| /* @(#)s_rint.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. |
| * ==================================================== |
| */ |
| |
| #if defined(LIBM_SCCS) && !defined(lint) |
| static char rcsid[] = "$NetBSD: s_rint.c,v 1.8 1995/05/10 20:48:04 jtc Exp $"; |
| #endif |
| |
| /* |
| * rint(x) |
| * Return x rounded to integral value according to the prevailing |
| * rounding mode. |
| * Method: |
| * Using floating addition. |
| * Exception: |
| * Inexact flag raised if x not equal to rint(x). |
| */ |
| |
| #include "math.h" |
| #include "math_private.h" |
| |
| #ifdef __STDC__ |
| static const double |
| #else |
| static double |
| #endif |
| TWO52[2]={ |
| 4.50359962737049600000e+15, /* 0x43300000, 0x00000000 */ |
| -4.50359962737049600000e+15, /* 0xC3300000, 0x00000000 */ |
| }; |
| |
| #ifdef __STDC__ |
| double __rint(double x) |
| #else |
| double __rint(x) |
| double x; |
| #endif |
| { |
| int32_t i0,j0,sx; |
| u_int32_t i,i1; |
| double w,t; |
| EXTRACT_WORDS(i0,i1,x); |
| sx = (i0>>31)&1; |
| j0 = ((i0>>20)&0x7ff)-0x3ff; |
| if(j0<20) { |
| if(j0<0) { |
| if(((i0&0x7fffffff)|i1)==0) return x; |
| i1 |= (i0&0x0fffff); |
| i0 &= 0xfffe0000; |
| i0 |= ((i1|-i1)>>12)&0x80000; |
| SET_HIGH_WORD(x,i0); |
| w = TWO52[sx]+x; |
| t = w-TWO52[sx]; |
| GET_HIGH_WORD(i0,t); |
| SET_HIGH_WORD(t,(i0&0x7fffffff)|(sx<<31)); |
| return t; |
| } else { |
| i = (0x000fffff)>>j0; |
| if(((i0&i)|i1)==0) return x; /* x is integral */ |
| i>>=1; |
| if(((i0&i)|i1)!=0) { |
| if (j0==19) |
| i1 = 0x40000000; |
| else if (j0<18) |
| i0 = (i0&(~i))|((0x20000)>>j0); |
| else |
| { |
| i0 &= ~i; |
| i1 = 0x80000000; |
| } |
| } |
| } |
| } 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 */ |
| i>>=1; |
| if((i1&i)!=0) i1 = (i1&(~i))|((0x40000000)>>(j0-20)); |
| } |
| INSERT_WORDS(x,i0,i1); |
| w = TWO52[sx]+x; |
| return w-TWO52[sx]; |
| } |
| weak_alias (__rint, rint) |
| #ifdef NO_LONG_DOUBLE |
| strong_alias (__rint, __rintl) |
| weak_alias (__rint, rintl) |
| #endif |
