mirror of
https://gitlab.com/sortix/sortix.git
synced 2023-02-13 20:55:38 -05:00
5980be9b3c
This work is based in part on code from NetBSD libm, libc and kernel. The library is partly public domain and partly BSD-style licensed.
78 lines
2 KiB
C
78 lines
2 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.
|
|
* ====================================================
|
|
*/
|
|
|
|
#include <sys/cdefs.h>
|
|
#if defined(LIBM_SCCS) && !defined(lint)
|
|
__RCSID("$NetBSD: s_modf.c,v 1.14 2010/01/27 14:07:41 drochner 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"
|
|
|
|
static const double one = 1.0;
|
|
|
|
double
|
|
modf(double x, double *iptr)
|
|
{
|
|
int32_t i0,i1,jj0;
|
|
uint32_t i;
|
|
EXTRACT_WORDS(i0,i1,x);
|
|
jj0 = (((uint32_t)i0>>20)&0x7ff)-0x3ff; /* exponent of x */
|
|
if(jj0<20) { /* integer part in high x */
|
|
if(jj0<0) { /* |x|<1 */
|
|
INSERT_WORDS(*iptr,i0&0x80000000,0); /* *iptr = +-0 */
|
|
return x;
|
|
} else {
|
|
i = (0x000fffff)>>jj0;
|
|
if(((i0&i)|i1)==0) { /* x is integral */
|
|
uint32_t high;
|
|
*iptr = x;
|
|
GET_HIGH_WORD(high,x);
|
|
INSERT_WORDS(x,high&0x80000000,0); /* return +-0 */
|
|
return x;
|
|
} else {
|
|
INSERT_WORDS(*iptr,i0&(~i),0);
|
|
return x - *iptr;
|
|
}
|
|
}
|
|
} else if (jj0>51) { /* no fraction part */
|
|
uint32_t high;
|
|
*iptr = x*one;
|
|
if (jj0 == 0x400) /* +-inf or NaN */
|
|
return 0.0 / x; /* +-0 or NaN */
|
|
GET_HIGH_WORD(high,x);
|
|
INSERT_WORDS(x,high&0x80000000,0); /* return +-0 */
|
|
return x;
|
|
} else { /* fraction part in low x */
|
|
i = ((uint32_t)(0xffffffff))>>(jj0-20);
|
|
if((i1&i)==0) { /* x is integral */
|
|
uint32_t high;
|
|
*iptr = x;
|
|
GET_HIGH_WORD(high,x);
|
|
INSERT_WORDS(x,high&0x80000000,0); /* return +-0 */
|
|
return x;
|
|
} else {
|
|
INSERT_WORDS(*iptr,i0,i1&(~i));
|
|
return x - *iptr;
|
|
}
|
|
}
|
|
}
|