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https://github.com/jart/cosmopolitan.git
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76 lines
3.9 KiB
C
76 lines
3.9 KiB
C
/*-*- mode:c;indent-tabs-mode:t;c-basic-offset:8;tab-width:8;coding:utf-8 -*-│
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│vi: set et ft=c ts=8 tw=8 fenc=utf-8 :vi│
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╚──────────────────────────────────────────────────────────────────────────────╝
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│ │
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│ The author of this software is David M. Gay. │
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│ Please send bug reports to David M. Gay <dmg@acm.org> │
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│ or Justine Tunney <jtunney@gmail.com> │
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│ │
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│ Copyright (C) 1998, 1999 by Lucent Technologies │
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│ All Rights Reserved │
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│ │
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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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│ │
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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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╚─────────────────────────────────────────────────────────────────────────────*/
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#include "third_party/gdtoa/gdtoa.internal.h"
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/* clang-format off */
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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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double
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strtod(const char *s, char **sp)
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{
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static const FPI fpi = { 53, 1-1023-53+1, 2046-1023-53+1, 1, SI, 0 /*unused*/ };
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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[0] = bits[0];
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u.L[1] = (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[0] = bits[0];
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u.L[1] = bits[1];
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break;
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case STRTOG_Infinite:
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u.L[1] = 0x7ff00000;
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u.L[0] = 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[1] = 0x7ff00000 | bits[1];
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u.L[0] = bits[0];
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}
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if (k & STRTOG_Neg)
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u.L[1] |= 0x80000000L;
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return u.d;
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}
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