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 int32_t i1,jj0; 32 u_int32_t i,j,se,i0,sx; 33 GET_LDOUBLE_WORDS(se,i0,i1,x); 34 sx = (se>>15)&1; 35 jj0 = (se&0x7fff)-0x3fff; 36 if(jj0<31) { 37 if(jj0<0) { /* raise inexact if x != 0 */ 38 if(huge+x>0.0) {/* return 0*sign(x) if |x|<1 */ 39 if(sx==0) {se=0;i0=i1=0;} 40 else if(((se&0x7fff)|i0|i1)!=0) 41 { se=0xbfff;i0=i1=0;} 42 } 43 } else { 44 i = (0x7fffffff)>>jj0; 45 if(((i0&i)|i1)==0) return x; /* x is integral */ 46 if(huge+x>0.0) { /* raise inexact flag */ 47 if(sx) { 48 if (jj0>0 && (i0+(0x80000000>>jj0))>i0) 49 i0 += (0x80000000)>>jj0; 50 else 51 { 52 i = 0x7fffffff; 53 ++se; 54 } 55 } 56 i0 &= (~i); i1=0; 57 } 58 } 59 } else if (jj0>62) { 60 if(jj0==0x4000) return x+x; /* inf or NaN */ 61 else return x; /* x is integral */ 62 } else { 63 i = ((u_int32_t)(0xffffffff))>>(jj0-31); 64 if((i1&i)==0) return x; /* x is integral */ 65 if(huge+x>0.0) { /* raise inexact flag */ 66 if(sx) { 67 if(jj0==31) i0+=1; 68 else { 69 j = i1+(1<<(63-jj0)); 70 if(j<i1) i0 +=1 ; /* got a carry */ 71 i1=j; 72 } 73 } 74 i1 &= (~i); 75 } 76 } 77 SET_LDOUBLE_WORDS(x,se,i0,i1); 78 return x; 79 } 80