1*05a0b428SJohn Marino /* s_logbf.c -- float version of s_logb.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 float
logbf(float x)20*05a0b428SJohn Marino logbf(float x)
21*05a0b428SJohn Marino {
22*05a0b428SJohn Marino int32_t ix;
23*05a0b428SJohn Marino GET_FLOAT_WORD(ix,x);
24*05a0b428SJohn Marino ix &= 0x7fffffff; /* high |x| */
25*05a0b428SJohn Marino if(ix==0) return (float)-1.0/fabsf(x);
26*05a0b428SJohn Marino if(ix>=0x7f800000) return x*x;
27*05a0b428SJohn Marino if((ix>>=23)==0) /* IEEE 754 logb */
28*05a0b428SJohn Marino return -126.0;
29*05a0b428SJohn Marino else
30*05a0b428SJohn Marino return (float) (ix-127);
31*05a0b428SJohn Marino }
32