2 * ====================================================
3 * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
5 * Developed at SunPro, a Sun Microsystems, Inc. business.
6 * Permission to use, copy, modify, and distribute this
7 * software is freely granted, provided that this notice
9 * ====================================================
14 * Return x rounded to integral value according to the prevailing
17 * Using floating addition.
19 * Inexact flag raised if x not equal to rint(x).
23 #include "math_private.h"
27 4.50359962737049600000e+15, /* 0x43300000, 0x00000000 */
28 -4.50359962737049600000e+15, /* 0xC3300000, 0x00000000 */
36 /* We use w = x + 2^52; t = w - 2^52; trick to round x to integer.
37 * This trick requires that compiler does not optimize it
38 * by keeping intermediate result w in a register wider than double.
39 * Declaring w volatile assures that value gets truncated to double
40 * (unfortunately, it also forces store+load):
44 EXTRACT_WORDS(i0,i1,x);
45 /* Unbiased exponent */
46 _j0 = ((((u_int32_t)i0) >> 20)&0x7ff)-0x3ff;
49 //Why bother? Just returning x works too
50 //if (_j0 == 0x400) /* inf or NaN */
52 return x; /* x is integral */
56 sx = ((u_int32_t)i0) >> 31;
59 if (_j0<0) { /* |x| < 1 */
60 if (((i0&0x7fffffff)|i1)==0) return x;
63 i0 |= ((i1|-i1)>>12)&0x80000;
68 SET_HIGH_WORD(t,(i0&0x7fffffff)|(sx<<31));
71 i = (0x000fffff)>>_j0;
72 if (((i0&i)|i1)==0) return x; /* x is integral */
75 if (_j0==19) i1 = 0x40000000;
76 else i0 = (i0&(~i))|((0x20000)>>_j0);
80 i = ((u_int32_t)(0xffffffff))>>(_j0-20);
81 if ((i1&i)==0) return x; /* x is integral */
83 if ((i1&i)!=0) i1 = (i1&(~i))|((0x40000000)>>(_j0-20));
85 INSERT_WORDS(x,i0,i1);
91 strong_alias(rint, nearbyint)
92 libm_hidden_def(nearbyint)