3a8617a83f
-- Begin comments from J.T. Conklin: The most significant improvement is the addition of "float" versions of the math functions that take float arguments, return floats, and do all operations in floating point. This doesn't help (performance) much on the i386, but they are still nice to have. The float versions were orginally done by Cygnus' Ian Taylor when fdlibm was integrated into the libm we support for embedded systems. I gave Ian a copy of my libm as a starting point since I had already fixed a lot of bugs & problems in Sun's original code. After he was done, I cleaned it up a bit and integrated the changes back into my libm. -- End comments Reviewed by: jkh Submitted by: jtc
84 lines
2.0 KiB
C
84 lines
2.0 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.
|
|
* ====================================================
|
|
*/
|
|
|
|
#ifndef lint
|
|
static char rcsid[] = "$Id: s_modf.c,v 1.6 1994/08/18 23:07:09 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 */
|
|
u_int32_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 (j0>51) { /* no fraction part */
|
|
u_int32_t high;
|
|
*iptr = x*one;
|
|
GET_HIGH_WORD(high,x);
|
|
INSERT_WORDS(x,high&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 */
|
|
u_int32_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;
|
|
}
|
|
}
|
|
}
|