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 /* LINTLIBRARY */ 14 15 /* 16 * ceil(x) 17 * Return x rounded toward -inf to integral value 18 * Method: 19 * Bit twiddling. 20 * Exception: 21 * Inexact flag raised if x not equal to ceil(x). 22 */ 23 24 #include <sys/cdefs.h> 25 #include <float.h> 26 #include <math.h> 27 28 #include "math_private.h" 29 30 static const double huge = 1.0e300; 31 32 double 33 ceil(double x) 34 { 35 int32_t i0,i1,jj0; 36 u_int32_t i,j; 37 EXTRACT_WORDS(i0,i1,x); 38 jj0 = ((i0>>20)&0x7ff)-0x3ff; 39 if(jj0<20) { 40 if(jj0<0) { /* raise inexact if x != 0 */ 41 if(huge+x>0.0) {/* return 0*sign(x) if |x|<1 */ 42 if(i0<0) {i0=0x80000000;i1=0;} 43 else if((i0|i1)!=0) { i0=0x3ff00000;i1=0;} 44 } 45 } else { 46 i = (0x000fffff)>>jj0; 47 if(((i0&i)|i1)==0) return x; /* x is integral */ 48 if(huge+x>0.0) { /* raise inexact flag */ 49 if(i0>0) i0 += (0x00100000)>>jj0; 50 i0 &= (~i); i1=0; 51 } 52 } 53 } else if (jj0>51) { 54 if(jj0==0x400) return x+x; /* inf or NaN */ 55 else return x; /* x is integral */ 56 } else { 57 i = ((u_int32_t)(0xffffffff))>>(jj0-20); 58 if((i1&i)==0) return x; /* x is integral */ 59 if(huge+x>0.0) { /* raise inexact flag */ 60 if(i0>0) { 61 if(jj0==20) i0+=1; 62 else { 63 j = i1 + (1<<(52-jj0)); 64 if(j<i1) i0+=1; /* got a carry */ 65 i1 = j; 66 } 67 } 68 i1 &= (~i); 69 } 70 } 71 INSERT_WORDS(x,i0,i1); 72 return x; 73 } 74 75 #if LDBL_MANT_DIG == 53 76 #ifdef lint 77 /* PROTOLIB1 */ 78 long double ceill(long double); 79 #else /* lint */ 80 __weak_alias(ceill, ceil); 81 #endif /* lint */ 82 #endif /* LDBL_MANT_DIG == 53 */ 83