78 lines
2.8 KiB
C
78 lines
2.8 KiB
C
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/*
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(C) Copyright 2001,2006,
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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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All rights reserved.
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Redistribution and use in source and binary forms, with or without
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modification, are permitted provided that the following conditions are met:
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* Redistributions of source code must retain the above copyright notice,
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this list of conditions and the following disclaimer.
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* Redistributions in binary form must reproduce the above copyright
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notice, this list of conditions and the following disclaimer in the
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documentation and/or other materials provided with the distribution.
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* Neither the names of the copyright holders nor the names of their
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contributors may be used to endorse or promote products derived from this
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software without specific prior written permission.
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THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
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IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
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TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
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PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER
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OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
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EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
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PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
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PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
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LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
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NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
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SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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#ifndef _SCALBNF_H_
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#define _SCALBNF_H_ 1
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#include <spu_intrinsics.h>
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#include "headers/vec_literal.h"
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/* scalbnf computes x * 2^exp. This function is computed without
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* the assistence of any floating point operations and as such does
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* not set any floating point exceptions.
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*/
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static __inline float _scalbnf(float x, int exp)
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{
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vec_int4 x_exp;
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vec_uint4 zero, overflow;
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vec_uint4 exp_mask = VEC_SPLAT_U32(0x7F800000);
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vec_float4 in, out;
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in = spu_promote(x, 0);
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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)in, -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(spu_promote(exp, 0), x_exp);
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zero = spu_orc(zero, spu_cmpgt(x_exp, 0));
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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(in, (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 (spu_extract(out, 0));
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}
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#endif /* _SCALBNF_H_ */
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