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48 lines
1.6 KiB
C
48 lines
1.6 KiB
C
/* Return positive difference between arguments. i386 version.
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Copyright (C) 1997-2018 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 <errno.h>
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#include <fpu_control.h>
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#include <math.h>
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#include <math_private.h>
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#include <libm-alias-double.h>
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double
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__fdim (double x, double y)
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{
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if (islessequal (x, y))
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return 0.0;
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/* To avoid double rounding, set double precision for the
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subtraction. math_narrow_eval is still needed to eliminate
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excess range in the case of overflow. If the result of the
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subtraction is in the subnormal range for double, it is exact, so
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no issues of double rounding for subnormals arise. */
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fpu_control_t cw, cw_double;
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_FPU_GETCW (cw);
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cw_double = (cw & ~_FPU_EXTENDED) | _FPU_DOUBLE;
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_FPU_SETCW (cw_double);
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double r = math_narrow_eval (x - y);
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_FPU_SETCW (cw);
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if (isinf (r) && !isinf (x) && !isinf (y))
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__set_errno (ERANGE);
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return r;
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}
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libm_alias_double (__fdim, fdim)
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