ref: 53aac62a54ebbcc1781c0000d3e2384ed038c7bb
dir: /libmath/fdlibm/s_ceil.c/
/* derived from /netlib/fdlibm */ /* @(#)s_ceil.c 1.3 95/01/18 */ /* * ==================================================== * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved. * * Developed at SunSoft, a Sun Microsystems, Inc. business. * Permission to use, copy, modify, and distribute this * software is freely granted, provided that this notice * is preserved. * ==================================================== */ /* * ceil(x) * Return x rounded toward -inf to integral value * Method: * Bit twiddling. * Exception: * Inexact flag raised if x not equal to ceil(x). */ #include "fdlibm.h" static const double Huge = 1.0e300; double ceil(double x) { int i0,i1,j0; unsigned i,j; i0 = __HI(x); i1 = __LO(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=0x80000000;i1=0;} else if((i0|i1)!=0) { i0=0x3ff00000;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 = ((unsigned)(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<i1) i0+=1; /* got a carry */ i1 = j; } } i1 &= (~i); } } __HI(x) = i0; __LO(x) = i1; return x; }