TCH decoding with libosmocore
diff --git a/lib/decoding/tch_f_decoder_impl.cc b/lib/decoding/tch_f_decoder_impl.cc
index 41e5f53..a84c47c 100644
--- a/lib/decoding/tch_f_decoder_impl.cc
+++ b/lib/decoding/tch_f_decoder_impl.cc
@@ -29,11 +29,34 @@
#include "stdio.h"
#include "tch_f_decoder_impl.h"
+extern "C" {
+ #include <osmocom/coding/gsm0503_coding.h>
+}
+
#define DATA_BYTES 23
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;
+ }
+
tch_f_decoder::sptr
tch_f_decoder::make(tch_mode mode, bool boundary_check)
{
@@ -107,6 +130,7 @@
if (d_collected_bursts_num == 8)
{
+ ubit_t bursts_u[116 * 8];
d_collected_bursts_num = 0;
// reorganize data
@@ -115,6 +139,9 @@
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);
+ memcpy(&bursts_u[ii*116], &burst_bits[3],58);
+ memcpy(&bursts_u[ii*116+58], &burst_bits[3+57+1+26],58);
+
for (int jj = 0; jj < 57; jj++)
{
iBLOCK[ii*114+jj] = burst_bits[jj + 3];
@@ -269,65 +296,26 @@
unsigned tail = mTCHU.peekField(185, 4);
bool good = (sentParity == calcParity) && (tail == 0);
+
if (good)
{
- unsigned char frameBuffer[33];
+ uint8_t frameBuffer[33];
+ sbit_t bursts_s[116 * 8];
+ int n_errors, n_bits_total;
unsigned int mTCHFrameLength;
+ ubits2sbits(bursts_u, bursts_s, 116 * 8);
+
if (d_tch_mode == TCH_FS) // GSM-FR
{
- unsigned char mFrameHeader = 0x0d;
mTCHFrameLength = 33;
-
- // Undo Um's importance-sorted bit ordering.
- // See GSM 05.03 3.1 and Table 2.
- BitVector frFrame(260 + 4); // FR has a frameheader of 4 bits only
- frFrame.fillField(0, mFrameHeader, 4);
- BitVector payload = frFrame.tail(4);
-
- mTCHD.unmap(GSM::g610BitOrder, 260, payload);
- frFrame.pack(frameBuffer);
-
+ gsm0503_tch_fr_decode(frameBuffer, bursts_s, 1, 0, &n_errors, &n_bits_total);
+ std::cout << "Errors: " << n_errors << std::endl;
}
else if (d_tch_mode == TCH_EFR) // GSM-EFR
{
- unsigned char mFrameHeader = 0x3c;
-
- // AMR Frame, consisting of a 8 bit frame header, plus the payload from decoding
- BitVector amrFrame(244 + 8); // Same output length as AMR 12.2
- BitVector payload = amrFrame.tail(8);
-
- BitVector TCHW(260), EFRBits(244);
-
- // write frame header
- amrFrame.fillField(0, mFrameHeader, 8);
-
- // Undo Um's EFR bit ordering.
- mTCHD.unmap(GSM::g660BitOrder, 260, TCHW);
-
- // Remove repeating bits and CRC to get raw EFR frame (244 bits)
- for (unsigned k=0; k<71; k++)
- EFRBits[k] = TCHW[k] & 1;
-
- for (unsigned k=73; k<123; k++)
- EFRBits[k-2] = TCHW[k] & 1;
-
- for (unsigned k=125; k<178; k++)
- EFRBits[k-4] = TCHW[k] & 1;
-
- for (unsigned k=180; k<230; k++)
- EFRBits[k-6] = TCHW[k] & 1;
-
- for (unsigned k=232; k<252; k++)
- EFRBits[k-8] = TCHW[k] & 1;
-
- // Map bits as AMR 12.2k
- EFRBits.map(GSM::gAMRBitOrderTCH_AFS12_2, 244, payload);
-
- // Put the whole frame (hdr + payload)
mTCHFrameLength = 32;
- amrFrame.pack(frameBuffer);
-
+ gsm0503_tch_fr_decode(frameBuffer, bursts_s, 1, 1, &n_errors, &n_bits_total);
}
message_port_pub(pmt::mp("voice"), pmt::cons(pmt::PMT_NIL, pmt::make_blob(frameBuffer,mTCHFrameLength)));
}