2007-09-29 02:44:24 +08:00
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/* -------------------------------------------------------------- */
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2008-09-05 01:50:56 +08:00
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/* (C)Copyright 2001,2008, */
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2007-09-29 02:44:24 +08:00
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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 _LOG2D2_H_
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#define _LOG2D2_H_ 1
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#include <spu_intrinsics.h>
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/*
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* FUNCTION
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* vector double _log2d2(vector double x)
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*
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* DESCRIPTION
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* The function _log2d2 computes log base 2 of the input x for each
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* of the double word elements of x. The log2 is decomposed
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* into two parts, log2 of the exponent and log2 of the
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* fraction. The log2 of the fraction is approximated
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* using a 21st order polynomial of the form:
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*
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* __20_
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* \
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* log(x) = x * (1 + \ (Ci * x^i))
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* /
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* /____
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* i=0
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*
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* for x in the range 0-1.
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*/
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#define LOG_C00
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#define LOG_C01
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#define LOG_C02
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static __inline vector double _log2d2(vector double vx)
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{
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vec_int4 addval;
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vec_ullong2 exp_mask = spu_splats(0x7FF0000000000000ULL);
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vec_double2 vy, vxw;
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vec_double2 v1 = spu_splats(1.0);
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vec_double2 x2, x4, x8, x10, p1, p2;
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/* Extract the fraction component of input by forcing
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* its exponent so that input is in the range [1.0, 2.0)
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* and then subtract 1.0 to force it in the range
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* [0.0, 1.0).
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*/
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vxw = spu_sub(spu_sel(vx, v1, exp_mask), v1);
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/* Compute the log2 of the exponent as exp - 1023.
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*/
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addval = spu_add(spu_rlmask((vec_int4)vx, -20), -1023);
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/* Compute the log2 of the fractional component using a 21st
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* order polynomial. The polynomial is evaluated in two halves
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* to improve efficiency.
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*/
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p1 = spu_madd(spu_splats(3.61276447184348752E-05), vxw, spu_splats(-4.16662127033480827E-04));
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p2 = spu_madd(spu_splats(-1.43988260692073185E-01), vxw, spu_splats(1.60245637034704267E-01));
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p1 = spu_madd(vxw, p1, spu_splats(2.28193656337578229E-03));
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p2 = spu_madd(vxw, p2, spu_splats(-1.80329036970820794E-01));
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p1 = spu_madd(vxw, p1, spu_splats(-7.93793829370930689E-03));
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p2 = spu_madd(vxw, p2, spu_splats(2.06098446037376922E-01));
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p1 = spu_madd(vxw, p1, spu_splats(1.98461565426430164E-02));
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p2 = spu_madd(vxw, p2, spu_splats(-2.40449108727688962E-01));
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p1 = spu_madd(vxw, p1, spu_splats(-3.84093543662501949E-02));
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p2 = spu_madd(vxw, p2, spu_splats(2.88539004851839364E-01));
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p1 = spu_madd(vxw, p1, spu_splats(6.08335872067172597E-02));
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p2 = spu_madd(vxw, p2, spu_splats(-3.60673760117245982E-01));
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p1 = spu_madd(vxw, p1, spu_splats(-8.27937055456904317E-02));
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p2 = spu_madd(vxw, p2, spu_splats(4.80898346961226595E-01));
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p1 = spu_madd(vxw, p1, spu_splats(1.01392360727236079E-01));
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p2 = spu_madd(vxw, p2, spu_splats(-7.21347520444469934E-01));
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p1 = spu_madd(vxw, p1, spu_splats(-1.16530490533844182E-01));
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p2 = spu_madd(vxw, p2, spu_splats(0.44269504088896339E+00));
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p1 = spu_madd(vxw, p1, spu_splats(1.30009193360025350E-01));
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x2 = spu_mul(vxw, vxw);
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x4 = spu_mul(x2, x2);
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x8 = spu_mul(x4, x4);
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x10 = spu_mul(x8, x2);
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vy = spu_madd(spu_madd(x10, p1, p2), vxw, vxw);
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/* Add the log2(exponent) and the log2(fraction) to
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* compute the final result.
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*/
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vy = spu_add(vy, spu_extend(spu_convtf(addval, 0)));
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vxw = spu_extend(spu_convtf(addval, 20));
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return(vy);
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}
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#endif /* _LOG2D2_H_ */
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#endif /* __SPU__ */
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