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/* Test whether long double value is canonical. ldbl-128ibm version.
Copyright (C) 2016-2025 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 <stdint.h>
int
__iscanonicall (long double x)
{
double xhi, xlo;
uint64_t hx, lx;
ldbl_unpack (x, &xhi, &xlo);
EXTRACT_WORDS64 (hx, xhi);
EXTRACT_WORDS64 (lx, xlo);
int64_t ix = hx & 0x7fffffffffffffffULL;
int64_t iy = lx & 0x7fffffffffffffffULL;
int hexp = (ix & 0x7ff0000000000000LL) >> 52;
int lexp = (iy & 0x7ff0000000000000LL) >> 52;
if (iy == 0)
/* Low part 0 is always OK. */
return 1;
if (hexp == 0x7ff)
/* If a NaN, the low part does not matter. If an infinity, the
low part must be 0, in which case we have already returned. */
return ix != 0x7ff0000000000000LL;
/* The high part is finite and the low part is nonzero. There must
be sufficient difference between the exponents. */
bool low_p2;
if (lexp == 0)
{
/* Adjust the exponent for subnormal low part. */
lexp = 12 - __builtin_clzll (iy);
low_p2 = iy == (1LL << (51 + lexp));
}
else
low_p2 = (iy & 0xfffffffffffffLL) == 0;
int expdiff = hexp - lexp;
return expdiff > 53 || (expdiff == 53 && low_p2 && (ix & 1) == 0);
}
libm_hidden_def (__iscanonicall)
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