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Added XOR for t=3 packets, added more verbiage, removed variable-length arrays.

This commit is contained in:
David E. Tiller 2022-04-09 13:51:45 -04:00
parent 67d5900719
commit 2048747ad5
1 changed files with 23 additions and 11 deletions
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34
src/bchapply.c
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@ -3,10 +3,13 @@
#include "bch.h" #include "bch.h"
#define SHOW_BYTES #define SHOW_BYTES
#define MAX_LENGTH 64
static uint8_t r2f_mask[] = { 0x07, 0x76, 0xa0 };
int test(bch_t *bch, char *msg, int *bits, int length) { int test(bch_t *bch, char *msg, int *bits, int length) {
int corrected = 0; int corrected = 0;
int temp_bits[length]; int temp_bits[MAX_LENGTH];
uint8_t bytes[8]; uint8_t bytes[8];
memcpy(temp_bits, bits, length * sizeof(int)); memcpy(temp_bits, bits, length * sizeof(int));
@ -43,7 +46,7 @@ int main(int argc, char **argv) {
if (argc != 4) { if (argc != 4) {
fprintf(stderr, "Expecting 3 arguments.\n"); fprintf(stderr, "Expecting 3 arguments: m, length, and t.\n");
return -1; return -1;
} }
@ -51,7 +54,13 @@ int main(int argc, char **argv) {
sscanf(argv[2], "%d", &length); sscanf(argv[2], "%d", &length);
sscanf(argv[3], "%d", &t); sscanf(argv[3], "%d", &t);
int orig_bits[length+1]; if (length > MAX_LENGTH) {
fprintf(stderr, "Max supported length is %d\n", MAX_LENGTH);
return -2;
}
int orig_bits[MAX_LENGTH+1];
init_bch(&bch, m, length, t); init_bch(&bch, m, length, t);
data_len = bch.k; data_len = bch.k;
@ -63,12 +72,12 @@ printf("data_len=%d, crc_len=%d\n", data_len, crc_len);
// //
// THIS IS THE LSB-FIRST VERSION // THIS IS THE LSB-FIRST VERSION
// //
fprintf(stderr, "Enter HCB+ATAD _WITH_ the parity bit intact and XOR already applied.\n"); fprintf(stderr, "Enter HCB+ATAD _WITH_ the parity bit intact.\n");
fprintf(stderr, "If 't' is 3, that implies an R2F packet and the given packet will be XOR'ed with 0x0776a0.\n");
while (1) { while (1) {
for (int i = 0; i < 8; i++) { for (int i = 0; i < 8; i++) {
int temp; int temp;
int status = scanf("%x ", &temp); int status = scanf("%x ", &temp);
bytes[i] = temp;
if (status == EOF) { if (status == EOF) {
return 0; return 0;
} }
@ -76,11 +85,14 @@ fprintf(stderr, "Enter HCB+ATAD _WITH_ the parity bit intact and XOR already app
if (status != 1) { if (status != 1) {
fprintf(stderr, "Error: %d", status); fprintf(stderr, "Error: %d", status);
} }
printf("%0x ", bytes[i]);
}
printf("\n");
int temp[length]; bytes[i] = temp;
if (t == 3 && i < sizeof(r2f_mask)) {
bytes[i] ^= r2f_mask[i];
}
}
int temp[MAX_LENGTH];
// HCB + ATAD // HCB + ATAD
bytes_to_bits(bytes, orig_bits, length+1); bytes_to_bits(bytes, orig_bits, length+1);
@ -111,7 +123,7 @@ printf("\n");
test(&bch, "DATA+BCH: ", temp, length); test(&bch, "DATA+BCH: ", temp, length);
// BCH+DATA // BCH+DATA
int swap[length]; int swap[MAX_LENGTH];
bytes_to_bits(bytes, orig_bits, length+1); bytes_to_bits(bytes, orig_bits, length+1);
rotate_bits(orig_bits+1, temp, length); rotate_bits(orig_bits+1, temp, length);
// now DATA+BCH // now DATA+BCH
@ -123,7 +135,7 @@ printf("\n");
printf("\n"); printf("\n");
test(&bch, "BCH+DATA: ", swap, length); test(&bch, "BCH+DATA: ", swap, length);
int rot[length]; int rot[MAX_LENGTH];
// DATA + HCB // DATA + HCB
bytes_to_bits(bytes, orig_bits, length+1); bytes_to_bits(bytes, orig_bits, length+1);
memcpy(rot+data_len, orig_bits + 1, crc_len * sizeof(int)); memcpy(rot+data_len, orig_bits + 1, crc_len * sizeof(int));