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 "math.h"
17 #include "math_private.h"
18
19 static const float
20 TWO23[2]={
21 8.3886080000e+06, /* 0x4b000000 */
22 -8.3886080000e+06, /* 0xcb000000 */
23 };
24
25 float
rintf(float x)26 rintf(float x)
27 {
28 int32_t i0,jj0,sx;
29 u_int32_t i,i1;
30 float t;
31 volatile float w; /* clip extra precision */
32 GET_FLOAT_WORD(i0,x);
33 sx = (i0>>31)&1;
34 jj0 = ((i0>>23)&0xff)-0x7f;
35 if(jj0<23) {
36 if(jj0<0) {
37 if((i0&0x7fffffff)==0) return x;
38 i1 = (i0&0x07fffff);
39 i0 &= 0xfff00000;
40 i0 |= ((i1|-i1)>>9)&0x400000;
41 SET_FLOAT_WORD(x,i0);
42 w = TWO23[sx]+x;
43 t = w-TWO23[sx];
44 GET_FLOAT_WORD(i0,t);
45 SET_FLOAT_WORD(t,(i0&0x7fffffff)|(sx<<31));
46 return t;
47 } else {
48 i = (0x007fffff)>>jj0;
49 if((i0&i)==0) return x; /* x is integral */
50 i>>=1;
51 if((i0&i)!=0) i0 = (i0&(~i))|((0x100000)>>jj0);
52 }
53 } else {
54 if(jj0==0x80) return x+x; /* inf or NaN */
55 else return x; /* x is integral */
56 }
57 SET_FLOAT_WORD(x,i0);
58 w = TWO23[sx]+x;
59 return w-TWO23[sx];
60 }
61