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jeremybenn |
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/* (C)Copyright 2006,2008, */
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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 _SCALBNF4_H_
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#define _SCALBNF4_H_ 1
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#include <spu_intrinsics.h>
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/*
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* FUNCTION
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* vector float _scalbnf4(vector float x, vector signed int exp)
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*
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* DESCRIPTION
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* The _scalbnf4 function returns a vector containing each element of x
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* multiplied by 2^n computed efficiently. This function is computed
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* without the assistance of any floating point operations and as such
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* does not set any floating point exceptions.
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*
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* Special Cases:
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* - if the exponent is 0, then x is either 0 or a subnormal, and the
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* result will be returned as 0.
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* - if the result if underflows, it will be returned as 0.
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* - if the result overflows, it will be returned as FLT_MAX.
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*
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*/
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static __inline vector float _scalbnf4(vector float x, vector signed int exp)
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{
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vec_int4 x_exp;
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vec_uint4 zero;
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vec_uint4 overflow;
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vec_uint4 exp_mask = (vec_uint4)spu_splats(0x7F800000);
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vec_float4 out;
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/* Extract exponent from x. If the exponent is 0, then
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* x is either 0 or a denorm and x*2^exp is a zero.
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*/
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x_exp = spu_and(spu_rlmask((vec_int4)x, -23), 0xFF);
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zero = spu_cmpeq(x_exp, 0);
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/* Compute the expected exponent and determine if the
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* result is within range.
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*/
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x_exp = spu_add(exp, x_exp);
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/* Check for zero or overflow of result.
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* Note: set high bit of flags = 0, since we have to
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* return -0 when x = -0
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*/
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zero = spu_rlmask(spu_orc(zero, spu_cmpgt(x_exp, 0)), -1);
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overflow = spu_rlmask(spu_cmpgt(x_exp, 255), -1);
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/* Merge the expect exponent with x's mantissa. Zero the
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* result if underflow and force to max if overflow.
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*/
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out = spu_sel(x, (vec_float4)spu_rl(x_exp, 23), exp_mask);
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out = spu_andc(out, (vec_float4)zero);
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out = spu_or(out, (vec_float4)overflow);
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return out;
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}
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#endif /* _SCALBNF4_H_ */
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#endif /* __SPU__ */
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