/**
* Digital Voice Modem - Host Software
* GPLv2 Open Source. Use is subject to license terms.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* @package DVM / Host Software
*
*/
//
// Based on code from the MMDVMHost project. (https://github.com/g4klx/MMDVMHost)
// Licensed under the GPLv2 License (https://opensource.org/licenses/GPL-2.0)
//
/*
*   Copyright (C) 2020 by Jonathan Naylor G4KLX
*   Copyright (C) 2022 by Bryan Biedenkapp N2PLL
*
*   This program is free software; you can redistribute it and/or modify
*   it under the terms of the GNU General Public License as published by
*   the Free Software Foundation; either version 2 of the License, or
*   (at your option) any later version.
*
*   This program is distributed in the hope that it will be useful,
*   but WITHOUT ANY WARRANTY; without even the implied warranty of
*   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
*   GNU General Public License for more details.
*
*   You should have received a copy of the GNU General Public License
*   along with this program; if not, write to the Free Software
*   Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*/
#include "Defines.h"
#include "nxdn/NXDNDefines.h"
#include "nxdn/NXDNUtils.h"

using namespace nxdn;

#include <cstdio>
#include <cassert>

// ---------------------------------------------------------------------------
//  Constants
// ---------------------------------------------------------------------------

const uint8_t SCRAMBLER[] = {
    0x00U, 0x00U, 0x00U, 0x82U, 0xA0U, 0x88U, 0x8AU, 0x00U, 0xA2U, 0xA8U, 0x82U, 0x8AU, 0x82U, 0x02U,
    0x20U, 0x08U, 0x8AU, 0x20U, 0xAAU, 0xA2U, 0x82U, 0x08U, 0x22U, 0x8AU, 0xAAU, 0x08U, 0x28U, 0x88U,
    0x28U, 0x28U, 0x00U, 0x0AU, 0x02U, 0x82U, 0x20U, 0x28U, 0x82U, 0x2AU, 0xAAU, 0x20U, 0x22U, 0x80U,
    0xA8U, 0x8AU, 0x08U, 0xA0U, 0xAAU, 0x02U };

// ---------------------------------------------------------------------------
//  Static Class Members
// ---------------------------------------------------------------------------

/// <summary>
/// Helper to scramble the NXDN frame data.
/// </summary>
/// <param name="data"></param>
void NXDNUtils::scrambler(uint8_t* data)
{
    assert(data != nullptr);

    for (uint32_t i = 0U; i < NXDN_FRAME_LENGTH_BYTES; i++)
        data[i] ^= SCRAMBLER[i];
}
