Implement common nr_get_mu() in nr_mac_common

These functions look up the numerology, and code can be harmonized:

- ssb_index_from_prach()
- find_SSB_and_RO_available()
- schedule_nr_prach()

The next commits also need to look up the numerology from the
UplinkConfigCommon. This provides the common implementation to be used
in follow-up commits.

openair2/LAYER2/NR_MAC_COMMON/nr_mac_common.c

@@ -5331,3 +5331,29 @@ int get_FeedbackDisabled(NR_DownlinkHARQ_FeedbackDisabled_r17_t *downlinkHARQ_Fe
 
   return (downlinkHARQ_FeedbackDisabled_r17->buf[byte_index] >> (7 - bit_index)) & 1;
 }
+
+int nr_get_mu(const NR_UplinkConfigCommon_t *uplinkConfigCommon)
+{
+  int mu;
+  NR_BWP_UplinkCommon_t *initialUplinkBWP = uplinkConfigCommon->initialUplinkBWP;
+
+  // if 2-Step configuration file exists
+  if (initialUplinkBWP->ext1 && initialUplinkBWP->ext1->msgA_ConfigCommon_r16) {
+    if (initialUplinkBWP->ext1->msgA_ConfigCommon_r16->choice.setup->rach_ConfigCommonTwoStepRA_r16.msgA_SubcarrierSpacing_r16) {
+      // Choose Subcarrier Spacing of configuration file of 2-Step
+      const NR_MsgA_ConfigCommon_r16_t *msgacc = initialUplinkBWP->ext1->msgA_ConfigCommon_r16->choice.setup;
+      mu = *msgacc->rach_ConfigCommonTwoStepRA_r16.msgA_SubcarrierSpacing_r16;
+    } else {
+      // Choose Subcarrier Spacing of configuration file of 4-Step
+      mu = uplinkConfigCommon->frequencyInfoUL->scs_SpecificCarrierList.list.array[0]->subcarrierSpacing;
+    }
+  } else {
+    if (initialUplinkBWP->rach_ConfigCommon->choice.setup->msg1_SubcarrierSpacing) {
+      mu = *initialUplinkBWP->rach_ConfigCommon->choice.setup->msg1_SubcarrierSpacing;
+    } else {
+      mu = uplinkConfigCommon->frequencyInfoUL->scs_SpecificCarrierList.list.array[0]->subcarrierSpacing;
+    }
+  }
+
+  return mu;
+}

openair2/LAYER2/NR_MAC_COMMON/nr_mac_common.h

@@ -327,4 +327,6 @@ int get_nrofHARQ_ProcessesForPDSCH(const NR_UE_ServingCell_Info_t *sc_info);
 
 int get_nrofHARQ_ProcessesForPUSCH(const NR_UE_ServingCell_Info_t *sc_info);
 
+int nr_get_mu(const NR_UplinkConfigCommon_t *uplinkConfigCommon);
+
 #endif

openair2/LAYER2/NR_MAC_gNB/gNB_scheduler_RA.c

@@ -91,16 +91,13 @@ static int16_t ssb_index_from_prach(module_id_t module_idP,
   
   float  num_ssb_per_RO = ssb_per_rach_occasion[cfg->prach_config.ssb_per_rach.value];	
   uint16_t start_symbol_index = 0;
-  uint8_t mu,N_dur=0,N_t_slot=0,start_symbol = 0, temp_start_symbol = 0, N_RA_slot=0;
+  uint8_t N_dur=0,N_t_slot=0,start_symbol = 0, temp_start_symbol = 0, N_RA_slot=0;
   uint16_t format,RA_sfn_index = -1;
   uint8_t config_period = 1;
   uint16_t prach_occasion_id = -1;
   uint8_t num_active_ssb = cc->num_active_ssb;
 
-  if (rach_ConfigCommon->msg1_SubcarrierSpacing)
-    mu = *rach_ConfigCommon->msg1_SubcarrierSpacing;
-  else
-    mu = scc->downlinkConfigCommon->frequencyInfoDL->scs_SpecificCarrierList.list.array[0]->subcarrierSpacing;
+  int mu = nr_get_mu(scc->uplinkConfigCommon);
 
   get_nr_prach_info_from_index(config_index,
 			       (int)frameP,
@@ -167,7 +164,7 @@ void find_SSB_and_RO_available(gNB_MAC_INST *nrmac)
   nfapi_nr_config_request_scf_t *cfg = &nrmac->config[0];
   NR_RACH_ConfigCommon_t *rach_ConfigCommon = scc->uplinkConfigCommon->initialUplinkBWP->rach_ConfigCommon->choice.setup;
   uint8_t config_index = rach_ConfigCommon->rach_ConfigGeneric.prach_ConfigurationIndex;
-  uint8_t mu,N_dur=0,N_t_slot=0,start_symbol=0,N_RA_slot = 0;
+  uint8_t N_dur=0,N_t_slot=0,start_symbol=0,N_RA_slot = 0;
   uint16_t format,N_RA_sfn = 0,unused_RA_occasion,repetition = 0;
   uint8_t num_active_ssb = 0;
   uint8_t max_association_period = 1;
@@ -204,10 +201,7 @@ void find_SSB_and_RO_available(gNB_MAC_INST *nrmac)
       break;
     }
 
-  if (rach_ConfigCommon->msg1_SubcarrierSpacing)
-    mu = *rach_ConfigCommon->msg1_SubcarrierSpacing;
-  else
-    mu = scc->downlinkConfigCommon->frequencyInfoDL->scs_SpecificCarrierList.list.array[0]->subcarrierSpacing;
+  int mu = nr_get_mu(scc->uplinkConfigCommon);
 
   // prach is scheduled according to configuration index and tables 6.3.3.2.2 to 6.3.3.2.4
   get_nr_prach_occasion_info_from_index(config_index,
@@ -267,11 +261,7 @@ void schedule_nr_prach(module_id_t module_idP, frame_t frameP, sub_frame_t slotP
   NR_COMMON_channels_t *cc = gNB->common_channels;
   NR_ServingCellConfigCommon_t *scc = cc->ServingCellConfigCommon;
   NR_RACH_ConfigCommon_t *rach_ConfigCommon = scc->uplinkConfigCommon->initialUplinkBWP->rach_ConfigCommon->choice.setup;
-  int mu;
-  if (rach_ConfigCommon->msg1_SubcarrierSpacing)
-    mu = *rach_ConfigCommon->msg1_SubcarrierSpacing;
-  else
-    mu = scc->downlinkConfigCommon->frequencyInfoDL->scs_SpecificCarrierList.list.array[0]->subcarrierSpacing;
+  int mu = nr_get_mu(scc->uplinkConfigCommon);
   int index = ul_buffer_index(frameP, slotP, mu, gNB->UL_tti_req_ahead_size);
   nfapi_nr_ul_tti_request_t *UL_tti_req = &RC.nrmac[module_idP]->UL_tti_req_ahead[0][index];
   nfapi_nr_config_request_scf_t *cfg = &RC.nrmac[module_idP]->config[0];