# OpenRCX **Repository Path**: osEDA/OpenRCX ## Basic Information - **Project Name**: OpenRCX - **Description**: No description available - **Primary Language**: Unknown - **License**: Not specified - **Default Branch**: master - **Homepage**: None - **GVP Project**: No ## Statistics - **Stars**: 0 - **Forks**: 0 - **Created**: 2021-05-13 - **Last Updated**: 2024-12-02 ## Categories & Tags **Categories**: Uncategorized **Tags**: None ## README # OpenRCX [![Standard](https://img.shields.io/badge/C%2B%2B-17-blue)](https://en.wikipedia.org/wiki/C%2B%2B#Standardization) [![License](https://img.shields.io/badge/License-BSD%203--Clause-blue.svg)](https://opensource.org/licenses/BSD-3-Clause) OpenRCX is an parasitics Extraction tool that works on OpenDB design APIs. It extracts routed designs based on the LEF/DEF model. It extracts both Resistance and Capacitance for wires, based on coupling distance to the nearest wire and the context over and/or under and cell abstracts. The capacitance and resistance measurements are based on equations of coupling distance interpolated on exact measurements from a calibration file, called Extraction Rules File. The Extraction Rules file (RC technology file) is generated once for every process node and corner automatically. OpenRCX stores resistance, coupling capacitance and ground capacitance on OpenDB objects with direct pointers to the associated wire and via db objects and optionally can generate a .spef file. #### Tests There is a set of regression tests in /test. ``` ./test/regression ``` #### Extraction Rules File Generation This flow generates an Extraction Rules file (RC tech file/RC Table) for OpenRCX. This file provides resistance and capacitance tables used for RC extraction for a specific process corner. The Extraction Rules file (RC technology file) is generated once for every process node and corner automatically. The detailed documentation can be found [here](doc/calibration.txt) #### Extract Parasitics ``` extract_parasitics [-ext_model_file filename] pointer to The Extraction Rules file [-corner_cnt count] process corner count [-max_res ohms] combine resistors in series up to value in OHMS [-coupling_threshold fF] coupling below the threshold is grounded [-lef_res] use per-unit RC defined in LEF [-cc_model track] calculate coupling within distance [-context_depth depth] caculate upper/lower coupling from level away ``` The `extract_parasitics` command performs parastic extraction based on the routed design. If there are no routed design information no parasitics are added. Use `ext_model_file` to specify the Extraction Rules file used for the extraction. The `cc_model` is used to specify the maximium number of tracks on same routing level. The default value is 10. The `context_depth` option is used to specify the levels that OpenRCX needs to consider The default value is 5. for the over/under context overlap for capacitance calculation. The `max_res` command combines resistors in series up to the threshold values. The `corner_cnt` defines the number of corners used during the parastic extractions. #### Write SPEF ``` write_spef [-net_id net_id] output the parasitics info for spesific nets [filename] the output filename ``` The `write_spef` command writes the .spef output of the parasitics stored in the database. Use `net_id` command to write the output for spesific nets. #### Scale RC ``` adjust_rc [-res_factor res] scale the res value [-cc_factor cc] scale the coupling capacitance value [-gndc_factor gndc] scale the ground cap value ``` Use the `adjust_rc` command to scale the the resistance, ground, and coupling capacitance. The `res_factor` specifies the scale factor for resistance. The `cc_factor` specifies the scale factor for coupling cap. The `gndc_factor` specifies the scale factor for ground cap. #### Comparing SPEF files ``` diff_spef [-file filename] specifies the input .spef filename ``` `diff_spef` command compares the parasitics in the database with the parasitic information from `.spef`. The output of this command is `diff_spef.out` and contains the RC numbers from the parasitics in the databse and the `.spef`, and the percentage RC difference of the two data. #### Extraction Rules File Generation ``` bench_wires [-cnt count] specify the metal count per pattern [-len wire_len] specify the wire length in the pattern [-s_list space_multiplier_list] list of wire spacing multiplier [-all] generate all patterns ``` `bench_wires` command produces a layout which contains various patterns that are used to characterize per-unit RC. The generated patterns model the lateral, vertical, and diagonal coupling capacitance, and the ground capacitance effects. This command generates a .def file. The `cnt` command determines the number of wires in each pattern, the default values is 5. Use `len` command to change the wire length in the pattern. `all` option is used to specify all diffrent pattern geometries (over, under, over_under, and digonal). The option `all` is required. The `s_list` option specifies the lists of wire spacing multipliers from the minimum spacing defined in the LEF. The list will be the input index on the OpenRCX RC table (Extraction Rules file). This command is specifically intended for the Extraction Rules file generation only. ``` bench_verilog [filename] the output verilog filename ``` `bench_verilog` is used after the `bench_wires` command. This command generates verilog netlist of the generated pattern layout by the `bench_wires` command. This command is optional when running the Extraction Rules generation flow. This step is required if the favorite extraction tool (i.e., reference extractor) requires a netlist to extract parasitics of the pattern layout. ``` bench_read_spef [filename] the input .spef filename ``` `bench_read_spef` command reads a `.spef` file and stores the parasitics into the database. ``` write_rules [-file filename] output file name [-db] read parasitics from the databse ``` `write_rules` command writes the Extraction Rules file (RC technology file) for OpenRCX. It processes the parasitics data from the pattern layout generated from `bench_wires` command, and writes the Extraction Rules file with `` as the output file. `db` command instructs OpenRCX to write the Extraction Rules file from the parasitics stored in the database. This option is required. This command is specifically intended for the Extraction Rules file generation purpose. ### Example Scripts Example scripts demonstrating how to run OpenRCX in the OpenROAD environment on sample designs that can be found in /test. Flow tests taking sample designs from synthesis verilog to routed design in the open source technologies Sky130 is shown below. ``` gcd.tcl ``` Example scripts demonstrating how to run the Extraction Rules File generation can be found in this [directory](calibration/script). ``` generate_patterns.tcl # generate patterns generate_rules.tcl # generate the Extraction Rules # file ext_patterns.tcl # check the accuracy of OpenRCX ```