-/* @(#)s_ilogb.c 5.1 93/09/24 */
-/*
- * ====================================================
- * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
- *
- * Developed at SunPro, a Sun Microsystems, Inc. business.
- * Permission to use, copy, modify, and distribute this
- * software is freely granted, provided that this notice
- * is preserved.
- * ====================================================
- */
-
-/* ilogb(double x)
- * return the binary exponent of non-zero x
- * ilogb(0) = FP_ILOGB0
- * ilogb(NaN) = FP_ILOGBNAN (no signal is raised)
- * ilogb(inf) = INT_MAX (no signal is raised)
- */
-
-#include <limits.h>
-
-#include <math.h>
-#include "math_private.h"
-
-int ilogb(double x)
-{
- int32_t hx,lx,ix;
-
- EXTRACT_WORDS(hx,lx,x);
- hx &= 0x7fffffff;
- if(hx<0x00100000) {
- if((hx|lx)==0)
- return FP_ILOGB0;
- else /* subnormal x */
- if(hx==0) {
- for (ix = -1043; lx>0; lx<<=1) ix -=1;
- } else {
- for (ix = -1022,hx<<=11; hx>0; hx<<=1) ix -=1;
- }
- return ix;
- }
- else if (hx<0x7ff00000) return (hx>>20)-1023;
- else if (hx>0x7ff00000 || lx!=0) return FP_ILOGBNAN;
- else return INT_MAX;
-}