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direwolf
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Last checkin before trying dev branch.

This commit is contained in:
David E. Tiller 2022-03-29 09:12:41 -04:00
parent 5be9e44c5b
commit 742dfb486b
4 changed files with 87 additions and 38 deletions
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86
src/bch.c
View File

@ -75,8 +75,6 @@
#include <string.h> #include <string.h>
#include "bch.h" #include "bch.h"
#undef DEBUG
int init_bch(bch_t *bch, int m, int length, int t) { int init_bch(bch_t *bch, int m, int length, int t) {
int p[21], n; int p[21], n;
@ -119,16 +117,16 @@ int init_bch(bch_t *bch, int m, int length, int t) {
else if (m == 20) p[3] = 1; else if (m == 20) p[3] = 1;
n = 1; n = 1;
#ifdef DEBUG #ifdef BCH_DEBUG
printf("p(x) = "); printf("p(x) = ");
#endif #endif
for (int i = 0; i <= m; i++) { for (int i = 0; i <= m; i++) {
n *= 2; n *= 2;
#ifdef DEBUG #ifdef BCH_DEBUG
printf("%1d", p[i]); printf("%1d", p[i]);
#endif #endif
} }
#ifdef DEBUG #ifdef BCH_DEBUG
printf("\n"); printf("\n");
#endif #endif
n = n / 2 - 1; n = n / 2 - 1;
@ -192,7 +190,7 @@ int init_bch(bch_t *bch, int m, int length, int t) {
cycle[1][0] = 1; cycle[1][0] = 1;
size[1] = 1; size[1] = 1;
jj = 1; /* cycle set index */ jj = 1; /* cycle set index */
#ifdef DEBUG #ifdef BCH_DEBUG
if (bch->m > 9) { if (bch->m > 9) {
printf("Computing cycle sets modulo %d\n", bch->n); printf("Computing cycle sets modulo %d\n", bch->n);
printf("(This may take some time)...\n"); printf("(This may take some time)...\n");
@ -260,7 +258,7 @@ int init_bch(bch_t *bch, int m, int length, int t) {
return -4; return -4;
} }
#ifdef DEBUG #ifdef BCH_DEBUG
printf("This is a (%d, %d, %d) binary BCH code\n", bch->length, bch->k, d); printf("This is a (%d, %d, %d) binary BCH code\n", bch->length, bch->k, d);
#endif #endif
@ -277,7 +275,7 @@ int init_bch(bch_t *bch, int m, int length, int t) {
bch->g[jj] = bch->g[jj - 1]; bch->g[jj] = bch->g[jj - 1];
bch->g[0] = bch->alpha_to[(bch->index_of[bch->g[0]] + zeros[ii]) % bch->n]; bch->g[0] = bch->alpha_to[(bch->index_of[bch->g[0]] + zeros[ii]) % bch->n];
} }
#ifdef DEBUG #ifdef BCH_DEBUG
printf("Generator polynomial:\ng(x) = "); printf("Generator polynomial:\ng(x) = ");
for (ii = 0; ii <= rdncy; ii++) { for (ii = 0; ii <= rdncy; ii++) {
printf("%d", bch->g[ii]); printf("%d", bch->g[ii]);
@ -287,7 +285,7 @@ int init_bch(bch_t *bch, int m, int length, int t) {
return 0; return 0;
} }
void generate_bch(bch_t *bch, int *data, int *bb) { void generate_bch(bch_t *bch, const int *data, int *bb) {
/* /*
* Compute redundacy bb[], the coefficients of b(x). The redundancy * Compute redundacy bb[], the coefficients of b(x). The redundancy
* polynomial b(x) is the remainder after dividing x^(length-k)*data(x) * polynomial b(x) is the remainder after dividing x^(length-k)*data(x)
@ -315,7 +313,7 @@ void generate_bch(bch_t *bch, int *data, int *bb) {
} }
int apply_bch(bch_t *bch, int *recd) int apply_bch(const bch_t *bch, int *recd)
/* /*
* Simon Rockliff's implementation of Berlekamp's algorithm. * Simon Rockliff's implementation of Berlekamp's algorithm.
* *
@ -346,7 +344,7 @@ int apply_bch(bch_t *bch, int *recd)
t2 = 2 * bch->t; t2 = 2 * bch->t;
/* first form the syndromes */ /* first form the syndromes */
#ifdef DEBUG #ifdef BCH_DEBUG
printf("S(x) = "); printf("S(x) = ");
#endif #endif
for (i = 1; i <= t2; i++) { for (i = 1; i <= t2; i++) {
@ -362,11 +360,11 @@ int apply_bch(bch_t *bch, int *recd)
*/ */
/* convert syndrome from polynomial form to index form */ /* convert syndrome from polynomial form to index form */
s[i] = bch->index_of[s[i]]; s[i] = bch->index_of[s[i]];
#ifdef DEBUG #ifdef BCH_DEBUG
printf("%3d ", s[i]); printf("%3d ", s[i]);
#endif #endif
} }
#ifdef DEBUG #ifdef BCH_DEBUG
printf("\n"); printf("\n");
#endif #endif
@ -468,7 +466,7 @@ int apply_bch(bch_t *bch, int *recd)
for (i = 0; i <= l[u]; i++) for (i = 0; i <= l[u]; i++)
elp[u][i] = bch->index_of[elp[u][i]]; elp[u][i] = bch->index_of[elp[u][i]];
#ifdef DEBUG #ifdef BCH_DEBUG
printf("sigma(x) = "); printf("sigma(x) = ");
for (i = 0; i <= l[u]; i++) for (i = 0; i <= l[u]; i++)
printf("%3d ", elp[u][i]); printf("%3d ", elp[u][i]);
@ -491,12 +489,12 @@ int apply_bch(bch_t *bch, int *recd)
root[count] = i; root[count] = i;
loc[count] = bch->n - i; loc[count] = bch->n - i;
count++; count++;
#ifdef DEBUG #ifdef BCH_DEBUG
printf("%3d ", bch->n - i); printf("%3d ", bch->n - i);
#endif #endif
} }
} }
#ifdef DEBUG #ifdef BCH_DEBUG
printf("\n"); printf("\n");
#endif #endif
if (count == l[u]) { if (count == l[u]) {
@ -506,7 +504,7 @@ int apply_bch(bch_t *bch, int *recd)
return l[u]; return l[u];
} }
else { /* elp has degree >t hence cannot solve */ else { /* elp has degree >t hence cannot solve */
#ifdef DEBUG #ifdef BCH_DEBUG
printf("Incomplete decoding: errors detected\n"); printf("Incomplete decoding: errors detected\n");
#endif #endif
return -1; return -1;
@ -520,7 +518,7 @@ int apply_bch(bch_t *bch, int *recd)
} }
/* LEFT justified in hex */ /* LEFT justified in hex */
void bytes_to_bits(int *bytes, int *bit_dest, int num_bits) { void bytes_to_bits(const int *bytes, int *bit_dest, int num_bits) {
for (int i = 0; i < num_bits; i++) { for (int i = 0; i < num_bits; i++) {
int index = i / 8; int index = i / 8;
int bit_pos = 7 - (i % 8); int bit_pos = 7 - (i % 8);
@ -529,7 +527,7 @@ void bytes_to_bits(int *bytes, int *bit_dest, int num_bits) {
} }
} }
void bits_to_bytes(int *bits, int *byte_dest, int num_bits) { void bits_to_bytes(const int *bits, int *byte_dest, int num_bits) {
int index; int index;
@ -540,30 +538,66 @@ void bits_to_bytes(int *bits, int *byte_dest, int num_bits) {
} }
byte_dest[index] <<= 1; byte_dest[index] <<= 1;
byte_dest[index] |= bits[i] & 0x01; byte_dest[index] |= (bits[i] & 0x01);
} }
byte_dest[index] <<= 8 - (num_bits % 8); byte_dest[index] <<= 8 - (num_bits % 8);
} }
void swap_format(int *bits, int cutoff, int num_bits) { void swap_format(const int *bits, int *dest, int cutoff, int num_bits) {
// Do it the easy way // Do it the easy way
int *temp = malloc(num_bits * sizeof(int));
for (int i = 0; i < num_bits; i++) { for (int i = 0; i < num_bits; i++) {
if (i < cutoff) { if (i < cutoff) {
temp[num_bits - cutoff + i] = bits[i]; dest[num_bits - cutoff + i] = bits[i];
} else { } else {
temp[i - cutoff] = bits[i]; dest[i - cutoff] = bits[i];
}
} }
} }
memcpy(bits, temp, num_bits * sizeof(int)); int rotate_byte(int x) {
int y = 0;
for (int i = 0; i < 8; i++) {
y <<= 1;
y |= (x & 0x01);
x >>= 1;
} }
void dump_bch(bch_t *bch) { return y;
}
void rotate_bits(const int *in, int *out, int num_bits) {
for (int i = 0; i < num_bits; i++) {
out[i] = in[num_bits - i - 1];
}
}
void invert_bits(const int *bits, int *dest, int num_bits) {
for (int i = 0; i < num_bits; i++) {
dest[i] = (bits[i] == 0);
}
}
void dump_bch(const bch_t *bch) {
printf("m: %d length: %d t: %d n: %d k: %d\n", bch->m, bch->length, bch->t, bch->n, bch->k); printf("m: %d length: %d t: %d n: %d k: %d\n", bch->m, bch->length, bch->t, bch->n, bch->k);
} }
void print_array(const char *msg, const char *format, const int *bytes, int num_bytes) {
printf("%s", msg);
for (int i = 0; i < num_bytes; i++) {
printf(format, bytes[i]);
}
}
void print_bytes(const char *msg, const int *bytes, int num_bytes) {
print_array(msg, "%02x ", bytes, num_bytes);
}
void print_bits(const char *msg, const int *bits, int num_bits) {
print_array(msg, "%d ", bits, num_bits);
}
#undef MAIN #undef MAIN
#undef TEST_BYTES_TO_BITS #undef TEST_BYTES_TO_BITS
#define TEST_SWAP #define TEST_SWAP

20
src/bch.h
View File

@ -17,14 +17,24 @@ typedef struct bch bch_t;
int init_bch(bch_t *bch, int m, int length, int t); int init_bch(bch_t *bch, int m, int length, int t);
void generate_bch(bch_t *bch, int *data, int *bb); void generate_bch(bch_t *bch, const int *data, int *bb);
int apply_bch(bch_t *bch, int *recd); int apply_bch(const bch_t *bch, int *recd);
void bytes_to_bits(int *bytes, int *bit_dest, int num_bits); void bytes_to_bits(const int *bytes, int *bit_dest, int num_bits);
void bits_to_bytes(int *bits, int *byte_dest, int num_bits); void bits_to_bytes(const int *bits, int *byte_dest, int num_bits);
void swap_format(int *bits, int cutoff, int num_bits); void swap_format(const int *bits, int *dest, int cutoff, int num_bits);
int rotate_byte(int x);
void rotate_bits(const int *in, int *out, int num_bits);
void print_bytes(const char *msg, const int *bytes, int num_bytes);
void print_bits(const char *msg, const int *bits, int num_bits);
void invert_bits(const int *bits, int *dest, int num_bits);
#endif #endif

2
src/eotd.c
View File

@ -67,7 +67,7 @@ void eotd_to_nmea (unsigned char *eotd, int eotd_len, char *nmea, int nmea_size)
strcat(nmea, ctime(&now)); strcat(nmea, ctime(&now));
for (int i = 0; i < eotd_len; i++) { for (int i = 0; i < eotd_len; i++) {
char temp[32]; char temp[32];
snprintf(temp, sizeof(temp), "%d=%02x ", i, eotd[i]); snprintf(temp, sizeof(temp), " %02x", eotd[i]);
strlcat(nmea, temp, nmea_size); strlcat(nmea, temp, nmea_size);
} }
} }

15
src/hdlc_rec.c
View File

@ -52,6 +52,8 @@
//#define DEBUG3 1 /* monitor the data detect signal. */ //#define DEBUG3 1 /* monitor the data detect signal. */
#undef EOTD_DEBUG
/* /*
@ -427,9 +429,10 @@ a good modem here and providing a result when it is received.
* *
***********************************************************************************/ ***********************************************************************************/
#define PREAMBLE_AND_BARKER_CODE 0x55555712 #define EOTD_PREAMBLE_AND_BARKER_CODE 0x55555712
#define HOTD_PREAMBLE_AND_BARKER_CODE 0x558f1129
#define EOTD_MAX_LEN 8 #define EOTD_MAX_LEN 8
#define DUMMY_BIT_HACK #undef DUMMY_BIT_HACK
static void eotd_rec_bit (int chan, int subchan, int slice, int raw, int future_use) static void eotd_rec_bit (int chan, int subchan, int slice, int raw, int future_use)
{ {
@ -441,7 +444,7 @@ static void eotd_rec_bit (int chan, int subchan, int slice, int raw, int future_
H = &hdlc_state[chan][subchan][slice]; H = &hdlc_state[chan][subchan][slice];
#ifdef EOTD_DEBUG #ifdef EOTD_DEBUG
dw_printf(stderr, "chan=%d subchan=%d slice=%d raw=%d\n", chan, subchan, slice, raw); dw_printf("chan=%d subchan=%d slice=%d raw=%d\n", chan, subchan, slice, raw);
#endif #endif
//dw_printf ("slice %d = %d\n", slice, raw); //dw_printf ("slice %d = %d\n", slice, raw);
@ -452,9 +455,11 @@ dw_printf(stderr, "chan=%d subchan=%d slice=%d raw=%d\n", chan, subchan, slice,
int done = 0; int done = 0;
if (!H->eotd_gathering && H->eotd_acc == PREAMBLE_AND_BARKER_CODE) { if (!H->eotd_gathering &&
(H->eotd_acc == EOTD_PREAMBLE_AND_BARKER_CODE ||
H->eotd_acc == HOTD_PREAMBLE_AND_BARKER_CODE)) {
#ifdef EOTD_DEBUG #ifdef EOTD_DEBUG
dw_printf ("Barker Code Found\n"); dw_printf ("Barker Code Found %x\n", H->eotd_acc);
#endif #endif
H->olen = 0; H->olen = 0;
H->eotd_gathering = 1; H->eotd_gathering = 1;