Compute the log2 of the fractional component using a 21st
* order polynomial. The polynomial is evaluated in two halves
* to improve efficiency.
*/
p1 = spu_madd(spu_splats(3.61276447184348752E-05), vxw, spu_splats(-4.16662127033480827E-04));
p2 = spu_madd(spu_splats(-1.43988260692073185E-01), vxw, spu_splats(1.60245637034704267E-01));
p1 = spu_madd(vxw, p1, spu_splats(2.28193656337578229E-03));
p2 = spu_madd(vxw, p2, spu_splats(-1.80329036970820794E-01));
p1 = spu_madd(vxw, p1, spu_splats(-7.93793829370930689E-03));
p2 = spu_madd(vxw, p2, spu_splats(2.06098446037376922E-01));
p1 = spu_madd(vxw, p1, spu_splats(1.98461565426430164E-02));
p2 = spu_madd(vxw, p2, spu_splats(-2.40449108727688962E-01));
p1 = spu_madd(vxw, p1, spu_splats(-3.84093543662501949E-02));
p2 = spu_madd(vxw, p2, spu_splats(2.88539004851839364E-01));
p1 = spu_madd(vxw, p1, spu_splats(6.08335872067172597E-02));
p2 = spu_madd(vxw, p2, spu_splats(-3.60673760117245982E-01));
p1 = spu_madd(vxw, p1, spu_splats(-8.27937055456904317E-02));
p2 = spu_madd(vxw, p2, spu_splats(4.80898346961226595E-01));
p1 = spu_madd(vxw, p1, spu_splats(1.01392360727236079E-01));
p2 = spu_madd(vxw, p2, spu_splats(-7.21347520444469934E-01));
p1 = spu_madd(vxw, p1, spu_splats(-1.16530490533844182E-01));
p2 = spu_madd(vxw, p2, spu_splats(0.44269504088896339E+00));
p1 = spu_madd(vxw, p1, spu_splats(1.30009193360025350E-01));
x2 = spu_mul(vxw, vxw);
x4 = spu_mul(x2, x2);
x8 = spu_mul(x4, x4);
x10 = spu_mul(x8, x2);
vy = spu_madd(spu_madd(x10, p1, p2), vxw, vxw);
/* Add the log2(exponent) and the log2(fraction) to
* compute the final result.
*/
vy = spu_add(vy, spu_extend(spu_convtf(addval, 0)));
vxw = spu_extend(spu_convtf(addval, 20));
return(vy);
}
#endif /* _LOG2D2_H_ */
#endif /* __SPU__ */
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