1 2 /* @(#)s_ceil.c 1.3 95/01/18 */ 3 /* 4 * ==================================================== 5 * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved. 6 * 7 * Developed at SunSoft, a Sun Microsystems, Inc. business. 8 * Permission to use, copy, modify, and distribute this 9 * software is freely granted, provided that this notice 10 * is preserved. 11 * ==================================================== 12 */ 13 14 /* 15 * ieee_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 ieee_ceil(x). 21 */ 22 23 #include "fdlibm.h" 24 25 #ifdef __STDC__ 26 static const double huge = 1.0e300; 27 #else 28 static double huge = 1.0e300; 29 #endif 30 31 #ifdef __STDC__ 32 double ieee_ceil(double x) 33 #else 34 double ieee_ceil(x) 35 double x; 36 #endif 37 { 38 int i0,i1,j0; 39 unsigned i,j; 40 i0 = __HI(x); 41 i1 = __LO(x); 42 j0 = ((i0>>20)&0x7ff)-0x3ff; 43 if(j0<20) { 44 if(j0<0) { /* raise inexact if x != 0 */ 45 if(huge+x>0.0) {/* return 0*sign(x) if |x|<1 */ 46 if(i0<0) {i0=0x80000000;i1=0;} 47 else if((i0|i1)!=0) { i0=0x3ff00000;i1=0;} 48 } 49 } else { 50 i = (0x000fffff)>>j0; 51 if(((i0&i)|i1)==0) return x; /* x is integral */ 52 if(huge+x>0.0) { /* raise inexact flag */ 53 if(i0>0) i0 += (0x00100000)>>j0; 54 i0 &= (~i); i1=0; 55 } 56 } 57 } else if (j0>51) { 58 if(j0==0x400) return x+x; /* inf or NaN */ 59 else return x; /* x is integral */ 60 } else { 61 i = ((unsigned)(0xffffffff))>>(j0-20); 62 if((i1&i)==0) return x; /* x is integral */ 63 if(huge+x>0.0) { /* raise inexact flag */ 64 if(i0>0) { 65 if(j0==20) i0+=1; 66 else { 67 j = i1 + (1<<(52-j0)); 68 if(j<i1) i0+=1; /* got a carry */ 69 i1 = j; 70 } 71 } 72 i1 &= (~i); 73 } 74 } 75 __HI(x) = i0; 76 __LO(x) = i1; 77 return x; 78 } 79
