1 /* @(#)s_floor.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 * floorl(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 floor(x). 20 */ 21 22 #include <math.h> 23 24 #include "math_private.h" 25 26 static const long double huge = 1.0e4930L; 27 28 long double 29 floorl(long double x) 30 { 31 int64_t i0,i1,jj0; 32 u_int64_t i,j; 33 GET_LDOUBLE_WORDS64(i0,i1,x); 34 jj0 = ((i0>>48)&0x7fff)-0x3fff; 35 if(jj0<48) { 36 if(jj0<0) { /* raise inexact if x != 0 */ 37 if(huge+x>0.0) { 38 if(i0>=0) 39 return 0.0L; 40 else if(((i0&0x7fffffffffffffffLL)|i1)!=0) 41 return -1.0L; 42 } 43 } else { 44 i = (0x0000ffffffffffffULL)>>jj0; 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 += (0x0001000000000000LL)>>jj0; 48 i0 &= (~i); i1=0; 49 } 50 } 51 } else if (jj0>111) { 52 if(jj0==0x4000) return x+x; /* inf or NaN */ 53 else return x; /* x is integral */ 54 } else { 55 i = -1ULL>>(jj0-48); 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(jj0==48) i0+=1; 60 else { 61 j = i1+(1LL<<(112-jj0)); 62 if(j<i1) i0 +=1 ; /* got a carry */ 63 i1=j; 64 } 65 } 66 i1 &= (~i); 67 } 68 } 69 SET_LDOUBLE_WORDS64(x,i0,i1); 70 return x; 71 } 72