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The Android Open Source Project1dc9e472009-03-03 19:28:35 -08001/* s_ilogbf.c -- float version of s_ilogb.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
Elliott Hughesa0ee0782013-01-30 19:06:37 -080016#include <sys/cdefs.h>
17__FBSDID("$FreeBSD$");
The Android Open Source Project1dc9e472009-03-03 19:28:35 -080018
19#include <limits.h>
20
21#include "math.h"
22#include "math_private.h"
23
24 int ilogbf(float x)
25{
26 int32_t hx,ix;
27
28 GET_FLOAT_WORD(hx,x);
29 hx &= 0x7fffffff;
30 if(hx<0x00800000) {
31 if(hx==0)
32 return FP_ILOGB0;
33 else /* subnormal x */
34 for (ix = -126,hx<<=8; hx>0; hx<<=1) ix -=1;
35 return ix;
36 }
37 else if (hx<0x7f800000) return (hx>>23)-127;
38 else if (hx>0x7f800000) return FP_ILOGBNAN;
39 else return INT_MAX;
40}