Add batch 1 (YosysHQ_picorv32, alexforencich_verilog-ethernet, The-OpenROAD-Project_OpenROAD, darklife_darkriscv, corundum_corundum)
f61bac1 verified | // SPDX-License-Identifier: BSD-3-Clause | |
| // Copyright (c) 2024-2025, The OpenROAD Authors | |
| # Author: Dimitris K. Fotakis | |
| # Version: v1.0 | |
| # Date: 11052024 | |
| Major Flow Steps: to run rcx command: extract_parasitics | |
| Prerequisite Reading: run_extraction.README, Architecture.README | |
| ------------------------------------------------------------------------------------------- | |
| 1. Set User Options | |
| User Command: extract_parasitics | |
| function: makeBlockRCsegs_v2 | |
| ------------------------------------------------------------------------------------------- | |
| 2. Read Model File and Associate User Defined | |
| function: SetCornersAndReadModels_v2 | |
| Note 1: if not set with Tcl cmd: <define_process_corner>, all model file corners will be extracted | |
| Note 2: if user option lefRC is used, a single corner is generated | |
| ------------------------------------------------------------------------------------------- | |
| 3. Read Model File | |
| Organize distance based Coupling/Fringe values to calculate RC values for every signal wire | |
| function: SetCornersAndReadModels_v2/ReadModels_v2 | |
| Note 1: DensityModel is equivalent to Process Corner | |
| Note 2: basic format for every distance based model is defined as follows: | |
| <dist_to_neighbor_in_microns> <coupling_cap> <ground_cap> <resistance> | |
| capacitance units are in fF/nm | |
| resistance unist are in Ohms/nm | |
| ------------------------------------------------------------------------------------------- | |
| 3. Generate Full RC network for all nets | |
| function: makeRCNetwork_v2 | |
| Objects: dbCapNode, dbRSeg | |
| Important User Options: -max_res -no_via_merge_res -lefRC -lef_res | |
| Prerequisite Step: odb::orderWires is called before makeBlockRCsegs_v2 | |
| A. Create Resistance Table per Layer to drive RC Merging | |
| Note: Values from first process corner are used | |
| B. Create RC Segments and Capacitance Nodes by traversing dbWire object | |
| Associate one or more Physical wires to an RC segment (dbRSeg) | |
| SPEF structure is dependent on the RC network generation | |
| Physical wires will be extracted for Coupling Capacitance and Resistance based on | |
| user option: max_res drives RC segment Merging in a net | |
| Merging stops at instance and block terms and wire branches | |
| Note 1: via resistance can be taken from Model File or from LEF if Via Models don't exist | |
| Note 2: via resistance is added to the connecting wires if user option -no_merge_via_res is not set | |
| Note 3: Extracted coupling caps for the wire segments | |
| ------------------------------------------------------------------------------------------- | |
| 4. Extract Coupling Caps | |
| function: couplingFlow_v2 | |
| Important Objects: dbCCseg, extDistRC | |
| Important User Options: -skip_over_cell, -coupling_threshold, -context_depth -cc_model | |
| A. RC Network Generation (see step 3) | |
| Note: the following steps are repeated on horizontal and vertical directions | |
| B. Load Signal and Power Wires on Search object: Ath__gridTable | |
| Functions: addPowerNets, addSignalNets | |
| C. Load Signal and Power Wires on Geometric Search object: gs | |
| Functions: fill_gs4, addShapeOnGS, | |
| Important Note: add instance obstructions and pin shapes on Geometric search, unless user option -skip_over_cell | |
| D. Find coupling neighbors on object Ath__wire on both sides and all levels | |
| User option -cc_model controls how far in tracks coupling neighbors are found | |
| Function: couplingFlow_v2/FindCouplingNeighbors | |
| important object: extMain->_search, extMeasure->_search, extMeasureRC->_search | |
| Note 1: Coupling neighbors on different levels are called Diagonal | |
| Note 2: Coupling neighbors on different levels overlapping latterally are called Vertical Diagonal | |
| E. Find Segments of Wires that directly coupled with segments of other wires and over/under CrossOverlaps | |
| User Option -context_depth controls low and upper bound of metal levels for cross ovelaps | |
| Function: couplingFlow_v2/CouplingFlow/GetCouplingSegments | |
| F. Calculate Resistance of every coupling segment based on distance of neighbors of both sides | |
| Function: couplingFlow_v2/CouplingFlow/CalcRes | |
| G. Calculate Coupling and Fringe Capacitance of every coupling segment | |
| based on distance of neighbors of both sides and CrossOveral Context | |
| User Option -coupling_threshold controls the creation of coupling caps | |
| Function: couplingFlow_v2/CouplingFlow/ | |
| VerticalDiagonalCouplingAndCrossOverlap | |
| CreateCouplingCaps_overUnder, CreateCouplingCaps_over | |