mirror of
https://sourceware.org/git/glibc.git
synced 2024-11-30 00:31:08 +00:00
86 lines
2.1 KiB
C
86 lines
2.1 KiB
C
/* @(#)s_modf.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.
|
|
* ====================================================
|
|
*/
|
|
|
|
#if defined(LIBM_SCCS) && !defined(lint)
|
|
static char rcsid[] = "$NetBSD: s_modf.c,v 1.8 1995/05/10 20:47:55 jtc Exp $";
|
|
#endif
|
|
|
|
/*
|
|
* modf(double x, double *iptr)
|
|
* return fraction part of x, and return x's integral part in *iptr.
|
|
* Method:
|
|
* Bit twiddling.
|
|
*
|
|
* Exception:
|
|
* No exception.
|
|
*/
|
|
|
|
#include "math.h"
|
|
#include "math_private.h"
|
|
|
|
#ifdef __STDC__
|
|
static const double one = 1.0;
|
|
#else
|
|
static double one = 1.0;
|
|
#endif
|
|
|
|
#ifdef __STDC__
|
|
double __modf(double x, double *iptr)
|
|
#else
|
|
double __modf(x, iptr)
|
|
double x,*iptr;
|
|
#endif
|
|
{
|
|
int32_t i0,i1,j0;
|
|
u_int32_t i;
|
|
EXTRACT_WORDS(i0,i1,x);
|
|
j0 = ((i0>>20)&0x7ff)-0x3ff; /* exponent of x */
|
|
if(j0<20) { /* integer part in high x */
|
|
if(j0<0) { /* |x|<1 */
|
|
INSERT_WORDS(*iptr,i0&0x80000000,0); /* *iptr = +-0 */
|
|
return x;
|
|
} else {
|
|
i = (0x000fffff)>>j0;
|
|
if(((i0&i)|i1)==0) { /* x is integral */
|
|
*iptr = x;
|
|
INSERT_WORDS(x,i0&0x80000000,0); /* return +-0 */
|
|
return x;
|
|
} else {
|
|
INSERT_WORDS(*iptr,i0&(~i),0);
|
|
return x - *iptr;
|
|
}
|
|
}
|
|
} else if (j0>51) { /* no fraction part */
|
|
*iptr = x*one;
|
|
/* We must handle NaNs separately. */
|
|
if (j0 == 0x400 && ((i0 & 0xfffff) | i1))
|
|
return x*one;
|
|
INSERT_WORDS(x,i0&0x80000000,0); /* return +-0 */
|
|
return x;
|
|
} else { /* fraction part in low x */
|
|
i = ((u_int32_t)(0xffffffff))>>(j0-20);
|
|
if((i1&i)==0) { /* x is integral */
|
|
*iptr = x;
|
|
INSERT_WORDS(x,i0&0x80000000,0); /* return +-0 */
|
|
return x;
|
|
} else {
|
|
INSERT_WORDS(*iptr,i0,i1&(~i));
|
|
return x - *iptr;
|
|
}
|
|
}
|
|
}
|
|
weak_alias (__modf, modf)
|
|
#ifdef NO_LONG_DOUBLE
|
|
strong_alias (__modf, __modfl)
|
|
weak_alias (__modf, modfl)
|
|
#endif
|