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/* Round to integer type. ldbl-128ibm version.
Copyright (C) 2016-2024 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 <errno.h>
#include <fenv.h>
#include <math.h>
#include <math_private.h>
#include <stdbool.h>
#include <stdint.h>
#define BIAS 0x3ff
#define MANT_DIG 53
#if UNSIGNED
# define RET_TYPE uintmax_t
#else
# define RET_TYPE intmax_t
#endif
#include <fromfp.h>
RET_TYPE
FUNC (long double x, int round, unsigned int width)
{
double hi, lo;
if (width > INTMAX_WIDTH)
width = INTMAX_WIDTH;
uint64_t hx, lx;
ldbl_unpack (x, &hi, &lo);
EXTRACT_WORDS64 (hx, hi);
EXTRACT_WORDS64 (lx, lo);
bool negative = (hx & 0x8000000000000000ULL) != 0;
bool lo_negative = (lx & 0x8000000000000000ULL) != 0;
if (width == 0)
return fromfp_domain_error (negative, width);
hx &= 0x7fffffffffffffffULL;
lx &= 0x7fffffffffffffffULL;
if ((hx | lx) == 0)
return 0;
int hi_exponent = hx >> (MANT_DIG - 1);
hi_exponent -= BIAS;
int exponent = hi_exponent;
hx &= ((1ULL << (MANT_DIG - 1)) - 1);
if (hx == 0 && lx != 0 && lo_negative != negative)
exponent--;
int max_exponent = fromfp_max_exponent (negative, width);
if (exponent > max_exponent)
return fromfp_domain_error (negative, width);
int lo_exponent = lx >> (MANT_DIG - 1);
lo_exponent -= BIAS;
/* Convert the high part to integer. */
hx |= 1ULL << (MANT_DIG - 1);
uintmax_t uret;
bool half_bit, more_bits;
if (hi_exponent >= MANT_DIG - 1)
{
uret = hx;
uret <<= hi_exponent - (MANT_DIG - 1);
half_bit = false;
more_bits = false;
}
else if (hi_exponent >= -1)
{
uint64_t h = 1ULL << (MANT_DIG - 2 - hi_exponent);
half_bit = (hx & h) != 0;
more_bits = (hx & (h - 1)) != 0;
uret = hx >> (MANT_DIG - 1 - hi_exponent);
}
else
{
uret = 0;
half_bit = false;
more_bits = true;
}
/* Likewise, the low part. */
if (lx != 0)
{
uintmax_t lo_uret;
bool lo_half_bit, lo_more_bits;
lx &= ((1ULL << (MANT_DIG - 1)) - 1);
lx |= 1ULL << (MANT_DIG - 1);
/* The high part exponent is at most 64, so the low part
exponent is at most 11. */
if (lo_exponent >= -1)
{
uint64_t h = 1ULL << (MANT_DIG - 2 - lo_exponent);
lo_half_bit = (lx & h) != 0;
lo_more_bits = (lx & (h - 1)) != 0;
lo_uret = lx >> (MANT_DIG - 1 - lo_exponent);
}
else
{
lo_uret = 0;
lo_half_bit = false;
lo_more_bits = true;
}
if (lo_negative == negative)
{
uret += lo_uret;
half_bit |= lo_half_bit;
more_bits |= lo_more_bits;
}
else
{
uret -= lo_uret;
if (lo_half_bit)
{
uret--;
half_bit = true;
}
if (lo_more_bits && !more_bits)
{
if (half_bit)
{
half_bit = false;
more_bits = true;
}
else
{
uret--;
half_bit = true;
more_bits = true;
}
}
}
}
return fromfp_round_and_return (negative, uret, half_bit, more_bits, round,
exponent, max_exponent, width);
}
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