153 lines
5.5 KiB
C
153 lines
5.5 KiB
C
/*
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This Software is provided under the Zope Public License (ZPL) Version 2.1.
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Copyright (c) 2009, 2010 by the mingw-w64 project
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See the AUTHORS file for the list of contributors to the mingw-w64 project.
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This license has been certified as open source. It has also been designated
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as GPL compatible by the Free Software Foundation (FSF).
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Redistribution and use in source and binary forms, with or without
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modification, are permitted provided that the following conditions are met:
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1. Redistributions in source code must retain the accompanying copyright
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notice, this list of conditions, and the following disclaimer.
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2. Redistributions in binary form must reproduce the accompanying
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copyright notice, this list of conditions, and the following disclaimer
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in the documentation and/or other materials provided with the
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distribution.
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3. Names of the copyright holders must not be used to endorse or promote
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products derived from this software without prior written permission
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from the copyright holders.
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4. The right to distribute this software or to use it for any purpose does
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not give you the right to use Servicemarks (sm) or Trademarks (tm) of
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the copyright holders. Use of them is covered by separate agreement
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with the copyright holders.
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5. If any files are modified, you must cause the modified files to carry
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prominent notices stating that you changed the files and the date of
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any change.
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Disclaimer
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THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS ``AS IS'' AND ANY EXPRESSED
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OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO
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EVENT SHALL THE COPYRIGHT HOLDERS BE LIABLE FOR ANY DIRECT, INDIRECT,
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INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
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LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA,
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OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
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LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
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NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE,
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EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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/* IEEE 754 - Elementary Functions - Special Cases
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* powi (x, +/-0) is 1 for any x (even a zero, quiet NaN, or infinity)
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* powi (+1, y) is 1 for any y (even a quiet NaN)
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* powi (+/-0, y) is +/-oo and signals the divideByZero exception for y an odd integer < 0
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* powi (+/-0, y) is +oo and signals the divideByZero exception for finite y < 0 and not an odd integer
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* powi (+/-0, y) is +/-0 for finite y > 0 an odd integer
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* powi (+/-0, y) is +0 for finite y > 0 and not an odd integer
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powi (-inf, y) = +0 for y<0 and not an odd integer
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powi (-inf, y) = -inf for y an odd integer > 0
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powi (-inf, y) = +inf for y>0 and not an odd integer
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powi (+/-inf, y) is +/-0 with no exception for y an odd integer < 0
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powi (+/-inf, y) is +0 with no exception for finite y < 0 and not an odd integer
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powi (+/-inf, y) is +/-inf with no exception for finite y > 0 an odd integer
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powi (+/-inf, y) is +inf with no exception for finite y > 0 and not an odd integer
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powi (x, y) signals the invalid operation exception for finite x < 0 and finite non-integer y.
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For x /= 0: lim y->oo (1/x)^y results as: for |x| < 1 that sgn(x)*0 and for |x| > 0 that sgn(x)*Infinity
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*/
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#include "complex_internal.h"
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#include <errno.h>
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#include <limits.h>
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#include <fenv.h>
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#include <math.h>
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#include <errno.h>
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__FLT_TYPE __cdecl
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__FLT_ABI(__powi) (__FLT_TYPE x, int y);
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__FLT_TYPE __cdecl
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__FLT_ABI(__powi) (__FLT_TYPE x, int y)
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{
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int x_class = fpclassify (x);
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int odd_y = y & 1;
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__FLT_TYPE d, rslt;
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if (y == 0 || x == __FLT_CST(1.0))
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return __FLT_CST(1.0);
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else if (x_class == FP_NAN)
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{
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rslt = (signbit(x) ? -__FLT_NAN : __FLT_NAN);
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errno = EDOM;
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return rslt;
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}
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else if (x_class == FP_ZERO)
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{
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if (y >= 0)
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{
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if (!odd_y || !signbit (x))
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return __FLT_CST (0.0);
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return -__FLT_CST(0.0);
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}
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if (!odd_y || !signbit (x))
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return __FLT_HUGE_VAL;
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return (signbit(x) ? -__FLT_HUGE_VAL : __FLT_HUGE_VAL);
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}
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else if (x_class == FP_INFINITE)
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{
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/* pow( -inf, y) = +0 for y<0 and not an odd integer, */
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if (signbit(x) && y < 0 && !odd_y)
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return __FLT_CST(0.0);
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/* pow( -inf, y) = -inf for y an odd integer > 0. */
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if (signbit(x) && y >= 0 && odd_y)
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return -__FLT_HUGE_VAL;
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/* pow( -inf, y) = +inf for y>0 and not an odd integer. */
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if (signbit(x) && y >= 0 && !odd_y)
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return __FLT_HUGE_VAL;
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/* pow (+/-inf, y) is +/-0 with no exception for y an odd integer < 0. */
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if (y < 0)
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{
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/* pow (+/-inf, y) is +0 with no exception for finite y < 0 and not an odd integer. */
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return (odd_y && signbit(x) ? -__FLT_CST(0.0) : __FLT_CST(0.0));
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}
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/* pow (+/-inf, y) is +/-inf with no exception for finite y > 0 an odd integer. */
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/* pow (+/-inf, y) is +inf with no exception for finite y > 0 and not an odd integer. */
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return (odd_y && signbit(x) ? -__FLT_HUGE_VAL : __FLT_HUGE_VAL);
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}
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d = __FLT_ABI(fabs) (x);
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if (y < 0)
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{
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d = __FLT_CST(1.0) / d;
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y = -y;
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}
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if (!y)
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rslt = __FLT_CST(1.0);
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else if (y == 1)
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rslt = d;
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else
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{
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unsigned int u = (unsigned int) y;
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rslt = ((u & 1) != 0) ? d : __FLT_CST(1.0);
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u >>= 1;
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do
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{
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d *= d;
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if ((u & 1) != 0)
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rslt *= d;
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u >>= 1;
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}
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while (u > 0);
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}
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if (signbit (x) && odd_y)
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rslt = -rslt;
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return rslt;
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}
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