| /* @(#)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. |
| * ==================================================== |
| */ |
| |
| /* |
| * 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 |
| { |
| int64_t i0,sx; |
| int32_t j0; |
| EXTRACT_WORDS64(i0,x); |
| sx = (i0>>63)&1; |
| j0 = ((i0>>52)&0x7ff)-0x3ff; |
| if(j0<52) { |
| if(j0<0) { |
| if((i0 & UINT64_C(0x7fffffffffffffff))==0) return x; |
| uint64_t i = i0 & UINT64_C(0xfffffffffffff); |
| i0 &= UINT64_C(0xfffe000000000000); |
| i0 |= (((i|-i) >> 12) & UINT64_C(0x8000000000000)); |
| INSERT_WORDS64(x,i0); |
| double w = TWO52[sx]+x; |
| double t = w-TWO52[sx]; |
| EXTRACT_WORDS64(i0,t); |
| INSERT_WORDS64(t,(i0&UINT64_C(0x7fffffffffffffff))|(sx<<63)); |
| return t; |
| } else { |
| uint64_t i = UINT64_C(0x000fffffffffffff)>>j0; |
| if((i0&i)==0) return x; /* x is integral */ |
| i>>=1; |
| if((i0&i)!=0) |
| i0 = (i0&(~i))|(UINT64_C(0x4000000000000)>>j0); |
| } |
| } else { |
| if(j0==0x400) return x+x; /* inf or NaN */ |
| else return x; /* x is integral */ |
| } |
| INSERT_WORDS64(x,i0); |
| double 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 |
