79 lines
2.2 KiB
C
79 lines
2.2 KiB
C
/*
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* Copyright © 2005-2014 Rich Felker, et al.
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*
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* Permission is hereby granted, free of charge, to any person obtaining
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* a copy of this software and associated documentation files (the
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* "Software"), to deal in the Software without restriction, including
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* without limitation the rights to use, copy, modify, merge, publish,
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* distribute, sublicense, and/or sell copies of the Software, and to
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* permit persons to whom the Software is furnished to do so, subject to
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* the following conditions:
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*
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* The above copyright notice and this permission notice shall be
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* included in all copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
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* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
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* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
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* IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
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* CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
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* TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
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* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
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*/
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#include <math.h>
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#include <inttypes.h>
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#include "local.h"
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union fshape {
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float value;
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uint32_t bits;
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};
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// This is only necessary because the implementation of isnan only works
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// properly when long double == double.
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// See: https://sourceware.org/ml/newlib/2014/msg00684.html
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#ifdef _LDBL_EQ_DBL
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float
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nexttowardf (float x, long double y)
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{
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union fshape ux;
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uint32_t e;
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if (isnan(x) || isnan(y))
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return x + y;
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if (x == y)
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return y;
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ux.value = x;
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if (x == 0) {
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ux.bits = 1;
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if (signbit(y))
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ux.bits |= 0x80000000;
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} else if (x < y) {
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if (signbit(x))
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ux.bits--;
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else
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ux.bits++;
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} else {
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if (signbit(x))
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ux.bits++;
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else
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ux.bits--;
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}
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e = ux.bits & 0x7f800000;
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/* raise overflow if ux.value is infinite and x is finite */
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if (e == 0x7f800000) {
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volatile float force_eval;
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force_eval = x + x;
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}
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/* raise underflow if ux.value is subnormal or zero */
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if (e == 0) {
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volatile float force_eval;
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force_eval = x*x + ux.value*ux.value;
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}
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return ux.value;
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}
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#endif // _LDBL_EQ_DBL
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