Implementation of TCH/F decoder supporting GSM-FR and GSM-EFR. Issue #50
diff --git a/lib/decoding/tch_f_decoder_impl.cc b/lib/decoding/tch_f_decoder_impl.cc
new file mode 100644
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+++ b/lib/decoding/tch_f_decoder_impl.cc
@@ -0,0 +1,242 @@
+/* -*- c++ -*- */
+/*
+ * @file
+ * @author Piotr Krysik <ptrkrysik@gmail.com>
+ * @section LICENSE
+ *
+ * Gr-gsm is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3, or (at your option)
+ * any later version.
+ *
+ * Gr-gsm is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with gr-gsm; see the file COPYING. If not, write to
+ * the Free Software Foundation, Inc., 51 Franklin Street,
+ * Boston, MA 02110-1301, USA.
+ */
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#endif
+
+#include <gnuradio/io_signature.h>
+#include <grgsm/gsmtap.h>
+#include "stdio.h"
+#include "tch_f_decoder_impl.h"
+
+#define DATA_BYTES 23
+
+namespace gr {
+ namespace gsm {
+
+ tch_f_decoder::sptr
+ tch_f_decoder::make(tch_mode mode, const std::string &file)
+ {
+ return gnuradio::get_initial_sptr
+ (new tch_f_decoder_impl(mode, file));
+ }
+
+ /*
+ * Constructor
+ */
+ tch_f_decoder_impl::tch_f_decoder_impl(tch_mode mode, const std::string &file)
+ : gr::block("tch_f_decoder",
+ gr::io_signature::make(0, 0, 0),
+ gr::io_signature::make(0, 0, 0)),
+ d_tch_mode(mode),
+ d_collected_bursts_num(0)
+ {
+ d_speech_file = fopen( file.c_str(), "wb" );
+ if (d_speech_file == NULL)
+ {
+ throw std::runtime_error("TCH/F Decoder: can't open file\n");
+ }
+
+ int j, k, B;
+ for (k = 0; k < CONV_SIZE; k++)
+ {
+ B = k % 8;
+ j = 2 * ((49 * k) % 57) + ((k % 8) / 4);
+ interleave_trans[k] = B * 114 + j;
+ }
+
+ //setup input/output ports
+ message_port_register_in(pmt::mp("bursts"));
+ set_msg_handler(pmt::mp("bursts"), boost::bind(&tch_f_decoder_impl::decode, this, _1));
+ message_port_register_out(pmt::mp("msgs"));
+ }
+
+ tch_f_decoder_impl::~tch_f_decoder_impl()
+ {
+ }
+
+ void tch_f_decoder_impl::decode(pmt::pmt_t msg)
+ {
+ d_bursts[d_collected_bursts_num] = msg;
+ d_collected_bursts_num++;
+
+ bool stolen = false;
+
+ if (d_collected_bursts_num == 8)
+ {
+ unsigned char iBLOCK[2*BLOCKS*iBLOCK_SIZE];
+ SoftVector mC(CONV_SIZE);
+ SoftVector mClass1_c(mC.head(378));
+ SoftVector mClass2_c(mC.segment(378, 78));
+ BitVector mTCHU(189);
+ BitVector mTCHD(260);
+ BitVector mClass1A_d(mTCHD.head(50));
+ ViterbiR2O4 mVCoder;
+
+ d_collected_bursts_num = 0;
+
+ // reorganize data
+ for (int ii = 0; ii < 8; ii++)
+ {
+ 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*114+jj] = burst_bits[jj + 3];
+ iBLOCK[ii*114+jj+57] = burst_bits[jj + 88]; //88 = 3+57+1+26+1
+ }
+
+ if ((ii <= 3 && static_cast<int>(burst_bits[87]) == 1) || (ii >= 4 && static_cast<int>(burst_bits[60]) == 1))
+ {
+ stolen = true;
+ }
+ }
+
+ // deinterleave
+ for (int k = 0; k < CONV_SIZE; k++)
+ {
+ mC[k] = iBLOCK[interleave_trans[k]];
+ }
+
+ // Decode stolen frames as FACCH/F
+ if (stolen)
+ {
+ BitVector mU(228);
+ BitVector mP(mU.segment(184,40));
+ BitVector mD(mU.head(184));
+ BitVector mDP(mU.head(224));
+ Parity mBlockCoder(0x10004820009ULL, 40, 224);
+
+ mC.decode(mVCoder, mU);
+ mP.invert();
+
+ unsigned syndrome = mBlockCoder.syndrome(mDP);
+
+ if (syndrome == 0)
+ {
+ unsigned char outmsg[27];
+ 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 |= (!!mU.bit(i + j)) << j;
+ }
+ outmsg[pos++] = c & 0xff;
+ }
+
+ pmt::pmt_t first_header_plus_burst = pmt::cdr(d_bursts[0]);
+ gsmtap_hdr * header = (gsmtap_hdr *)pmt::blob_data(first_header_plus_burst);
+ header->type = GSMTAP_TYPE_UM;
+ int8_t * header_content = (int8_t *)header;
+ int8_t header_plus_data[sizeof(gsmtap_hdr)+DATA_BYTES];
+ memcpy(header_plus_data, header_content, sizeof(gsmtap_hdr));
+ memcpy(header_plus_data+sizeof(gsmtap_hdr), outmsg, DATA_BYTES);
+
+ pmt::pmt_t msg_binary_blob = pmt::make_blob(header_plus_data,DATA_BYTES+sizeof(gsmtap_hdr));
+ pmt::pmt_t msg_out = pmt::cons(pmt::PMT_NIL, msg_binary_blob);
+
+ message_port_pub(pmt::mp("msgs"), msg_out);
+ }
+ }
+
+ mClass1_c.decode(mVCoder, mTCHU);
+ mClass2_c.sliced().copyToSegment(mTCHD, 182);
+
+ // 3.1.2.1
+ // copy class 1 bits u[] to d[]
+ for (unsigned k = 0; k <= 90; k++) {
+ mTCHD[2*k] = mTCHU[k];
+ mTCHD[2*k+1] = mTCHU[184-k];
+ }
+
+ Parity mTCHParity(0x0b, 3, 50);
+
+ // 3.1.2.1
+ // check parity of class 1A
+ unsigned sentParity = (~mTCHU.peekField(91, 3)) & 0x07;
+ //unsigned calcParity = mTCHD.head(50).parity(mTCHParity) & 0x07;
+ unsigned calcParity = mClass1A_d.parity(mTCHParity) & 0x07;
+
+ // 3.1.2.2
+ // Check the tail bits, too.
+ unsigned tail = mTCHU.peekField(185, 4);
+
+ bool good = (sentParity == calcParity) && (tail == 0);
+
+ if (good)
+ {
+ unsigned char mTCHFrame[33];
+ unsigned int mTCHFrameLength;
+
+ if (d_tch_mode == MODE_SPEECH_FR) // GSM-FR
+ {
+ // Undo Um's importance-sorted bit ordering.
+ // See GSM 05.03 3.1 and Tablee 2.
+ VocoderFrame mVFrame;
+
+ BitVector payload = mVFrame.payload();
+ mTCHD.unmap(GSM::g610BitOrder, 260, payload);
+ mVFrame.pack(mTCHFrame);
+ mTCHFrameLength = 33;
+ }
+ else if (d_tch_mode == MODE_SPEECH_EFR) // GSM-EFR / AMR 12.2
+ {
+ VocoderAMRFrame mVFrameAMR;
+
+ BitVector payload = mVFrameAMR.payload();
+ BitVector TCHW(260), EFRBits(244);
+
+ // 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::g690_12_2_BitOrder, 244, payload);
+
+ // Put the whole frame (hdr + payload)
+ mVFrameAMR.pack(mTCHFrame);
+ mTCHFrameLength = 32;
+ }
+ fwrite(mTCHFrame, 1 , mTCHFrameLength, d_speech_file);
+ }
+ }
+ }
+ } /* namespace gsm */
+} /* namespace gr */
+