fix msg4 failing retransmissions

openair2/LAYER2/NR_MAC_gNB/gNB_scheduler_RA.c

@@ -1470,9 +1470,17 @@ void nr_generate_Msg4(module_id_t module_idP, int CC_id, frame_t frameP, sub_fra
     int rbSize = 0;
     uint8_t tb_scaling = 0;
     uint32_t tb_size = 0;
-    uint8_t subheader_len = (mac_sdu_length < 256) ? sizeof(NR_MAC_SUBHEADER_SHORT) : sizeof(NR_MAC_SUBHEADER_LONG);
-    uint16_t pdu_length = mac_sdu_length + subheader_len + 7; //7 is contetion resolution length
-    uint16_t *vrb_map = cc[CC_id].vrb_map;
+    uint16_t pdu_length;
+    if(current_harq_pid >= 0) { // in case of retransmission
+      NR_UE_harq_t *harq = &sched_ctrl->harq_processes[current_harq_pid];
+      DevAssert(!harq->is_waiting);
+      pdu_length = harq->tb_size;
+    }
+    else {
+      uint8_t subheader_len = (mac_sdu_length < 256) ? sizeof(NR_MAC_SUBHEADER_SHORT) : sizeof(NR_MAC_SUBHEADER_LONG);
+      pdu_length = mac_sdu_length + subheader_len + 7; //7 is contetion resolution length
+    }
+
     // increase PRBs until we get to BWPSize or TBS is bigger than MAC PDU size
     do {
       if(rbSize < BWPSize)
@@ -1488,6 +1496,7 @@ void nr_generate_Msg4(module_id_t module_idP, int CC_id, frame_t frameP, sub_fra
     AssertFatal(tb_size >= pdu_length,"Cannot allocate Msg4\n");
 
     int i = 0;
+    uint16_t *vrb_map = cc[CC_id].vrb_map;
     while ((i < rbSize) && (rbStart + rbSize <= BWPSize)) {
       if (vrb_map[BWPStart + rbStart + i]&SL_to_bitmap(msg4_tda.startSymbolIndex, msg4_tda.nrOfSymbols)) {
         rbStart += i+1;