1 /* @(#)s_ceil.c 5.1 93/09/24 */ 2 /* 3 * ==================================================== 4 * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved. 5 * 6 * Developed at SunPro, a Sun Microsystems, Inc. business. 7 * Permission to use, copy, modify, and distribute this 8 * software is freely granted, provided that this notice 9 * is preserved. 10 * ==================================================== 11 */ 12 13 #include <sys/cdefs.h> 14 #if defined(LIBM_SCCS) && !defined(lint) 15 __RCSID("$NetBSD: s_ceil.c,v 1.14 2013/11/11 23:57:34 joerg Exp $"); 16 #endif 17 18 /* 19 * ceil(x) 20 * Return x rounded toward -inf to integral value 21 * Method: 22 * Bit twiddling. 23 * Exception: 24 * Inexact flag raised if x not equal to ceil(x). 25 */ 26 27 #include "math.h" 28 #include "math_private.h" 29 30 static const double huge = 1.0e300; 31 32 #ifndef __HAVE_LONG_DOUBLE 33 __strong_alias(_ceill, ceil) 34 __weak_alias(ceill, ceil) 35 #endif 36 37 double 38 ceil(double x) 39 { 40 int32_t i0,i1,jj0; 41 u_int32_t i,j; 42 EXTRACT_WORDS(i0,i1,x); 43 jj0 = ((i0>>20)&0x7ff)-0x3ff; 44 if(jj0<20) { 45 if(jj0<0) { /* raise inexact if x != 0 */ 46 if(huge+x>0.0) {/* return 0*sign(x) if |x|<1 */ 47 if(i0<0) {i0=0x80000000;i1=0;} 48 else if((i0|i1)!=0) { i0=0x3ff00000;i1=0;} 49 } 50 } else { 51 i = (0x000fffff)>>jj0; 52 if(((i0&i)|i1)==0) return x; /* x is integral */ 53 if(huge+x>0.0) { /* raise inexact flag */ 54 if(i0>0) i0 += (0x00100000)>>jj0; 55 i0 &= (~i); i1=0; 56 } 57 } 58 } else if (jj0>51) { 59 if(jj0==0x400) return x+x; /* inf or NaN */ 60 else return x; /* x is integral */ 61 } else { 62 i = ((u_int32_t)(0xffffffff))>>(jj0-20); 63 if((i1&i)==0) return x; /* x is integral */ 64 if(huge+x>0.0) { /* raise inexact flag */ 65 if(i0>0) { 66 if(jj0==20) i0+=1; 67 else { 68 j = i1 + (1<<(52-jj0)); 69 if(j<(u_int32_t)i1) i0+=1; /* got a carry */ 70 i1 = j; 71 } 72 } 73 i1 &= (~i); 74 } 75 } 76 INSERT_WORDS(x,i0,i1); 77 return x; 78 } 79