mpz.c

/*
 * This file is part of the Micro Python project, http://micropython.org/
 *
 * The MIT License (MIT)
 *
 * Copyright (c) 2013, 2014 Damien P. George
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 */

#include <string.h>
#include <assert.h>

#include "py/mpz.h"

#if MICROPY_LONGINT_IMPL == MICROPY_LONGINT_IMPL_MPZ

#define DIG_SIZE (MPZ_DIG_SIZE)
#define DIG_MASK ((MPZ_LONG_1 << DIG_SIZE) - 1)
#define DIG_MSB  (MPZ_LONG_1 << (DIG_SIZE - 1))
#define DIG_BASE (MPZ_LONG_1 << DIG_SIZE)

/*
 mpz is an arbitrary precision integer type with a public API.

 mpn functions act on non-negative integers represented by an array of generalised
 digits (eg a word per digit).  You also need to specify separately the length of the
 array.  There is no public API for mpn.  Rather, the functions are used by mpz to
 implement its features.

 Integer values are stored little endian (first digit is first in memory).

 Definition of normalise: ?
*/

/* compares i with j
   returns sign(i - j)
   assumes i, j are normalised
*/
STATIC int mpn_cmp(const mpz_dig_t *idig, mp_uint_t ilen, const mpz_dig_t *jdig, mp_uint_t jlen) {
    if (ilen < jlen) { return -1; }
    if (ilen > jlen) { return 1; }

    for (idig += ilen, jdig += ilen; ilen > 0; --ilen) {
        mpz_dbl_dig_signed_t cmp = (mpz_dbl_dig_t)*(--idig) - (mpz_dbl_dig_t)*(--jdig);
        if (cmp < 0) { return -1; }
        if (cmp > 0) { return 1; }
    }

    return 0;
}

/* computes i = j << n
   returns number of digits in i