110 lines
2.7 KiB
C
110 lines
2.7 KiB
C
/*
|
|
* ====================================================
|
|
* 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.
|
|
* ====================================================
|
|
*/
|
|
/*
|
|
FUNCTION
|
|
<<lround>>, <<lroundf>>, <<llround>>, <<llroundf>>--round to integer, to nearest
|
|
INDEX
|
|
lround
|
|
INDEX
|
|
lroundf
|
|
INDEX
|
|
llround
|
|
INDEX
|
|
llroundf
|
|
|
|
ANSI_SYNOPSIS
|
|
#include <math.h>
|
|
long int lround(double <[x]>);
|
|
long int lroundf(float <[x]>);
|
|
long long int llround(double <[x]>);
|
|
long long int llroundf(float <[x]>);
|
|
|
|
DESCRIPTION
|
|
The <<lround>> and <<llround>> functions round their argument to the
|
|
nearest integer value, rounding halfway cases away from zero, regardless
|
|
of the current rounding direction. If the rounded value is outside the
|
|
range of the return type, the numeric result is unspecified (depending
|
|
upon the floating-point implementation, not the library). A range
|
|
error may occur if the magnitude of x is too large.
|
|
|
|
RETURNS
|
|
<[x]> rounded to an integral value as an integer.
|
|
|
|
SEEALSO
|
|
See the <<round>> functions for the return being the same floating-point type
|
|
as the argument. <<lrint>>, <<llrint>>.
|
|
|
|
PORTABILITY
|
|
ANSI C, POSIX
|
|
|
|
*/
|
|
|
|
#include "fdlibm.h"
|
|
|
|
#ifndef _DOUBLE_IS_32BITS
|
|
|
|
#ifdef __STDC__
|
|
long int lround(double x)
|
|
#else
|
|
long int lround(x)
|
|
double x;
|
|
#endif
|
|
{
|
|
__int32_t sign, exponent_less_1023;
|
|
/* Most significant word, least significant word. */
|
|
__uint32_t msw, lsw;
|
|
long int result;
|
|
|
|
EXTRACT_WORDS(msw, lsw, x);
|
|
|
|
/* Extract sign. */
|
|
sign = ((msw & 0x80000000) ? -1 : 1);
|
|
/* Extract exponent field. */
|
|
exponent_less_1023 = ((msw & 0x7ff00000) >> 20) - 1023;
|
|
msw &= 0x000fffff;
|
|
msw |= 0x00100000;
|
|
|
|
if (exponent_less_1023 < 20)
|
|
{
|
|
if (exponent_less_1023 < 0)
|
|
{
|
|
if (exponent_less_1023 < -1)
|
|
return 0;
|
|
else
|
|
return sign;
|
|
}
|
|
else
|
|
{
|
|
msw += 0x80000 >> exponent_less_1023;
|
|
result = msw >> (20 - exponent_less_1023);
|
|
}
|
|
}
|
|
else if (exponent_less_1023 < (8 * sizeof (long int)) - 1)
|
|
{
|
|
if (exponent_less_1023 >= 52)
|
|
result = ((long int) msw << (exponent_less_1023 - 20)) | (lsw << (exponent_less_1023 - 52));
|
|
else
|
|
{
|
|
unsigned int tmp = lsw + (0x80000000 >> (exponent_less_1023 - 20));
|
|
if (tmp < lsw)
|
|
++msw;
|
|
result = ((long int) msw << (exponent_less_1023 - 20)) | (tmp >> (52 - exponent_less_1023));
|
|
}
|
|
}
|
|
else
|
|
/* Result is too large to be represented by a long int. */
|
|
return (long int)x;
|
|
|
|
return sign * result;
|
|
}
|
|
|
|
#endif /* _DOUBLE_IS_32BITS */
|