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TCH decoding with libosmocore

This commit is contained in:
Piotr Krysik 2016-10-02 18:56:04 +02:00
parent ea90c6d640
commit 694ed81d7b
1 changed files with 36 additions and 48 deletions
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84
lib/decoding/tch_f_decoder_impl.cc
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@ -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 @@ namespace gr {
if (d_collected_bursts_num == 8)
{
ubit_t bursts_u[116 * 8];
d_collected_bursts_num = 0;
// reorganize data
@ -115,6 +139,9 @@ 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);
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 @@ namespace gr {
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)));
}