newlib-cygwin/newlib/libm/common/sf_rint.c

/* sf_rint.c -- float version of s_rint.c.
 * Conversion to float by Ian Lance Taylor, Cygnus Support, ian@cygnus.com.
 */

/*
 * ====================================================
 * 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 "fdlibm.h"

#ifdef __STDC__
static const float
#else
static float 
#endif
TWO23[2]={
  8.3886080000e+06, /* 0x4b000000 */
 -8.3886080000e+06, /* 0xcb000000 */
};

#ifdef __STDC__
	float rintf(float x)
#else
	float rintf(x)
	float x;
#endif
{
	__int32_t i0,j0,sx;
	__uint32_t i,i1,ix;
	float t;
	volatile float w;
	GET_FLOAT_WORD(i0,x);
	sx = (i0>>31)&1;
	ix = (i0&0x7fffffff);
	j0 = (ix>>23)-0x7f;
	if(j0<23) {
	    if(FLT_UWORD_IS_ZERO(ix))
	        return x;
	    if(j0<0) {
		i1 = (i0&0x07fffff);
		i0 &= 0xfff00000;
		i0 |= ((i1|-i1)>>9)&0x400000;
		SET_FLOAT_WORD(x,i0);
	        w = TWO23[sx]+x;
	        t =  w-TWO23[sx];
		GET_FLOAT_WORD(i0,t);
		SET_FLOAT_WORD(t,(i0&0x7fffffff)|(sx<<31));
	        return t;
	    } else {
		i = (0x007fffff)>>j0;
		if((i0&i)==0) return x; /* x is integral */
		i>>=1;
		if((i0&i)!=0) i0 = (i0&(~i))|((0x100000)>>j0);
	    }
	} else {
	    if(!FLT_UWORD_IS_FINITE(ix)) return x+x; /* inf or NaN */
	    else
	      return x;		/* x is integral */
	}
	SET_FLOAT_WORD(x,i0);
	w = TWO23[sx]+x;
	return w-TWO23[sx];
}

#ifdef _DOUBLE_IS_32BITS

#ifdef __STDC__
	double rint(double x)
#else
	double rint(x)
	double x;
#endif
{
	return (double) rintf((float) x);
}

#endif /* defined(_DOUBLE_IS_32BITS) */