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