typedef struct PyLongLayout {
    // Bits per digit
    uint8_t bits_per_digit;

    // Digit size in bytes
    uint8_t digit_size;

    // Digits order:
    // * 1 for most significant digit first
    // * -1 for least significant digit first
    int8_t digits_order;

    // Endian:
    // * 1 for most significant byte first (big endian)
    // * -1 for least significant byte first (little endian)
    int8_t endian;
} PyLongLayout;

PyAPI_FUNC(const PyLongLayout*) PyLong_GetNativeLayout(void);

typedef struct PyLong_DigitArray {
    // Strong reference to the Python int object.
    PyObject *obj;

    // 1 if the number is negative, 0 otherwise.
    int negative;

    // Number of digits in the 'digits' array.
    Py_ssize_t ndigits;

    // Read-only array of unsigned digits.
    const void *digits;
} PyLong_DigitArray;

PyAPI_FUNC(int) PyLong_AsDigitArray(
    PyObject *obj,
    PyLong_DigitArray *array);
PyAPI_FUNC(void) PyLong_FreeDigitArray(
    PyLong_DigitArray *array);

// A Python integer writer instance.
// The instance must be destroyed by PyLongWriter_Finish().
typedef struct PyLongWriter PyLongWriter;

PyAPI_FUNC(PyLongWriter*) PyLongWriter_Create(
    int negative,
    Py_ssize_t ndigits,
    void **digits);
PyAPI_FUNC(PyObject*) PyLongWriter_Finish(PyLongWriter *writer);
PyAPI_FUNC(void) PyLongWriter_Discard(PyLongWriter *writer);

static void
mpz_set_PyLong(mpz_t z, PyObject *obj)
{
    int overflow;
    long val = PyLong_AsLongAndOverflow(obj, &overflow);

    if (overflow) {
        const PyLongLayout* layout = PyLong_GetNativeLayout();
        static PyLong_DigitArray long_export;

        PyLong_AsDigitArray(obj, &long_export);
        mpz_import(z, long_export.ndigits, layout->endian,
                   layout->digit_size, layout->digits_order,
                   layout->digit_size*8 - layout->bits_per_digit,
                   long_export.digits);
        if (long_export.negative) {
            mpz_neg(z, z);
        }
        PyLong_FreeDigitArray(&long_export);
    }
    else {
        mpz_set_si(z, val);
    }
}

static PyObject *
GMPy_PyLong_From_MPZ(MPZ_Object *obj, CTXT_Object *context)
{
    if (mpz_fits_slong_p(obj->z)) {
        return PyLong_FromLong(mpz_get_si(obj->z));
    }

    const PyLongLayout *layout = PyLong_GetNativeLayout();
    size_t size = (mpz_sizeinbase(obj->z, 2) +
                   layout->bits_per_digit - 1) / layout->bits_per_digit;
    void *digits;
    PyLongWriter *writer = PyLongWriter_Create(mpz_sgn(obj->z) < 0, size,
                                               &digits);
    if (writer == NULL) {
        return NULL;
    }

    mpz_export(digits, NULL, layout->endian,
               layout->digit_size, layout->digits_order,
               layout->digit_size*8 - layout->bits_per_digit,
               obj->z);

    return PyLongWriter_Finish(writer);
}