/* @(#)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. * ==================================================== */ /* FUNCTION <>, <>, <>, <>---floor and ceiling INDEX floor INDEX floorf INDEX ceil INDEX ceilf ANSI_SYNOPSIS #include double floor(double <[x]>); float floorf(float <[x]>); double ceil(double <[x]>); float ceilf(float <[x]>); TRAD_SYNOPSIS #include double floor(<[x]>) double <[x]>; float floorf(<[x]>) float <[x]>; double ceil(<[x]>) double <[x]>; float ceilf(<[x]>) float <[x]>; DESCRIPTION <> and <> find @tex $\lfloor x \rfloor$, @end tex the nearest integer less than or equal to <[x]>. <> and <> find @tex $\lceil x\rceil$, @end tex the nearest integer greater than or equal to <[x]>. RETURNS <> and <> return the integer result as a double. <> and <> return the integer result as a float. PORTABILITY <> and <> are ANSI. <> and <> are extensions. */ /* * 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 "fdlibm.h" #ifndef _DOUBLE_IS_32BITS #ifdef __STDC__ static const double huge = 1.0e300; #else static double huge = 1.0e300; #endif #ifdef __STDC__ double floor(double x) #else double floor(x) double x; #endif { int32_t i0,i1,j0; uint32_t i,j; EXTRACT_WORDS(i0,i1,x); j0 = ((i0>>20)&0x7ff)-0x3ff; if(j0<20) { if(j0<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)>>j0; if(((i0&i)|i1)==0) return x; /* x is integral */ if(huge+x>0.0) { /* raise inexact flag */ if(i0<0) i0 += (0x00100000)>>j0; i0 &= (~i); i1=0; } } } else if (j0>51) { if(j0==0x400) return x+x; /* inf or NaN */ else return x; /* x is integral */ } else { i = ((uint32_t)(0xffffffff))>>(j0-20); if((i1&i)==0) return x; /* x is integral */ if(huge+x>0.0) { /* raise inexact flag */ if(i0<0) { if(j0==20) i0+=1; else { j = i1+(1<<(52-j0)); if(j<(uint32_t)i1) i0 +=1 ; /* got a carry */ i1=j; } } i1 &= (~i); } } INSERT_WORDS(x,i0,i1); return x; } #endif /* _DOUBLE_IS_32BITS */