MMDVMHost-Private/P25LowSpeedData.cpp

/*
*   Copyright (C) 2016 by Jonathan Naylor G4KLX
*
*   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 "P25LowSpeedData.h"
#include "P25Utils.h"

#include <cstdio>
#include <cassert>

const unsigned char CCS_PARITY[] = {
	0x00U, 0x39U, 0x72U, 0x4BU, 0xE4U, 0xDDU, 0x96U, 0xAFU, 0xF1U, 0xC8U, 0x83U, 0xBAU, 0x15U, 0x2CU, 0x67U, 0x5EU,
	0xDBU, 0xE2U, 0xA9U, 0x90U, 0x3FU, 0x06U, 0x4DU, 0x74U, 0x2AU, 0x13U, 0x58U, 0x61U, 0xCEU, 0xF7U, 0xBCU, 0x85U,
	0x8FU, 0xB6U, 0xFDU, 0xC4U, 0x6BU, 0x52U, 0x19U, 0x20U, 0x7EU, 0x47U, 0x0CU, 0x35U, 0x9AU, 0xA3U, 0xE8U, 0xD1U,
	0x54U, 0x6DU, 0x26U, 0x1FU, 0xB0U, 0x89U, 0xC2U, 0xFBU, 0xA5U, 0x9CU, 0xD7U, 0xEEU, 0x41U, 0x78U, 0x33U, 0x0AU,
	0x27U, 0x1EU, 0x55U, 0x6CU, 0xC3U, 0xFAU, 0xB1U, 0x88U, 0xD6U, 0xEFU, 0xA4U, 0x9DU, 0x32U, 0x0BU, 0x40U, 0x79U,
	0xFCU, 0xC5U, 0x8EU, 0xB7U, 0x18U, 0x21U, 0x6AU, 0x53U, 0x0DU, 0x34U, 0x7FU, 0x46U, 0xE9U, 0xD0U, 0x9BU, 0xA2U,
	0xA8U, 0x91U, 0xDAU, 0xE3U, 0x4CU, 0x75U, 0x3EU, 0x07U, 0x59U, 0x60U, 0x2BU, 0x12U, 0xBDU, 0x84U, 0xCFU, 0xF6U,
	0x73U, 0x4AU, 0x01U, 0x38U, 0x97U, 0xAEU, 0xE5U, 0xDCU, 0x82U, 0xBBU, 0xF0U, 0xC9U, 0x66U, 0x5FU, 0x14U, 0x2DU,
	0x4EU, 0x77U, 0x3CU, 0x05U, 0xAAU, 0x93U, 0xD8U, 0xE1U, 0xBFU, 0x86U, 0xCDU, 0xF4U, 0x5BU, 0x62U, 0x29U, 0x10U,
	0x95U, 0xACU, 0xE7U, 0xDEU, 0x71U, 0x48U, 0x03U, 0x3AU, 0x64U, 0x5DU, 0x16U, 0x2FU, 0x80U, 0xB9U, 0xF2U, 0xCBU,
	0xC1U, 0xF8U, 0xB3U, 0x8AU, 0x25U, 0x1CU, 0x57U, 0x6EU, 0x30U, 0x09U, 0x42U, 0x7BU, 0xD4U, 0xEDU, 0xA6U, 0x9FU,
	0x1AU, 0x23U, 0x68U, 0x51U, 0xFEU, 0xC7U, 0x8CU, 0xB5U, 0xEBU, 0xD2U, 0x99U, 0xA0U, 0x0FU, 0x36U, 0x7DU, 0x44U,
	0x69U, 0x50U, 0x1BU, 0x22U, 0x8DU, 0xB4U, 0xFFU, 0xC6U, 0x98U, 0xA1U, 0xEAU, 0xD3U, 0x7CU, 0x45U, 0x0EU, 0x37U,
	0xB2U, 0x8BU, 0xC0U, 0xF9U, 0x56U, 0x6FU, 0x24U, 0x1DU, 0x43U, 0x7AU, 0x31U, 0x08U, 0xA7U, 0x9EU, 0xD5U, 0xECU,
	0xE6U, 0xDFU, 0x94U, 0xADU, 0x02U, 0x3BU, 0x70U, 0x49U, 0x17U, 0x2EU, 0x65U, 0x5CU, 0xF3U, 0xCAU, 0x81U, 0xB8U,
	0x3DU, 0x04U, 0x4FU, 0x76U, 0xD9U, 0xE0U, 0xABU, 0x92U, 0xCCU, 0xF5U, 0xBEU, 0x87U, 0x28U, 0x11U, 0x5AU, 0x63U};
	
const unsigned int MAX_CCS_ERRS = 4U;

CP25LowSpeedData::CP25LowSpeedData() :
m_lsd1(0x00U),
m_lsd2(0x00U)
{
}

CP25LowSpeedData::~CP25LowSpeedData()
{
}

void CP25LowSpeedData::process(unsigned char* data)
{
	assert(data != NULL);

	unsigned char lsd[4U];
	CP25Utils::decode(data, lsd, 1546U, 1578U);

	for (unsigned int a = 0x00U; a < 0x100U; a++) {
		unsigned char ccs[2U];
		ccs[0U] = a;
		ccs[1U] = encode(ccs[0U]);

		unsigned int errs = CP25Utils::compare(ccs, lsd + 0U, 2U);
		if (errs < MAX_CCS_ERRS) {
			lsd[0U] = ccs[0U];
			lsd[1U] = ccs[1U];
			break;
		}
	}

	for (unsigned int a = 0x00U; a < 0x100U; a++) {
		unsigned char ccs[2U];
		ccs[0U] = a;
		ccs[1U] = encode(ccs[0U]);

		unsigned int errs = CP25Utils::compare(ccs, lsd + 2U, 2U);
		if (errs < MAX_CCS_ERRS) {
			lsd[2U] = ccs[0U];
			lsd[3U] = ccs[1U];
			break;
		}
	}

	m_lsd1 = lsd[0U];
	m_lsd2 = lsd[2U];

	CP25Utils::encode(lsd, data, 1546U, 1578U);
}

void CP25LowSpeedData::encode(unsigned char* data) const
{
	assert(data != NULL);

	unsigned char lsd[4U];
	lsd[0U] = m_lsd1;
	lsd[1U] = encode(m_lsd1);
	lsd[2U] = m_lsd2;
	lsd[3U] = encode(m_lsd2);

	CP25Utils::encode(lsd, data, 1546U, 1578U);
}

unsigned char CP25LowSpeedData::getLSD1() const
{
	return m_lsd1;
}

void CP25LowSpeedData::setLSD1(unsigned char lsd1)
{
	m_lsd1 = lsd1;
}

unsigned char CP25LowSpeedData::getLSD2() const
{
	return m_lsd2;
}

void CP25LowSpeedData::setLSD2(unsigned char lsd2)
{
	m_lsd2 = lsd2;
}

unsigned char CP25LowSpeedData::encode(unsigned char in) const
{
	return CCS_PARITY[in];
}