mirror of
https://github.com/jart/cosmopolitan.git
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64 lines
3.2 KiB
C
64 lines
3.2 KiB
C
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/*-*- 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/limits.h"
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#include "libc/math.h"
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#include "libc/tinymath/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 log₂𝑥 exponent part of double.
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*/
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int ilogbf(float x)
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{
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// #pragma STDC FENV_ACCESS ON
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union {float f; uint32_t i;} u = {x};
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uint32_t i = u.i;
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int e = i>>23 & 0xff;
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if (!e) {
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i <<= 9;
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if (i == 0) {
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FORCE_EVAL(0/0.0f);
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return FP_ILOGB0;
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}
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/* subnormal x */
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for (e = -0x7f; i>>31 == 0; e--, i<<=1);
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return e;
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}
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if (e == 0xff) {
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FORCE_EVAL(0/0.0f);
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return i<<9 ? FP_ILOGBNAN : INT_MAX;
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}
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return e - 0x7f;
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}
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