52 lines
1.5 KiB
C
52 lines
1.5 KiB
C
/* Copyright (C) 2007-2017 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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Contributed by Richard Henderson.
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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 <math_ldbl_opt.h>
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/* Use the chopped rounding mode conversion instructions to implement trunc. */
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double
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__trunc (double x)
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{
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double two52 = copysign (0x1.0p52, x);
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double r, tmp;
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if (isgreaterequal (fabs (x), 0x1.0p52))
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return x;
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__asm (
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"addt/suc %2, %3, %1\n\tsubt/suc %1, %3, %0"
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: "=&f"(r), "=&f"(tmp)
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: "f"(x), "f"(two52));
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/* trunc(-0) == -0, and in general we'll always have the same
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sign as our input. */
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return copysign (r, x);
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}
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weak_alias (__trunc, trunc)
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#ifdef NO_LONG_DOUBLE
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strong_alias (__trunc, __truncl)
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weak_alias (__trunc, truncl)
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#endif
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#if LONG_DOUBLE_COMPAT(libm, GLIBC_2_1)
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compat_symbol (libm, __trunc, truncl, GLIBC_2_1);
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#endif
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