112 lines
2.4 KiB
C
112 lines
2.4 KiB
C
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/* Compute remainder and a congruent to the quotient.
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Copyright (C) 1997-2022 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 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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<https://www.gnu.org/licenses/>. */
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#include <math.h>
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#include <math_private.h>
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#include <libm-alias-ldouble.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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uint32_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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libm_alias_ldouble (__remquo, remquo)
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