mirror of
https://github.com/autc04/Retro68.git
synced 2024-12-03 10:49:58 +00:00
116 lines
2.6 KiB
C
116 lines
2.6 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
|
|
<<round>>, <<roundf>>---round to integer, to nearest
|
|
INDEX
|
|
round
|
|
INDEX
|
|
roundf
|
|
|
|
SYNOPSIS
|
|
#include <math.h>
|
|
double round(double <[x]>);
|
|
float roundf(float <[x]>);
|
|
|
|
DESCRIPTION
|
|
The <<round>> functions round their argument to the nearest integer
|
|
value in floating-point format, rounding halfway cases away from zero,
|
|
regardless of the current rounding direction. (While the "inexact"
|
|
floating-point exception behavior is unspecified by the C standard, the
|
|
<<round>> functions are written so that "inexact" is not raised if the
|
|
result does not equal the argument, which behavior is as recommended by
|
|
IEEE 754 for its related functions.)
|
|
|
|
RETURNS
|
|
<[x]> rounded to an integral value.
|
|
|
|
PORTABILITY
|
|
ANSI C, POSIX
|
|
|
|
SEEALSO
|
|
<<nearbyint>>, <<rint>>
|
|
|
|
*/
|
|
|
|
#include "fdlibm.h"
|
|
|
|
#ifndef _DOUBLE_IS_32BITS
|
|
|
|
#ifdef __STDC__
|
|
double round(double x)
|
|
#else
|
|
double round(x)
|
|
double x;
|
|
#endif
|
|
{
|
|
/* Most significant word, least significant word. */
|
|
__int32_t msw, exponent_less_1023;
|
|
__uint32_t lsw;
|
|
|
|
EXTRACT_WORDS(msw, lsw, x);
|
|
|
|
/* Extract exponent field. */
|
|
exponent_less_1023 = ((msw & 0x7ff00000) >> 20) - 1023;
|
|
|
|
if (exponent_less_1023 < 20)
|
|
{
|
|
if (exponent_less_1023 < 0)
|
|
{
|
|
msw &= 0x80000000;
|
|
if (exponent_less_1023 == -1)
|
|
/* Result is +1.0 or -1.0. */
|
|
msw |= (1023 << 20);
|
|
lsw = 0;
|
|
}
|
|
else
|
|
{
|
|
__uint32_t exponent_mask = 0x000fffff >> exponent_less_1023;
|
|
if ((msw & exponent_mask) == 0 && lsw == 0)
|
|
/* x in an integral value. */
|
|
return x;
|
|
|
|
msw += 0x00080000 >> exponent_less_1023;
|
|
msw &= ~exponent_mask;
|
|
lsw = 0;
|
|
}
|
|
}
|
|
else if (exponent_less_1023 > 51)
|
|
{
|
|
if (exponent_less_1023 == 1024)
|
|
/* x is NaN or infinite. */
|
|
return x + x;
|
|
else
|
|
return x;
|
|
}
|
|
else
|
|
{
|
|
__uint32_t exponent_mask = 0xffffffff >> (exponent_less_1023 - 20);
|
|
__uint32_t tmp;
|
|
|
|
if ((lsw & exponent_mask) == 0)
|
|
/* x is an integral value. */
|
|
return x;
|
|
|
|
tmp = lsw + (1 << (51 - exponent_less_1023));
|
|
if (tmp < lsw)
|
|
msw += 1;
|
|
lsw = tmp;
|
|
|
|
lsw &= ~exponent_mask;
|
|
}
|
|
INSERT_WORDS(x, msw, lsw);
|
|
|
|
return x;
|
|
}
|
|
|
|
#endif /* _DOUBLE_IS_32BITS */
|