| /* @(#)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 "../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; |
| } |
