mirror of
https://github.com/jart/cosmopolitan.git
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114 lines
4.8 KiB
C
114 lines
4.8 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/limits.h"
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#include "libc/math.h"
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#include "libc/runtime/fenv.h"
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#include "libc/tinymath/expo.internal.h"
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#include "libc/tinymath/feval.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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If the result cannot be represented (overflow, nan), then
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lrint raises the invalid exception.
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Otherwise if the input was not an integer then the inexact
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exception is raised.
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C99 is a bit vague about whether inexact exception is
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allowed to be raised when invalid is raised.
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(F.9 explicitly allows spurious inexact exceptions, F.9.6.5
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does not make it clear if that rule applies to lrint, but
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IEEE 754r 7.8 seems to forbid spurious inexact exception in
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the ineger conversion functions)
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So we try to make sure that no spurious inexact exception is
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raised in case of an overflow.
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If the bit size of long > precision of double, then there
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cannot be inexact rounding in case the result overflows,
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otherwise LONG_MAX and LONG_MIN can be represented exactly
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as a double.
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*/
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#if LONG_MAX < 1U<<53 && defined(FE_INEXACT)
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#if FLT_EVAL_METHOD==0 || FLT_EVAL_METHOD==1
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#define EPS DBL_EPSILON
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#elif FLT_EVAL_METHOD==2
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#define EPS LDBL_EPSILON
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#endif
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static dontinline long lrint_slow(double x) {
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// #pragma STDC FENV_ACCESS ON
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int e;
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e = fetestexcept(FE_INEXACT);
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x = rint(x);
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if (!e && (x > LONG_MAX || x < LONG_MIN))
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feclearexcept(FE_INEXACT);
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/* conversion */
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return x;
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}
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#else
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#define JUST_CALL_RINT
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#endif
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/**
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* Rounds to nearest integer.
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*/
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long lrint(double x) {
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#ifdef __x86_64__
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long res;
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asm("cvtsd2si\t%1,%0" : "=r"(res) : "x"(x));
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return res;
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#elif defined(__aarch64__)
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long res;
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asm("frintx\t%d1,%d1\n\t"
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"fcvtzs\t%x0,%d1"
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: "=r"(res), "+w"(x));
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return res;
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#elif defined(__powerpc64__) && defined(_ARCH_PWR5X)
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long res;
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asm("fctid\t%0,%1" : "=d"(res) : "d"(x));
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return res;
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#elif defined(JUST_CALL_RINT)
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return rint(x);
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#else
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uint32_t abstop = asuint64(x)>>32 & 0x7fffffff;
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uint64_t sign = asuint64(x) & (1ULL << 63);
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if (abstop < 0x41dfffff) {
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/* |x| < 0x7ffffc00, no overflow */
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double_t toint = asdouble(asuint64(1/EPS) | sign);
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double_t y = x + toint - toint;
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return (long)y;
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}
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return lrint_slow(x);
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#endif /* __x86_64__ */
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}
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