42 lines
1.6 KiB
C
42 lines
1.6 KiB
C
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/* Subtract _Float64 values, converting the result to _Float32x. i386 version.
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Copyright (C) 2018-2022 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 <math.h>
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#include <fpu_control.h>
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#include <math-narrow-eval.h>
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#include <math-narrow.h>
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_Float32x
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__f32xsubf64 (_Float64 x, _Float64 y)
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{
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/* To avoid double rounding, set double precision for the subtraction.
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math_narrow_eval is still needed to eliminate excess range in the
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case of overflow. If the result of the subtraction is in the
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subnormal range for double, it is exact, so no issues of double
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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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_Float32x ret = math_narrow_eval (x - y);
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_FPU_SETCW (cw);
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CHECK_NARROW_SUB (ret, x, y);
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return ret;
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}
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libm_alias_float32x_float64 (sub)
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