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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 _RECIPD2_H_
#define _RECIPD2_H_ 1
#include <spu_intrinsics.h>
/*
* FUNCTION
* vector double _recipd2(vector double value)
*
* DESCRIPTION
* The _recipd2 function inverts "value" and returns the result.
* Computation is performed using the single precision reciprocal
* estimate and interpolate instructions to produce a 12 accurate
* estimate.
*
* One (1) iteration of a Newton-Raphson is performed to improve
* accuracy to single precision floating point. Two additional double
* precision iterations are needed to achieve a full double
* preicision result.
*
* The Newton-Raphson iteration is of the form:
* X[i+1] = X[i] * (2.0 - b*X[i])
* where b is the input value to be inverted
*
*/
static __inline vector double _recipd2(vector double value_d)
{
vector unsigned long long expmask = (vector unsigned long long) { 0x7FF0000000000000ULL, 0x7FF0000000000000ULL };
vector float x0;
vector float value;
vector float two = spu_splats(2.0f);
vector double two_d = spu_splats(2.0);
vector double x1, x2, x3;
vector double bias;
/* Bias the divisor to correct for double precision floating
* point exponents that are out of single precision range.
*/
bias = spu_xor(spu_and(value_d, (vector double)expmask), (vector double)expmask);
value = spu_roundtf(spu_mul(value_d, bias));
x0 = spu_re(value);
x1 = spu_extend(spu_mul(x0, spu_nmsub(value, x0, two)));
x1 = spu_mul(x1, bias);
x2 = spu_mul(x1, spu_nmsub(value_d, x1, two_d));
x3 = spu_mul(x2, spu_nmsub(value_d, x2, two_d));
/* Handle input = +/- infinity or +/-0. */
#ifdef __SPU_EDP__
vec_ullong2 is0inf = spu_testsv(value_d, SPU_SV_NEG_ZERO | SPU_SV_POS_ZERO |
SPU_SV_NEG_INFINITY | SPU_SV_POS_INFINITY);
#else
vec_double2 nzero = spu_splats(-0.0);
vec_double2 xabs = spu_andc(value_d, nzero);
vector unsigned char swap = (vector unsigned char) {4,5,6,7, 0,1,2,3, 12,13,14,15, 8,9,10,11};
vec_uint4 isinf = spu_cmpeq((vec_uint4)xabs, (vec_uint4)expmask);
vec_uint4 iszero = spu_cmpeq((vec_uint4)xabs, 0);
isinf = spu_and(isinf, spu_shuffle(isinf, isinf, swap));
iszero = spu_and(iszero, spu_shuffle(iszero, iszero, swap));
vec_ullong2 is0inf = (vec_ullong2)spu_or(isinf, iszero);
#endif /* __SPU_EDP__ */
x3 = spu_sel(x3, spu_xor(value_d, (vector double)expmask), is0inf);
return (x3);
}
#endif /* _RECIPD2_H_ */
#endif /* __SPU__ */
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