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 #include <sys/cdefs.h> 14 /* 15 * floor(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 floor(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 floor(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=i1=0;} 41 else if(((i0&0x7fffffff)|i1)!=0) 42 { i0=0xbff00000;i1=0;} 43 } 44 } else { 45 i = (0x000fffff)>>j0; 46 if(((i0&i)|i1)==0) return x; /* x is integral */ 47 if(huge+x>0.0) { /* raise inexact flag */ 48 if(i0<0) i0 += (0x00100000)>>j0; 49 i0 &= (~i); i1=0; 50 } 51 } 52 } else if (j0>51) { 53 if(j0==0x400) return x+x; /* inf or NaN */ 54 else return x; /* x is integral */ 55 } else { 56 i = ((u_int32_t)(0xffffffff))>>(j0-20); 57 if((i1&i)==0) return x; /* x is integral */ 58 if(huge+x>0.0) { /* raise inexact flag */ 59 if(i0<0) { 60 if(j0==20) i0+=1; 61 else { 62 j = i1+(1<<(52-j0)); 63 if(j<i1) i0 +=1 ; /* got a carry */ 64 i1=j; 65 } 66 } 67 i1 &= (~i); 68 } 69 } 70 INSERT_WORDS(x,i0,i1); 71 return x; 72 } 73 74 #if LDBL_MANT_DIG == 53 75 __weak_reference(floor, floorl); 76 #endif 77