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viterbi.cpp
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1173 lines (960 loc) · 46 KB
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/*
* viterbi.c -- viterbi encoder/decoder + PRIMITIVE Interleaver
*
* Created: 2017-04-03 8:34:15
* Author: seobi
*/
#include "viterbi.h"
#define PRIMITIVE_ROOT 31
#define FEC_PRIMITIVE_BIT_LEN (NBYTE_DIVISION*8*2)
#define FEC_PRIMITIVE_LAST_BIT_LEN ((NBYTE_LAST_DIVISION*8+(CONSTRAINT_LEN_K-1))*2)
#if CONSTRAINT_LEN_K == 3
#define V27POLYA 0x07
#define V27POLYB 0x05
#elif CONSTRAINT_LEN_K == 4
#define V27POLYA 0x0F
#define V27POLYB 0x0B
#elif CONSTRAINT_LEN_K == 5 //0x17, 0x19 | 0x13, 0x1b
#define V27POLYA 0x13
#define V27POLYB 0x1b
#else
#error not support CONSTRAINT_LEN_K
#endif
/*
*******************************************************************************
* constants and define declarations
*******************************************************************************
*/
typedef union { unsigned long w[2]; } decision_t;
unsigned int metric_array[2][2][(1<<(CONSTRAINT_LEN_K-2))];// ={{{0,15,8,8},{8,8,15,0}},{{8,8,0,15},{15,0,8,8}}};
/* State info for instance of Viterbi decoder
*/
struct viterbi_Info {
decision_t *dp; /* Pointer to decision output for current bit */
unsigned int *old_metrics,*new_metrics,*temp_metrics; /* Pointers to path metrics, swapped on every bit */
decision_t decisions[(N_FULL_BITS+(CONSTRAINT_LEN_K-1))]; /* Beginning of decisions for block */
unsigned int metrics1[1<<(CONSTRAINT_LEN_K-1)]; /* path metric buffer 1 */
unsigned int metrics2[1<<(CONSTRAINT_LEN_K-1)]; /* path metric buffer 2 */
};
typedef struct _interleaver_info {
unsigned int nInterleaver_byte_idx;
unsigned int nInterleaver_bit_idx;
}interleaver_info;
interleaver_info g_interleaver_info[FEC_PRIMITIVE_BIT_LEN];
interleaver_info g_interleaver_last_info[FEC_PRIMITIVE_LAST_BIT_LEN];
/* 8-bit parity lookup table */
unsigned int Partab[256];
int P_init = 0;
int g_chainback_cnt = 0;
int g_encstate = 0;
int g_symbol_frame_idx = 0;
unsigned char symbol_frame_1[TMP_HDR_SIZE+FEC_SYMBOL_LEN];
unsigned char symbol_frame_2[TMP_HDR_SIZE+FEC_SYMBOL_LEN];
unsigned char symbol_frame_double[TMP_HDR_SIZE+(FEC_SYMBOL_LEN*2)];
struct viterbi_Info g_vInfo;
/*
*******************************************************************************
* local object definition
*******************************************************************************
*/
/* Create 256-entry odd-parity lookup table
* Needed only on non-ia32 machines
*/
static void partab_init(void){
int i,cnt,ti;
/* Initialize parity lookup table */
for(i=0;i<256;i++){
cnt = 0;
ti = i;
while(ti){
if(ti & 1)
cnt++;
ti >>= 1;
}
Partab[i] = cnt & 1;
}
P_init=1;
}
static int parity(int x)
{
if(!P_init)
partab_init();
/* Fold down to one byte */
x ^= (x >> 16);
x ^= (x >> 8);
return Partab[x];
}
static void create_viterbi(void)
{
struct viterbi_Info *vp = &g_vInfo;
unsigned int Branchtab_1[(1<<(CONSTRAINT_LEN_K-2))];
unsigned int Branchtab_2[(1<<(CONSTRAINT_LEN_K-2))];
int state, i, j;
/* Initialize metric tables */
for(state=0;state < (1<<(CONSTRAINT_LEN_K-2));state++){
Branchtab_1[state] = parity((2*state) & V27POLYA) ? 15:0;
Branchtab_2[state] = parity((2*state) & V27POLYB) ? 15:0;
}
for(i=0;i<2;i++){
for(j=0;j<2;j++){
for(state=0;state < (1<<(CONSTRAINT_LEN_K-2));state++){
metric_array[i][j][state] = ((Branchtab_1[state] ^ i*0x0F) + (Branchtab_2[state] ^ j*0x0F) + 1)>>1;
}
}
}
vp->dp = vp->decisions;
vp->old_metrics = vp->metrics1;
vp->new_metrics = vp->metrics2;
}
/* Do Viterbi chainback */
static inline void chainback_viterbi(
unsigned char *data, /* Decoded output data */
unsigned int nbits /* Number of data bits */ )
{ /* Terminal encoder state */
register unsigned int k, n_frame_bit, n_frame_end_bit;
decision_t *decisions = (decision_t *)(g_vInfo.decisions);
unsigned int endstate = 0;
/* Make room beyond the end of the encoder register so we can
* accumulate a full byte of decoded data
*/
if( nbits != N_FULL_BITS ){
g_chainback_cnt ++;
if( g_chainback_cnt > 1 ){
n_frame_bit = nbits * g_chainback_cnt;
n_frame_end_bit = n_frame_bit - nbits - 8;
}
else{
n_frame_bit = nbits;
n_frame_end_bit = 0;
}
}else{
n_frame_bit = nbits;
n_frame_end_bit = n_frame_bit - N_LAST_BITS - 8;
}
// endstate %= (1<<(CONSTRAINT_LEN_K-1));
// endstate <<= 2;
decisions += (CONSTRAINT_LEN_K-1); /* Look past tail */
while(n_frame_bit != n_frame_end_bit){
#if CONSTRAINT_LEN_K == 5
/* The store into data[] only needs to be done every 8 bits.
* But this avoids a conditional branch, and the writes will
* combine in the cache anyway
*/
k = ((decisions[n_frame_bit-1].w[endstate >> 7] >> ((endstate >> 4)&15)) & 1);
data[(n_frame_bit-1)>>3] = endstate = (endstate >> 1) | (k<<7);
k = ((decisions[n_frame_bit-2].w[endstate >> 7] >> ((endstate >> 4)&15)) & 1);
data[(n_frame_bit-2)>>3] = endstate = (endstate >> 1) | (k<<7);
k = ((decisions[n_frame_bit-3].w[endstate >> 7] >> ((endstate >> 4)&15)) & 1);
data[(n_frame_bit-3)>>3] = endstate = (endstate >> 1) | (k<<7);
k = ((decisions[n_frame_bit-4].w[endstate >> 7] >> ((endstate >> 4)&15)) & 1);
data[(n_frame_bit-4)>>3] = endstate = (endstate >> 1) | (k<<7);
k = ((decisions[n_frame_bit-5].w[endstate >> 7] >> ((endstate >> 4)&15)) & 1);
data[(n_frame_bit-5)>>3] = endstate = (endstate >> 1) | (k<<7);
k = ((decisions[n_frame_bit-6].w[endstate >> 7] >> ((endstate >> 4)&15)) & 1);
data[(n_frame_bit-6)>>3] = endstate = (endstate >> 1) | (k<<7);
k = ((decisions[n_frame_bit-7].w[endstate >> 7] >> ((endstate >> 4)&15)) & 1);
data[(n_frame_bit-7)>>3] = endstate = (endstate >> 1) | (k<<7);
k = ((decisions[n_frame_bit-8].w[endstate >> 7] >> ((endstate >> 4)&15)) & 1);
data[(n_frame_bit-8)>>3] = endstate = (endstate >> 1) | (k<<7);
n_frame_bit-=8;
#elif CONSTRAINT_LEN_K == 4
/* The store into data[] only needs to be done every 8 bits.
* But this avoids a conditional branch, and the writes will
* combine in the cache anyway
*/
k = ((decisions[n_frame_bit-1].w[endstate >> 7] >> ((endstate >> 5)&7)) & 1);
data[(n_frame_bit-1)>>3] = endstate = (endstate >> 1) | (k<<7);
k = ((decisions[n_frame_bit-2].w[endstate >> 7] >> ((endstate >> 5)&7)) & 1);
data[(n_frame_bit-2)>>3] = endstate = (endstate >> 1) | (k<<7);
k = ((decisions[n_frame_bit-3].w[endstate >> 7] >> ((endstate >> 5)&7)) & 1);
data[(n_frame_bit-3)>>3] = endstate = (endstate >> 1) | (k<<7);
k = ((decisions[n_frame_bit-4].w[endstate >> 7] >> ((endstate >> 5)&7)) & 1);
data[(n_frame_bit-4)>>3] = endstate = (endstate >> 1) | (k<<7);
k = ((decisions[n_frame_bit-5].w[endstate >> 7] >> ((endstate >> 5)&7)) & 1);
data[(n_frame_bit-5)>>3] = endstate = (endstate >> 1) | (k<<7);
k = ((decisions[n_frame_bit-6].w[endstate >> 7] >> ((endstate >> 5)&7)) & 1);
data[(n_frame_bit-6)>>3] = endstate = (endstate >> 1) | (k<<7);
k = ((decisions[n_frame_bit-7].w[endstate >> 7] >> ((endstate >> 5)&7)) & 1);
data[(n_frame_bit-7)>>3] = endstate = (endstate >> 1) | (k<<7);
k = ((decisions[n_frame_bit-8].w[endstate >> 7] >> ((endstate >> 5)&7)) & 1);
data[(n_frame_bit-8)>>3] = endstate = (endstate >> 1) | (k<<7);
n_frame_bit-=8;
#elif CONSTRAINT_LEN_K == 3
/* The store into data[] only needs to be done every 8 bits.
* But this avoids a conditional branch, and the writes will
* combine in the cache anyway
*/
k = ((decisions[n_frame_bit-1].w[endstate >> 7] >> ((endstate >> 6)&3)) & 1);
data[(n_frame_bit-1)>>3] = endstate = (endstate >> 1) | (k<<7);
k = ((decisions[n_frame_bit-2].w[endstate >> 7] >> ((endstate >> 6)&3)) & 1);
data[(n_frame_bit-2)>>3] = endstate = (endstate >> 1) | (k<<7);
k = ((decisions[n_frame_bit-3].w[endstate >> 7] >> ((endstate >> 6)&3)) & 1);
data[(n_frame_bit-3)>>3] = endstate = (endstate >> 1) | (k<<7);
k = ((decisions[n_frame_bit-4].w[endstate >> 7] >> ((endstate >> 6)&3)) & 1);
data[(n_frame_bit-4)>>3] = endstate = (endstate >> 1) | (k<<7);
k = ((decisions[n_frame_bit-5].w[endstate >> 7] >> ((endstate >> 6)&3)) & 1);
data[(n_frame_bit-5)>>3] = endstate = (endstate >> 1) | (k<<7);
k = ((decisions[n_frame_bit-6].w[endstate >> 7] >> ((endstate >> 6)&3)) & 1);
data[(n_frame_bit-6)>>3] = endstate = (endstate >> 1) | (k<<7);
k = ((decisions[n_frame_bit-7].w[endstate >> 7] >> ((endstate >> 6)&3)) & 1);
data[(n_frame_bit-7)>>3] = endstate = (endstate >> 1) | (k<<7);
k = ((decisions[n_frame_bit-8].w[endstate >> 7] >> ((endstate >> 6)&3)) & 1);
data[(n_frame_bit-8)>>3] = endstate = (endstate >> 1) | (k<<7);
n_frame_bit-=8;
#else
#error not support CONSTRAINT_LEN_K
#endif
}
return;
}
//unsigned int g_sym1 = 0;
//unsigned int g_sym2 = 0;
/* C-language butterfly */
#if CONSTRAINT_LEN_K==5
#define BFLY0() \
metric = metric_array[g_sym1][g_sym2][0];\
m0 = g_vInfo.old_metrics[0] + metric;\
m1 = g_vInfo.old_metrics[8] + (15 - metric);\
decision1 = (m0-m1) >= 0;\
g_vInfo.new_metrics[0] = decision1 ? m1 : m0;\
m0 -= (metric+metric-15);\
m1 += (metric+metric-15);\
decision2 = (m0-m1) >= 0;\
g_vInfo.new_metrics[1] = decision2 ? m1 : m0;
#define BFLY1() \
metric = metric_array[g_sym1][g_sym2][1];\
m0 = g_vInfo.old_metrics[1] + metric;\
m1 = g_vInfo.old_metrics[9] + (15 - metric);\
decision3 = (m0-m1) >= 0;\
g_vInfo.new_metrics[2] = decision3 ? m1 : m0;\
m0 -= (metric+metric-15);\
m1 += (metric+metric-15);\
decision4 = (m0-m1) >= 0;\
g_vInfo.new_metrics[3] = decision4 ? m1 : m0;
#define BFLY2() \
metric = metric_array[g_sym1][g_sym2][2];\
m0 = g_vInfo.old_metrics[2] + metric;\
m1 = g_vInfo.old_metrics[10] + (15 - metric);\
decision5 = (m0-m1) >= 0;\
g_vInfo.new_metrics[4] = decision5 ? m1 : m0;\
m0 -= (metric+metric-15);\
m1 += (metric+metric-15);\
decision6 = (m0-m1) >= 0;\
g_vInfo.new_metrics[5] = decision6 ? m1 : m0;
#define BFLY3() \
metric = metric_array[g_sym1][g_sym2][3];\
m0 = g_vInfo.old_metrics[3] + metric;\
m1 = g_vInfo.old_metrics[11] + (15 - metric);\
decision7 = (m0-m1) >= 0;\
g_vInfo.new_metrics[6] = decision7 ? m1 : m0;\
m0 -= (metric+metric-15);\
m1 += (metric+metric-15);\
decision8 = (m0-m1) >= 0;\
g_vInfo.new_metrics[7] = decision8 ? m1 : m0;\
g_vInfo.dp->w[0] = (decision1 | decision2 << 1 | decision3 << 2 | decision4 << 3 | decision5<<4 | decision6 << 5 | decision7 << 6 | decision8 << 7);
#define BFLY4() \
metric = metric_array[g_sym1][g_sym2][4];\
m0 = g_vInfo.old_metrics[4] + metric;\
m1 = g_vInfo.old_metrics[12] + (15 - metric);\
decision1 = (m0-m1) >= 0;\
g_vInfo.new_metrics[8] = decision1 ? m1 : m0;\
m0 -= (metric+metric-15);\
m1 += (metric+metric-15);\
decision2 = (m0-m1) >= 0;\
g_vInfo.new_metrics[9] = decision2 ? m1 : m0;
#define BFLY5() \
metric = metric_array[g_sym1][g_sym2][5];\
m0 = g_vInfo.old_metrics[5] + metric;\
m1 = g_vInfo.old_metrics[13] + (15 - metric);\
decision3 = (m0-m1) >= 0;\
g_vInfo.new_metrics[10] = decision3 ? m1 : m0;\
m0 -= (metric+metric-15);\
m1 += (metric+metric-15);\
decision4 = (m0-m1) >= 0;\
g_vInfo.new_metrics[11] = decision4 ? m1 : m0;
#define BFLY6() \
metric = metric_array[g_sym1][g_sym2][6];\
m0 = g_vInfo.old_metrics[6] + metric;\
m1 = g_vInfo.old_metrics[14] + (15 - metric);\
decision5 = (m0-m1) >= 0;\
g_vInfo.new_metrics[12] = decision5 ? m1 : m0;\
m0 -= (metric+metric-15);\
m1 += (metric+metric-15);\
decision6 = (m0-m1) >= 0;\
g_vInfo.new_metrics[13] = decision6 ? m1 : m0;
#define BFLY7() \
metric = metric_array[g_sym1][g_sym2][7];\
m0 = g_vInfo.old_metrics[7] + metric;\
m1 = g_vInfo.old_metrics[15] + (15 - metric);\
decision7 = (m0-m1) >= 0;\
g_vInfo.new_metrics[14] = decision7 ? m1 : m0;\
m0 -= (metric+metric-15);\
m1 += (metric+metric-15);\
decision8 = (m0-m1) >= 0;\
g_vInfo.new_metrics[15] = decision8 ? m1 : m0;\
g_vInfo.dp->w[1] = (decision1<<8 | decision2 << 9 | decision3 << 10 | decision4 << 11 | decision5<<12 | decision6 << 13 | decision7 << 14 | decision8 << 15);
#define update_viterbi() \
BFLY0();\
BFLY1();\
BFLY2();\
BFLY3();\
BFLY4();\
BFLY5();\
BFLY6();\
BFLY7();\
if(g_vInfo.new_metrics[0] > 150){\
unsigned char minmetric = 255;\
for(k=0;k<(1<<(CONSTRAINT_LEN_K-1));k++)\
if(g_vInfo.new_metrics[k] < minmetric)\
minmetric = g_vInfo.new_metrics[k];\
for(k=0;k<(1<<(CONSTRAINT_LEN_K-1));k++)\
g_vInfo.new_metrics[k] -= minmetric;\
}\
g_vInfo.dp++;\
g_vInfo.temp_metrics = g_vInfo.old_metrics;\
g_vInfo.old_metrics = g_vInfo.new_metrics;\
g_vInfo.new_metrics = g_vInfo.temp_metrics;
#elif CONSTRAINT_LEN_K == 4
#define BFLY0() \
metric = metric_array[g_sym1][g_sym2][0];\
m0 = g_vInfo.old_metrics[0] + metric;\
m1 = g_vInfo.old_metrics[4] + 15 - metric;\
decision1 = (m0-m1) >= 0;\
g_vInfo.new_metrics[0] = decision1 ? m1 : m0;\
m0 -= (metric+metric-15);\
m1 += (metric+metric-15);\
decision2 = (m0-m1) >= 0;\
g_vInfo.new_metrics[1] = decision2 ? m1 : m0;
#define BFLY1() \
metric = metric_array[g_sym1][g_sym2][1];\
m0 = g_vInfo.old_metrics[1] + metric;\
m1 = g_vInfo.old_metrics[5] + 15 - metric;\
decision3 = (m0-m1) >= 0;\
g_vInfo.new_metrics[2] = decision3 ? m1 : m0;\
m0 -= (metric+metric-15);\
m1 += (metric+metric-15);\
decision4 = (m0-m1) >= 0;\
g_vInfo.new_metrics[3] = decision4 ? m1 : m0;\
g_vInfo.dp->w[0] = (decision1 | decision2 << 1 | decision3 << 2 | decision4 << 3);
#define BFLY2() \
metric = metric_array[g_sym1][g_sym2][2];\
m0 = g_vInfo.old_metrics[2] + metric;\
m1 = g_vInfo.old_metrics[6] + 15 - metric;\
decision1 = (m0-m1) >= 0;\
g_vInfo.new_metrics[4] = decision1 ? m1 : m0;\
m0 -= (metric+metric-15);\
m1 += (metric+metric-15);\
decision2 = (m0-m1) >= 0;\
g_vInfo.new_metrics[5] = decision2 ? m1 : m0;
#define BFLY3() \
metric = metric_array[g_sym1][g_sym2][3];\
m0 = g_vInfo.old_metrics[3] + metric;\
m1 = g_vInfo.old_metrics[7] + 15 - metric;\
decision3 = (m0-m1) >= 0;\
g_vInfo.new_metrics[6] = decision3 ? m1 : m0;\
m0 -= (metric+metric-15);\
m1 += (metric+metric-15);\
decision4 = (m0-m1) >= 0;\
g_vInfo.new_metrics[7] = decision4 ? m1 : m0;\
g_vInfo.dp->w[1] = (decision1<<4 | decision2 << 5 | decision3 << 6 | decision4 << 7);
// update_viterbi : 2.62us
#define update_viterbi() \
BFLY0();\
BFLY1();\
BFLY2();\
BFLY3();\
if(g_vInfo.new_metrics[0] > 150){\
unsigned char minmetric = 255;\
for(k=0;k<8;k++)\
if(g_vInfo.new_metrics[k] < minmetric)\
minmetric = g_vInfo.new_metrics[k];\
for(k=0;k<8;k++)\
g_vInfo.new_metrics[k] -= minmetric;\
}\
g_vInfo.dp++;\
g_vInfo.temp_metrics = g_vInfo.old_metrics;\
g_vInfo.old_metrics = g_vInfo.new_metrics;\
g_vInfo.new_metrics = g_vInfo.temp_metrics;
#elif CONSTRAINT_LEN_K == 3
#define BFLY0() \
metric = metric_array[g_sym1][g_sym2][0];\
m0 = g_vInfo.old_metrics[0] + metric;\
m1 = g_vInfo.old_metrics[2] + (15 - metric);\
decision1 = (m0-m1) >= 0;\
g_vInfo.new_metrics[0] = decision1 ? m1 : m0;\
m0 -= (metric+metric-15);\
m1 += (metric+metric-15);\
decision2 = (m0-m1) >= 0;\
g_vInfo.new_metrics[1] = decision2 ? m1 : m0;\
g_vInfo.dp->w[0] = (decision1 | decision2 << 1);
#define BFLY1() \
metric = metric_array[g_sym1][g_sym2][1];\
m0 = g_vInfo.old_metrics[1] + metric;\
m1 = g_vInfo.old_metrics[3] + (15 - metric);\
decision1 = (m0-m1) >= 0;\
g_vInfo.new_metrics[2] = decision1 ? m1 : m0;\
m0 -= (metric+metric-15);\
m1 += (metric+metric-15);\
decision2 = (m0-m1) >= 0;\
g_vInfo.new_metrics[3] = decision2 ? m1 : m0;\
g_vInfo.dp->w[1] = (decision1<<2 | decision2 << 3);
#define update_viterbi() \
BFLY0();\
BFLY1();\
if(g_vInfo.new_metrics[0] > 150){\
unsigned char minmetric = 255;\
for(k=0;k<4;k++)\
if(g_vInfo.new_metrics[k] < minmetric)\
minmetric = g_vInfo.new_metrics[k];\
for(k=0;k<4;k++)\
g_vInfo.new_metrics[k] -= minmetric;\
}\
g_vInfo.dp++;\
g_vInfo.temp_metrics = g_vInfo.old_metrics;\
g_vInfo.old_metrics = g_vInfo.new_metrics;\
g_vInfo.new_metrics = g_vInfo.temp_metrics;
#else
#error not support CONSTRAINT_LEN_K
#endif
/* Initialize Viterbi decoder for start of new frame */
void init_fec_decode( void )
{
register int i;
for(i=0;i<1<<(CONSTRAINT_LEN_K-1);i++)
g_vInfo.metrics1[i] = 60;
g_vInfo.old_metrics = g_vInfo.metrics1;
g_vInfo.new_metrics = g_vInfo.metrics2;
g_vInfo.dp = g_vInfo.decisions;
g_vInfo.old_metrics[0] = 0;
g_chainback_cnt = 0;
}
/*
*******************************************************************************
* description:
* decode_fec : decoding main function + PRIMITIVE Interleaver + Data Chainback
* input:
* unsigned char *data : decoded data (OUT)
* unsigned char *symbols : viterbi encoded symbols data (IN)
* output:
* none
*
* 12(24) :: 166us , 1/2 coderate, K=4
*
* function reference:
* author:
* seobi, 2017-04-03 created
*******************************************************************************
*/
void decode_fec( unsigned char *data, /* Decoded output data */
unsigned char *symbols /* Raw deinterleaved input symbols */ )
{
register unsigned int g_sym1, g_sym2;
register unsigned int metric;
#if CONSTRAINT_LEN_K == 4
unsigned int decision1, decision2, decision3, decision4;
#elif CONSTRAINT_LEN_K == 3
unsigned int decision1, decision2;
#else
unsigned int decision1, decision2, decision3, decision4, decision5, decision6, decision7, decision8;
#endif
int m0, m1;
int k, i = 0;
/* Decode block */
do
{
g_sym1 = (symbols[g_interleaver_info[i].nInterleaver_byte_idx] & g_interleaver_info[i].nInterleaver_bit_idx) != 0; // ? 15 : 0;
g_sym2 = (symbols[g_interleaver_info[i+1].nInterleaver_byte_idx] & g_interleaver_info[i+1].nInterleaver_bit_idx) != 0; // ? 15 : 0;
update_viterbi();
g_sym1 = (symbols[g_interleaver_info[i+2].nInterleaver_byte_idx] & g_interleaver_info[i+2].nInterleaver_bit_idx) != 0;
g_sym2 = (symbols[g_interleaver_info[i+3].nInterleaver_byte_idx] & g_interleaver_info[i+3].nInterleaver_bit_idx) != 0;
update_viterbi();
g_sym1 = (symbols[g_interleaver_info[i+4].nInterleaver_byte_idx] & g_interleaver_info[i+4].nInterleaver_bit_idx) != 0;
g_sym2 = (symbols[g_interleaver_info[i+5].nInterleaver_byte_idx] & g_interleaver_info[i+5].nInterleaver_bit_idx) != 0;
update_viterbi();
g_sym1 = (symbols[g_interleaver_info[i+6].nInterleaver_byte_idx] & g_interleaver_info[i+6].nInterleaver_bit_idx) != 0;
g_sym2 = (symbols[g_interleaver_info[i+7].nInterleaver_byte_idx] & g_interleaver_info[i+7].nInterleaver_bit_idx) != 0;
update_viterbi();
g_sym1 = (symbols[g_interleaver_info[i+8].nInterleaver_byte_idx] & g_interleaver_info[i+8].nInterleaver_bit_idx) != 0;
g_sym2 = (symbols[g_interleaver_info[i+9].nInterleaver_byte_idx] & g_interleaver_info[i+9].nInterleaver_bit_idx) != 0;
update_viterbi();
g_sym1 = (symbols[g_interleaver_info[i+10].nInterleaver_byte_idx] & g_interleaver_info[i+10].nInterleaver_bit_idx) != 0;
g_sym2 = (symbols[g_interleaver_info[i+11].nInterleaver_byte_idx] & g_interleaver_info[i+11].nInterleaver_bit_idx) != 0;
update_viterbi();
g_sym1 = (symbols[g_interleaver_info[i+12].nInterleaver_byte_idx] & g_interleaver_info[i+12].nInterleaver_bit_idx) != 0;
g_sym2 = (symbols[g_interleaver_info[i+13].nInterleaver_byte_idx] & g_interleaver_info[i+13].nInterleaver_bit_idx) != 0;
update_viterbi();
g_sym1 = (symbols[g_interleaver_info[i+14].nInterleaver_byte_idx] & g_interleaver_info[i+14].nInterleaver_bit_idx) != 0;
g_sym2 = (symbols[g_interleaver_info[i+15].nInterleaver_byte_idx] & g_interleaver_info[i+15].nInterleaver_bit_idx) != 0;
update_viterbi();
g_sym1 = (symbols[g_interleaver_info[i+16].nInterleaver_byte_idx] & g_interleaver_info[i+16].nInterleaver_bit_idx) != 0;
g_sym2 = (symbols[g_interleaver_info[i+17].nInterleaver_byte_idx] & g_interleaver_info[i+17].nInterleaver_bit_idx) != 0;
update_viterbi();
g_sym1 = (symbols[g_interleaver_info[i+18].nInterleaver_byte_idx] & g_interleaver_info[i+18].nInterleaver_bit_idx) != 0;
g_sym2 = (symbols[g_interleaver_info[i+19].nInterleaver_byte_idx] & g_interleaver_info[i+19].nInterleaver_bit_idx) != 0;
update_viterbi();
g_sym1 = (symbols[g_interleaver_info[i+20].nInterleaver_byte_idx] & g_interleaver_info[i+20].nInterleaver_bit_idx) != 0;
g_sym2 = (symbols[g_interleaver_info[i+21].nInterleaver_byte_idx] & g_interleaver_info[i+21].nInterleaver_bit_idx) != 0;
update_viterbi();
g_sym1 = (symbols[g_interleaver_info[i+22].nInterleaver_byte_idx] & g_interleaver_info[i+22].nInterleaver_bit_idx) != 0;
g_sym2 = (symbols[g_interleaver_info[i+23].nInterleaver_byte_idx] & g_interleaver_info[i+23].nInterleaver_bit_idx) != 0;
update_viterbi();
g_sym1 = (symbols[g_interleaver_info[i+24].nInterleaver_byte_idx] & g_interleaver_info[i+24].nInterleaver_bit_idx) != 0;
g_sym2 = (symbols[g_interleaver_info[i+25].nInterleaver_byte_idx] & g_interleaver_info[i+25].nInterleaver_bit_idx) != 0;
update_viterbi();
g_sym1 = (symbols[g_interleaver_info[i+26].nInterleaver_byte_idx] & g_interleaver_info[i+26].nInterleaver_bit_idx) != 0;
g_sym2 = (symbols[g_interleaver_info[i+27].nInterleaver_byte_idx] & g_interleaver_info[i+27].nInterleaver_bit_idx) != 0;
update_viterbi();
g_sym1 = (symbols[g_interleaver_info[i+28].nInterleaver_byte_idx] & g_interleaver_info[i+28].nInterleaver_bit_idx) != 0;
g_sym2 = (symbols[g_interleaver_info[i+29].nInterleaver_byte_idx] & g_interleaver_info[i+29].nInterleaver_bit_idx) != 0;
update_viterbi();
g_sym1 = (symbols[g_interleaver_info[i+30].nInterleaver_byte_idx] & g_interleaver_info[i+30].nInterleaver_bit_idx) != 0;
g_sym2 = (symbols[g_interleaver_info[i+31].nInterleaver_byte_idx] & g_interleaver_info[i+31].nInterleaver_bit_idx) != 0;
update_viterbi();
i+=32;
}while(i != FEC_DEC_BIT_LEN);
/* Do Viterbi chainback */
chainback_viterbi(data, N_BITS);
return;
}
/*
*******************************************************************************
* description:
* decode_fec : decoding main function + PRIMITIVE Interleaver + Data Chainback
* input:
* unsigned char *data : decoded data (OUT)
* unsigned char *symbols : viterbi encoded symbols data (IN)
* output:
* none
*
* 10(21) :: 160us, 1/2 coderate, K=4
*
* function reference:
* author:
* seobi, 2017-04-03 created
*******************************************************************************
*/
void decode_last_fec( unsigned char *data, /* Decoded output data */
unsigned char *symbols /* Raw deinterleaved input symbols */ )
{
register unsigned int g_sym1, g_sym2;
register unsigned int metric;
#if CONSTRAINT_LEN_K == 4
unsigned int decision1, decision2, decision3, decision4;
#elif CONSTRAINT_LEN_K == 3
unsigned int decision1, decision2;
#else
unsigned int decision1, decision2, decision3, decision4, decision5, decision6, decision7, decision8;
#endif
int m0, m1;
int k, i = 0;
/* Decode block */
do{
g_sym1 = (symbols[g_interleaver_last_info[i].nInterleaver_byte_idx] & g_interleaver_last_info[i].nInterleaver_bit_idx) != 0;
g_sym2 = (symbols[g_interleaver_last_info[i+1].nInterleaver_byte_idx] & g_interleaver_last_info[i+1].nInterleaver_bit_idx) != 0;
update_viterbi();
g_sym1 = (symbols[g_interleaver_last_info[i+2].nInterleaver_byte_idx] & g_interleaver_last_info[i+2].nInterleaver_bit_idx) != 0;
g_sym2 = (symbols[g_interleaver_last_info[i+3].nInterleaver_byte_idx] & g_interleaver_last_info[i+3].nInterleaver_bit_idx) != 0;
update_viterbi();
g_sym1 = (symbols[g_interleaver_last_info[i+4].nInterleaver_byte_idx] & g_interleaver_last_info[i+4].nInterleaver_bit_idx) != 0;
g_sym2 = (symbols[g_interleaver_last_info[i+5].nInterleaver_byte_idx] & g_interleaver_last_info[i+5].nInterleaver_bit_idx) != 0;
update_viterbi();
g_sym1 = (symbols[g_interleaver_last_info[i+6].nInterleaver_byte_idx] & g_interleaver_last_info[i+6].nInterleaver_bit_idx) != 0;
g_sym2 = (symbols[g_interleaver_last_info[i+7].nInterleaver_byte_idx] & g_interleaver_last_info[i+7].nInterleaver_bit_idx) != 0;
update_viterbi();
g_sym1 = (symbols[g_interleaver_last_info[i+8].nInterleaver_byte_idx] & g_interleaver_last_info[i+8].nInterleaver_bit_idx) != 0;
g_sym2 = (symbols[g_interleaver_last_info[i+9].nInterleaver_byte_idx] & g_interleaver_last_info[i+9].nInterleaver_bit_idx) != 0;
update_viterbi();
g_sym1 = (symbols[g_interleaver_last_info[i+10].nInterleaver_byte_idx] & g_interleaver_last_info[i+10].nInterleaver_bit_idx) != 0;
g_sym2 = (symbols[g_interleaver_last_info[i+11].nInterleaver_byte_idx] & g_interleaver_last_info[i+11].nInterleaver_bit_idx) != 0;
update_viterbi();
g_sym1 = (symbols[g_interleaver_last_info[i+12].nInterleaver_byte_idx] & g_interleaver_last_info[i+12].nInterleaver_bit_idx) != 0;
g_sym2 = (symbols[g_interleaver_last_info[i+13].nInterleaver_byte_idx] & g_interleaver_last_info[i+13].nInterleaver_bit_idx) != 0;
update_viterbi();
g_sym1 = (symbols[g_interleaver_last_info[i+14].nInterleaver_byte_idx] & g_interleaver_last_info[i+14].nInterleaver_bit_idx) != 0;
g_sym2 = (symbols[g_interleaver_last_info[i+15].nInterleaver_byte_idx] & g_interleaver_last_info[i+15].nInterleaver_bit_idx) != 0;
update_viterbi();
g_sym1 = (symbols[g_interleaver_last_info[i+16].nInterleaver_byte_idx] & g_interleaver_last_info[i+16].nInterleaver_bit_idx) != 0;
g_sym2 = (symbols[g_interleaver_last_info[i+17].nInterleaver_byte_idx] & g_interleaver_last_info[i+17].nInterleaver_bit_idx) != 0;
update_viterbi();
g_sym1 = (symbols[g_interleaver_last_info[i+18].nInterleaver_byte_idx] & g_interleaver_last_info[i+18].nInterleaver_bit_idx) != 0;
g_sym2 = (symbols[g_interleaver_last_info[i+19].nInterleaver_byte_idx] & g_interleaver_last_info[i+19].nInterleaver_bit_idx) != 0;
update_viterbi();
g_sym1 = (symbols[g_interleaver_last_info[i+20].nInterleaver_byte_idx] & g_interleaver_last_info[i+20].nInterleaver_bit_idx) != 0;
g_sym2 = (symbols[g_interleaver_last_info[i+21].nInterleaver_byte_idx] & g_interleaver_last_info[i+21].nInterleaver_bit_idx) != 0;
update_viterbi();
g_sym1 = (symbols[g_interleaver_last_info[i+22].nInterleaver_byte_idx] & g_interleaver_last_info[i+22].nInterleaver_bit_idx) != 0;
g_sym2 = (symbols[g_interleaver_last_info[i+23].nInterleaver_byte_idx] & g_interleaver_last_info[i+23].nInterleaver_bit_idx) != 0;
update_viterbi();
g_sym1 = (symbols[g_interleaver_last_info[i+24].nInterleaver_byte_idx] & g_interleaver_last_info[i+24].nInterleaver_bit_idx) != 0;
g_sym2 = (symbols[g_interleaver_last_info[i+25].nInterleaver_byte_idx] & g_interleaver_last_info[i+25].nInterleaver_bit_idx) != 0;
update_viterbi();
g_sym1 = (symbols[g_interleaver_last_info[i+26].nInterleaver_byte_idx] & g_interleaver_last_info[i+26].nInterleaver_bit_idx) != 0;
g_sym2 = (symbols[g_interleaver_last_info[i+27].nInterleaver_byte_idx] & g_interleaver_last_info[i+27].nInterleaver_bit_idx) != 0;
update_viterbi();
g_sym1 = (symbols[g_interleaver_last_info[i+28].nInterleaver_byte_idx] & g_interleaver_last_info[i+28].nInterleaver_bit_idx) != 0;
g_sym2 = (symbols[g_interleaver_last_info[i+29].nInterleaver_byte_idx] & g_interleaver_last_info[i+29].nInterleaver_bit_idx) != 0;
update_viterbi();
g_sym1 = (symbols[g_interleaver_last_info[i+30].nInterleaver_byte_idx] & g_interleaver_last_info[i+30].nInterleaver_bit_idx) != 0;
g_sym2 = (symbols[g_interleaver_last_info[i+31].nInterleaver_byte_idx] & g_interleaver_last_info[i+31].nInterleaver_bit_idx) != 0;
update_viterbi();
i+=32;
}while(i != FEC_DEC_LAST_BIT_LEN);
#if CONSTRAINT_LEN_K == 4
g_sym1 = (symbols[g_interleaver_last_info[FEC_DEC_LAST_BIT_LEN].nInterleaver_byte_idx] & g_interleaver_last_info[FEC_DEC_LAST_BIT_LEN].nInterleaver_bit_idx) != 0;
g_sym2 = (symbols[g_interleaver_last_info[FEC_DEC_LAST_BIT_LEN+1].nInterleaver_byte_idx] & g_interleaver_last_info[FEC_DEC_LAST_BIT_LEN+1].nInterleaver_bit_idx) != 0;
update_viterbi();
g_sym1 = (symbols[g_interleaver_last_info[FEC_DEC_LAST_BIT_LEN+2].nInterleaver_byte_idx] & g_interleaver_last_info[FEC_DEC_LAST_BIT_LEN+2].nInterleaver_bit_idx) != 0;
g_sym2 = (symbols[g_interleaver_last_info[FEC_DEC_LAST_BIT_LEN+3].nInterleaver_byte_idx] & g_interleaver_last_info[FEC_DEC_LAST_BIT_LEN+3].nInterleaver_bit_idx) != 0;
update_viterbi();
g_sym1 = (symbols[g_interleaver_last_info[FEC_DEC_LAST_BIT_LEN+4].nInterleaver_byte_idx] & g_interleaver_last_info[FEC_DEC_LAST_BIT_LEN+4].nInterleaver_bit_idx) != 0;
g_sym2 = (symbols[g_interleaver_last_info[FEC_DEC_LAST_BIT_LEN+5].nInterleaver_byte_idx] & g_interleaver_last_info[FEC_DEC_LAST_BIT_LEN+5].nInterleaver_bit_idx) != 0;
update_viterbi();
#else
for(i=0;i<(CONSTRAINT_LEN_K-1)*2;i+=2){
g_sym1 = (symbols[g_interleaver_last_info[FEC_DEC_LAST_BIT_LEN+i].nInterleaver_byte_idx] & g_interleaver_last_info[FEC_DEC_LAST_BIT_LEN+i].nInterleaver_bit_idx) != 0;
g_sym2 = (symbols[g_interleaver_last_info[FEC_DEC_LAST_BIT_LEN+i+1].nInterleaver_byte_idx] & g_interleaver_last_info[FEC_DEC_LAST_BIT_LEN+i+1].nInterleaver_bit_idx) != 0;
update_viterbi();
}
#endif
/* Do Viterbi chainback */
chainback_viterbi(data, N_FULL_BITS);
return;
}
/*
*******************************************************************************
* description:
* encode_first_fec : encoding main function + PRIMITIVE Interleaver
* input:
* unsigned char *data : original data frame (IN)
* unsigned int nbytes : byte size of data frame (IN)
*
* output:
* unsigned char * : encoded viterbi frame (OUT)
*
* function reference:
*
* 12bytes(24) : 25 us + 11us (SPI interrupt setup time), 1/2 coderate, K=4
*
* author:
* seobi, 2017-04-03 created
*******************************************************************************
*/
unsigned char *encode_first_fec( unsigned char *data,
unsigned int nbytes )
{
register unsigned int sym_idx = 0;
unsigned char *pSymbolPtr = &symbol_frame_double[TMP_HDR_SIZE];
memset(symbol_frame_double, 0, sizeof(symbol_frame_double));
g_encstate = 0;
while(nbytes-- != 0){
g_encstate = (g_encstate << 1) | ((*data & 0x80) != 0 );
if( Partab[g_encstate & V27POLYA] )
pSymbolPtr[g_interleaver_info[sym_idx].nInterleaver_byte_idx] |= g_interleaver_info[sym_idx].nInterleaver_bit_idx;
if( Partab[g_encstate & V27POLYB] )
pSymbolPtr[g_interleaver_info[sym_idx+1].nInterleaver_byte_idx] |= g_interleaver_info[sym_idx+1].nInterleaver_bit_idx;
g_encstate = (g_encstate << 1) | ((*data & 0x40) != 0 );
if( Partab[g_encstate & V27POLYA] )
pSymbolPtr[g_interleaver_info[sym_idx+2].nInterleaver_byte_idx] |= g_interleaver_info[sym_idx+2].nInterleaver_bit_idx;
if( Partab[g_encstate & V27POLYB] )
pSymbolPtr[g_interleaver_info[sym_idx+3].nInterleaver_byte_idx] |= g_interleaver_info[sym_idx+3].nInterleaver_bit_idx;
g_encstate = (g_encstate << 1) | ((*data & 0x20) != 0 );
if( Partab[g_encstate & V27POLYA] )
pSymbolPtr[g_interleaver_info[sym_idx+4].nInterleaver_byte_idx] |= g_interleaver_info[sym_idx+4].nInterleaver_bit_idx;
if( Partab[g_encstate & V27POLYB] )
pSymbolPtr[g_interleaver_info[sym_idx+5].nInterleaver_byte_idx] |= g_interleaver_info[sym_idx+5].nInterleaver_bit_idx;
g_encstate = (g_encstate << 1) | ((*data & 0x10) != 0 );
if( Partab[g_encstate & V27POLYA] )
pSymbolPtr[g_interleaver_info[sym_idx+6].nInterleaver_byte_idx] |= g_interleaver_info[sym_idx+6].nInterleaver_bit_idx;
if( Partab[g_encstate & V27POLYB] )
pSymbolPtr[g_interleaver_info[sym_idx+7].nInterleaver_byte_idx] |= g_interleaver_info[sym_idx+7].nInterleaver_bit_idx;
g_encstate = (g_encstate << 1) | ((*data & 0x08) != 0 );
if( Partab[g_encstate & V27POLYA] )
pSymbolPtr[g_interleaver_info[sym_idx+8].nInterleaver_byte_idx] |= g_interleaver_info[sym_idx+8].nInterleaver_bit_idx;
if( Partab[g_encstate & V27POLYB] )
pSymbolPtr[g_interleaver_info[sym_idx+9].nInterleaver_byte_idx] |= g_interleaver_info[sym_idx+9].nInterleaver_bit_idx;
g_encstate = (g_encstate << 1) | ((*data & 0x04) != 0 );
if( Partab[g_encstate & V27POLYA] )
pSymbolPtr[g_interleaver_info[sym_idx+10].nInterleaver_byte_idx] |= g_interleaver_info[sym_idx+10].nInterleaver_bit_idx;
if( Partab[g_encstate & V27POLYB] )
pSymbolPtr[g_interleaver_info[sym_idx+11].nInterleaver_byte_idx] |= g_interleaver_info[sym_idx+11].nInterleaver_bit_idx;
g_encstate = (g_encstate << 1) | ((*data & 0x02) != 0 );
if( Partab[g_encstate & V27POLYA] )
pSymbolPtr[g_interleaver_info[sym_idx+12].nInterleaver_byte_idx] |= g_interleaver_info[sym_idx+12].nInterleaver_bit_idx;
if( Partab[g_encstate & V27POLYB] )
pSymbolPtr[g_interleaver_info[sym_idx+13].nInterleaver_byte_idx] |= g_interleaver_info[sym_idx+13].nInterleaver_bit_idx;
g_encstate = (g_encstate << 1) | ((*data & 0x01) != 0 );
if( Partab[g_encstate & V27POLYA] )
pSymbolPtr[g_interleaver_info[sym_idx+14].nInterleaver_byte_idx] |= g_interleaver_info[sym_idx+14].nInterleaver_bit_idx;
if( Partab[g_encstate & V27POLYB] )
pSymbolPtr[g_interleaver_info[sym_idx+15].nInterleaver_byte_idx] |= g_interleaver_info[sym_idx+15].nInterleaver_bit_idx;
sym_idx+=16;
data++;
}
return symbol_frame_double;
}
/*
*******************************************************************************
* description:
* encode_fec : encoding main function + PRIMITIVE Interleaver
* input:
* unsigned char *data : original data frame (IN)
* unsigned int nbytes : byte size of data frame (IN)
*
* output:
* unsigned char * : encoded viterbi frame (OUT)
*
* function reference:
*
* 12bytes(24) : 25 us + 11us (SPI interrupt setup time), 1/2 coderate, K=4
*
* author:
* seobi, 2017-04-03 created
*******************************************************************************
*/
unsigned char *encode_fec( unsigned char *data,
unsigned int nbytes )
{
register int sym_idx = 0;
unsigned char *pSymbolPtr;
unsigned char *pRetPtr;
if( !g_symbol_frame_idx ){
g_symbol_frame_idx = 1;
memset(symbol_frame_1, 0, sizeof(symbol_frame_1));
pSymbolPtr = &symbol_frame_1[TMP_HDR_SIZE];
pRetPtr = symbol_frame_1;
}else{
g_symbol_frame_idx = 0;
memset(symbol_frame_2, 0, sizeof(symbol_frame_2));
pSymbolPtr = &symbol_frame_2[TMP_HDR_SIZE];
pRetPtr = symbol_frame_2;
}
while(nbytes-- != 0){
g_encstate = (g_encstate << 1) | ((*data & 0x80) != 0 );
if( Partab[g_encstate & V27POLYA] )
pSymbolPtr[g_interleaver_info[sym_idx].nInterleaver_byte_idx] |= g_interleaver_info[sym_idx].nInterleaver_bit_idx;
if( Partab[g_encstate & V27POLYB] )
pSymbolPtr[g_interleaver_info[sym_idx+1].nInterleaver_byte_idx] |= g_interleaver_info[sym_idx+1].nInterleaver_bit_idx;
g_encstate = (g_encstate << 1) | ((*data & 0x40) != 0 );
if( Partab[g_encstate & V27POLYA] )
pSymbolPtr[g_interleaver_info[sym_idx+2].nInterleaver_byte_idx] |= g_interleaver_info[sym_idx+2].nInterleaver_bit_idx;
if( Partab[g_encstate & V27POLYB] )
pSymbolPtr[g_interleaver_info[sym_idx+3].nInterleaver_byte_idx] |= g_interleaver_info[sym_idx+3].nInterleaver_bit_idx;
g_encstate = (g_encstate << 1) | ((*data & 0x20) != 0 );
if( Partab[g_encstate & V27POLYA] )
pSymbolPtr[g_interleaver_info[sym_idx+4].nInterleaver_byte_idx] |= g_interleaver_info[sym_idx+4].nInterleaver_bit_idx;
if( Partab[g_encstate & V27POLYB] )
pSymbolPtr[g_interleaver_info[sym_idx+5].nInterleaver_byte_idx] |= g_interleaver_info[sym_idx+5].nInterleaver_bit_idx;
g_encstate = (g_encstate << 1) | ((*data & 0x10) != 0 );
if( Partab[g_encstate & V27POLYA] )
pSymbolPtr[g_interleaver_info[sym_idx+6].nInterleaver_byte_idx] |= g_interleaver_info[sym_idx+6].nInterleaver_bit_idx;
if( Partab[g_encstate & V27POLYB] )
pSymbolPtr[g_interleaver_info[sym_idx+7].nInterleaver_byte_idx] |= g_interleaver_info[sym_idx+7].nInterleaver_bit_idx;
g_encstate = (g_encstate << 1) | ((*data & 0x08) != 0 );
if( Partab[g_encstate & V27POLYA] )
pSymbolPtr[g_interleaver_info[sym_idx+8].nInterleaver_byte_idx] |= g_interleaver_info[sym_idx+8].nInterleaver_bit_idx;
if( Partab[g_encstate & V27POLYB] )
pSymbolPtr[g_interleaver_info[sym_idx+9].nInterleaver_byte_idx] |= g_interleaver_info[sym_idx+9].nInterleaver_bit_idx;
g_encstate = (g_encstate << 1) | ((*data & 0x04) != 0 );
if( Partab[g_encstate & V27POLYA] )
pSymbolPtr[g_interleaver_info[sym_idx+10].nInterleaver_byte_idx] |= g_interleaver_info[sym_idx+10].nInterleaver_bit_idx;
if( Partab[g_encstate & V27POLYB] )
pSymbolPtr[g_interleaver_info[sym_idx+11].nInterleaver_byte_idx] |= g_interleaver_info[sym_idx+11].nInterleaver_bit_idx;
g_encstate = (g_encstate << 1) | ((*data & 0x02) != 0 );
if( Partab[g_encstate & V27POLYA] )
pSymbolPtr[g_interleaver_info[sym_idx+12].nInterleaver_byte_idx] |= g_interleaver_info[sym_idx+12].nInterleaver_bit_idx;
if( Partab[g_encstate & V27POLYB] )
pSymbolPtr[g_interleaver_info[sym_idx+13].nInterleaver_byte_idx] |= g_interleaver_info[sym_idx+13].nInterleaver_bit_idx;
g_encstate = (g_encstate << 1) | ((*data & 0x01) != 0 );
if( Partab[g_encstate & V27POLYA] )
pSymbolPtr[g_interleaver_info[sym_idx+14].nInterleaver_byte_idx] |= g_interleaver_info[sym_idx+14].nInterleaver_bit_idx;
if( Partab[g_encstate & V27POLYB] )
pSymbolPtr[g_interleaver_info[sym_idx+15].nInterleaver_byte_idx] |= g_interleaver_info[sym_idx+15].nInterleaver_bit_idx;
sym_idx+=16;
data++;
}
return pRetPtr;
}
/*
*******************************************************************************
* description:
* encode_fec : encoding main function + PRIMITIVE Interleaver
* input:
* unsigned char *data : original data frame (IN)
* unsigned int nbytes : byte size of data frame (IN)
*
* output:
* unsigned char * : encoded viterbi frame (OUT)
*
* function reference:
*
* 12bytes(24) : 25 us, 1/2 coderate, K=4
*
* author:
* seobi, 2017-04-03 created
*******************************************************************************
*/
unsigned char *encode_last_fec( unsigned char *data,
unsigned int nbytes )
{
register int sym_idx = 0, endstate = 0;
unsigned char *pSymbolPtr = &symbol_frame_double[TMP_HDR_SIZE];
memset(symbol_frame_double, 0, sizeof(symbol_frame_double));
while(nbytes-- != 0){
g_encstate = (g_encstate << 1) | ((*data & 0x80) != 0 );
if( Partab[g_encstate & V27POLYA] )
pSymbolPtr[g_interleaver_last_info[sym_idx].nInterleaver_byte_idx] |= g_interleaver_last_info[sym_idx].nInterleaver_bit_idx;
if( Partab[g_encstate & V27POLYB] )
pSymbolPtr[g_interleaver_last_info[sym_idx+1].nInterleaver_byte_idx] |= g_interleaver_last_info[sym_idx+1].nInterleaver_bit_idx;
g_encstate = (g_encstate << 1) | ((*data & 0x40) != 0 );
if( Partab[g_encstate & V27POLYA] )
pSymbolPtr[g_interleaver_last_info[sym_idx+2].nInterleaver_byte_idx] |= g_interleaver_last_info[sym_idx+2].nInterleaver_bit_idx;
if( Partab[g_encstate & V27POLYB] )
pSymbolPtr[g_interleaver_last_info[sym_idx+3].nInterleaver_byte_idx] |= g_interleaver_last_info[sym_idx+3].nInterleaver_bit_idx;
g_encstate = (g_encstate << 1) | ((*data & 0x20) != 0 );
if( Partab[g_encstate & V27POLYA] )
pSymbolPtr[g_interleaver_last_info[sym_idx+4].nInterleaver_byte_idx] |= g_interleaver_last_info[sym_idx+4].nInterleaver_bit_idx;
if( Partab[g_encstate & V27POLYB] )
pSymbolPtr[g_interleaver_last_info[sym_idx+5].nInterleaver_byte_idx] |= g_interleaver_last_info[sym_idx+5].nInterleaver_bit_idx;
g_encstate = (g_encstate << 1) | ((*data & 0x10) != 0 );
if( Partab[g_encstate & V27POLYA] )
pSymbolPtr[g_interleaver_last_info[sym_idx+6].nInterleaver_byte_idx] |= g_interleaver_last_info[sym_idx+6].nInterleaver_bit_idx;
if( Partab[g_encstate & V27POLYB] )
pSymbolPtr[g_interleaver_last_info[sym_idx+7].nInterleaver_byte_idx] |= g_interleaver_last_info[sym_idx+7].nInterleaver_bit_idx;
g_encstate = (g_encstate << 1) | ((*data & 0x08) != 0 );
if( Partab[g_encstate & V27POLYA] )
pSymbolPtr[g_interleaver_last_info[sym_idx+8].nInterleaver_byte_idx] |= g_interleaver_last_info[sym_idx+8].nInterleaver_bit_idx;
if( Partab[g_encstate & V27POLYB] )
pSymbolPtr[g_interleaver_last_info[sym_idx+9].nInterleaver_byte_idx] |= g_interleaver_last_info[sym_idx+9].nInterleaver_bit_idx;
g_encstate = (g_encstate << 1) | ((*data & 0x04) != 0 );
if( Partab[g_encstate & V27POLYA] )
pSymbolPtr[g_interleaver_last_info[sym_idx+10].nInterleaver_byte_idx] |= g_interleaver_last_info[sym_idx+10].nInterleaver_bit_idx;