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114 lines
2.8 KiB
C
114 lines
2.8 KiB
C
/* Round double value to long int.
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Copyright (C) 1997-2016 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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Contributed by Ulrich Drepper <drepper@cygnus.com>, 1997.
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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 <fenv.h>
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#include <limits.h>
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#include <math.h>
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#include <math_private.h>
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#include <fix-fp-int-convert-overflow.h>
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long int
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__lround (double x)
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{
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int32_t j0;
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u_int32_t i1, i0;
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long int result;
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int sign;
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EXTRACT_WORDS (i0, i1, x);
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j0 = ((i0 >> 20) & 0x7ff) - 0x3ff;
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sign = (i0 & 0x80000000) != 0 ? -1 : 1;
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i0 &= 0xfffff;
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i0 |= 0x100000;
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if (j0 < 20)
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{
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if (j0 < 0)
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return j0 < -1 ? 0 : sign;
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else
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{
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i0 += 0x80000 >> j0;
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result = i0 >> (20 - j0);
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}
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}
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else if (j0 < (int32_t) (8 * sizeof (long int)) - 1)
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{
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if (j0 >= 52)
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result = ((long int) i0 << (j0 - 20)) | ((long int) i1 << (j0 - 52));
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else
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{
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u_int32_t j = i1 + (0x80000000 >> (j0 - 20));
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if (j < i1)
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++i0;
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if (j0 == 20)
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result = (long int) i0;
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else
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{
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result = ((long int) i0 << (j0 - 20)) | (j >> (52 - j0));
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#ifdef FE_INVALID
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if (sizeof (long int) == 4
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&& sign == 1
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&& result == LONG_MIN)
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/* Rounding brought the value out of range. */
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feraiseexcept (FE_INVALID);
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#endif
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}
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}
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}
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else
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{
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/* The number is too large. Unless it rounds to LONG_MIN,
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FE_INVALID must be raised and the return value is
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unspecified. */
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#ifdef FE_INVALID
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if (FIX_DBL_LONG_CONVERT_OVERFLOW
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&& !(sign == -1
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&& (sizeof (long int) == 4
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? x > (double) LONG_MIN - 0.5
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: x >= (double) LONG_MIN)))
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{
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feraiseexcept (FE_INVALID);
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return sign == 1 ? LONG_MAX : LONG_MIN;
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}
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else if (!FIX_DBL_LONG_CONVERT_OVERFLOW
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&& sizeof (long int) == 4
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&& x <= (double) LONG_MIN - 0.5)
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{
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/* If truncation produces LONG_MIN, the cast will not raise
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the exception, but may raise "inexact". */
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feraiseexcept (FE_INVALID);
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return LONG_MIN;
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}
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#endif
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return (long int) x;
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}
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return sign * result;
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}
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weak_alias (__lround, lround)
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#ifdef NO_LONG_DOUBLE
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strong_alias (__lround, __lroundl)
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weak_alias (__lround, lroundl)
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#endif
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