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88 lines
2.5 KiB
C
88 lines
2.5 KiB
C
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/****************************************************************
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The author of this software is David M. Gay.
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Copyright (C) 2004 by David M. Gay.
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All Rights Reserved
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Based on material in the rest of /netlib/fp/gdota.tar.gz,
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which is copyright (C) 1998, 2000 by Lucent Technologies.
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Permission to use, copy, modify, and distribute this software and
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its documentation for any purpose and without fee is hereby
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granted, provided that the above copyright notice appear in all
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copies and that both that the copyright notice and this
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permission notice and warranty disclaimer appear in supporting
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documentation, and that the name of Lucent or any of its entities
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not be used in advertising or publicity pertaining to
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distribution of the software without specific, written prior
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permission.
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LUCENT DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE,
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INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS.
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IN NO EVENT SHALL LUCENT OR ANY OF ITS ENTITIES BE LIABLE FOR ANY
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SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
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WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER
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IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION,
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ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF
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THIS SOFTWARE.
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****************************************************************/
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/* This is a variant of strtod that works on Intel ia32 systems */
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/* with the default extended-precision arithmetic -- it does not */
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/* require setting the precision control to 53 bits. */
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/* Please send bug reports to David M. Gay (dmg at acm dot org,
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* with " at " changed at "@" and " dot " changed to "."). */
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#include "gdtoaimp.h"
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double
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#ifdef KR_headers
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strtod(s, sp) CONST char *s; char **sp;
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#else
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strtod(CONST char *s, char **sp)
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#endif
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{
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static CONST FPI fpi = { 53, 1-1023-53+1, 2046-1023-53+1, 1, SI };
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ULong bits[2];
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Long exp;
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int k;
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union { ULong L[2]; double d; } u;
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k = strtodg(s, sp, &fpi, &exp, bits);
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switch(k & STRTOG_Retmask) {
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case STRTOG_NoNumber:
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case STRTOG_Zero:
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u.L[0] = u.L[1] = 0;
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break;
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case STRTOG_Normal:
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u.L[_1] = bits[0];
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u.L[_0] = (bits[1] & ~0x100000) | ((exp + 0x3ff + 52) << 20);
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break;
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case STRTOG_Denormal:
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u.L[_1] = bits[0];
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u.L[_0] = bits[1];
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break;
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case STRTOG_Infinite:
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u.L[_0] = 0x7ff00000;
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u.L[_1] = 0;
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break;
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case STRTOG_NaN:
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u.L[0] = d_QNAN0;
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u.L[1] = d_QNAN1;
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break;
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case STRTOG_NaNbits:
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u.L[_0] = 0x7ff00000 | bits[1];
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u.L[_1] = bits[0];
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}
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if (k & STRTOG_Neg)
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u.L[_0] |= 0x80000000L;
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return u.d;
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}
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