Reading Timing Data

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What data does XTop need from STA tools?

Timing data of design under different scenarios are needed.

User can source the script in STA tools,  and then run cmd to prepare the timing data.

% ls sta_data

func_fast_data_dont_touch_objects.txt.gz  # don’t touch objects

func_fast_data_ilm_objects.txt.gz              # interface logic objects

func_fast_data_pin_timing.txt.gz                # pin transition timing

func_fast_data_timing_derates.txt.gz         #  timing derate

func_fast_data_total_capacitances.txt.gz   # parasitic data

func_fast_data_pin_slack.txt.gz                  # global slack

func_fast_data_si_delta.txt.gz                     # si delta delay

func_fast_data_timing_rpt.txt.gz                  # timing report data

func_fast_data_used_as_clocks.txt.gz        # clock objects

func_fast_data_finish                                   # dumping data finish flag

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How to read timing report incementally?

Run the read_timing_report command for specified scenario. 

If scenario is not specified, it refers to the reference scenario.

xtop> read_timing_report -scenario fast_worst  sta_data/cpu_data_timing_rpt.txt

  scenario: fast_worst

    timing_rpt ok

    sta_data/cpu_data_timing_rpt.txt

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Why XTop reports timing clean after reading pt timing data？

1) Check if the timing data dumped is correct.

Sometimes user wants to only dump block data in top STA, using the -only _hier_path option (Check the header of the written data file, if design name is TOP and current inst is blank).

2) Check if the timing data is matched with netlist

The program will print the annotate ratio during read_timing_data command. If the ratio is too low (e.g. less than 95%), user needs to double-check if the netlist used is matched with the timing data.

xtop> read_timing_data -data_dir ../input_files/sta_data

...

Success : 100.0% pins and 97.7% nets have annotated data.

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