fix padding BSR generation and add test for it

srsue/src/stack/mac/proc_bsr.cc

@@ -369,8 +369,9 @@ bool bsr_proc::generate_padding_bsr(uint32_t nof_padding_bytes, bsr_t* bsr)
 
   pthread_mutex_lock(&mutex);
 
-  if (triggered_bsr_type != NONE && nof_padding_bytes >= 2) {
-
+  if (triggered_bsr_type == NONE && nof_padding_bytes >= 2) {
+    // generate padding BSR
+    triggered_bsr_type = PADDING;
     generate_bsr(bsr, nof_padding_bytes);
     ret = true;
 

srsue/test/mac_test.cc

@@ -644,6 +644,61 @@ int mac_ul_sch_pdu_with_short_bsr_test()
   return SRSLTE_SUCCESS;
 }
 
+// PDU with only padding BSR (long BSR) and the rest padding
+int mac_ul_sch_pdu_with_padding_bsr_test()
+{
+  const uint8_t tv[] = {0x3e, 0x1f, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00};
+
+  srslte::log_filter mac_log("MAC");
+  mac_log.set_level(srslte::LOG_LEVEL_DEBUG);
+  mac_log.set_hex_limit(100000);
+
+  srslte::log_filter rlc_log("RLC");
+  rlc_log.set_level(srslte::LOG_LEVEL_DEBUG);
+  rlc_log.set_hex_limit(100000);
+
+  // dummy layers
+  phy_dummy phy;
+  rlc_dummy rlc(&rlc_log);
+  rrc_dummy rrc;
+
+  // the actual MAC
+  mac mac;
+  mac.init(&phy, &rlc, &rrc, &mac_log);
+  const uint16_t crnti = 0x1001;
+  mac.set_ho_rnti(crnti, 0);
+
+  // create UL action and grant and push MAC PDU
+  {
+    mac_interface_phy_lte::tb_action_ul_t ul_action = {};
+    mac_interface_phy_lte::mac_grant_ul_t mac_grant = {};
+
+    mac_grant.rnti           = crnti; // make sure MAC picks it up as valid UL grant
+    mac_grant.tb.ndi_present = true;
+    mac_grant.tb.ndi         = true;
+    mac_grant.tb.tbs         = 10; // give enough room for Padding BSR
+    int cc_idx               = 0;
+
+    // Send grant to MAC and get action for this TB, then call tb_decoded to unlock MAC
+    mac.new_grant_ul(cc_idx, mac_grant, &ul_action);
+
+    // print generated PDU
+    mac_log.info_hex(ul_action.tb.payload, mac_grant.tb.tbs, "Generated PDU (%d B)\n", mac_grant.tb.tbs);
+#if HAVE_PCAP
+    pcap_handle->write_ul_crnti(ul_action.tb.payload, mac_grant.tb.tbs, 0x1001, true, 1);
+#endif
+
+    TESTASSERT(memcmp(ul_action.tb.payload, tv, sizeof(tv)) == 0);
+  }
+
+  // make sure MAC PDU thread picks up before stopping
+  sleep(1);
+  mac.run_tti(0);
+  mac.stop();
+
+  return SRSLTE_SUCCESS;
+}
+
 int main(int argc, char** argv)
 {
 #if HAVE_PCAP
@@ -681,5 +736,10 @@ int main(int argc, char** argv)
     return -1;
   }
 
+  if (mac_ul_sch_pdu_with_padding_bsr_test()) {
+    printf("mac_ul_sch_pdu_with_padding_bsr_test() test failed.\n");
+    return -1;
+  }
+
   return 0;
 }