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/* Compute remainder and a congruent to the quotient.
Copyright (C) 1997-2024 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library; if not, see
<https://www.gnu.org/licenses/>. */
#include <math.h>
#include <math_private.h>
#include <libm-alias-double.h>
#include <stdint.h>
static const double zero = 0.0;
double
__remquo (double x, double y, int *quo)
{
int64_t hx, hy;
uint64_t sx, qs;
int cquo;
EXTRACT_WORDS64 (hx, x);
EXTRACT_WORDS64 (hy, y);
sx = hx & UINT64_C(0x8000000000000000);
qs = sx ^ (hy & UINT64_C(0x8000000000000000));
hy &= UINT64_C(0x7fffffffffffffff);
hx &= UINT64_C(0x7fffffffffffffff);
/* Purge off exception values. */
if (__glibc_unlikely (hy == 0))
return (x * y) / (x * y); /* y = 0 */
if (__builtin_expect (hx >= UINT64_C(0x7ff0000000000000) /* x not finite */
|| hy > UINT64_C(0x7ff0000000000000), 0))/* y is NaN */
return (x * y) / (x * y);
if (hy <= UINT64_C(0x7fbfffffffffffff))
x = __ieee754_fmod (x, 8 * y); /* now x < 8y */
if (__glibc_unlikely (hx == hy))
{
*quo = qs ? -1 : 1;
return zero * x;
}
x = fabs (x);
INSERT_WORDS64 (y, hy);
cquo = 0;
if (hy <= UINT64_C(0x7fcfffffffffffff) && x >= 4 * y)
{
x -= 4 * y;
cquo += 4;
}
if (hy <= UINT64_C(0x7fdfffffffffffff) && x >= 2 * y)
{
x -= 2 * y;
cquo += 2;
}
if (hy < UINT64_C(0x0020000000000000))
{
if (x + x > y)
{
x -= y;
++cquo;
if (x + x >= y)
{
x -= y;
++cquo;
}
}
}
else
{
double y_half = 0.5 * y;
if (x > y_half)
{
x -= y;
++cquo;
if (x >= y_half)
{
x -= y;
++cquo;
}
}
}
*quo = qs ? -cquo : cquo;
/* Ensure correct sign of zero result in round-downward mode. */
if (x == 0.0)
x = 0.0;
if (sx)
x = -x;
return x;
}
libm_alias_double (__remquo, remquo)
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