Tcl_Interp *interp,		/* Used for error reporting. May be NULL. */
    Tcl_Obj *objPtr,		/* Object to receive the internal rep. */
    const char *expected,	/* Description of the type of number the
				 * caller expects to be able to parse
				 * ("integer", "boolean value", etc.). */
    const char *bytes,		/* Pointer to the start of the string to
				 * scan. */
    size_t numBytes,		/* Maximum number of bytes to scan, see
				 * above. */
    const char **endPtrPtr,	/* Place to store pointer to the character
				 * that terminated the scan. */
    int flags)			/* Flags governing the parse. */
{
    enum State {
	INITIAL, SIGNUM, ZERO, ZERO_X,

				 * point in the parse. */
    int numDigitsAfterDp = 0;	/* Number of digits scanned after the decimal
				 * point. */
    int exponentSignum = 0;	/* Signum of the exponent of a floating point
				 * number. */
    long exponent = 0;		/* Exponent of a floating point number. */
    const char *p;		/* Pointer to next character to scan. */
    size_t len;			/* Number of characters remaining after p. */
    const char *acceptPoint;	/* Pointer to position after last character in
				 * an acceptable number. */
    size_t acceptLen;		/* Number of characters following that
				 * point. */
    int status = TCL_OK;	/* Status to return to caller. */
    char d = 0;			/* Last hexadecimal digit scanned; initialized
				 * to avoid a compiler warning. */
    int shift = 0;		/* Amount to shift when accumulating binary */
    mp_err err = MP_OKAY;
    int under = 0;              /* Flag trailing '_' as error if true once

    if (bytes == NULL) {
	if (interp == NULL && endPtrPtr == NULL) {
	    if (TclHasInternalRep(objPtr, &tclDictType)) {
		/* A dict can never be a (single) number */
		return TCL_ERROR;
	    }
	    if (TclHasInternalRep(objPtr, &tclListType.objType)) {
		size_t length;
		/* A list can only be a (single) number if its length == 1 */
		TclListObjLengthM(NULL, objPtr, &length);
		if (length != 1) {
		    return TCL_ERROR;
		}
	    }
	}

    if (status != TCL_OK) {
	if (interp != NULL) {
	    Tcl_Obj *msg = Tcl_ObjPrintf("expected %s but got \"",
		    expected);

	    Tcl_AppendLimitedToObj(msg, bytes, numBytes, 50, "");
	    Tcl_AppendToObj(msg, "\"", TCL_INDEX_NONE);
	    Tcl_SetObjResult(interp, msg);
	    Tcl_SetErrorCode(interp, "TCL", "VALUE", "NUMBER", NULL);
	}
    }

    /*
     * Free memory.

     * Infinite values can't convert to bignum.
     */

    if (isinf(d)) {
	if (interp != NULL) {
	    const char *s = "integer value too large to represent";

	    Tcl_SetObjResult(interp, Tcl_NewStringObj(s, TCL_INDEX_NONE));
	    Tcl_SetErrorCode(interp, "ARITH", "IOVERFLOW", s, NULL);
	}
	return TCL_ERROR;
    }

    fract = frexp(d, &expt);
    if (expt <= 0) {