s_ilogbf.c (1053B)
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 #ifndef lint 17 static char rcsid[] = "$FreeBSD: src/lib/msun/src/s_ilogbf.c,v 1.7 2004/10/09 17:14:28 stefanf Exp $"; 18 #endif 19 20 #include <limits.h> 21 22 #include "math.h" 23 #include "math_private.h" 24 25 int ilogbf(float x) 26 { 27 int32_t hx,ix; 28 29 GET_FLOAT_WORD(hx,x); 30 hx &= 0x7fffffff; 31 if(hx<0x00800000) { 32 if(hx==0) 33 return FP_ILOGB0; 34 else /* subnormal x */ 35 for (ix = -126,hx<<=8; hx>0; hx<<=1) ix -=1; 36 return ix; 37 } 38 else if (hx<0x7f800000) return (hx>>23)-127; 39 else if (hx>0x7f800000) return FP_ILOGBNAN; 40 else return INT_MAX; 41 }