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 * trunc(x) 15 * Return x rounded toward 0 to integral value 16 * Method: 17 * Bit twiddling. 18 * Exception: 19 * Inexact flag raised if x not equal to trunc(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 trunc(double x) 31 { 32 int32_t i0,i1,j0; 33 u_int32_t i; 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) {/* |x|<1, so return 0*sign(x) */ 39 i0 &= 0x80000000U; 40 i1 = 0; 41 } 42 } else { 43 i = (0x000fffff)>>j0; 44 if(((i0&i)|i1)==0) return x; /* x is integral */ 45 if(huge+x>0.0) { /* raise inexact flag */ 46 i0 &= (~i); i1=0; 47 } 48 } 49 } else if (j0>51) { 50 if(j0==0x400) return x+x; /* inf or NaN */ 51 else return x; /* x is integral */ 52 } else { 53 i = ((u_int32_t)(0xffffffff))>>(j0-20); 54 if((i1&i)==0) return x; /* x is integral */ 55 if(huge+x>0.0) /* raise inexact flag */ 56 i1 &= (~i); 57 } 58 INSERT_WORDS(x,i0,i1); 59 return x; 60 } 61 62 #if LDBL_MANT_DIG == 53 63 __weak_reference(trunc, truncl); 64 #endif 65