source: trunk/libs/newlib/src/newlib/libm/common/sf_ilogb.c @ 567

/* sf_ilogb.c -- float version of s_ilogb.c.
 * Conversion to float by Ian Lance Taylor, Cygnus Support, ian@cygnus.com.
 */

/*
 * ====================================================
 * 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.
 * ====================================================
 */

#include <limits.h>
#include "fdlibm.h"

#ifdef __STDC__
        int ilogbf(float x)
#else
        int ilogbf(x)
        float x;
#endif
{
        __int32_t hx,ix;

        GET_FLOAT_WORD(hx,x);
        hx &= 0x7fffffff;
        if(FLT_UWORD_IS_ZERO(hx))
            return FP_ILOGB0;   /* ilogb(0) = special case error */
        if(FLT_UWORD_IS_SUBNORMAL(hx)) {
            for (ix = -126,hx<<=8; hx>0; hx<<=1) ix -=1;
            return ix;
        }
        #if FP_ILOGBNAN != INT_MAX
        else if (FLT_UWORD_IS_NAN(hx)) return FP_ILOGBNAN;      /* NAN */
        #endif
        else if (!FLT_UWORD_IS_FINITE(hx)) return INT_MAX;
        else return (hx>>23)-127;
}

#ifdef _DOUBLE_IS_32BITS

#ifdef __STDC__
        int ilogb(double x)
#else
        int ilogb(x)
        double x;
#endif
{
        return ilogbf((float) x);
}

#endif /* defined(_DOUBLE_IS_32BITS) */