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 /* LINTLIBRARY */ 14 15 #if 0 16 #include <sys/cdefs.h> 17 __FBSDID("$FreeBSD: src/lib/msun/src/s_trunc.c,v 1.1 2004/06/20 09:25:43 das Exp $"); 18 #endif 19 20 /* 21 * trunc(x) 22 * Return x rounded toward 0 to integral value 23 * Method: 24 * Bit twiddling. 25 * Exception: 26 * Inexact flag raised if x not equal to trunc(x). 27 */ 28 29 #include <sys/cdefs.h> 30 #include <float.h> 31 #include <math.h> 32 33 #include "math_private.h" 34 35 static const double huge = 1.0e300; 36 37 double 38 trunc(double x) 39 { 40 int32_t i0,i1,jj0; 41 u_int32_t i; 42 EXTRACT_WORDS(i0,i1,x); 43 jj0 = ((i0>>20)&0x7ff)-0x3ff; 44 if(jj0<20) { 45 if(jj0<0) { /* raise inexact if x != 0 */ 46 if(huge+x>0.0) {/* |x|<1, so return 0*sign(x) */ 47 i0 &= 0x80000000U; 48 i1 = 0; 49 } 50 } else { 51 i = (0x000fffff)>>jj0; 52 if(((i0&i)|i1)==0) return x; /* x is integral */ 53 if(huge+x>0.0) { /* raise inexact flag */ 54 i0 &= (~i); i1=0; 55 } 56 } 57 } else if (jj0>51) { 58 if(jj0==0x400) return x+x; /* inf or NaN */ 59 else return x; /* x is integral */ 60 } else { 61 i = ((u_int32_t)(0xffffffff))>>(jj0-20); 62 if((i1&i)==0) return x; /* x is integral */ 63 if(huge+x>0.0) /* raise inexact flag */ 64 i1 &= (~i); 65 } 66 INSERT_WORDS(x,i0,i1); 67 return x; 68 } 69 70 #if LDBL_MANT_DIG == 53 71 #ifdef lint 72 /* PROTOLIB1 */ 73 long double truncl(long double); 74 #else /* lint */ 75 __weak_alias(truncl, trunc); 76 #endif /* lint */ 77 #endif /* LDBL_MANT_DIG == 53 */ 78