lib,rlc_am_lte: added fix for full tx window with wraparround

lib/src/rlc/rlc_am_lte.cc

@@ -361,10 +361,7 @@ void rlc_am_lte_tx::retransmit_pdu(uint32_t sn)
 
 bool rlc_am_lte_tx::window_full()
 {
-  if ((vt_s - vt_a) >= RLC_AM_WINDOW_SIZE) {
-    return true;
-  }
-  return false;
+  return TX_MOD_BASE(vt_s) >= RLC_AM_WINDOW_SIZE;
 };
 
 /**

lib/test/rlc/rlc_am_lte_test.cc

@@ -3927,6 +3927,152 @@ bool full_window_check_test()
   return SRSRAN_SUCCESS;
 }
 
+bool full_window_check_wraparound_test()
+{
+  rlc_config_t config = rlc_config_t::default_rlc_am_config();
+  // [I] SRB1 configured: t_poll_retx=65, poll_pdu=-1, poll_byte=-1, max_retx_thresh=6, t_reordering=55,
+  // t_status_prohibit=0
+  config.am.t_poll_retx       = 65;
+  config.am.poll_pdu          = -1;
+  config.am.poll_byte         = -1;
+  config.am.max_retx_thresh   = 6;
+  config.am.t_reordering      = 55;
+  config.am.t_status_prohibit = 55;
+
+#if HAVE_PCAP
+  rlc_pcap pcap;
+  pcap.open("rlc_am_poll_rext_expiry_test.pcap", config);
+  rlc_am_tester tester(true, &pcap);
+#else
+  rlc_am_tester tester(true, NULL);
+#endif
+
+  uint32_t pdcp_count = 0;
+
+  srsran::timer_handler timers(8);
+
+  rlc_am rlc1(srsran_rat_t::lte, srslog::fetch_basic_logger("RLC_AM_1"), 1, &tester, &tester, &timers);
+  rlc_am rlc2(srsran_rat_t::lte, srslog::fetch_basic_logger("RLC_AM_2"), 1, &tester, &tester, &timers);
+
+  srslog::fetch_basic_logger("RLC_AM_1").set_hex_dump_max_size(100);
+  srslog::fetch_basic_logger("RLC_AM_2").set_hex_dump_max_size(100);
+  srslog::fetch_basic_logger("RLC").set_hex_dump_max_size(100);
+
+  if (not rlc1.configure(config)) {
+    return -1;
+  }
+
+  if (not rlc2.configure(config)) {
+    return -1;
+  }
+
+  // Advance vt_a to 512 and vt_s to 512 as well.
+  {
+    // Initial Tx
+    uint32_t num_tx_pdus = 512;
+    for (uint32_t i = 0; i < num_tx_pdus; ++i) {
+      // Write SDU
+      unique_byte_buffer_t sdu = srsran::make_byte_buffer();
+      TESTASSERT(sdu != nullptr);
+      sdu->N_bytes    = 1;
+      sdu->msg[0]     = i;
+      sdu->md.pdcp_sn = pdcp_count++;
+      rlc1.write_sdu(std::move(sdu));
+
+      unique_byte_buffer_t pdu = srsran::make_byte_buffer();
+      TESTASSERT(pdu != nullptr);
+      pdu->N_bytes = rlc1.read_pdu(pdu->msg, 3);
+      TESTASSERT(pdu->N_bytes == 3);
+    }
+
+    // ACK all SNs to advance the TX window.
+    rlc_status_pdu_t status = {};
+    status.ack_sn           = num_tx_pdus;
+    status.N_nack           = 0;
+
+    unique_byte_buffer_t status_buf = srsran::make_byte_buffer();
+    TESTASSERT(status_buf != nullptr);
+    rlc_am_write_status_pdu(&status, status_buf.get());
+    rlc1.write_pdu(status_buf->msg, status_buf->N_bytes);
+  }
+
+  // Advance vt_a and vt_s to 1023
+  {
+    // Initial Tx
+    uint32_t num_tx_pdus = 511;
+    for (uint32_t i = 0; i < num_tx_pdus; ++i) {
+      // Write SDU
+      unique_byte_buffer_t sdu = srsran::make_byte_buffer();
+      TESTASSERT(sdu != nullptr);
+      sdu->N_bytes    = 1;
+      sdu->msg[0]     = i;
+      sdu->md.pdcp_sn = pdcp_count++;
+      rlc1.write_sdu(std::move(sdu));
+
+      unique_byte_buffer_t pdu = srsran::make_byte_buffer();
+      TESTASSERT(pdu != nullptr);
+      pdu->N_bytes = rlc1.read_pdu(pdu->msg, 3);
+      TESTASSERT(pdu->N_bytes == 3);
+    }
+
+    // ACK all SNs to advance the TX window.
+    rlc_status_pdu_t status = {};
+    status.ack_sn           = 512 + num_tx_pdus;
+    status.N_nack           = 0;
+
+    unique_byte_buffer_t status_buf = srsran::make_byte_buffer();
+    TESTASSERT(status_buf != nullptr);
+    rlc_am_write_status_pdu(&status, status_buf.get());
+    rlc1.write_pdu(status_buf->msg, status_buf->N_bytes);
+  }
+
+  // Now, fill up the window
+  {
+    // Initial Tx
+    uint32_t num_tx_pdus = 512;
+    for (uint32_t i = 0; i < num_tx_pdus; ++i) {
+      // Write SDU
+      unique_byte_buffer_t sdu = srsran::make_byte_buffer();
+      TESTASSERT(sdu != nullptr);
+      sdu->N_bytes    = 1;
+      sdu->msg[0]     = i;
+      sdu->md.pdcp_sn = pdcp_count++;
+      rlc1.write_sdu(std::move(sdu));
+
+      unique_byte_buffer_t pdu = srsran::make_byte_buffer();
+      TESTASSERT(pdu != nullptr);
+      pdu->N_bytes = rlc1.read_pdu(pdu->msg, 3);
+      TESTASSERT(pdu->N_bytes == 3);
+    }
+  }
+  {
+    // Tx one more to check the window is full
+    unique_byte_buffer_t sdu = srsran::make_byte_buffer();
+    TESTASSERT(sdu != nullptr);
+    sdu->N_bytes    = 1;
+    sdu->msg[0]     = 0;
+    sdu->md.pdcp_sn = pdcp_count++;
+    rlc1.write_sdu(std::move(sdu));
+
+    unique_byte_buffer_t pdu = srsran::make_byte_buffer();
+    TESTASSERT(pdu != nullptr);
+    pdu->N_bytes = rlc1.read_pdu(pdu->msg, 3);
+    TESTASSERT(pdu->N_bytes == 3);
+
+    // If the TX window is full, we should RETX SN=1023
+    rlc_amd_pdu_header_t header = {};
+    rlc_am_read_data_pdu_header(&pdu->msg, &pdu->N_bytes, &header);
+    TESTASSERT_EQ(header.sn, 1023);
+    TESTASSERT_EQ(header.N_li, 0);
+    TESTASSERT_EQ(header.fi, 0);
+  }
+
+#if HAVE_PCAP
+  pcap.close();
+#endif
+
+  return SRSRAN_SUCCESS;
+}
 int main(int argc, char** argv)
 {
   // Setup the log message spy to intercept error and warning log entries from RLC
@@ -4141,5 +4287,10 @@ int main(int argc, char** argv)
     printf("full_window_check_test failed\n");
     exit(-1);
   };
+
+  if (full_window_check_wraparound_test()) {
+    printf("full_window_check_wraparound_test failed\n");
+    exit(-1);
+  };
   return SRSRAN_SUCCESS;
 }