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 /* 15 * ceil(x) 16 * Return x rounded toward -inf to integral value 17 * Method: 18 * Bit twiddling. 19 * Exception: 20 * Inexact flag raised if x not equal to ceil(x). 21 */ 22 23 #include <float.h> 24 25 #include "math.h" 26 #include "math_private.h" 27 28 static const double huge = 1.0e300; 29 30 double 31 ceil(double x) 32 { 33 int32_t i0,i1,j0; 34 u_int32_t i,j; 35 EXTRACT_WORDS(i0,i1,x); 36 j0 = ((i0>>20)&0x7ff)-0x3ff; 37 if(j0<20) { 38 if(j0<0) { /* raise inexact if x != 0 */ 39 if(huge+x>0.0) {/* return 0*sign(x) if |x|<1 */ 40 if(i0<0) {i0=0x80000000;i1=0;} 41 else if((i0|i1)!=0) { i0=0x3ff00000;i1=0;} 42 } 43 } else { 44 i = (0x000fffff)>>j0; 45 if(((i0&i)|i1)==0) return x; /* x is integral */ 46 if(huge+x>0.0) { /* raise inexact flag */ 47 if(i0>0) i0 += (0x00100000)>>j0; 48 i0 &= (~i); i1=0; 49 } 50 } 51 } else if (j0>51) { 52 if(j0==0x400) return x+x; /* inf or NaN */ 53 else return x; /* x is integral */ 54 } else { 55 i = ((u_int32_t)(0xffffffff))>>(j0-20); 56 if((i1&i)==0) return x; /* x is integral */ 57 if(huge+x>0.0) { /* raise inexact flag */ 58 if(i0>0) { 59 if(j0==20) i0+=1; 60 else { 61 j = i1 + (1<<(52-j0)); 62 if(j<i1) i0+=1; /* got a carry */ 63 i1 = j; 64 } 65 } 66 i1 &= (~i); 67 } 68 } 69 INSERT_WORDS(x,i0,i1); 70 return x; 71 } 72 73 #if LDBL_MANT_DIG == 53 74 __weak_reference(ceil, ceill); 75 #endif 76