mirror of
https://github.com/jart/cosmopolitan.git
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85 lines
3.6 KiB
C
85 lines
3.6 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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union ldshape {
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long double f;
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struct {
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uint64_t m;
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uint16_t se;
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} i;
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};
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static inline void force_eval(long double x)
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{
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volatile long double y;
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y = x;
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}
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long double nextafterl(long double x, long double y)
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{
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union ldshape ux, uy;
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if (isnan(x) || isnan(y))
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return x + y;
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if (x == y)
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return y;
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ux.f = x;
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if (x == 0) {
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uy.f = y;
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ux.i.m = 1;
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ux.i.se = uy.i.se & 0x8000;
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} else if ((x < y) == !(ux.i.se & 0x8000)) {
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ux.i.m++;
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if (ux.i.m << 1 == 0) {
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ux.i.m = 1ULL << 63;
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ux.i.se++;
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}
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} else {
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if (ux.i.m << 1 == 0) {
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ux.i.se--;
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if (ux.i.se)
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ux.i.m = 0;
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}
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ux.i.m--;
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}
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/* raise overflow if ux is infinite and x is finite */
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if ((ux.i.se & 0x7fff) == 0x7fff)
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return x + x;
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/* raise underflow if ux is subnormal or zero */
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if ((ux.i.se & 0x7fff) == 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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