mirror of
https://github.com/jart/cosmopolitan.git
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71 lines
3.4 KiB
C
71 lines
3.4 KiB
C
/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
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│vi: set net ft=c ts=2 sts=2 sw=2 fenc=utf-8 :vi│
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╚──────────────────────────────────────────────────────────────────────────────╝
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│ │
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│ Musl Libc │
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│ Copyright © 2005-2014 Rich Felker, et al. │
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│ │
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│ Permission is hereby granted, free of charge, to any person obtaining │
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│ a copy of this software and associated documentation files (the │
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│ "Software"), to deal in the Software without restriction, including │
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│ without limitation the rights to use, copy, modify, merge, publish, │
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│ distribute, sublicense, and/or sell copies of the Software, and to │
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│ permit persons to whom the Software is furnished to do so, subject to │
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│ the following conditions: │
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│ │
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│ The above copyright notice and this permission notice shall be │
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│ included in all copies or substantial portions of the Software. │
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│ │
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│ THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, │
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│ EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF │
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│ MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. │
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│ IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY │
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│ CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, │
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│ TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE │
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│ SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. │
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│ │
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╚─────────────────────────────────────────────────────────────────────────────*/
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#include "libc/math.h"
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asm(".ident\t\"\\n\\n\
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Musl libc (MIT License)\\n\
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Copyright 2005-2014 Rich Felker, et. al.\"");
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asm(".include \"libc/disclaimer.inc\"");
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/* clang-format off */
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static inline void force_eval(double x)
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{
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volatile double y;
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y = x;
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}
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double nextafter(double x, double y)
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{
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union {double f; uint64_t i;} ux={x}, uy={y};
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uint64_t ax, ay;
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int e;
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if (isnan(x) || isnan(y))
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return x + y;
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if (ux.i == uy.i)
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return y;
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ax = ux.i & -1ULL/2;
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ay = uy.i & -1ULL/2;
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if (ax == 0) {
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if (ay == 0)
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return y;
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ux.i = (uy.i & 1ULL<<63) | 1;
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} else if (ax > ay || ((ux.i ^ uy.i) & 1ULL<<63))
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ux.i--;
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else
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ux.i++;
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e = ux.i >> 52 & 0x7ff;
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/* raise overflow if ux.f is infinite and x is finite */
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if (e == 0x7ff)
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force_eval(x+x);
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/* raise underflow if ux.f is subnormal or zero */
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if (e == 0)
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force_eval(x*x + ux.f*ux.f);
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return ux.f;
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}
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