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-rw-r--r--gsm-receiver/src/lib/decoder/cch.c74
-rw-r--r--gsm-receiver/src/lib/decoder/cch.h1
-rw-r--r--gsm-receiver/src/lib/decoder/gsmstack.c2
-rw-r--r--gsm-receiver/src/lib/decoder/gsmstack.h2
-rw-r--r--gsm-receiver/src/lib/decoder/interleave.c21
-rw-r--r--gsm-receiver/src/lib/decoder/interleave.h1
6 files changed, 99 insertions, 2 deletions
diff --git a/gsm-receiver/src/lib/decoder/cch.c b/gsm-receiver/src/lib/decoder/cch.c
index c6da29d..fa18141 100644
--- a/gsm-receiver/src/lib/decoder/cch.c
+++ b/gsm-receiver/src/lib/decoder/cch.c
@@ -415,10 +415,12 @@ static unsigned char *decode_sacch(GS_CTX *ctx, unsigned char *burst, unsigned i
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);
+ 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);
+ DEBUGF("Successfully corrected parity bits! (errors=%d fn=%d)\n",
+ errors, ctx->fn);
memcpy(decoded_data, crc_result, sizeof crc_result);
errors = 0;
}
@@ -481,3 +483,71 @@ unsigned char *decode_cch(GS_CTX *ctx, unsigned char *e, unsigned int *datalen)
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;
+}
diff --git a/gsm-receiver/src/lib/decoder/cch.h b/gsm-receiver/src/lib/decoder/cch.h
index a642721..c430714 100644
--- a/gsm-receiver/src/lib/decoder/cch.h
+++ b/gsm-receiver/src/lib/decoder/cch.h
@@ -46,6 +46,7 @@ extern "C" {
#define eBLOCK_SIZE (iBLOCK_SIZE + 2)
unsigned char *decode_cch(GS_CTX *ctx, unsigned char *burst, unsigned int *len);
+unsigned char *decode_facch(GS_CTX *ctx, unsigned char *burst, unsigned int *len, int offset);
//unsigned char *decode_cch(GS_CTX *ctx, unsigned char *, unsigned char *, unsigned char *, unsigned char *, unsigned int *len);
//unsigned char *decode_cch(GS_CTX *ctx, unsigned char *, unsigned int *);
diff --git a/gsm-receiver/src/lib/decoder/gsmstack.c b/gsm-receiver/src/lib/decoder/gsmstack.c
index 6c91395..2bdbf12 100644
--- a/gsm-receiver/src/lib/decoder/gsmstack.c
+++ b/gsm-receiver/src/lib/decoder/gsmstack.c
@@ -96,6 +96,8 @@ GS_new(GS_CTX *ctx)
memset(ctx, 0, sizeof *ctx);
interleave_init(&ctx->interleave_ctx, 456, 114);
+ interleave_init_facch_f(&ctx->interleave_facch_f1_ctx, 456, 114, 0);
+ interleave_init_facch_f(&ctx->interleave_facch_f2_ctx, 456, 114, 4);
ctx->fn = -1;
ctx->bsic = -1;
ctx->gsmtap_fd = -1;
diff --git a/gsm-receiver/src/lib/decoder/gsmstack.h b/gsm-receiver/src/lib/decoder/gsmstack.h
index d02440c..62427d2 100644
--- a/gsm-receiver/src/lib/decoder/gsmstack.h
+++ b/gsm-receiver/src/lib/decoder/gsmstack.h
@@ -23,6 +23,8 @@ typedef struct
char msg[23]; /* last decoded message */
INTERLEAVE_CTX interleave_ctx;
+ INTERLEAVE_CTX interleave_facch_f1_ctx;
+ INTERLEAVE_CTX interleave_facch_f2_ctx;
struct gs_ts_ctx ts_ctx[8];
diff --git a/gsm-receiver/src/lib/decoder/interleave.c b/gsm-receiver/src/lib/decoder/interleave.c
index 7b45927..8d11286 100644
--- a/gsm-receiver/src/lib/decoder/interleave.c
+++ b/gsm-receiver/src/lib/decoder/interleave.c
@@ -25,6 +25,27 @@ interleave_init(INTERLEAVE_CTX *ictx, int size, int block_size)
}
int
+interleave_init_facch_f(INTERLEAVE_CTX *ictx, int size, int block_size, int block_offset)
+{
+ ictx->trans_size = size;
+ ictx->trans = (unsigned short *)malloc(size * sizeof *ictx->trans);
+
+// DEBUGF("size: %d\n", size);
+// DEBUGF("Block size: %d\n", block_size);
+ int j, k, B;
+ for (k = 0; k < size; k++)
+ {
+ B = (k + block_offset) % 8;
+ j = 2 * ((49 * k) % 57) + ((k % 8) / 4);
+ ictx->trans[k] = B * block_size + j;
+ /* Mapping: pos1 goes to pos2: pos1 -> pos2 */
+// DEBUGF("%d -> %d\n", ictx->trans[k], k);
+ }
+// exit(0);
+ return 0;
+}
+
+int
interleave_deinit(INTERLEAVE_CTX *ictx)
{
if (ictx->trans != NULL)
diff --git a/gsm-receiver/src/lib/decoder/interleave.h b/gsm-receiver/src/lib/decoder/interleave.h
index fa1912f..de71a9f 100644
--- a/gsm-receiver/src/lib/decoder/interleave.h
+++ b/gsm-receiver/src/lib/decoder/interleave.h
@@ -13,6 +13,7 @@ typedef struct _interleave_ctx
} INTERLEAVE_CTX;
int interleave_init(INTERLEAVE_CTX *ictx, int size, int block_size);
+int interleave_init_facch_f(INTERLEAVE_CTX *ictx, int size, int block_size, int block_offset);
int interleave_deinit(INTERLEAVE_CTX *ictx);
void interleave_decode(INTERLEAVE_CTX *ictx, unsigned char *dst, unsigned char *src);
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