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153 lines
4.0 KiB
C
153 lines
4.0 KiB
C
/*
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(C) Copyright IBM Corp. 2009
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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 name of IBM nor the names of its contributors may be
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used to endorse or promote products derived from this software without
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specific prior written permission.
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THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
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LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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POSSIBILITY OF SUCH DAMAGE.
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*/
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#include <math.h>
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#include <float.h>
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#include "local.h"
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/* On platforms where long double is as wide as double. */
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#if defined(_LDBL_EQ_DBL)
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long double
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frexpl (long double x, int *eptr)
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{
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return frexp(x, eptr);
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}
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#else /* !_DBL_EQ_DBL */
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# if (LDBL_MANT_DIG == 53) /* 64-bit long double */
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static const double scale = 0x1p54;
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union ldbl {
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long double x;
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struct {
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# ifdef __IEEE_LITTLE_ENDIAN /* for Intel CPU */
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__uint32_t fracl;
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__uint32_t frach:20;
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__uint32_t exp:11;
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__uint32_t sign:1;
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# endif
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# ifdef __IEEE_BIG_ENDIAN
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__uint32_t sign:1;
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__uint32_t exp:11;
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__uint32_t frach:20;
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# ifndef ___IEEE_BYTES_LITTLE_ENDIAN
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# else /* ARMEL without __VFP_FP__ */
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__uint32_t frach:20;
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__uint32_t exp:11;
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__uint32_t sign:1;
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# endif
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__uint32_t fracl;
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# endif
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} u32;
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};
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# elif (LDBL_MANT_DIG == 64) /* 80-bit long double */
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static const double scale = 0x1p65;
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union ldbl {
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long double x;
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struct {
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# ifdef __IEEE_LITTLE_ENDIAN /* for Intel CPU */
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__uint32_t fracl;
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__uint32_t frach;
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__uint32_t exp:15;
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__uint32_t sign:1;
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__uint32_t pad:16;
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# endif
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# ifdef __IEEE_BIG_ENDIAN
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# ifndef ___IEEE_BYTES_LITTLE_ENDIAN /* for m86k */
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__uint32_t sign:1;
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__uint32_t exp:15;
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__uint32_t pad:16;
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# else /* ARM FPA10 math copprocessor */
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__uint32_t exp:15;
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__uint32_t pad:16;
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__uint32_t sign:1;
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# endif
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__uint32_t frach;
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__uint32_t fracl;
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# endif
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} u32;
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};
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# elif (LDBL_MANT_DIG == 113) /* 128-bit long double */
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static const double scale = 0x1p114;
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union ldbl {
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long double x;
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struct {
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# ifdef __IEEE_LITTLE_ENDIAN
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__uint32_t fracl;
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__uint32_t fraclm;
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__uint32_t frachm;
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__uint32_t frach:16;
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__uint32_t exp:15;
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__uint32_t sign:1;
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# endif
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# ifdef __IEEE_BIG_ENDIAN
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# ifndef ___IEEE_BYTES_LITTLE_ENDIAN
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__uint32_t sign:1;
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__uint32_t exp:15;
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__uint32_t frach:16;
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# else /* ARMEL without __VFP_FP__ */
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__uint32_t frach:16;
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__uint32_t exp:15;
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__uint32_t sign:1;
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# endif
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__uint32_t frachm;
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__uint32_t fraclm;
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__uint32_t fracl;
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# endif
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} u32;
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};
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# else
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# error Unsupported long double format.
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# endif
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static const int scale_exp = LDBL_MANT_DIG + 1;
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long double
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frexpl (long double x, int *eptr)
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{
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union ldbl u;
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u.x = x;
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int e = u.u32.exp;
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*eptr = 0;
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if (e == (LDBL_MAX_EXP*2 - 1) || x == 0)
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return x; /* inf,nan,0 */
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if (e == 0) /* subnormal */
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{
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u.x *= scale;
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e = u.u32.exp;
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*eptr -= scale_exp;
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}
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*eptr += e - (LDBL_MAX_EXP - 2);
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u.u32.exp = LDBL_MAX_EXP - 2; /* -1 */
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return u.x;
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}
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#endif /* !_LDBL_EQ_DBL */
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