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Decode and encode the System Fusion FICH.

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This commit is contained in:
Jonathan Naylor
2016-02-23 19:30:35 +00:00
parent 6792894c00
commit dc819b8821
10 changed files with 219 additions and 74 deletions
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123
YSFFICH.cpp
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@@ -17,9 +17,11 @@
*/
#include "YSFConvolution.h"
#include "YSFDefines.h"
#include "Golay24128.h"
#include "YSFFICH.h"
#include "CRC.h"
#include "Log.h"
#include <cstdio>
#include <cassert>
@@ -30,7 +32,7 @@ const unsigned char BIT_MASK_TABLE[] = {0x80U, 0x40U, 0x20U, 0x10U, 0x08U, 0x04U
#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 unsigned int INTERLEAVE_TABLE_RX[] = {
const unsigned int INTERLEAVE_TABLE[] = {
0U, 40U, 80U, 120U, 160U,
2U, 42U, 82U, 122U, 162U,
4U, 44U, 84U, 124U, 164U,
@@ -52,32 +54,37 @@ const unsigned int INTERLEAVE_TABLE_RX[] = {
36U, 76U, 116U, 156U, 196U,
38U, 78U, 118U, 158U, 198U};
CYSFFICH::CYSFFICH()
CYSFFICH::CYSFFICH() :
m_fich(NULL)
{
m_fich = new unsigned char[6U];
}
CYSFFICH::~CYSFFICH()
{
delete[] m_fich;
}
bool CYSFFICH::decode(const unsigned char* data, unsigned char* fich) const
bool CYSFFICH::decode(const unsigned char* bytes)
{
assert(data != NULL);
assert(fich != NULL);
assert(bytes != NULL);
// Skip the sync bytes
bytes += YSF_SYNC_LENGTH_BYTES;
CYSFConvolution viterbi;
viterbi.start();
// Deinterleave the FICH and send bits to the Viterbi decoder
for (unsigned int i = 0U; i < 100U; i++) {
unsigned int n = INTERLEAVE_TABLE_RX[i];
unsigned int s0 = READ_BIT1(data, n) ? 1U : 0U;
unsigned int n = INTERLEAVE_TABLE[i];
uint8_t s0 = READ_BIT1(bytes, n) ? 1U : 0U;
n++;
unsigned int s1 = READ_BIT1(data, n) ? 1U : 0U;
uint8_t s1 = READ_BIT1(bytes, n) ? 1U : 0U;
viterbi.decode(s0, s1);
}
}
unsigned char output[13U];
viterbi.chainback(output);
@@ -87,12 +94,96 @@ bool CYSFFICH::decode(const unsigned char* data, unsigned char* fich) const
unsigned int b2 = CGolay24128::decode24128(output + 6U);
unsigned int b3 = CGolay24128::decode24128(output + 9U);
fich[0U] = (b0 >> 16) & 0xFFU;
fich[1U] = ((b0 >> 8) & 0xF0U) | ((b1 >> 20) & 0x0FU);
fich[2U] = (b1 >> 12) & 0xFFU;
fich[3U] = (b2 >> 16) & 0xFFU;
fich[4U] = ((b2 >> 8) & 0xF0U) | ((b3 >> 20) & 0x0FU);
fich[5U] = (b3 >> 12) & 0xFFU;
m_fich[0U] = (b0 >> 4) & 0xFFU;
m_fich[1U] = ((b0 << 4) & 0xF0U) | ((b1 >> 8) & 0x0FU);
m_fich[2U] = (b1 >> 0) & 0xFFU;
m_fich[3U] = (b2 >> 4) & 0xFFU;
m_fich[4U] = ((b2 << 4) & 0xF0U) | ((b3 >> 8) & 0x0FU);
m_fich[5U] = (b3 >> 0) & 0xFFU;
return CCRC::crcFICH(fich);
return CCRC::checkCCITT162(m_fich, 6U);
}
void CYSFFICH::encode(unsigned char* bytes)
{
assert(bytes != NULL);
// Skip the sync bytes
bytes += YSF_SYNC_LENGTH_BYTES;
CCRC::addCCITT162(m_fich, 6U);
unsigned int b0 = ((m_fich[0U] << 4) & 0xFF0U) | ((m_fich[1U] >> 4) & 0x00FU);
unsigned int b1 = ((m_fich[1U] << 8) & 0xF00U) | ((m_fich[2U] >> 0) & 0x0FFU);
unsigned int b2 = ((m_fich[3U] << 4) & 0xFF0U) | ((m_fich[4U] >> 4) & 0x00FU);
unsigned int b3 = ((m_fich[4U] << 8) & 0xF00U) | ((m_fich[5U] >> 0) & 0x0FFU);
unsigned int c0 = CGolay24128::encode24128(b0);
unsigned int c1 = CGolay24128::encode24128(b1);
unsigned int c2 = CGolay24128::encode24128(b2);
unsigned int c3 = CGolay24128::encode24128(b3);
unsigned char conv[13U];
conv[0U] = (c0 >> 16) & 0xFFU;
conv[1U] = (c0 >> 8) & 0xFFU;
conv[2U] = (c0 >> 0) & 0xFFU;
conv[3U] = (c1 >> 16) & 0xFFU;
conv[4U] = (c1 >> 8) & 0xFFU;
conv[5U] = (c1 >> 0) & 0xFFU;
conv[6U] = (c2 >> 16) & 0xFFU;
conv[7U] = (c2 >> 8) & 0xFFU;
conv[8U] = (c2 >> 0) & 0xFFU;
conv[9U] = (c3 >> 16) & 0xFFU;
conv[10U] = (c3 >> 8) & 0xFFU;
conv[11U] = (c3 >> 0) & 0xFFU;
conv[12U] = 0x00U;
CYSFConvolution convolution;
unsigned char convolved[25U];
convolution.encode(conv, convolved, 100U);
unsigned int j = 0U;
for (unsigned int i = 0U; i < 100U; i++) {
unsigned int n = INTERLEAVE_TABLE[i];
bool s0 = READ_BIT1(convolved, j) != 0U;
j++;
bool s1 = READ_BIT1(convolved, j) != 0U;
j++;
WRITE_BIT1(bytes, n, s0);
n++;
WRITE_BIT1(bytes, n, s1);
}
}
unsigned char CYSFFICH::getCM() const
{
return m_fich[0U] & 0x0CU;
}
unsigned char CYSFFICH::getFT() const
{
return m_fich[1U] & 0x07U;
}
unsigned char CYSFFICH::getFN() const
{
return (m_fich[1U] & 0x38U) >> 3;
}
void CYSFFICH::setMR(unsigned char mr)
{
m_fich[2U] &= 0xC7U;
m_fich[2U] |= mr;
}
void CYSFFICH::setVoIP(bool on)
{
if (on)
m_fich[2U] |= 0x04U;
else
m_fich[2U] &= 0xFBU;
}