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 1.10 2016/08/26 08:20:31 christos Exp $"); 19 #endif 20 21 #include <math.h> 22 #define __TEST_FENV 23 #include <fenv.h> 24 #ifndef __HAVE_FENV 25 #define feraiseexcept(a) 26 #endif 27 #include "math_private.h" 28 29 int 30 ilogbf(float x) 31 { 32 int32_t hx, ix; 33 34 GET_FLOAT_WORD(hx, x); 35 hx &= 0x7fffffff; 36 if (hx < 0x00800000) { 37 if (hx == 0) { 38 feraiseexcept(FE_INVALID); 39 return FP_ILOGB0; /* ilogb(0) = 0x80000001 */ 40 } 41 for (ix = -126, hx <<= 8; hx > 0; hx <<= 1) ix -= 1; 42 return ix; 43 } 44 45 if (hx < 0x7f800000) { 46 return (hx >> 23) - 127; 47 } 48 49 feraiseexcept(FE_INVALID); 50 return isnan(x) ? FP_ILOGBNAN : INT_MAX; 51 } 52