/* @(#)s_floor.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 #if 0 __FBSDID("\$FreeBSD: src/lib/msun/src/s_trunc.c,v 1.1 2004/06/20 09:25:43 das Exp \$"); #endif #if defined(LIBM_SCCS) && !defined(lint) __RCSID("\$NetBSD: s_trunc.c,v 1.3 2008/04/25 22:21:53 christos Exp \$"); #endif /* * trunc(x) * Return x rounded toward 0 to integral value * Method: * Bit twiddling. * Exception: * Inexact flag raised if x not equal to trunc(x). */ #include "math.h" #include "math_private.h" static const double huge = 1.0e300; double trunc(double x) { int32_t i0,i1,jj0; uint32_t i; EXTRACT_WORDS(i0,i1,x); jj0 = ((i0>>20)&0x7ff)-0x3ff; if(jj0<20) { if(jj0<0) { /* raise inexact if x != 0 */ if(huge+x>0.0) {/* |x|<1, so return 0*sign(x) */ i0 &= 0x80000000U; i1 = 0; } } else { i = (0x000fffff)>>jj0; if(((i0&i)|i1)==0) return x; /* x is integral */ if(huge+x>0.0) { /* raise inexact flag */ i0 &= (~i); i1=0; } } } 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 */ if(huge+x>0.0) /* raise inexact flag */ i1 &= (~i); } INSERT_WORDS(x,i0,i1); return x; }