mirror of
https://github.com/ShaYmez/MMDVM_CM.git
synced 2024-12-22 09:10:57 -05:00
142 lines
3.6 KiB
C++
142 lines
3.6 KiB
C++
/*
|
|
* Copyright (C) 2009-2016 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 "YSFConvolution.h"
|
|
|
|
#include <cstdio>
|
|
#include <cassert>
|
|
#include <cstring>
|
|
|
|
const unsigned char BIT_MASK_TABLE[] = {0x80U, 0x40U, 0x20U, 0x10U, 0x08U, 0x04U, 0x02U, 0x01U};
|
|
|
|
#define WRITE_BIT1(p,i,b) p[(i)>>3] = (b) ? (p[(i)>>3] | BIT_MASK_TABLE[(i)&7]) : (p[(i)>>3] & ~BIT_MASK_TABLE[(i)&7])
|
|
#define READ_BIT1(p,i) (p[(i)>>3] & BIT_MASK_TABLE[(i)&7])
|
|
|
|
const uint8_t BRANCH_TABLE1[] = {0U, 0U, 0U, 0U, 1U, 1U, 1U, 1U};
|
|
const uint8_t BRANCH_TABLE2[] = {0U, 1U, 1U, 0U, 0U, 1U, 1U, 0U};
|
|
|
|
const unsigned int NUM_OF_STATES_D2 = 8U;
|
|
const unsigned int NUM_OF_STATES = 16U;
|
|
const uint32_t M = 2U;
|
|
const unsigned int K = 5U;
|
|
|
|
CYSFConvolution::CYSFConvolution() :
|
|
m_metrics1(NULL),
|
|
m_metrics2(NULL),
|
|
m_oldMetrics(NULL),
|
|
m_newMetrics(NULL),
|
|
m_decisions(NULL),
|
|
m_dp(NULL)
|
|
{
|
|
m_metrics1 = new uint16_t[16U];
|
|
m_metrics2 = new uint16_t[16U];
|
|
m_decisions = new uint64_t[180U];
|
|
}
|
|
|
|
CYSFConvolution::~CYSFConvolution()
|
|
{
|
|
delete[] m_metrics1;
|
|
delete[] m_metrics2;
|
|
delete[] m_decisions;
|
|
}
|
|
|
|
void CYSFConvolution::start()
|
|
{
|
|
::memset(m_metrics1, 0x00U, NUM_OF_STATES * sizeof(uint16_t));
|
|
::memset(m_metrics2, 0x00U, NUM_OF_STATES * sizeof(uint16_t));
|
|
|
|
m_oldMetrics = m_metrics1;
|
|
m_newMetrics = m_metrics2;
|
|
m_dp = m_decisions;
|
|
}
|
|
|
|
void CYSFConvolution::decode(uint8_t s0, uint8_t s1)
|
|
{
|
|
*m_dp = 0U;
|
|
|
|
for (uint8_t i = 0U; i < NUM_OF_STATES_D2; i++) {
|
|
uint8_t j = i * 2U;
|
|
|
|
uint16_t metric = (BRANCH_TABLE1[i] ^ s0) + (BRANCH_TABLE2[i] ^ s1);
|
|
|
|
uint16_t m0 = m_oldMetrics[i] + metric;
|
|
uint16_t m1 = m_oldMetrics[i + NUM_OF_STATES_D2] + (M - metric);
|
|
uint8_t decision0 = (m0 >= m1) ? 1U : 0U;
|
|
m_newMetrics[j + 0U] = decision0 != 0U ? m1 : m0;
|
|
|
|
m0 = m_oldMetrics[i] + (M - metric);
|
|
m1 = m_oldMetrics[i + NUM_OF_STATES_D2] + metric;
|
|
uint8_t decision1 = (m0 >= m1) ? 1U : 0U;
|
|
m_newMetrics[j + 1U] = decision1 != 0U ? m1 : m0;
|
|
|
|
*m_dp |= (uint64_t(decision1) << (j + 1U)) | (uint64_t(decision0) << (j + 0U));
|
|
}
|
|
|
|
++m_dp;
|
|
|
|
assert((m_dp - m_decisions) <= 180);
|
|
|
|
uint16_t* tmp = m_oldMetrics;
|
|
m_oldMetrics = m_newMetrics;
|
|
m_newMetrics = tmp;
|
|
}
|
|
|
|
void CYSFConvolution::chainback(unsigned char* out, unsigned int nBits)
|
|
{
|
|
assert(out != NULL);
|
|
|
|
uint32_t state = 0U;
|
|
|
|
while (nBits-- > 0) {
|
|
--m_dp;
|
|
|
|
uint32_t i = state >> (9 - K);
|
|
uint8_t bit = uint8_t(*m_dp >> i) & 1;
|
|
state = (bit << 7) | (state >> 1);
|
|
|
|
WRITE_BIT1(out, nBits, bit != 0U);
|
|
}
|
|
}
|
|
|
|
void CYSFConvolution::encode(const unsigned char* in, unsigned char* out, unsigned int nBits) const
|
|
{
|
|
assert(in != NULL);
|
|
assert(out != NULL);
|
|
assert(nBits > 0U);
|
|
|
|
uint8_t d1 = 0U, d2 = 0U, d3 = 0U, d4 = 0U;
|
|
uint32_t k = 0U;
|
|
for (unsigned int i = 0U; i < nBits; i++) {
|
|
uint8_t d = READ_BIT1(in, i) ? 1U : 0U;
|
|
|
|
uint8_t g1 = (d + d3 + d4) & 1;
|
|
uint8_t g2 = (d + d1 + d2 + d4) & 1;
|
|
|
|
d4 = d3;
|
|
d3 = d2;
|
|
d2 = d1;
|
|
d1 = d;
|
|
|
|
WRITE_BIT1(out, k, g1 != 0U);
|
|
k++;
|
|
|
|
WRITE_BIT1(out, k, g2 != 0U);
|
|
k++;
|
|
}
|
|
}
|