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72 lines
1.8 KiB
C
72 lines
1.8 KiB
C
/* Copyright (C) 1991, 1992, 1994 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 Library General Public License as
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published by the Free Software Foundation; either version 2 of the
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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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Library General Public License for more details.
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You should have received a copy of the GNU Library General Public
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License along with the GNU C Library; see the file COPYING.LIB. If
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not, write to the Free Software Foundation, Inc., 675 Mass Ave,
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Cambridge, MA 02139, USA. */
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#include <ansidecl.h>
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#include <math.h>
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#ifdef __GNUC__
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__CONSTVALUE double
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DEFUN(atan2, (y, x), double y AND double x)
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{
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static CONST double one = 1.0, zero = 0.0;
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double signx, signy;
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double pi, PIo4, PIo2;
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if (__isnan(x))
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return x;
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if (__isnan(y))
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return y;
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signy = __copysign(one, y);
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signx = __copysign(one, x);
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asm("fmovecr%.x %1, %0" : "=f" (pi) : "i" (0));
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PIo2 = pi / 2;
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PIo4 = pi / 4;
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if (y == zero)
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return signx == one ? y : __copysign(pi, signy);
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if (x == zero)
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return __copysign(PIo2, signy);
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if (__isinf(x))
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{
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if (__isinf(y))
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return __copysign(signx == one ? PIo4 : 3 * PIo4, signy);
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else
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return __copysign(signx == one ? zero : pi, signy);
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}
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if (__isinf(y))
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return __copysign(PIo2, signy);
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y = fabs(y);
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if (x < 0.0)
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/* X is negative. */
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return __copysign(pi - atan(y / -x), signy);
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return __copysign(atan(y / x), signy);
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}
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#else
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#include <sysdeps/generic/atan2.c>
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#endif
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