mirror of
https://sourceware.org/git/glibc.git
synced 2024-11-30 00:31:08 +00:00
61 lines
2.0 KiB
C
61 lines
2.0 KiB
C
/* Test whether long double value is canonical. ldbl-128ibm version.
|
|
Copyright (C) 2016-2020 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)
|