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107 lines
2.7 KiB
C
107 lines
2.7 KiB
C
/* Round argument to nearest integral value according to current rounding
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direction.
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Copyright (C) 1997-2023 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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<https://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-narrow-eval.h>
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#include <math_private.h>
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#include <libm-alias-double.h>
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#include <fix-fp-int-convert-overflow.h>
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#include <math-use-builtins.h>
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long long int
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__llrint (double x)
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{
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#if USE_LLRINT_BUILTIN
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return __builtin_llrint (x);
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#else
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/* Use generic implementation. */
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static const double two52[2] =
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{
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4.50359962737049600000e+15, /* 0x43300000, 0x00000000 */
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-4.50359962737049600000e+15, /* 0xC3300000, 0x00000000 */
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};
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int32_t j0;
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uint32_t i1, i0;
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long long int result;
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double w;
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double t;
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int sx;
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EXTRACT_WORDS (i0, i1, x);
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j0 = ((i0 >> 20) & 0x7ff) - 0x3ff;
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sx = i0 >> 31;
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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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w = math_narrow_eval (two52[sx] + x);
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t = w - two52[sx];
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EXTRACT_WORDS (i0, i1, t);
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j0 = ((i0 >> 20) & 0x7ff) - 0x3ff;
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i0 &= 0xfffff;
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i0 |= 0x100000;
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result = (j0 < 0 ? 0 : i0 >> (20 - j0));
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}
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else if (j0 < (int32_t) (8 * sizeof (long long int)) - 1)
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{
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if (j0 >= 52)
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result = (((long long int) i0 << 32) | i1) << (j0 - 52);
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else
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{
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w = math_narrow_eval (two52[sx] + x);
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t = w - two52[sx];
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EXTRACT_WORDS (i0, i1, t);
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j0 = ((i0 >> 20) & 0x7ff) - 0x3ff;
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i0 &= 0xfffff;
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i0 |= 0x100000;
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if (j0 == 20)
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result = (long long int) i0;
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else
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result = ((long long int) i0 << (j0 - 20)) | (i1 >> (52 - j0));
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}
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}
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else
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{
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#ifdef FE_INVALID
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/* The number is too large. Unless it rounds to LLONG_MIN,
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FE_INVALID must be raised and the return value is
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unspecified. */
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if (FIX_DBL_LLONG_CONVERT_OVERFLOW && x != (double) LLONG_MIN)
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{
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feraiseexcept (FE_INVALID);
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return sx == 0 ? LLONG_MAX : LLONG_MIN;
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}
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#endif
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return (long long int) x;
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}
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return sx ? -result : result;
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#endif /* ! USE_LLRINT_BUILTIN */
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}
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libm_alias_double (__llrint, llrint)
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