1 /* @(#)s_floor.c 5.1 93/09/24 */
2 /*
3 * ====================================================
4 * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
5 *
6 * Developed at SunPro, a Sun Microsystems, Inc. business.
7 * Permission to use, copy, modify, and distribute this
8 * software is freely granted, provided that this notice
9 * is preserved.
10 * ====================================================
11 */
12
13 #include <sys/cdefs.h>
14 __FBSDID("$FreeBSD$");
15
16 /*
17 * truncf(x)
18 * Return x rounded toward 0 to integral value
19 * Method:
20 * Bit twiddling.
21 * Exception:
22 * Inexact flag raised if x not equal to truncf(x).
23 */
24
25 #include "math.h"
26 #include "math_private.h"
27
28 static const float huge = 1.0e30F;
29
30 float
truncf(float x)31 truncf(float x)
32 {
33 int32_t i0,j0;
34 u_int32_t i;
35 GET_FLOAT_WORD(i0,x);
36 j0 = ((i0>>23)&0xff)-0x7f;
37 if(j0<23) {
38 if(j0<0) { /* raise inexact if x != 0 */
39 if(huge+x>0.0F) /* |x|<1, so return 0*sign(x) */
40 i0 &= 0x80000000;
41 } else {
42 i = (0x007fffff)>>j0;
43 if((i0&i)==0) return x; /* x is integral */
44 if(huge+x>0.0F) /* raise inexact flag */
45 i0 &= (~i);
46 }
47 } else {
48 if(j0==0x80) return x+x; /* inf or NaN */
49 else return x; /* x is integral */
50 }
51 SET_FLOAT_WORD(x,i0);
52 return x;
53 }
54