#define TWO_OVER_3LOG10 0.28952965460216784
#define LOG10_3HALVES_PLUS_FUDGE 0.1760912590558

/*
 * Definitions of the parts of an IEEE754-format floating point number.
 */

#define SIGN_BIT 	0x80000000
				/* Mask for the sign bit in the first word of
				 * a double. */
#define EXP_MASK	0x7FF00000
				/* Mask for the exponent field in the first
				 * word of a double. */
#define EXP_SHIFT	20	/* Shift count to make the exponent an
				 * integer. */

			    long exponent);
#ifdef IEEE_FLOATING_POINT
static double		MakeNaN(int signum, Tcl_WideUInt tag);
#endif
static double		RefineApproximation(double approx,
			    mp_int *exactSignificand, int exponent);
static mp_err		MulPow5(mp_int *, unsigned, mp_int *) MP_WUR;
static int 		NormalizeRightward(Tcl_WideUInt *);
static int		RequiredPrecision(Tcl_WideUInt);
static void		DoubleToExpAndSig(double, Tcl_WideUInt *, int *,
			    int *);
static void		TakeAbsoluteValue(Double *, int *);
static char *		FormatInfAndNaN(Double *, int *, char **);
static char *		FormatZero(int *, char **);
static int		ApproximateLog10(Tcl_WideUInt, int, int);

 *	Stores base*5**n in result.
 *
 *----------------------------------------------------------------------
 */

static inline mp_err
MulPow5(
    mp_int *base, 		/* Number to multiply. */
    unsigned n,			/* Power of 5 to multiply by. */
    mp_int *result)		/* Place to store the result. */
{
    mp_int *p = base;
    int n13 = n / 13;
    int r = n % 13;
    mp_err err = MP_OKAY;

 *	"1" and moves the decimal point (*kPtr) one place to the right.
 *
 *----------------------------------------------------------------------
 */

static inline char *
BumpUp(
    char *s,		    	/* Cursor pointing one past the end of the
				 * string. */
    char *retval,		/* Start of the string of digits. */
    int *kPtr)			/* Position of the decimal point. */
{
    while (*--s == '9') {
	if (s == retval) {
	    ++(*kPtr);

    }
    if (mp_init_u64(&b, bw) != MP_OKAY) {
	mp_clear(&dig);
	return NULL;
    }
    err = mp_mul_2d(&b, b2, &b);
    if (err == MP_OKAY) {
 	err = mp_init_set(&S, 1);
    }
    if (err == MP_OKAY) {
	err = MulPow5(&S, s5, &S);
	if (err == MP_OKAY) {
	    err = mp_mul_2d(&S, s2, &S);
	}
    }