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jeremybenn |
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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 _EXP2D2_H_
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#define _EXP2D2_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 _exp2d2(vector double x)
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*
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* DESCRIPTION
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* _exp2d2 computes 2 raised to the input x for each
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* of the double word elements of x. Computation is
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* performed by observing the 2^(a+b) = 2^a * 2^b.
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* We decompose x into a and b (above) by letting.
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* a = ceil(x), b = x - a;
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*
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* 2^a is easily computed by placing a into the exponent
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* or a floating point number whose mantissa is all zeros.
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*
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* 2^b is computed using the polynomial approximation.
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*
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* __13_
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* \
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* \
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* 2^x = / Ci*x^i
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* /____
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* i=0
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*
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* for x in the range 0.0 to 1.0.
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*
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*/
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#define EXP_C00 1.0
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#define EXP_C01 6.93147180559945286227e-01
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#define EXP_C02 2.40226506959100694072e-01
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#define EXP_C03 5.55041086648215761801e-02
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#define EXP_C04 9.61812910762847687873e-03
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#define EXP_C05 1.33335581464284411157e-03
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#define EXP_C06 1.54035303933816060656e-04
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#define EXP_C07 1.52527338040598376946e-05
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#define EXP_C08 1.32154867901443052734e-06
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#define EXP_C09 1.01780860092396959520e-07
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#define EXP_C10 7.05491162080112087744e-09
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#define EXP_C11 4.44553827187081007394e-10
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#define EXP_C12 2.56784359934881958182e-11
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#define EXP_C13 1.36914888539041240648e-12
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static __inline vector double _exp2d2(vector double vx)
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{
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vec_int4 ix, exp;
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vec_uint4 overflow, underflow;
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vec_float4 vxf;
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vec_double2 p1, p2, x2, x4, x8;
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vec_double2 vy, vxw, out_of_range;
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/* Compute: vxw = x - ceil(x)
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*/
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vxw = spu_add(vx, spu_splats(0.5));
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vxf = spu_roundtf(vxw);
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ix = spu_convts(vxf, 0);
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ix = spu_add(ix, (vec_int4)spu_andc(spu_cmpgt(spu_splats(0.0f), vxf), spu_cmpeq(ix, spu_splats((int)0x80000000))));
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vxf = spu_convtf(ix, 0);
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vxw = spu_sub(vx, spu_extend(vxf));
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/* Detect overflow and underflow. If overflow, force the result
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* to infinity (at the end).
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*/
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exp = spu_shuffle(ix, ix, ((vec_uchar16) { 0,1,2,3, 0,1,2,3, 8,9,10,11, 8,9,10,11 }));
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overflow = spu_cmpgt(exp, 1023);
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underflow = spu_cmpgt(exp, -1023);
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out_of_range = (vec_double2)spu_and(overflow, ((vec_uint4) { 0x7FF00000, 0, 0x7FF00000, 0 }));
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/* Calculate the result by evaluating the 13th order polynomial.
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* For efficiency, the polynomial is broken into two parts and
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* evaluate then using nested
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*
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* result = (((((c13*x + c12)*x + c11)*x + c10)*x + c9)*x + c8)*x^8 +
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* ((((((c7*x + c6)*x + c5)*x + c4)*x + c3)*x + c2)*x + c1)*x + c0
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*/
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p2 = spu_madd(spu_splats(EXP_C07), vxw, spu_splats(EXP_C06));
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p1 = spu_madd(spu_splats(EXP_C13), vxw, spu_splats(EXP_C12));
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x2 = spu_mul(vxw, vxw);
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p2 = spu_madd(vxw, p2, spu_splats(EXP_C05));
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p1 = spu_madd(vxw, p1, spu_splats(EXP_C11));
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x4 = spu_mul(x2, x2);
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p2 = spu_madd(vxw, p2, spu_splats(EXP_C04));
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p1 = spu_madd(vxw, p1, spu_splats(EXP_C10));
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p2 = spu_madd(vxw, p2, spu_splats(EXP_C03));
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p1 = spu_madd(vxw, p1, spu_splats(EXP_C09));
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x8 = spu_mul(x4, x4);
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p2 = spu_madd(vxw, p2, spu_splats(EXP_C02));
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p1 = spu_madd(vxw, p1, spu_splats(EXP_C08));
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p2 = spu_madd(vxw, p2, spu_splats(EXP_C01));
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p2 = spu_madd(vxw, p2, spu_splats(EXP_C00));
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vy = spu_madd(x8, p1, p2);
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/* Align the integer integer portion of x with the exponent.
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*/
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ix = spu_sl(ix, ((vec_uint4) { 20, 32, 20, 32 }));
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vy = (vec_double2)spu_add((vec_int4)vy, ix);
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/* Select the result if not overflow or underflow. Otherwise select the
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* the out of range value.
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*/
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return (spu_sel(vy, out_of_range, (vec_ullong2)spu_orc(overflow, underflow)));
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}
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#endif /* _EXP2D2_H_ */
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#endif /* __SPU__ */
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