1 /* 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 16 #include <sys/cdefs.h> 17 #if defined(LIBM_SCCS) && !defined(lint) 18 __RCSID("$NetBSD: s_ilogbf.c,v 1.5 1997/10/09 11:32:16 lukem Exp $"); 19 #endif 20 21 #include "math.h" 22 #include "math_private.h" 23 24 #ifdef __STDC__ 25 int ilogbf(float x) 26 #else 27 int ilogbf(x) 28 float x; 29 #endif 30 { 31 int32_t hx,ix; 32 33 GET_FLOAT_WORD(hx,x); 34 hx &= 0x7fffffff; 35 if(hx<0x00800000) { 36 if(hx==0) 37 return 0x80000001; /* ilogb(0) = 0x80000001 */ 38 else /* subnormal x */ 39 for (ix = -126,hx<<=8; hx>0; hx<<=1) ix -=1; 40 return ix; 41 } 42 else if (hx<0x7f800000) return (hx>>23)-127; 43 else return 0x7fffffff; 44 } 45