/*
 * ====================================================
 * 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 <float.h>
#include <limits.h>
#include <math.h>

#include "fpmath.h"

long double
logbl(long double x)
{
        union IEEEl2bits u;
        unsigned long m;
        int b;

        u.e = x;
        if (u.bits.exp == 0) {
                if ((u.bits.manl | u.bits.manh) == 0) { /* x == 0 */
                        u.bits.sign = 1;
                        return (1.0L / u.e);
                }
                /* denormalized */
                if (u.bits.manh == 0) {
                        m = 1lu << (LDBL_MANL_SIZE - 1);
                        for (b = LDBL_MANH_SIZE; !(u.bits.manl & m); m >>= 1)
                                b++;
                } else {
                        m = 1lu << (LDBL_MANH_SIZE - 1);
                        for (b = 0; !(u.bits.manh & m); m >>= 1)
                                b++;
                }
#ifdef LDBL_IMPLICIT_NBIT
                b++;
#endif
                return ((long double)(LDBL_MIN_EXP - b - 1));
        }
        if (u.bits.exp < (LDBL_MAX_EXP << 1) - 1)       /* normal */
                return ((long double)(u.bits.exp - LDBL_MAX_EXP + 1));
        else                                            /* +/- inf or nan */
                return (x * x);
}