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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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71
YSFConvolution.cpp
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@@ -29,8 +29,8 @@ 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 char BRANCH_TABLE1[] = {0U, 0U, 0U, 0U, 1U, 1U, 1U, 1U};
const unsigned char BRANCH_TABLE2[] = {0U, 1U, 1U, 0U, 0U, 1U, 1U, 0U};
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};
CYSFConvolution::CYSFConvolution() :
m_metrics1(NULL),
@@ -40,9 +40,9 @@ m_newMetrics(NULL),
m_decisions(NULL),
m_dp(NULL)
{
m_metrics1 = new unsigned short[16U];
m_metrics2 = new unsigned short[16U];
m_decisions = new unsigned long long[100U];
m_metrics1 = new uint16_t[16U];
m_metrics2 = new uint16_t[16U];
m_decisions = new uint64_t[100U];
}
CYSFConvolution::~CYSFConvolution()
@@ -54,44 +54,44 @@ CYSFConvolution::~CYSFConvolution()
const unsigned int NUM_OF_STATES_D2 = 8U;
const unsigned int NUM_OF_STATES = 16U;
const unsigned int M = 3U;
const uint32_t M = 3U;
const unsigned int K = 5U;
void CYSFConvolution::start()
{
::memset(m_metrics1, 0x00U, NUM_OF_STATES * sizeof(unsigned short));
::memset(m_metrics2, 0x00U, NUM_OF_STATES * sizeof(unsigned short));
::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(unsigned char s0, unsigned char s1)
void CYSFConvolution::decode(uint8_t s0, uint8_t s1)
{
*m_dp = 0U;
for (unsigned int i = 0U; i < NUM_OF_STATES_D2; i++) {
unsigned int j = i * 2U;
for (uint8_t i = 0U; i < NUM_OF_STATES_D2; i++) {
uint8_t j = i * 2U;
unsigned short metric = (BRANCH_TABLE1[i] ^ s0) + (BRANCH_TABLE2[i] ^ s1);
uint16_t metric = (BRANCH_TABLE1[i] ^ s0) + (BRANCH_TABLE2[i] ^ s1);
unsigned short m0 = m_oldMetrics[i] + metric;
unsigned short m1 = m_oldMetrics[i + NUM_OF_STATES_D2] + (M - metric);
unsigned char decision0 = (m0 >= m1) ? 1U : 0U;
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;
unsigned char decision1 = (m0 >= m1) ? 1U : 0U;
uint8_t decision1 = (m0 >= m1) ? 1U : 0U;
m_newMetrics[j + 1U] = decision1 != 0U ? m1 : m0;
*m_dp |= ((unsigned long long)(decision1) << (j + 1U)) | ((unsigned long long)(decision0) << (j + 0U));
*m_dp |= (uint64_t(decision1) << (j + 1U)) | (uint64_t(decision0) << (j + 0U));
}
++m_dp;
unsigned short* tmp = m_oldMetrics;
uint16_t* tmp = m_oldMetrics;
m_oldMetrics = m_newMetrics;
m_newMetrics = tmp;
}
@@ -100,16 +100,43 @@ void CYSFConvolution::chainback(unsigned char* out)
{
assert(out != NULL);
unsigned int state = 0U;
uint32_t state = 0U;
unsigned char nbits = 96U;
uint8_t nbits = 96U;
while (nbits-- > 0) {
--m_dp;
unsigned int i = state >> (9 - K);
unsigned char bit = (unsigned char)(*m_dp >> i) & 1;
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++;
}
}