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dsd-fme_18_05_2023
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Remove Unused OP25 NXDN Trellis Decoder;

This commit is contained in:
lwvmobile 2022-11-23 08:59:56 -05:00
parent 136ed75342
commit 0f227e40c3
1 changed files with 1 additions and 66 deletions
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67
src/nxdn_deperm.c
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@ -1,4 +1,4 @@
//NXDN descramble/deperm/depuncture and utility functions
//NXDN descramble/deperm/depuncture and crc/utility functions
//Reworked portions from Osmocom OP25
/* -*- c++ -*- */
@ -69,8 +69,6 @@ void nxdn_deperm_facch(dsd_opts * opts, dsd_state * state, uint8_t bits[144])
depunc[out++] = deperm[i+2];
}
//trellis_decode(trellis_buf, depunc, 92);
//switch to the convolutional decoder
uint8_t temp[210];
uint8_t s0;
@ -169,8 +167,6 @@ void nxdn_deperm_sacch(dsd_opts * opts, dsd_state * state, uint8_t bits[60])
depunc[o++] = 0;
}
//trellis_decode(trellis_buf, depunc, 32);
//switch to the convolutional decoder
uint8_t temp[90];
uint8_t s0;
@ -337,8 +333,6 @@ void nxdn_deperm_facch2_udch(dsd_opts * opts, dsd_state * state, uint8_t bits[34
depunc[id++] = deperm[i*12+11];
}
//trellis_decode(trellis_buf, depunc, 199);
//switch to the convolutional decoder
uint8_t temp[220];
uint8_t s0;
@ -444,8 +438,6 @@ void nxdn_deperm_cac(dsd_opts * opts, dsd_state * state, uint8_t bits[300])
depunc[id++] = deperm[i*12+11];
}
//trellis_decode(trellis_buf, depunc, 171);
//switch to the convolutional decoder
uint8_t temp[360];
uint8_t s0;
@ -598,13 +590,6 @@ void LFSRN(char * BufferIn, char * BufferOut, dsd_state * state)
state->payload_miN = lfsr & 0x7FFF;
}
//utility functions here, consider moving to its own file later
static inline void cfill(uint8_t result[], const uint8_t src[], int len)
{
for (int i=0; i<len; i++)
result[i] = load_i(src+i*8, 8);
}
static inline int load_i(const uint8_t val[], int len) {
int acc = 0;
for (int i=0; i<len; i++){
@ -613,56 +598,6 @@ static inline int load_i(const uint8_t val[], int len) {
return acc;
}
// trellis_1_2 encode: source is in bits, result in bits
static inline void trellis_encode(uint8_t result[], const uint8_t source[], int result_len, int reg)
{
for (int i=0; i<result_len; i+=2) {
reg = (reg << 1) | source[i>>1];
result[i] = PARITY[reg & 0x19];
result[i+1] = PARITY[reg & 0x17];
}
}
// simplified trellis 2:1 decode; source and result in bits
// assumes that encoding was done with NTEST trailing zero bits
// result_len should be set to the actual number of data bits
// in the original unencoded message (excl. these trailing bits)
static inline void trellis_decode(uint8_t result[], const uint8_t source[], int result_len)
{
int reg = 0;
int min_d;
int min_bt;
static const int NTEST = 4;
static const int NTESTC = 1 << NTEST;
uint8_t bt[NTEST];
uint8_t tt[NTEST*2];
int dstats[4];
int sum;
for (int p=0; p < 4; p++)
dstats[p] = 0;
for (int p=0; p < result_len; p++) {
for (int i=0; i<NTESTC; i++) {
bt[0] = (i&8)>>3;
bt[1] = (i&4)>>2;
bt[2] = (i&2)>>1;
bt[3] = (i&1);
trellis_encode(tt, bt, NTEST*2, reg);
sum=0;
for (int j=0; j<NTEST*2; j++) {
sum += tt[j] ^ source[p*2+j];
}
if (i == 0 || sum < min_d) {
min_d = sum;
min_bt = bt[0];
}
}
result[p] = min_bt;
reg = (reg << 1) | min_bt;
dstats[(min_d > 3) ? 3 : min_d] += 1;
}
// fprintf (stderr, "stats\t%d %d %d %d\n", dstats[0], dstats[1], dstats[2], dstats[3]);
}
static uint8_t crc6(const uint8_t buf[], int len)
{
uint8_t s[6];