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115 lines
2.5 KiB
C
115 lines
2.5 KiB
C
/* Compute remainder and a congruent to the quotient.
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Copyright (C) 1997-2015 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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Contributed by Ulrich Drepper <drepper@cygnus.com>, 1997 and
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Jakub Jelinek <jj@ultra.linux.cz>, 1999.
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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 <math.h>
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#include <math_private.h>
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#include <math_ldbl_opt.h>
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static const long double zero = 0.0;
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long double
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__remquol (long double x, long double y, int *quo)
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{
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int64_t hx,hy;
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u_int64_t sx,lx,ly,qs;
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int cquo;
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double xhi, xlo, yhi, ylo;
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ldbl_unpack (x, &xhi, &xlo);
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EXTRACT_WORDS64 (hx, xhi);
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EXTRACT_WORDS64 (lx, xlo);
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ldbl_unpack (y, &yhi, &ylo);
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EXTRACT_WORDS64 (hy, yhi);
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EXTRACT_WORDS64 (ly, ylo);
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sx = hx & 0x8000000000000000ULL;
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qs = sx ^ (hy & 0x8000000000000000ULL);
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hy &= 0x7fffffffffffffffLL;
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hx &= 0x7fffffffffffffffLL;
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/* Purge off exception values. */
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if (hy == 0)
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return (x * y) / (x * y); /* y = 0 */
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if ((hx >= 0x7ff0000000000000LL) /* x not finite */
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|| (hy > 0x7ff0000000000000LL)) /* y is NaN */
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return (x * y) / (x * y);
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if (hy <= 0x7fbfffffffffffffLL)
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x = __ieee754_fmodl (x, 8 * y); /* now x < 8y */
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if (((hx - hy) | (lx - ly)) == 0)
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{
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*quo = qs ? -1 : 1;
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return zero * x;
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}
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x = fabsl (x);
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y = fabsl (y);
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cquo = 0;
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if (x >= 4 * y)
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{
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x -= 4 * y;
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cquo += 4;
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}
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if (x >= 2 * y)
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{
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x -= 2 * y;
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cquo += 2;
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}
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if (hy < 0x0020000000000000LL)
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{
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if (x + x > y)
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{
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x -= y;
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++cquo;
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if (x + x >= y)
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{
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x -= y;
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++cquo;
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}
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}
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}
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else
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{
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long double y_half = 0.5L * y;
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if (x > y_half)
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{
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x -= y;
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++cquo;
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if (x >= y_half)
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{
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x -= y;
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++cquo;
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}
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}
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}
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*quo = qs ? -cquo : cquo;
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if (sx)
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x = -x;
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return x;
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}
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long_double_symbol (libm, __remquol, remquol);
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