/*
    Copyright (C) 2008, 2009 William Hart.
    Copyright (C) 2008, Richard Howell-Peak
    Copyright (C) 2008, Martin Albrecht
    Copyright (C) 2010, Fredrik Johansson

    This file is part of FLINT.

    FLINT is free software: you can redistribute it and/or modify it under
    the terms of the GNU Lesser General Public License (LGPL) as published
    by the Free Software Foundation; either version 2.1 of the License, or
    (at your option) any later version.  See <https://www.gnu.org/licenses/>.
*/

#include <stdlib.h>
#include <gmp.h>
#include "flint.h"
#include "nmod_mat.h"

void
nmod_mat_window_init(nmod_mat_t window, const nmod_mat_t mat,
    slong r1, slong c1, slong r2, slong c2)
{
    slong i;
    window->entries = NULL;

    if (r2 > r1)
        window->rows = (mp_limb_t **) flint_malloc((r2 - r1) * sizeof(mp_limb_t *));
    else
        window->rows = NULL;

    if (mat->c > 0)
    {
        for (i = 0; i < r2 - r1; i++)
            window->rows[i] = mat->rows[r1 + i] + c1;
    } else
    {
        for (i = 0; i < r2 - r1; i++)
            window->rows[i] = NULL;
    }

    window->r = r2 - r1;
    window->c = c2 - c1;
    window->mod = mat->mod;
}