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/* @(#)sf_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.
* ====================================================
*/
/*
* lrintf(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 lrintf(x).
*/
#include "fdlibm.h"
#ifdef __STDC__
static const float
#else
static float
#endif
/* Adding a float, x, to 2^23 will cause the result to be rounded based on
the fractional part of x, according to the implementation's current rounding
mode. 2^23 is the smallest float that can be represented using all 23 significant
digits. */
TWO23[2]={
8.3886080000e+06, /* 0x4b000000 */
-8.3886080000e+06, /* 0xcb000000 */
};
#ifdef __STDC__
long int lrintf(float x)
#else
long int lrintf(x)
float x;
#endif
{
__int32_t j0,sx;
__uint32_t i0;
float t;
volatile float w;
long int result;
GET_FLOAT_WORD(i0,x);
/* Extract sign bit. */
sx = (i0 >> 31);
/* Extract exponent field. */
j0 = ((i0 & 0x7f800000) >> 23) - 127;
if (j0 < (int)(sizeof (long int) * 8) - 1)
{
if (j0 < -1)
return 0;
else if (j0 >= 23)
result = (long int) ((i0 & 0x7fffff) | 0x800000) << (j0 - 23);
else
{
w = TWO23[sx] + x;
t = w - TWO23[sx];
GET_FLOAT_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 >> 23) & 0xff) - 0x7f;
i0 &= 0x7fffff;
i0 |= 0x800000;
result = i0 >> (23 - j0);
}
}
else
{
return (long int) x;
}
return sx ? -result : result;
}
#ifdef _DOUBLE_IS_32BITS
#ifdef __STDC__
long int lrint(double x)
#else
long int lrint(x)
double x;
#endif
{
return (double) lrintf((float) x);
}
#endif /* defined(_DOUBLE_IS_32BITS) */
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