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https://github.com/jart/cosmopolitan.git
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70 lines
3.4 KiB
C
70 lines
3.4 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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│ 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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#include "libc/tinymath/feval.internal.h"
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#include "libc/tinymath/kernel.internal.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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/**
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* Returns 𝑥 × 2ʸ.
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*/
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double ldexp(double x, int n)
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{
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union {double f; uint64_t i;} u;
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double_t y = x;
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if (n > 1023) {
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y *= 0x1p1023;
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n -= 1023;
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if (n > 1023) {
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y *= 0x1p1023;
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n -= 1023;
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if (n > 1023)
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n = 1023;
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}
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} else if (n < -1022) {
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/* make sure final n < -53 to avoid double
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rounding in the subnormal range */
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y *= 0x1p-1022 * 0x1p53;
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n += 1022 - 53;
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if (n < -1022) {
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y *= 0x1p-1022 * 0x1p53;
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n += 1022 - 53;
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if (n < -1022)
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n = -1022;
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}
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}
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u.i = (uint64_t)(0x3ff+n)<<52;
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x = y * u.f;
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return x;
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}
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