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authorPiotr Krysik <ptrkrysik@gmail.com>2016-09-28 11:53:26 +0200
committerPiotr Krysik <ptrkrysik@gmail.com>2016-09-28 11:53:26 +0200
commitb516e6dcdb758d0b8ba513dbfe812d6e1ed4a0e5 (patch)
tree1fdc159584c23841325ddb3d6e4763a9d6af6b47 /lib/decoding/control_channels_decoder_impl.cc
parent679a9bd874685bcc95776e85ef0b78350d49008f (diff)
Moved control channels decoder to libosmocore implementation
Diffstat (limited to 'lib/decoding/control_channels_decoder_impl.cc')
-rw-r--r--lib/decoding/control_channels_decoder_impl.cc95
1 files changed, 34 insertions, 61 deletions
diff --git a/lib/decoding/control_channels_decoder_impl.cc b/lib/decoding/control_channels_decoder_impl.cc
index 532e255..ddea256 100644
--- a/lib/decoding/control_channels_decoder_impl.cc
+++ b/lib/decoding/control_channels_decoder_impl.cc
@@ -33,6 +33,25 @@
namespace gr {
namespace gsm {
+ static int ubits2sbits(ubit_t *ubits, sbit_t *sbits, int count)
+ {
+ int i;
+
+ for (i = 0; i < count; i++) {
+ if (*ubits == 0x23) {
+ ubits++;
+ sbits++;
+ continue;
+ }
+ if ((*ubits++) & 1)
+ *sbits++ = -127;
+ else
+ *sbits++ = 127;
+ }
+
+ return count;
+ }
+
control_channels_decoder::sptr
control_channels_decoder::make()
{
@@ -49,18 +68,6 @@ namespace gr {
gr::io_signature::make(0, 0, 0)),
d_collected_bursts_num(0)
{
- //initialize de/interleaver
- int j, k, B;
- for (k = 0; k < CONV_SIZE; k++)
- {
- B = k % 4;
- j = 2 * ((49 * k) % 57) + ((k % 8) / 4);
- interleave_trans[k] = B * 114 + j; //114=57 + 57
- }
-
- //initialize decoder
- FC_init(&fc_ctx, 40, 184);
-
//setup input/output ports
message_port_register_in(pmt::mp("bursts"));
set_msg_handler(pmt::mp("bursts"), boost::bind(&control_channels_decoder_impl::decode, this, _1));
@@ -73,7 +80,11 @@ namespace gr {
void control_channels_decoder_impl::decode(pmt::pmt_t msg)
{
- unsigned char iBLOCK[BLOCKS*iBLOCK_SIZE], hl, hn, conv_data[CONV_SIZE], decoded_data[PARITY_OUTPUT_SIZE];
+ ubit_t bursts_u[116 * 4];
+ sbit_t bursts_s[116 * 4];
+ uint8_t result[23];
+ int n_errors, n_bits_total;
+
d_bursts[d_collected_bursts_num] = msg;
d_collected_bursts_num++;
//get convecutive bursts
@@ -86,60 +97,22 @@ namespace gr {
{
pmt::pmt_t header_plus_burst = pmt::cdr(d_bursts[ii]);
int8_t * burst_bits = (int8_t *)(pmt::blob_data(header_plus_burst))+sizeof(gsmtap_hdr);
-
- for(int jj = 0; jj < 57; jj++)
- {
- iBLOCK[ii*iBLOCK_SIZE+jj] = burst_bits[jj + 3];
- iBLOCK[ii*iBLOCK_SIZE+jj+57] = burst_bits[jj + 88]; //88 = 3+57+1+26+1
- }
- }
- //deinterleave
- for (int k = 0; k < CONV_SIZE; k++)
- {
- conv_data[k] = iBLOCK[interleave_trans[k]];
+
+ memcpy(&bursts_u[ii*116], &burst_bits[3],58);
+ memcpy(&bursts_u[ii*116+58], &burst_bits[3+57+1+26],58);
}
- //convolutional code decode
- int errors = conv_decode(decoded_data, conv_data);
- //std::cout << "Errors:" << errors << " " << parity_check(decoded_data) << std::endl;
- // check parity
- // If parity check error detected try to fix it.
+ //convert to soft bits
+ ubits2sbits(bursts_u, bursts_s, 116 * 4);
+ //decode
+ gsm0503_xcch_decode(result, bursts_s, &n_errors, &n_bits_total);
- if (parity_check(decoded_data))
- {
- FC_init(&fc_ctx, 40, 184);
- unsigned char crc_result[PARITY_OUTPUT_SIZE];
- if (FC_check_crc(&fc_ctx, decoded_data, crc_result) == 0)
- {
- //("error: sacch: parity error (errors=%d fn=%d)\n", errors, ctx->fn);
- //std::cout << "Uncorrectable errors!" << std::endl;
- errors = -1;
- return;
- } else {
- //DEBUGF("Successfully corrected parity bits! (errors=%d fn=%d)\n", errors, ctx->fn);
- //std::cout << "Corrected some errors" << std::endl;
- memcpy(decoded_data, crc_result, PARITY_OUTPUT_SIZE);
- errors = 0;
- }
- } else {
- //std::cout << "Everything correct" << std::endl;
- }
- //compress bits
- unsigned char outmsg[28];
- unsigned char sbuf_len=224;
- int i, j, c, pos=0;
- for(i = 0; i < sbuf_len; i += 8) {
- for(j = 0, c = 0; (j < 8) && (i + j < sbuf_len); j++){
- c |= (!!decoded_data[i + j]) << j;
- }
- outmsg[pos++] = c & 0xff;
- }
-
- //send message with header of the first burst
+ //send to the output
pmt::pmt_t first_header_plus_burst = pmt::cdr(d_bursts[0]);
gsmtap_hdr * header = (gsmtap_hdr *)pmt::blob_data(first_header_plus_burst);
int8_t header_plus_data[sizeof(gsmtap_hdr)+DATA_BYTES];
memcpy(header_plus_data, header, sizeof(gsmtap_hdr));
- memcpy(header_plus_data+sizeof(gsmtap_hdr), outmsg, DATA_BYTES);
+
+ memcpy(header_plus_data+sizeof(gsmtap_hdr), result, DATA_BYTES);
((gsmtap_hdr*)header_plus_data)->type = GSMTAP_TYPE_UM;
pmt::pmt_t msg_binary_blob = pmt::make_blob(header_plus_data,DATA_BYTES+sizeof(gsmtap_hdr));