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121 lines
3.2 KiB
C
121 lines
3.2 KiB
C
/* Round to long long int long double floating-point values.
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IBM extended format long double version.
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Copyright (C) 2006-2016 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library; if not, see
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<http://www.gnu.org/licenses/>. */
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#include <math.h>
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#include <fenv.h>
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#include <math_ldbl_opt.h>
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#include <float.h>
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#include <ieee754.h>
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long long
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__llroundl (long double x)
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{
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double xh, xl;
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long long res, hi, lo;
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ldbl_unpack (x, &xh, &xl);
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/* Limit the range of values handled by the conversion to long long.
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We do this because we aren't sure whether that conversion properly
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raises FE_INVALID. */
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if (__builtin_expect
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((__builtin_fabs (xh) <= -(double) (-__LONG_LONG_MAX__ - 1)), 1)
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#if !defined (FE_INVALID)
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|| 1
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#endif
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)
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{
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if (__glibc_unlikely ((xh == -(double) (-__LONG_LONG_MAX__ - 1))))
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{
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/* When XH is 9223372036854775808.0, converting to long long will
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overflow, resulting in an invalid operation. However, XL might
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be negative and of sufficient magnitude that the overall long
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double is in fact in range. Avoid raising an exception. In any
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case we need to convert this value specially, because
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the converted value is not exactly represented as a double
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thus subtracting HI from XH suffers rounding error. */
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hi = __LONG_LONG_MAX__;
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xh = 1.0;
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}
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else
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{
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hi = (long long) xh;
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xh -= hi;
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}
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ldbl_canonicalize (&xh, &xl);
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lo = (long long) xh;
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/* Peg at max/min values, assuming that the above conversions do so.
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Strictly speaking, we can return anything for values that overflow,
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but this is more useful. */
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res = hi + lo;
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/* This is just sign(hi) == sign(lo) && sign(res) != sign(hi). */
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if (__glibc_unlikely (((~(hi ^ lo) & (res ^ hi)) < 0)))
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goto overflow;
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xh -= lo;
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ldbl_canonicalize (&xh, &xl);
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hi = res;
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if (xh > 0.5)
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{
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res += 1;
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}
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else if (xh == 0.5)
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{
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if (xl > 0.0 || (xl == 0.0 && res >= 0))
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res += 1;
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}
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else if (-xh > 0.5)
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{
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res -= 1;
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}
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else if (-xh == 0.5)
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{
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if (xl < 0.0 || (xl == 0.0 && res <= 0))
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res -= 1;
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}
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if (__glibc_unlikely (((~(hi ^ (res - hi)) & (res ^ hi)) < 0)))
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goto overflow;
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return res;
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}
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else
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{
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if (xh > 0.0)
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hi = __LONG_LONG_MAX__;
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else if (xh < 0.0)
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hi = -__LONG_LONG_MAX__ - 1;
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else
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/* Nan */
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hi = 0;
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}
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overflow:
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#ifdef FE_INVALID
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feraiseexcept (FE_INVALID);
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#endif
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return hi;
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}
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long_double_symbol (libm, __llroundl, llroundl);
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