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 __FBSDID("$FreeBSD$"); 15 16 /* 17 * trunc(x) 18 * Return x rounded toward 0 to integral value 19 * Method: 20 * Bit twiddling. 21 * Exception: 22 * Inexact flag raised if x not equal to trunc(x). 23 */ 24 25 #include <float.h> 26 27 #include "math.h" 28 #include "math_private.h" 29 30 static const double huge = 1.0e300; 31 32 double 33 trunc(double x) 34 { 35 int32_t i0,i1,j0; 36 u_int32_t i; 37 EXTRACT_WORDS(i0,i1,x); 38 j0 = ((i0>>20)&0x7ff)-0x3ff; 39 if(j0<20) { 40 if(j0<0) { /* raise inexact if x != 0 */ 41 if(huge+x>0.0) {/* |x|<1, so return 0*sign(x) */ 42 i0 &= 0x80000000U; 43 i1 = 0; 44 } 45 } else { 46 i = (0x000fffff)>>j0; 47 if(((i0&i)|i1)==0) return x; /* x is integral */ 48 if(huge+x>0.0) { /* raise inexact flag */ 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 i1 &= (~i); 60 } 61 INSERT_WORDS(x,i0,i1); 62 return x; 63 } 64 65 #if LDBL_MANT_DIG == 53 66 __weak_reference(trunc, truncl); 67 #endif 68