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/* @(#)s_lrint.c 5.1 93/09/24 */
/*
* ====================================================
* Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
*
* Developed at SunPro, a Sun Microsystems, Inc. business.
* Permission to use, copy, modify, and distribute this
* software is freely granted, provided that this notice
* is preserved.
* ====================================================
*/
/*
* lrint(x)
* Return x rounded to integral value according to the prevailing
* rounding mode.
* Method:
* Using floating addition.
* Exception:
* Inexact flag raised if x not equal to lrint(x).
*/
#include "fdlibm.h"
#ifndef _DOUBLE_IS_32BITS
#ifdef __STDC__
static const double
#else
static double
#endif
/* Adding a double, x, to 2^52 will cause the result to be rounded based on
the fractional part of x, according to the implementation's current rounding
mode. 2^52 is the smallest double that can be represented using all 52 significant
digits. */
TWO52[2]={
4.50359962737049600000e+15, /* 0x43300000, 0x00000000 */
-4.50359962737049600000e+15, /* 0xC3300000, 0x00000000 */
};
#ifdef __STDC__
long int lrint(double x)
#else
long int lrint(x)
double x;
#endif
{
__int32_t i0,j0,sx;
__uint32_t i1;
double t;
volatile double w;
long int result;
EXTRACT_WORDS(i0,i1,x);
/* Extract sign bit. */
sx = (i0>>31)&1;
/* Extract exponent field. */
j0 = ((i0 & 0x7ff00000) >> 20) - 1023;
if(j0 < 20)
{
if(j0 < -1)
return 0;
else
{
w = TWO52[sx] + x;
t = w - TWO52[sx];
GET_HIGH_WORD(i0, t);
/* Detect the all-zeros representation of plus and
minus zero, which fails the calculation below. */
if ((i0 & ~(1 << 31)) == 0)
return 0;
j0 = ((i0 & 0x7ff00000) >> 20) - 1023;
i0 &= 0x000fffff;
i0 |= 0x00100000;
result = i0 >> (20 - j0);
}
}
else if (j0 < (int)(8 * sizeof (long int)) - 1)
{
if (j0 >= 52)
result = ((long int) ((i0 & 0x000fffff) | 0x0010000) << (j0 - 20)) |
(i1 << (j0 - 52));
else
{
w = TWO52[sx] + x;
t = w - TWO52[sx];
EXTRACT_WORDS (i0, i1, t);
j0 = ((i0 & 0x7ff00000) >> 20) - 1023;
i0 &= 0x000fffff;
i0 |= 0x00100000;
result = ((long int) i0 << (j0 - 20)) | (i1 >> (52 - j0));
}
}
else
{
return (long int) x;
}
return sx ? -result : result;
}
#endif /* _DOUBLE_IS_32BITS */
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