|
Packit Service |
82fcde |
/* Round to nearest integer value, rounding halfway cases to even.
|
|
Packit Service |
82fcde |
dbl-64 version.
|
|
Packit Service |
82fcde |
Copyright (C) 2016-2018 Free Software Foundation, Inc.
|
|
Packit Service |
82fcde |
This file is part of the GNU C Library.
|
|
Packit Service |
82fcde |
|
|
Packit Service |
82fcde |
The GNU C Library is free software; you can redistribute it and/or
|
|
Packit Service |
82fcde |
modify it under the terms of the GNU Lesser General Public
|
|
Packit Service |
82fcde |
License as published by the Free Software Foundation; either
|
|
Packit Service |
82fcde |
version 2.1 of the License, or (at your option) any later version.
|
|
Packit Service |
82fcde |
|
|
Packit Service |
82fcde |
The GNU C Library is distributed in the hope that it will be useful,
|
|
Packit Service |
82fcde |
but WITHOUT ANY WARRANTY; without even the implied warranty of
|
|
Packit Service |
82fcde |
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
|
|
Packit Service |
82fcde |
Lesser General Public License for more details.
|
|
Packit Service |
82fcde |
|
|
Packit Service |
82fcde |
You should have received a copy of the GNU Lesser General Public
|
|
Packit Service |
82fcde |
License along with the GNU C Library; if not, see
|
|
Packit Service |
82fcde |
<http://www.gnu.org/licenses/>. */
|
|
Packit Service |
82fcde |
|
|
Packit Service |
82fcde |
#include <math.h>
|
|
Packit Service |
82fcde |
#include <math_private.h>
|
|
Packit Service |
82fcde |
#include <libm-alias-double.h>
|
|
Packit Service |
82fcde |
#include <stdint.h>
|
|
Packit Service |
82fcde |
|
|
Packit Service |
82fcde |
#define BIAS 0x3ff
|
|
Packit Service |
82fcde |
#define MANT_DIG 53
|
|
Packit Service |
82fcde |
#define MAX_EXP (2 * BIAS + 1)
|
|
Packit Service |
82fcde |
|
|
Packit Service |
82fcde |
double
|
|
Packit Service |
82fcde |
__roundeven (double x)
|
|
Packit Service |
82fcde |
{
|
|
Packit Service |
82fcde |
uint32_t hx, lx, uhx;
|
|
Packit Service |
82fcde |
EXTRACT_WORDS (hx, lx, x);
|
|
Packit Service |
82fcde |
uhx = hx & 0x7fffffff;
|
|
Packit Service |
82fcde |
int exponent = uhx >> (MANT_DIG - 1 - 32);
|
|
Packit Service |
82fcde |
if (exponent >= BIAS + MANT_DIG - 1)
|
|
Packit Service |
82fcde |
{
|
|
Packit Service |
82fcde |
/* Integer, infinity or NaN. */
|
|
Packit Service |
82fcde |
if (exponent == MAX_EXP)
|
|
Packit Service |
82fcde |
/* Infinity or NaN; quiet signaling NaNs. */
|
|
Packit Service |
82fcde |
return x + x;
|
|
Packit Service |
82fcde |
else
|
|
Packit Service |
82fcde |
return x;
|
|
Packit Service |
82fcde |
}
|
|
Packit Service |
82fcde |
else if (exponent >= BIAS + MANT_DIG - 32)
|
|
Packit Service |
82fcde |
{
|
|
Packit Service |
82fcde |
/* Not necessarily an integer; integer bit is in low word.
|
|
Packit Service |
82fcde |
Locate the bits with exponents 0 and -1. */
|
|
Packit Service |
82fcde |
int int_pos = (BIAS + MANT_DIG - 1) - exponent;
|
|
Packit Service |
82fcde |
int half_pos = int_pos - 1;
|
|
Packit Service |
82fcde |
uint32_t half_bit = 1U << half_pos;
|
|
Packit Service |
82fcde |
uint32_t int_bit = 1U << int_pos;
|
|
Packit Service |
82fcde |
if ((lx & (int_bit | (half_bit - 1))) != 0)
|
|
Packit Service |
82fcde |
{
|
|
Packit Service |
82fcde |
/* Carry into the exponent works correctly. No need to test
|
|
Packit Service |
82fcde |
whether HALF_BIT is set. */
|
|
Packit Service |
82fcde |
lx += half_bit;
|
|
Packit Service |
82fcde |
hx += lx < half_bit;
|
|
Packit Service |
82fcde |
}
|
|
Packit Service |
82fcde |
lx &= ~(int_bit - 1);
|
|
Packit Service |
82fcde |
}
|
|
Packit Service |
82fcde |
else if (exponent == BIAS + MANT_DIG - 33)
|
|
Packit Service |
82fcde |
{
|
|
Packit Service |
82fcde |
/* Not necessarily an integer; integer bit is bottom of high
|
|
Packit Service |
82fcde |
word, half bit is top of low word. */
|
|
Packit Service |
82fcde |
if (((hx & 1) | (lx & 0x7fffffff)) != 0)
|
|
Packit Service |
82fcde |
{
|
|
Packit Service |
82fcde |
lx += 0x80000000;
|
|
Packit Service |
82fcde |
hx += lx < 0x80000000;
|
|
Packit Service |
82fcde |
}
|
|
Packit Service |
82fcde |
lx = 0;
|
|
Packit Service |
82fcde |
}
|
|
Packit Service |
82fcde |
else if (exponent >= BIAS)
|
|
Packit Service |
82fcde |
{
|
|
Packit Service |
82fcde |
/* At least 1; not necessarily an integer, integer bit and half
|
|
Packit Service |
82fcde |
bit are in the high word. Locate the bits with exponents 0
|
|
Packit Service |
82fcde |
and -1 (when the unbiased exponent is 0, the bit with
|
|
Packit Service |
82fcde |
exponent 0 is implicit, but as the bias is odd it is OK to
|
|
Packit Service |
82fcde |
take it from the low bit of the exponent). */
|
|
Packit Service |
82fcde |
int int_pos = (BIAS + MANT_DIG - 33) - exponent;
|
|
Packit Service |
82fcde |
int half_pos = int_pos - 1;
|
|
Packit Service |
82fcde |
uint32_t half_bit = 1U << half_pos;
|
|
Packit Service |
82fcde |
uint32_t int_bit = 1U << int_pos;
|
|
Packit Service |
82fcde |
if (((hx & (int_bit | (half_bit - 1))) | lx) != 0)
|
|
Packit Service |
82fcde |
hx += half_bit;
|
|
Packit Service |
82fcde |
hx &= ~(int_bit - 1);
|
|
Packit Service |
82fcde |
lx = 0;
|
|
Packit Service |
82fcde |
}
|
|
Packit Service |
82fcde |
else if (exponent == BIAS - 1 && (uhx > 0x3fe00000 || lx != 0))
|
|
Packit Service |
82fcde |
{
|
|
Packit Service |
82fcde |
/* Interval (0.5, 1). */
|
|
Packit Service |
82fcde |
hx = (hx & 0x80000000) | 0x3ff00000;
|
|
Packit Service |
82fcde |
lx = 0;
|
|
Packit Service |
82fcde |
}
|
|
Packit Service |
82fcde |
else
|
|
Packit Service |
82fcde |
{
|
|
Packit Service |
82fcde |
/* Rounds to 0. */
|
|
Packit Service |
82fcde |
hx &= 0x80000000;
|
|
Packit Service |
82fcde |
lx = 0;
|
|
Packit Service |
82fcde |
}
|
|
Packit Service |
82fcde |
INSERT_WORDS (x, hx, lx);
|
|
Packit Service |
82fcde |
return x;
|
|
Packit Service |
82fcde |
}
|
|
Packit Service |
82fcde |
hidden_def (__roundeven)
|
|
Packit Service |
82fcde |
libm_alias_double (__roundeven, roundeven)
|