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87 lines
3.0 KiB
C
87 lines
3.0 KiB
C
/*
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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 _ILOGB_H_
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#define _ILOGB_H_ 1
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#include <spu_intrinsics.h>
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#include "headers/vec_literal.h"
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#include <limits.h>
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#include <math.h>
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/* ilogb returns the signed exponent in the floating-point
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* input. Special numbers include:
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* Input Output
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* ===== =====================
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* INF FP_ILOGBNAN (INT_MAX)
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* NAN FP_ILOGBNAN (INT_MAX)
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* denorm exponent - leading zeros
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* 0 FP_ILOGB0 (INT_MIN)
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* else signed exponent
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*/
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static __inline int _ilogb(double x)
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{
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vec_uint4 v, exp, exp_0, mant, mask, count;
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vec_uint4 flg_exp_0, flg_exp_max;
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mask = VEC_SPLAT_U32(0x7FF);
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/* Extract the exponent and mantissa.
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*/
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v = (vec_uint4)spu_promote(x, 0);
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exp = spu_and(spu_rlmask(v, -20), mask);
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mant = spu_and(v, VEC_LITERAL(vec_uint4, 0x000FFFFF, 0xFFFFFFFF, 0, 0));
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/* Count the leading zeros in the mantissa for denorm handling
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* and zero identification.
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*/
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count = spu_cntlz(mant);
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count = spu_add(count, spu_and(spu_rlqwbyte(count, 4), spu_cmpeq(count, 32)));
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flg_exp_0 = spu_cmpeq(exp, 0);
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flg_exp_max = spu_cmpeq(exp, mask);
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exp = spu_add(exp, -1023);
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/* Determine the exponent if the input is a denorm or zero.
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*/
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exp_0 = spu_sel(spu_sub(spu_add(exp, 12), count), VEC_SPLAT_U32(FP_ILOGB0), spu_cmpeq(count, 64));
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exp = spu_sel(spu_sel(exp, VEC_SPLAT_U32(FP_ILOGBNAN), flg_exp_max), exp_0, flg_exp_0);
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return (spu_extract((vec_int4)(exp), 0));
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}
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#endif /* _ILOGB_H_ */
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