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/* -------------------------------------------------------------- */
/* (C)Copyright 2006,2007, */
/* 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. */
/* 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 _HYPOTF4_H_
#define _HYPOTF4_H_ 1
#include <spu_intrinsics.h>
#include "sqrtf4.h"
/*
* FUNCTION
* vector float _hypotf4(vector float x, vector float y)
*
* DESCRIPTION
* The function hypotf4 returns a float vector in which each element is
* the square root of the sum of the squares of the corresponding
* elements of x and y. In other words, each element is sqrt(x^2 + y^2).
*
* The purpose of this function is to avoid overflow during
* intermediate calculations, and therefore it is slower than
* simply calcualting sqrt(x^2 + y^2).
*
* This function is performed by factoring out the larger of the 2
* input exponents and moving this factor outside of the sqrt calculation.
* This will minimize the possibility of over/underflow when the square
* of the values are calculated. Think of it as normalizing the larger
* input to the range [1,2).
*
*
* Special Cases:
* - hypot(x, +/-0) returns |x|
* - hypot(+/- infinity, y) returns +infinity
* - hypot(+/- infinity, NaN) returns +infinity
*
*/
static __inline vector float _hypotf4(vector float x, vector float y)
{
vector unsigned int emask = spu_splats(0x7F800000u);
vector unsigned int mmask = spu_splats(0x007FFFFFu);
vector signed int bias = spu_splats(0x3F800000);
vector float inf = (vec_float4)spu_splats(0x7F800000);
vector float onef = spu_splats(1.0f);
vector float sbit = spu_splats(-0.0f);
vector float max, max_e, max_m;
vector float min, min_e, min_m;
vector unsigned int xgty;
vector float sum;
vector float result;
/* Only need absolute values for this function */
x = spu_andc(x, sbit);
y = spu_andc(y, sbit);
xgty = spu_cmpgt(x,y);
max = spu_sel(y,x,xgty);
min = spu_sel(x,y,xgty);
/* Extract exponents and mantissas */
max_e = (vec_float4)spu_and((vec_uint4)max, emask);
max_m = (vec_float4)spu_and((vec_uint4)max, mmask);
min_e = (vec_float4)spu_and((vec_uint4)min, emask);
min_m = (vec_float4)spu_and((vec_uint4)min, mmask);
/* Adjust the exponent of the smaller of the 2 input values by
* subtracting max_exp from min_exp.
*/
vec_int4 min_e_int = spu_sub((vec_int4)min_e, (vec_int4)max_e);
min_e = (vec_float4)spu_add(min_e_int, bias);
/* If the new min exponent is too small, just set it to 0. It
* wouldn't contribute to the final result in either case.
*/
min_e = spu_sel(min_e, sbit, spu_cmpgt(sbit, min_e));
/* Combine new exponents with original mantissas */
max = spu_or(onef, max_m);
min = spu_or(min_e, min_m);
sum = _sqrtf4(spu_madd(max, max, spu_mul(min, min)));
sum = spu_mul(max_e, sum);
/* Special case: x = +/- infinity */
result = spu_sel(sum, inf, spu_cmpeq(x, inf));
return result;
}
#endif /* _HYPOTF4_H_ */
#endif /* __SPU__ */
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