1 /* s_rintf.c -- float version of s_rint.c.
2 * Conversion to float by Ian Lance Taylor, Cygnus Support, ian@cygnus.com.
3 */
4
5 /*
6 * ====================================================
7 * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
8 *
9 * Developed at SunPro, a Sun Microsystems, Inc. business.
10 * Permission to use, copy, modify, and distribute this
11 * software is freely granted, provided that this notice
12 * is preserved.
13 * ====================================================
14 */
15
16 #include <sys/cdefs.h>
17 #if defined(LIBM_SCCS) && !defined(lint)
18 __RCSID("$NetBSD: s_rintf.c,v 1.9 2008/04/25 22:21:53 christos Exp $");
19 #endif
20
21 #include "math.h"
22 #include "math_private.h"
23
24 static const float
25 TWO23[2]={
26 8.3886080000e+06, /* 0x4b000000 */
27 -8.3886080000e+06, /* 0xcb000000 */
28 };
29
30 float
rintf(float x)31 rintf(float x)
32 {
33 int32_t i0,jj0,sx;
34 u_int32_t i,i1;
35 #ifdef __i386__ /* XXX gcc4 will omit the rounding otherwise */
36 volatile
37 #endif
38 float w;
39 float t;
40 GET_FLOAT_WORD(i0,x);
41 sx = (i0>>31)&1;
42 jj0 = ((i0>>23)&0xff)-0x7f;
43 if(jj0<23) {
44 if(jj0<0) {
45 if((i0&0x7fffffff)==0) return x;
46 i1 = (i0&0x07fffff);
47 i0 &= 0xfff00000;
48 i0 |= ((i1|-i1)>>9)&0x400000;
49 SET_FLOAT_WORD(x,i0);
50 w = TWO23[sx]+x;
51 t = w-TWO23[sx];
52 GET_FLOAT_WORD(i0,t);
53 SET_FLOAT_WORD(t,(i0&0x7fffffff)|(sx<<31));
54 return t;
55 } else {
56 i = (0x007fffff)>>jj0;
57 if((i0&i)==0) return x; /* x is integral */
58 i>>=1;
59 if((i0&i)!=0) i0 = (i0&(~i))|((0x100000)>>jj0);
60 }
61 } else {
62 if(jj0==0x80) return x+x; /* inf or NaN */
63 else return x; /* x is integral */
64 }
65 SET_FLOAT_WORD(x,i0);
66 w = TWO23[sx]+x;
67 return w-TWO23[sx];
68 }
69