Add comment header to srslte_sfidx_tdd_type.

Remove else after return.

lib/include/srslte/phy/common/phy_common.h

@@ -369,6 +369,14 @@ SRSLTE_API bool srslte_cellid_isvalid(uint32_t cell_id);
 
 SRSLTE_API bool srslte_nofprb_isvalid(uint32_t nof_prb);
 
+/**
+ * Returns the subframe type for a given subframe number and a TDD configuration.
+ * Check TS 36.211 v8.9.0 Table 4.2-2.
+ *
+ * @param tdd_config TDD configuration.
+ * @param sf_idx Subframe number, must be in range [0,9].
+ * @return Returns the subframe type.
+ */
 SRSLTE_API srslte_tdd_sf_t srslte_sfidx_tdd_type(srslte_tdd_config_t tdd_config, uint32_t sf_idx);
 
 SRSLTE_API uint32_t srslte_tdd_nof_harq(srslte_tdd_config_t tdd_config);

lib/src/phy/common/phy_common.c

@@ -93,7 +93,9 @@ void srslte_cell_fprint(FILE* stream, srslte_cell_t* cell, uint32_t sfn)
 #define U SRSLTE_TDD_SF_U
 #define S SRSLTE_TDD_SF_S
 
-static srslte_tdd_sf_t tdd_sf[7][10] = {{D, S, U, U, U, D, S, U, U, U},
+// TDD uplink-downlink configurations.
+// TS 36.211 v8.9.0 Table 4.2-2.
+static const srslte_tdd_sf_t tdd_sf[7][10] = {{D, S, U, U, U, D, S, U, U, U},
                                               {D, S, U, U, D, D, S, U, U, D},
                                               {D, S, U, D, D, D, S, U, D, D},
                                               {D, S, U, U, U, D, D, D, D, D},
@@ -109,9 +111,9 @@ srslte_tdd_sf_t srslte_sfidx_tdd_type(srslte_tdd_config_t tdd_config, uint32_t s
 {
   if (tdd_config.sf_config < 7 && sf_idx < 10 && tdd_config.configured) {
     return tdd_sf[tdd_config.sf_config][sf_idx];
-  } else {
-    return SRSLTE_TDD_SF_D;
   }
+
+  return SRSLTE_TDD_SF_D;
 }
 
 uint32_t srslte_sfidx_tdd_nof_dw_slot(srslte_tdd_config_t tdd_config, uint32_t slot, srslte_cp_t cp)