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Changing metric calculation for Viterbi decoder NXDN

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juribeparada
2018-02-01 11:56:18 -03:00
parent 0f9f24310a
commit 885562539e
4 changed files with 10 additions and 19 deletions
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17
NXDNConvolution.cpp
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@@ -27,12 +27,12 @@ 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 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 uint8_t BRANCH_TABLE1[] = {0U, 0U, 0U, 0U, 2U, 2U, 2U, 2U};
const uint8_t BRANCH_TABLE2[] = {0U, 2U, 2U, 0U, 0U, 2U, 2U, 0U};
const unsigned int NUM_OF_STATES_D2 = 8U;
const unsigned int NUM_OF_STATES = 16U;
const uint32_t M = 2U;
const uint32_t M = 4U;
const unsigned int K = 5U;
CNXDNConvolution::CNXDNConvolution() :
@@ -72,16 +72,7 @@ void CNXDNConvolution::decode(uint8_t s0, uint8_t s1)
for (uint8_t i = 0U; i < NUM_OF_STATES_D2; i++) {
uint8_t j = i * 2U;
uint16_t metric0 = 0;
uint16_t metric1 = 0;
if (s0 != 99U)
metric0 = (BRANCH_TABLE1[i] ^ s0);
if (s1 != 99U)
metric1 = (BRANCH_TABLE2[i] ^ s1);
uint16_t metric = metric0 + metric1;
uint16_t metric = abs(BRANCH_TABLE1[i] - s0) + abs(BRANCH_TABLE2[i] - s1);
uint16_t m0 = m_oldMetrics[i] + metric;
uint16_t m1 = m_oldMetrics[i + NUM_OF_STATES_D2] + (M - metric);