/* @(#)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 defined(LIBM_SCCS) && !defined(lint) __RCSID("\$NetBSD: s_floor.c,v 1.12 2008/04/25 22:21:53 christos Exp \$"); #endif /* * floor(x) * Return x rounded toward -inf to integral value * Method: * Bit twiddling. * Exception: * Inexact flag raised if x not equal to floor(x). */ #include "math.h" #include "math_private.h" static const double huge = 1.0e300; double floor(double x) { int32_t i0,i1,jj0; u_int32_t i,j; 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) {/* return 0*sign(x) if |x|<1 */ if(i0>=0) {i0=i1=0;} else if(((i0&0x7fffffff)|i1)!=0) { i0=0xbff00000;i1=0;} } } else { i = (0x000fffff)>>jj0; if(((i0&i)|i1)==0) return x; /* x is integral */ if(huge+x>0.0) { /* raise inexact flag */ if(i0<0) i0 += (0x00100000)>>jj0; 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 */ if(i0<0) { if(jj0==20) i0+=1; else { j = i1+(1<<(52-jj0)); if(j