1*05a0b428SJohn Marino /* s_ilogbf.c -- float version of s_ilogb.c.
2*05a0b428SJohn Marino * Conversion to float by Ian Lance Taylor, Cygnus Support, ian@cygnus.com.
3*05a0b428SJohn Marino */
4*05a0b428SJohn Marino
5*05a0b428SJohn Marino /*
6*05a0b428SJohn Marino * ====================================================
7*05a0b428SJohn Marino * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
8*05a0b428SJohn Marino *
9*05a0b428SJohn Marino * Developed at SunPro, a Sun Microsystems, Inc. business.
10*05a0b428SJohn Marino * Permission to use, copy, modify, and distribute this
11*05a0b428SJohn Marino * software is freely granted, provided that this notice
12*05a0b428SJohn Marino * is preserved.
13*05a0b428SJohn Marino * ====================================================
14*05a0b428SJohn Marino */
15*05a0b428SJohn Marino
16*05a0b428SJohn Marino #include "math.h"
17*05a0b428SJohn Marino #include "math_private.h"
18*05a0b428SJohn Marino
19*05a0b428SJohn Marino int
ilogbf(float x)20*05a0b428SJohn Marino ilogbf(float x)
21*05a0b428SJohn Marino {
22*05a0b428SJohn Marino int32_t hx,ix;
23*05a0b428SJohn Marino
24*05a0b428SJohn Marino GET_FLOAT_WORD(hx,x);
25*05a0b428SJohn Marino hx &= 0x7fffffff;
26*05a0b428SJohn Marino if(hx<0x00800000) {
27*05a0b428SJohn Marino if(hx==0)
28*05a0b428SJohn Marino return 0x80000001; /* ilogb(0) = 0x80000001 */
29*05a0b428SJohn Marino else /* subnormal x */
30*05a0b428SJohn Marino for (ix = -126,hx<<=8; hx>0; hx<<=1) ix -=1;
31*05a0b428SJohn Marino return ix;
32*05a0b428SJohn Marino }
33*05a0b428SJohn Marino else if (hx<0x7f800000) return (hx>>23)-127;
34*05a0b428SJohn Marino else return 0x7fffffff;
35*05a0b428SJohn Marino }
36