Aesthetical changes scell synchronization class

srsue/hdr/phy/scell/scell_sync.h

@@ -45,13 +45,18 @@ private:
    */
   typedef enum { STATE_IDLE = 0, STATE_SEARCH_PSS, STATE_IN_SYNCH } state_t;
 
+  /**
+   * Buffer length in subframes, only 2 subframes are allowed
+   */
+  static const uint32_t BUFFER_LEN = 2;
+
   state_t                                         state    = STATE_IDLE;
   sync_callback*                                  callback = nullptr;
   uint32_t                                        channel  = 0;
   srslte_sync_t                                   find_pss = {};
   int32_t                                         sf_len   = 0;
   int32_t                                         cell_id  = -1;
-  std::array<cf_t, 2 * SRSLTE_SF_LEN_MAX> temp     = {};
+  std::array<cf_t, BUFFER_LEN* SRSLTE_SF_LEN_MAX> temp     = {};
   std::mutex mutex; ///< Used for avoiding reconfiguring (set_cell) while it is searching
 
   /**
@@ -103,6 +108,35 @@ private:
     }
   }
 
+  /**
+   * Unprotected internal resize method for a given bandwidth
+   */
+  void resize(uint32_t new_nof_prb)
+  {
+    uint32_t symbol_sz  = srslte_symbol_sz(new_nof_prb);
+    int32_t  new_sf_len = SRSLTE_SF_LEN_PRB(new_nof_prb);
+
+    // Reset Temporal buffer
+    srslte_vec_cf_zero(temp.data(), BUFFER_LEN * new_sf_len);
+
+    // Skip if no BW is changed
+    if (new_sf_len == sf_len) {
+      return;
+    }
+
+    // Resizes synchronization object. As the secondary serving cell base-band might be unaligned respect the primary
+    // serving cell, the PSS may be located away from the primary serving cell PSS time. The secondary serving cell PSS
+    // could be in the boundary between subframes, so more than a subframe is required to ensure PSS is captured. Two
+    // subframes is a simple and conservative buffer size.
+    if (srslte_sync_resize(&find_pss, BUFFER_LEN * new_sf_len, BUFFER_LEN * new_sf_len, symbol_sz) != SRSLTE_SUCCESS) {
+      ERROR("Error setting cell sync find");
+    }
+
+    // Update values
+    sf_len  = new_sf_len;
+    cell_id = -1; // Force next set_cell to set the ID
+  }
+
 public:
   /**
    * Constructor
@@ -128,22 +162,8 @@ public:
     // Protect DSP objects and buffers; As it is called by asynchronous thread, it can wait to finish current processing
     std::unique_lock<std::mutex> lock(mutex);
 
-    uint32_t symbol_sz  = srslte_symbol_sz(nof_prb);
-    int32_t  new_sf_len = SRSLTE_SF_LEN_PRB(nof_prb);
-
-    // Skip if no BW is changed
-    if (new_sf_len == sf_len) {
-      return;
-    }
-
-    // Resize
-    if (srslte_sync_resize(&find_pss, 2 * new_sf_len, 2 * new_sf_len, symbol_sz) != SRSLTE_SUCCESS) {
-      ERROR("Error setting cell sync find");
-    }
-
-    // Update values
-    sf_len  = new_sf_len;
-    cell_id = -1; // Force next set_cell to set the ID
+    // Resizes the DSP objects for the given bandwidth
+    resize(nof_prb);
 
     // Reset state to idle
     state = STATE_IDLE;
@@ -157,21 +177,11 @@ public:
     // Protect DSP objects and buffers; As it is called by asynchronous thread, it can wait to finish current processing
     std::unique_lock<std::mutex> lock(mutex);
 
-    uint32_t symbol_sz   = srslte_symbol_sz(cell.nof_prb);
-    int32_t  new_sf_len  = SRSLTE_SF_LEN_PRB(cell.nof_prb);
-    int32_t  new_cell_id = cell.id;
+    // Resize DSP for the new cell bandwidth
+    resize(cell.nof_prb);
 
-    // Resize Sync object
-    if (new_sf_len != sf_len) {
-      if (srslte_sync_resize(&find_pss, 2 * new_sf_len, 2 * new_sf_len, symbol_sz) != SRSLTE_SUCCESS) {
-        ERROR("Error setting cell sync find");
-      }
-
-      // Force cell_id set
-      cell_id = -1;
-    }
-
-    // Configure
+    // Configure only if the cell identifier has changed
+    int32_t new_cell_id = cell.id;
     if (cell_id != new_cell_id) {
       srslte_sync_set_frame_type(&find_pss, cell.frame_type);
       srslte_sync_set_N_id_2(&find_pss, new_cell_id % SRSLTE_NOF_NID_2);
@@ -179,14 +189,8 @@ public:
       srslte_sync_set_cfo_ema_alpha(&find_pss, 0.1);
       srslte_sync_set_em_alpha(&find_pss, 1);
       srslte_sync_set_threshold(&find_pss, 3.0);
-    }
-
-    // Reset Temporal buffer
-    srslte_vec_cf_zero(temp.data(), 2 * sf_len);
-
-    // Update new values
-    sf_len  = new_sf_len;
       cell_id = new_cell_id;
+    }
 
     // Go to search PSS
     state = STATE_SEARCH_PSS;
@@ -198,7 +202,7 @@ public:
   void stop() { state = STATE_IDLE; }
 
   /**
-   * Runs internal FSM, performing Synchronization operations on the provided buffer. It expects data per sub-frame
+   * Runs internal FSM, performing Synchronization operations on the provided buffer. It expects data per subframe
    * basis (1 ms).
    * @param tti Current primary serving cell time
    * @param buffer Base-band buffer of the given secondary serving cell
@@ -206,7 +210,7 @@ public:
   void run(uint32_t tti, cf_t* buffer)
   {
     // Try to get lock. The lock is unsuccessful if the DSP objects are getting configured. In this case, ignore
-    // the sub-frame.
+    // the subframe.
     if (not mutex.try_lock()) {
       return;
     }