[vpr][analysis] update comments

Author: amin1377

doc/src/vpr/command_line_usage.rst

@@ -1520,26 +1520,26 @@ VPR uses a negotiated congestion algorithm (based on Pathfinder) to perform rout
 
 .. option:: --generate_net_timing_report {on | off}
 
-    Generates a report that lists the bounding box, slack, and delay of every routed connection in a design in csv format (``report_net_timing.csv``). Fields in the report are:
+    Generates a report that lists the bounding box, slack, and delay of every routed connection in a design in CSV format (``report_net_timing.csv``). Each row in the CSV corresponds to a single net.
+
+    Fields in the report are:
 
     .. code-block:: none
-        netname: The name assigned to the net in atom netlist
-        Fanout : Net's fanout
-        bb_xmin: X coordinate of the net's bounding box's bottom left corner
-        bb_ymin: Y coordinate of the net's bounding box's bottom left corner
-        bb_layer_min: Lowest layer number of the net's bounding box
-        bb_xmax: X coordinate of the net's bounding box's top right corner
-        bb_ymax: Y coordinate of the net's bounding box's top right corner
-        bb_layer_max: Highest layer number of the net's bounding box
-        src_pin_name: Name of the net's source pin
-        src_pin_slack: Slack of the net's source pin
-        sink_1_pin_name: Name of the net's first sink pin
-        sink_1_pin_slack: Slack of the net's first sink pin
-        sink_1_pin_delay: Delay of the net's first sink pin
-        sink_2_pin_name: Name of the net's second sink pin
-        sink_2_pin_slack: Slack of the net's second sink pin
-        sink_2_pin_delay: Delay of the net's second sink pin
-        ...
+        netname         : The name assigned to the net in the atom netlist
+        Fanout          : Net's fanout (number of sinks)
+        bb_xmin         : X coordinate of the net's bounding box's bottom-left corner
+        bb_ymin         : Y coordinate of the net's bounding box's bottom-left corner
+        bb_layer_min    : Lowest layer number of the net's bounding box
+        bb_xmax         : X coordinate of the net's bounding box's top-right corner
+        bb_ymax         : Y coordinate of the net's bounding box's top-right corner
+        bb_layer_max    : Highest layer number of the net's bounding box
+        src_pin_name    : Name of the net's source pin
+        src_pin_slack   : Setup slack of the net's source pin
+        sinks           : A semicolon-separated list of sink pin entries, each in the format:
+                          <sink_pin_name>,<sink_pin_slack>,<sink_pin_delay>
+
+    Example value for the ``sinks`` field:
+    ``"U2.B,0.12,0.5;U3.C,0.10,0.6;U4.D,0.08,0.7"``
 
     **Default:** ``off``
 

vpr/src/analysis/timing_reports.h

@@ -22,17 +22,25 @@ void generate_hold_timing_stats(const std::string& prefix,
                                 const BlkLocRegistry& blk_loc_registry);
 
 /**
- * @brief Generates timing information for each net in atom netlist. For each net, the timing information
- * is reported in the following format:
- * netname : Fanout : 
- * (bounding_box_xmin,bounding_box_ymin,bounding_box_layermin),(bounding_box_xmax,bounding_box_ymax,bounding_box_layermax) : 
- * source_instance <slack_on source pin> : 
- * <load pin name1> <slack on load pin name1> <net delay for this net> : 
- * <load pin name2> <slack on load pin name2> <net delay for this net> : ...
+ * @brief Generates a CSV report of timing information for each net in the atom netlist.
  * 
- * @param prefix The prefix for the report file to be added to filename: report_net_timing.rpt
- * @param timing_info Updated timing information
- * @param delay_calc Delay calculator
+ * Each row in the CSV corresponds to a single net and includes:
+ * - Net name
+ * - Fanout count
+ * - Bounding box (xmin, ymin, layer_min, xmax, ymax, layer_max)
+ * - Source pin name and slack
+ * - A single "sinks" field that encodes information for all sink pins
+ * 
+ * The "sinks" field is a semicolon-separated list of all sink pins.
+ * Each sink pin is represented as a comma-separated triple:
+ *   <sink_pin_name>,<sink_pin_slack>,<sink_pin_delay>
+ * 
+ * Example row:
+ * netA,2,0,0,0,5,5,1,U1.A,0.25,"U2.B,0.12,0.5;U3.C,0.10,0.6"
+ * 
+ * @param prefix       Prefix for the output file name (report will be saved as <prefix>report_net_timing.csv)
+ * @param timing_info  Timing analysis results (slacks)
+ * @param delay_calc   Delay calculator used to extract delay between nodes
  */
 void generate_net_timing_report(const std::string& prefix,
                                 const SetupHoldTimingInfo& timing_info,