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-rw-r--r--lib/decoding/cch.c558
1 files changed, 0 insertions, 558 deletions
diff --git a/lib/decoding/cch.c b/lib/decoding/cch.c
deleted file mode 100644
index df83d3e..0000000
--- a/lib/decoding/cch.c
+++ /dev/null
@@ -1,558 +0,0 @@
-/*
- The Hacker's Choice - http://www.thc.org
- Part of THC's GSM SCANNER PROJECT
-*/
-
-//#include "system.h"
-#include <stdio.h>
-#include <stdlib.h>
-#include <unistd.h>
-#include <string.h>
-#include <ctype.h>
-
-//#include <exception>
-//#include <stdexcept>
-#include <math.h>
-//#include "burst_types.h"
-#include "cch.h"
-#include "fire_crc.h"
-
-
-/*
- * GSM SACCH -- Slow Associated Control Channel
- *
- * These messages are encoded exactly the same as on the BCCH.
- * (Broadcast Control Channel.)
- *
- * Input: 184 bits
- *
- * 1. Add parity and flushing bits. (Output 184 + 40 + 4 = 228 bit)
- * 2. Convolutional encode. (Output 228 * 2 = 456 bit)
- * 3. Interleave. (Output 456 bit)
- * 4. Map on bursts. (4 x 156 bit bursts with each 2x57 bit content data)
- */
-
-
-/*
- * Parity (FIRE) for the GSM SACCH channel.
- *
- * g(x) = (x^23 + 1)(x^17 + x^3 + 1)
- * = x^40 + x^26 + x^23 + x^17 + x^3 + 1
- */
-
-static const unsigned char parity_polynomial[PARITY_SIZE + 1] = {
- 1, 0, 0, 0, 0, 0, 0, 0,
- 0, 0, 0, 0, 0, 0, 1, 0,
- 0, 1, 0, 0, 0, 0, 0, 1,
- 0, 0, 0, 0, 0, 0, 0, 0,
- 0, 0, 0, 0, 0, 1, 0, 0,
- 1
-};
-
-// remainder after dividing data polynomial by g(x)
-static const unsigned char parity_remainder[PARITY_SIZE] = {
- 1, 1, 1, 1, 1, 1, 1, 1,
- 1, 1, 1, 1, 1, 1, 1, 1,
- 1, 1, 1, 1, 1, 1, 1, 1,
- 1, 1, 1, 1, 1, 1, 1, 1,
- 1, 1, 1, 1, 1, 1, 1, 1
-};
-
-
-/*
-static void parity_encode(unsigned char *d, unsigned char *p) {
-
- int i;
- unsigned char buf[DATA_BLOCK_SIZE + PARITY_SIZE], *q;
-
- memcpy(buf, d, DATA_BLOCK_SIZE);
- memset(buf + DATA_BLOCK_SIZE, 0, PARITY_SIZE);
-
- for(q = buf; q < buf + DATA_BLOCK_SIZE; q++)
- if(*q)
- for(i = 0; i < PARITY_SIZE + 1; i++)
- q[i] ^= parity_polynomial[i];
- for(i = 0; i < PARITY_SIZE; i++)
- p[i] = !buf[DATA_BLOCK_SIZE + i];
-}
- */
-
-
-int parity_check(unsigned char *d) {
-
- unsigned int i;
- unsigned char buf[DATA_BLOCK_SIZE + PARITY_SIZE], *q;
-
- memcpy(buf, d, DATA_BLOCK_SIZE + PARITY_SIZE);
-
- for(q = buf; q < buf + DATA_BLOCK_SIZE; q++)
- if(*q)
- for(i = 0; i < PARITY_SIZE + 1; i++)
- q[i] ^= parity_polynomial[i];
- return memcmp(buf + DATA_BLOCK_SIZE, parity_remainder, PARITY_SIZE);
-}
-
-
-/*
- * Convolutional encoding and Viterbi decoding for the GSM SACCH channel.
- */
-
-/*
- * Convolutional encoding:
- *
- * G_0 = 1 + x^3 + x^4
- * G_1 = 1 + x + x^3 + x^4
- *
- * i.e.,
- *
- * c_{2k} = u_k + u_{k - 3} + u_{k - 4}
- * c_{2k + 1} = u_k + u_{k - 1} + u_{k - 3} + u_{k - 4}
- */
-#define K 5
-#define MAX_ERROR (2 * CONV_INPUT_SIZE + 1)
-
-
-/*
- * Given the current state and input bit, what are the output bits?
- *
- * encode[current_state][input_bit]
- */
-static const unsigned int encode[1 << (K - 1)][2] = {
- {0, 3}, {3, 0}, {3, 0}, {0, 3},
- {0, 3}, {3, 0}, {3, 0}, {0, 3},
- {1, 2}, {2, 1}, {2, 1}, {1, 2},
- {1, 2}, {2, 1}, {2, 1}, {1, 2}
-};
-
-
-/*
- * Given the current state and input bit, what is the next state?
- *
- * next_state[current_state][input_bit]
- */
-static const unsigned int next_state[1 << (K - 1)][2] = {
- {0, 8}, {0, 8}, {1, 9}, {1, 9},
- {2, 10}, {2, 10}, {3, 11}, {3, 11},
- {4, 12}, {4, 12}, {5, 13}, {5, 13},
- {6, 14}, {6, 14}, {7, 15}, {7, 15}
-};
-
-
-/*
- * Given the previous state and the current state, what input bit caused
- * the transition? If it is impossible to transition between the two
- * states, the value is 2.
- *
- * prev_next_state[previous_state][current_state]
- */
-static const unsigned int prev_next_state[1 << (K - 1)][1 << (K - 1)] = {
- { 0, 2, 2, 2, 2, 2, 2, 2, 1, 2, 2, 2, 2, 2, 2, 2},
- { 0, 2, 2, 2, 2, 2, 2, 2, 1, 2, 2, 2, 2, 2, 2, 2},
- { 2, 0, 2, 2, 2, 2, 2, 2, 2, 1, 2, 2, 2, 2, 2, 2},
- { 2, 0, 2, 2, 2, 2, 2, 2, 2, 1, 2, 2, 2, 2, 2, 2},
- { 2, 2, 0, 2, 2, 2, 2, 2, 2, 2, 1, 2, 2, 2, 2, 2},
- { 2, 2, 0, 2, 2, 2, 2, 2, 2, 2, 1, 2, 2, 2, 2, 2},
- { 2, 2, 2, 0, 2, 2, 2, 2, 2, 2, 2, 1, 2, 2, 2, 2},
- { 2, 2, 2, 0, 2, 2, 2, 2, 2, 2, 2, 1, 2, 2, 2, 2},
- { 2, 2, 2, 2, 0, 2, 2, 2, 2, 2, 2, 2, 1, 2, 2, 2},
- { 2, 2, 2, 2, 0, 2, 2, 2, 2, 2, 2, 2, 1, 2, 2, 2},
- { 2, 2, 2, 2, 2, 0, 2, 2, 2, 2, 2, 2, 2, 1, 2, 2},
- { 2, 2, 2, 2, 2, 0, 2, 2, 2, 2, 2, 2, 2, 1, 2, 2},
- { 2, 2, 2, 2, 2, 2, 0, 2, 2, 2, 2, 2, 2, 2, 1, 2},
- { 2, 2, 2, 2, 2, 2, 0, 2, 2, 2, 2, 2, 2, 2, 1, 2},
- { 2, 2, 2, 2, 2, 2, 2, 0, 2, 2, 2, 2, 2, 2, 2, 1},
- { 2, 2, 2, 2, 2, 2, 2, 0, 2, 2, 2, 2, 2, 2, 2, 1}
-};
-
-
-static inline unsigned int hamming_distance2(unsigned int w) {
-
- return (w & 1) + !!(w & 2);
-}
-
-
-/*
-static void conv_encode(unsigned char *data, unsigned char *output) {
-
- unsigned int i, state = 0, o;
-
- // encode data
- for(i = 0; i < CONV_INPUT_SIZE; i++) {
- o = encode[state][data[i]];
- state = next_state[state][data[i]];
- *output++ = !!(o & 2);
- *output++ = o & 1;
- }
-}
- */
-
-
-int conv_decode(unsigned char *output, unsigned char *data) {
-
- int i, t;
- unsigned int rdata, state, nstate, b, o, distance, accumulated_error,
- min_state, min_error, cur_state;
-
- unsigned int ae[1 << (K - 1)]; // accumulated error
- unsigned int nae[1 << (K - 1)]; // next accumulated error
- unsigned int state_history[1 << (K - 1)][CONV_INPUT_SIZE + 1];
-
- // initialize accumulated error, assume starting state is 0
- for(i = 0; i < (1 << (K - 1)); i++){
- ae[i] = nae[i] = MAX_ERROR;
- }
-
- ae[0] = 0;
-
- // build trellis
- for(t = 0; t < CONV_INPUT_SIZE; t++) {
-
- // get received data symbol
- rdata = (data[2 * t] << 1) | data[2 * t + 1];
-
- // for each state
- for(state = 0; state < (1 << (K - 1)); state++) {
-
- // make sure this state is possible
- if(ae[state] >= MAX_ERROR)
- continue;
-
- // find all states we lead to
- for(b = 0; b < 2; b++) {
-
- // get next state given input bit b
- nstate = next_state[state][b];
-
- // find output for this transition
- o = encode[state][b];
-
- // calculate distance from received data
- distance = hamming_distance2(rdata ^ o);
-
- // choose surviving path
- accumulated_error = ae[state] + distance;
- if(accumulated_error < nae[nstate]) {
-
- // save error for surviving state
- nae[nstate] = accumulated_error;
-
- // update state history
- state_history[nstate][t + 1] = state;
- }
- }
- }
-
- // get accumulated error ready for next time slice
- for(i = 0; i < (1 << (K - 1)); i++) {
- ae[i] = nae[i];
- nae[i] = MAX_ERROR;
- }
- }
-
- // the final state is the state with the fewest errors
- min_state = (unsigned int)-1;
- min_error = MAX_ERROR;
- for(i = 0; i < (1 << (K - 1)); i++) {
- if(ae[i] < min_error) {
- min_state = i;
- min_error = ae[i];
- }
- }
-
- // trace the path
- cur_state = min_state;
- for(t = CONV_INPUT_SIZE; t >= 1; t--) {
- min_state = cur_state;
- cur_state = state_history[cur_state][t]; // get previous
- output[t - 1] = prev_next_state[cur_state][min_state];
- }
-
- // return the number of errors detected (hard-decision)
- return min_error;
-}
-
-
-/*
- * GSM SACCH interleaving and burst mapping
- *
- * Interleaving:
- *
- * Given 456 coded input bits, form 4 blocks of 114 bits:
- *
- * i(B, j) = c(n, k) k = 0, ..., 455
- * n = 0, ..., N, N + 1, ...
- * B = B_0 + 4n + (k mod 4)
- * j = 2(49k mod 57) + ((k mod 8) div 4)
- *
- * Mapping on Burst:
- *
- * e(B, j) = i(B, j)
- * e(B, 59 + j) = i(B, 57 + j) j = 0, ..., 56
- * e(B, 57) = h_l(B)
- * e(B, 58) = h_n(B)
- *
- * Where h_l(B) and h_n(B) are bits in burst B indicating flags.
- */
-
-/*
-static void interleave(unsigned char *data, unsigned char *iBLOCK) {
-
- int j, k, B;
-
- // for each bit in input data
- for(k = 0; k < CONV_SIZE; k++) {
- B = k % 4;
- j = 2 * ((49 * k) % 57) + ((k % 8) / 4);
- iBLOCK[B * iBLOCK_SIZE + j] = data[k];
- }
-}
- */
-
-
-#if 0
-static void decode_interleave(unsigned char *data, unsigned char *iBLOCK) {
-
- int j, k, B;
-
- for(k = 0; k < CONV_SIZE; k++) {
- B = k % 4;
- j = 2 * ((49 * k) % 57) + ((k % 8) / 4);
- data[k] = iBLOCK[B * iBLOCK_SIZE + j];
- }
-}
-
-#endif
-
-/*
-static void burstmap(unsigned char *iBLOCK, unsigned char *eBLOCK,
- unsigned char hl, unsigned char hn) {
-
- int j;
-
- for(j = 0; j < 57; j++) {
- eBLOCK[j] = iBLOCK[j];
- eBLOCK[j + 59] = iBLOCK[j + 57];
- }
- eBLOCK[57] = hl;
- eBLOCK[58] = hn;
-}
- */
-
-
-static void decode_burstmap(unsigned char *iBLOCK, unsigned char *eBLOCK,
- unsigned char *hl, unsigned char *hn) {
-
- int j;
-
- for(j = 0; j < 57; j++) {
- iBLOCK[j] = eBLOCK[j];
- iBLOCK[j + 57] = eBLOCK[j + 59];
- }
- *hl = eBLOCK[57];
- *hn = eBLOCK[58];
-}
-
-
-/*
- * Transmitted bits are sent least-significant first.
- */
-static int compress_bits(unsigned char *dbuf, unsigned int dbuf_len,
- unsigned char *sbuf, unsigned int sbuf_len) {
-
- unsigned int i, j, c, pos = 0;
-
- if(dbuf_len < ((sbuf_len + 7) >> 3))
- return -1;
-
- for(i = 0; i < sbuf_len; i += 8) {
- for(j = 0, c = 0; (j < 8) && (i + j < sbuf_len); j++)
- c |= (!!sbuf[i + j]) << j;
- dbuf[pos++] = c & 0xff;
- }
- return pos;
-}
-
-
-#if 0
-int get_ns_l3_len(unsigned char *data, unsigned int datalen) {
-
- if((data[0] & 3) != 1) {
- fprintf(stderr, "error: get_ns_l3_len: pseudo-length reserved "
- "bits bad (%2.2x)\n", data[0] & 3);
- return -1;
- }
- return (data[0] >> 2);
-}
-
-#endif
-
-
-/*static unsigned char *decode_sacch(GS_CTX *ctx, unsigned char *burst, unsigned int *datalen) {*/
-
-/* int errors, len, data_size;*/
-/* unsigned char conv_data[CONV_SIZE], iBLOCK[BLOCKS][iBLOCK_SIZE],*/
-/* hl, hn, decoded_data[PARITY_OUTPUT_SIZE];*/
-/* FC_CTX fc_ctx;*/
-
-/* data_size = sizeof ctx->msg;*/
-/* if(datalen)*/
-/* *datalen = 0;*/
-
-/* // unmap the bursts*/
-/* decode_burstmap(iBLOCK[0], burst, &hl, &hn); // XXX ignore stealing bits*/
-/* decode_burstmap(iBLOCK[1], burst + 116, &hl, &hn);*/
-/* decode_burstmap(iBLOCK[2], burst + 116 * 2, &hl, &hn);*/
-/* decode_burstmap(iBLOCK[3], burst + 116 * 3, &hl, &hn);*/
-
-/* // remove interleave*/
-/* interleave_decode(&ctx->interleave_ctx, conv_data, (unsigned char *)iBLOCK);*/
-/* //decode_interleave(conv_data, (unsigned char *)iBLOCK);*/
-
-/* // Viterbi decode*/
-/* errors = conv_decode(decoded_data, conv_data);*/
-/* //DEBUGF("conv_decode: %d\n", errors);*/
-
-/* // check parity*/
-/* // If parity check error detected try to fix it.*/
-/* if (parity_check(decoded_data))*/
-/* {*/
-/* unsigned char crc_result[224];*/
-/* if (FC_check_crc(&fc_ctx, decoded_data, crc_result) == 0)*/
-/* {*/
-/* errors = -1;*/
-/* //DEBUGF("error: sacch: parity error (%d fn=%d)\n",*/
-/* // errors, ctx->fn);*/
-/* return NULL;*/
-/* } else {*/
-/* //DEBUGF("Successfully corrected parity bits! (errors=%d fn=%d)\n",*/
-/* // errors, ctx->fn);*/
-/* memcpy(decoded_data, crc_result, sizeof crc_result);*/
-/* errors = 0;*/
-/* }*/
-/* }*/
-
-/* if (errors)*/
-/* printf("WRN: errors=%d fn=%d\n", errors, ctx->fn);*/
-
-/* if((len = compress_bits(ctx->msg, data_size, decoded_data,*/
-/* DATA_BLOCK_SIZE)) < 0) {*/
-/* fprintf(stderr, "error: compress_bits\n");*/
-/* return NULL;*/
-/* }*/
-/* if(len < data_size) {*/
-/* fprintf(stderr, "error: buf too small (%d < %d)\n",*/
-/* sizeof(ctx->msg), len);*/
-/* return NULL;*/
-/* }*/
-
-/* if(datalen)*/
-/* *datalen = (unsigned int)len;*/
-/* return ctx->msg;*/
-/*}*/
-
-
-/*
- * decode_cch
- *
- * Decode a "common" control channel. Most control channels use
- * the same burst, interleave, Viterbi and parity configuration.
- * The documentation for the control channels defines SACCH first
- * and then just keeps referring to that.
- *
- * The current (investigated) list is as follows:
- *
- * BCCH Norm
- * BCCH Ext
- * PCH
- * AGCH
- * CBCH (SDCCH/4)
- * CBCH (SDCCH/8)
- * SDCCH/4
- * SACCH/C4
- * SDCCH/8
- * SACCH/C8
- *
- * We provide two functions, one for where all four bursts are
- * contiguous, and one where they aren't.
- */
-/*unsigned char *decode_cch(GS_CTX *ctx, unsigned char *burst, unsigned int *datalen) {*/
-
-/* return decode_sacch(ctx, burst, datalen);*/
-/*}*/
-
-
-#if 0
-unsigned char *decode_cch(GS_CTX *ctx, unsigned char *e, unsigned int *datalen) {
-
- return decode_sacch(ctx, e, e + eBLOCK_SIZE, e + 2 * eBLOCK_SIZE,
- e + 3 * eBLOCK_SIZE, datalen);
-}
-#endif
-
-/*unsigned char *decode_facch(GS_CTX *ctx, unsigned char *burst, unsigned int *datalen, int offset) {*/
-
-/* int errors, len, data_size;*/
-/* unsigned char conv_data[CONV_SIZE], iBLOCK[BLOCKS * 2][iBLOCK_SIZE],*/
-/* hl, hn, decoded_data[PARITY_OUTPUT_SIZE];*/
-/* FC_CTX fc_ctx;*/
-
-/* data_size = sizeof ctx->msg;*/
-/* if(datalen)*/
-/* *datalen = 0;*/
-
-/* // unmap the bursts*/
-/* decode_burstmap(iBLOCK[0], burst, &hl, &hn); // XXX ignore stealing bits*/
-/* decode_burstmap(iBLOCK[1], burst + 116, &hl, &hn);*/
-/* decode_burstmap(iBLOCK[2], burst + 116 * 2, &hl, &hn);*/
-/* decode_burstmap(iBLOCK[3], burst + 116 * 3, &hl, &hn);*/
-/* decode_burstmap(iBLOCK[4], burst + 116 * 4, &hl, &hn);*/
-/* decode_burstmap(iBLOCK[5], burst + 116 * 5, &hl, &hn);*/
-/* decode_burstmap(iBLOCK[6], burst + 116 * 6, &hl, &hn);*/
-/* decode_burstmap(iBLOCK[7], burst + 116 * 7, &hl, &hn);*/
-
-/* // remove interleave*/
-/* if (offset == 0)*/
-/* interleave_decode(&ctx->interleave_facch_f1_ctx, conv_data, (unsigned char *)iBLOCK);*/
-/* else*/
-/* interleave_decode(&ctx->interleave_facch_f2_ctx, conv_data, (unsigned char *)iBLOCK);*/
-/* //decode_interleave(conv_data, (unsigned char *)iBLOCK);*/
-
-/* // Viterbi decode*/
-/* errors = conv_decode(decoded_data, conv_data);*/
-/* //DEBUGF("conv_decode: %d\n", errors);*/
-
-/* // check parity*/
-/* // If parity check error detected try to fix it.*/
-/* if (parity_check(decoded_data)) {*/
-/* FC_init(&fc_ctx, 40, 184);*/
-/* unsigned char crc_result[224];*/
-/* if (FC_check_crc(&fc_ctx, decoded_data, crc_result) == 0)*/
-/* {*/
-/* //DEBUGF("error: sacch: parity error (errors=%d fn=%d)\n", errors, ctx->fn);*/
-/* errors = -1;*/
-/* return NULL;*/
-/* } else {*/
-/* //DEBUGF("Successfully corrected parity bits! (errors=%d fn=%d)\n", errors, ctx->fn);*/
-/* memcpy(decoded_data, crc_result, sizeof crc_result);*/
-/* errors = 0;*/
-/* }*/
-/* }*/
-
-/* if (errors)*/
-/* fprintf(stderr, "WRN: errors=%d fn=%d\n", errors, ctx->fn);*/
-
-/* if ((len = compress_bits(ctx->msg, data_size, decoded_data,*/
-/* DATA_BLOCK_SIZE)) < 0) {*/
-/* fprintf(stderr, "error: compress_bits\n");*/
-/* return NULL;*/
-/* }*/
-/* if (len < data_size) {*/
-/* fprintf(stderr, "error: buf too small (%d < %d)\n",*/
-/* sizeof(ctx->msg), len);*/
-/* return NULL;*/
-/* }*/
-
-/* if (datalen)*/
-/* *datalen = (unsigned int)len;*/
-/* return ctx->msg;*/
-/*}*/
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