1 /* 2 * ==================================================== 3 * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved. 4 * 5 * Developed at SunPro, a Sun Microsystems, Inc. business. 6 * Permission to use, copy, modify, and distribute this 7 * software is freely granted, provided that this notice 8 * is preserved. 9 * ==================================================== 10 */ 11 12 #include <sys/cdefs.h> 13 /* 14 * floor(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 <float.h> 23 24 #include "math.h" 25 #include "math_private.h" 26 27 static const double huge = 1.0e300; 28 29 double 30 floor(double x) 31 { 32 int32_t i0,i1,j0; 33 u_int32_t i,j; 34 EXTRACT_WORDS(i0,i1,x); 35 j0 = ((i0>>20)&0x7ff)-0x3ff; 36 if(j0<20) { 37 if(j0<0) { /* raise inexact if x != 0 */ 38 if(huge+x>0.0) {/* return 0*sign(x) if |x|<1 */ 39 if(i0>=0) {i0=i1=0;} 40 else if(((i0&0x7fffffff)|i1)!=0) 41 { i0=0xbff00000;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(floor, floorl); 75 #endif 76