| /* @(#)s_floor.c 5.1 93/09/24 */ | |
| /* | |
| * ==================================================== | |
| * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved. | |
| * | |
| * Developed at SunPro, a Sun Microsystems, Inc. business. | |
| * Permission to use, copy, modify, and distribute this | |
| * software is freely granted, provided that this notice | |
| * is preserved. | |
| * ==================================================== | |
| */ | |
| #include <sys/cdefs.h> | |
| /* | |
| * trunc(x) | |
| * Return x rounded toward 0 to integral value | |
| * Method: | |
| * Bit twiddling. | |
| * Exception: | |
| * Inexact flag raised if x not equal to trunc(x). | |
| */ | |
| #include <float.h> | |
| #include <math.h> | |
| #include "../bsd_private_base.h" | |
| static const double huge = 1.0e300; | |
| double | |
| trunc(double x) | |
| { | |
| int32_t i0,i1,j0; | |
| u_int32_t i; | |
| EXTRACT_WORDS(i0,i1,x); | |
| j0 = ((i0>>20)&0x7ff)-0x3ff; | |
| if(j0<20) { | |
| if(j0<0) { /* raise inexact if x != 0 */ | |
| if(huge+x>0.0) {/* |x|<1, so return 0*sign(x) */ | |
| i0 &= 0x80000000U; | |
| i1 = 0; | |
| } | |
| } else { | |
| i = (0x000fffff)>>j0; | |
| if(((i0&i)|i1)==0) return x; /* x is integral */ | |
| if(huge+x>0.0) { /* raise inexact flag */ | |
| i0 &= (~i); i1=0; | |
| } | |
| } | |
| } else if (j0>51) { | |
| if(j0==0x400) return x+x; /* inf or NaN */ | |
| else return x; /* x is integral */ | |
| } else { | |
| i = ((u_int32_t)(0xffffffff))>>(j0-20); | |
| if((i1&i)==0) return x; /* x is integral */ | |
| if(huge+x>0.0) /* raise inexact flag */ | |
| i1 &= (~i); | |
| } | |
| INSERT_WORDS(x,i0,i1); | |
| return x; | |
| } |