67 lines
1.6 KiB
C
67 lines
1.6 KiB
C
/* @(#)s_floor.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.
|
|
* ====================================================
|
|
*/
|
|
|
|
#include <sys/cdefs.h>
|
|
#if 0
|
|
__FBSDID("$FreeBSD: src/lib/msun/src/s_trunc.c,v 1.1 2004/06/20 09:25:43 das Exp $");
|
|
#endif
|
|
#if defined(LIBM_SCCS) && !defined(lint)
|
|
__RCSID("$NetBSD: s_trunc.c,v 1.3 2008/04/25 22:21:53 christos Exp $");
|
|
#endif
|
|
|
|
/*
|
|
* trunc(x)
|
|
* Return x rounded toward 0 to integral value
|
|
* Method:
|
|
* Bit twiddling.
|
|
* Exception:
|
|
* Inexact flag raised if x not equal to trunc(x).
|
|
*/
|
|
|
|
#include "math.h"
|
|
#include "math_private.h"
|
|
|
|
static const double huge = 1.0e300;
|
|
|
|
double
|
|
trunc(double x)
|
|
{
|
|
int32_t i0,i1,jj0;
|
|
uint32_t i;
|
|
EXTRACT_WORDS(i0,i1,x);
|
|
jj0 = ((i0>>20)&0x7ff)-0x3ff;
|
|
if(jj0<20) {
|
|
if(jj0<0) { /* raise inexact if x != 0 */
|
|
if(huge+x>0.0) {/* |x|<1, so return 0*sign(x) */
|
|
i0 &= 0x80000000U;
|
|
i1 = 0;
|
|
}
|
|
} else {
|
|
i = (0x000fffff)>>jj0;
|
|
if(((i0&i)|i1)==0) return x; /* x is integral */
|
|
if(huge+x>0.0) { /* raise inexact flag */
|
|
i0 &= (~i); i1=0;
|
|
}
|
|
}
|
|
} else if (jj0>51) {
|
|
if(jj0==0x400) return x+x; /* inf or NaN */
|
|
else return x; /* x is integral */
|
|
} else {
|
|
i = ((uint32_t)(0xffffffff))>>(jj0-20);
|
|
if((i1&i)==0) return x; /* x is integral */
|
|
if(huge+x>0.0) /* raise inexact flag */
|
|
i1 &= (~i);
|
|
}
|
|
INSERT_WORDS(x,i0,i1);
|
|
return x;
|
|
}
|