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3ce2232efb
ldbl-96 remquol wrongly handles the case where the first argument is finite and the second infinite, because the check for the second argument being a NaN fails to disregard the explicit high mantissa bit and so wrongly interprets an infinity as being a NaN. This patch fixes this by masking off that bit, and improves test coverage for both remainder and remquo (various cases were missing tests, or, as in the case of the bug, were tested only for one of the two functions). Tested for x86_64 and x86. [BZ #18244] * sysdeps/ieee754/ldbl-96/s_remquol.c (__remquol): Ignore explicit high mantissa bit when testing whether P is a NaN. * math/libm-test.inc (remainder_test_data): Add more tests. (remquo_test_data): Likewise.
112 lines
2.4 KiB
C
112 lines
2.4 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.
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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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static const long double zero = 0.0;
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long double
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__remquol (long double x, long double p, int *quo)
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{
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int32_t ex,ep,hx,hp;
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u_int32_t sx,lx,lp;
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int cquo,qs;
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GET_LDOUBLE_WORDS (ex, hx, lx, x);
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GET_LDOUBLE_WORDS (ep, hp, lp, p);
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sx = ex & 0x8000;
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qs = (sx ^ (ep & 0x8000)) >> 15;
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ep &= 0x7fff;
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ex &= 0x7fff;
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/* Purge off exception values. */
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if ((ep | hp | lp) == 0)
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return (x * p) / (x * p); /* p = 0 */
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if ((ex == 0x7fff) /* x not finite */
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|| ((ep == 0x7fff) /* p is NaN */
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&& (((hp & 0x7fffffff) | lp) != 0)))
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return (x * p) / (x * p);
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if (ep <= 0x7ffb)
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x = __ieee754_fmodl (x, 8 * p); /* now x < 8p */
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if (((ex - ep) | (hx - hp) | (lx - lp)) == 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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p = fabsl (p);
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cquo = 0;
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if (ep <= 0x7ffc && x >= 4 * p)
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{
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x -= 4 * p;
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cquo += 4;
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}
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if (ep <= 0x7ffd && x >= 2 * p)
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{
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x -= 2 * p;
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cquo += 2;
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}
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if (ep < 0x0002)
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{
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if (x + x > p)
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{
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x -= p;
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++cquo;
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if (x + x >= p)
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{
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x -= p;
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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 p_half = 0.5 * p;
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if (x > p_half)
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{
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x -= p;
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++cquo;
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if (x >= p_half)
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{
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x -= p;
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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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/* Ensure correct sign of zero result in round-downward mode. */
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if (x == 0.0L)
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x = 0.0L;
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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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weak_alias (__remquol, remquol)
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