/* @(#)s_rint.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_rint.c,v 1.8 1995/05/10 20:48:04 jtc Exp $"; #endif /* * rint(x) * Return x rounded to integral value according to the prevailing * rounding mode. * Method: * Using floating addition. * Exception: * Inexact flag raised if x not equal to rint(x). */ #include "math.h" #include "math_private.h" static const double TWO52[2]={ 4.50359962737049600000e+15, /* 0x43300000, 0x00000000 */ -4.50359962737049600000e+15, /* 0xC3300000, 0x00000000 */ }; double rint(double x) { int32_t i0,jj0,sx; u_int32_t i,i1; double w,t; EXTRACT_WORDS(i0,i1,x); sx = (i0>>31)&1; jj0 = ((i0>>20)&0x7ff)-0x3ff; if(jj0<20) { if(jj0<0) { if(((i0&0x7fffffff)|i1)==0) return x; i1 |= (i0&0x0fffff); i0 &= 0xfffe0000; i0 |= ((i1|-i1)>>12)&0x80000; SET_HIGH_WORD(x,i0); w = TWO52[sx]+x; t = w-TWO52[sx]; GET_HIGH_WORD(i0,t); SET_HIGH_WORD(t,(i0&0x7fffffff)|(sx<<31)); return t; } else { i = (0x000fffff)>>jj0; if(((i0&i)|i1)==0) return x; /* x is integral */ i>>=1; if(((i0&i)|i1)!=0) { if(jj0==19) i1 = 0x40000000; else i0 = (i0&(~i))|((0x20000)>>jj0); } } } else if (jj0>51) { if(jj0==0x400) return x+x; /* inf or NaN */ else return x; /* x is integral */ } else { i = ((u_int32_t)(0xffffffff))>>(jj0-20); if((i1&i)==0) return x; /* x is integral */ i>>=1; if((i1&i)!=0) i1 = (i1&(~i))|((0x40000000)>>(jj0-20)); } INSERT_WORDS(x,i0,i1); w = TWO52[sx]+x; return w-TWO52[sx]; }