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[] = "$FreeBSD$"; 18 #endif 19 20 #include "math.h" 21 #include "math_private.h" 22 23 #ifdef __STDC__ 24 int ilogbf(float x) 25 #else 26 int ilogbf(x) 27 float x; 28 #endif 29 { 30 int32_t hx,ix; 31 32 GET_FLOAT_WORD(hx,x); 33 hx &= 0x7fffffff; 34 if(hx<0x00800000) { 35 if(hx==0) 36 return 0x80000001; /* ilogb(0) = 0x80000001 */ 37 else /* subnormal x */ 38 for (ix = -126,hx<<=8; hx>0; hx<<=1) ix -=1; 39 return ix; 40 } 41 else if (hx<0x7f800000) return (hx>>23)-127; 42 else return 0x7fffffff; 43 } 44