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September 2004 OpenAccess Gear David Papa 1, Zhong Xiu 2, Christoph Albrecht, Philip Chong, Andreas Kuehlmann 3 Cadence Berkeley Labs 1 University of Michigan, 2 Carnegie Mellon University, 3 University of California at Berkeley Built on OpenAccess for integration into other tools, e.g. placement Two modes: Full timing analysis and incremental timing analysis Different models for wires: No wire delay, bounding box model; can be extended easily to more accurate models Library formats: Cadence.tlf and Synopsys.lib Timing constraints: Subset of.sdc constraints Standardized timing reports Detailed documentation Cell (DFFX1) { … … pin(Q) { … … timing() { related_pin : "CK"; related_pin : "CK"; timing_sense : non_unate; timing_sense : non_unate; timing_type : rising_edge; timing_type : rising_edge; cell_rise(7x7) { cell_rise(7x7) { index_1 (“… …"); index_1 (“… …"); index_2 (“… …"); index_2 (“… …"); values ( … …); values ( … …); }}}CELL(DFFX1 … … … … TIMING_Model(7x7 TIMING_Model(7x7 (Spline (Spline (LOAD_AXIS …) (LOAD_AXIS …) (INPUT_SLEW_AXIS …) (INPUT_SLEW_AXIS …) data(… …) data(… …) ) ) … … … … Path( CK => Q … …) … … Setup( D => CK … …) … … ) #SDC constraint file create_clock –period 1 [get_ports {CK}] –period 1 [get_ports {CK}] set_input_delay 0.04 –clock CK [all_inputs] –clock CK [all_inputs] set_output_delay 0.02 –clock CK [all_outputs] –clock CK [all_outputs]set_driving_cell –lib_cell INVX2 [get_ports {G*5}] –lib_cell INVX2 [get_ports {G*5}] set_load 0.01 [get_ports {G2*}].tlf.lib.sdcDocumentation Static Timing Analysis: OAGear Timer BUF1 AND … Standard Cell Library oaTerm oaGearTimerPointMaster (with arcs) Instantiated Inst1 Inst6 Inst5 Inst4 Inst3 Inst2 oaInst oaInstTerm oaGearTimerPoint oaTerm oaGearTimerPoint oaGearTimerExtDelay oaNet Design The timing information is stored using the OpenAccess extension mechanism (oaGearTimerPoint, …) Incremental timing analysis When a modification occurs: –Mark the required arrival time of nodes in the fan-in cone invalid –Mark the arrival time of nodes in the fan-out cone invalid Later if there is a query, update the timing information Fanin cone Fanout cone Modification Query: update arrival time, required arrival time and slew rate Benchmarks OAGear provides two sets of benchmark designs: –Open Benchmarks: ISCAS89 benchmark suite and a hypothetical 250nm standard cell library –Restricted Benchmarks: http://crete.cadence.com/, Verilog files and scripts are available, Faraday benchmark suite and a 250nm GSC (Generic Standard Cell) library Necessary binary files to convert those designs into OpenAccess formats Aimed for researchers to test their timing driven placement algorithms and incremental placement algorithms BENCHMARKS Timing Library OpenAccess Format Benchmarks GUI: Bazaar Easy to read and extend, built on Qt and OpenGL In the style and spirit of the OpenAccess standard Layout Editor displays design directly from database Controller operates Capo API for on-demand placement Schematic Editor displays design’s logical connectivity Fast OpenGL rendering scales to very large designs “oaRegionQuery” accesses only relevant portions of the design Introduction OpenAccess is a “community-source” industry-standard EDA database developed to help promote tool interoperability Tools using OpenAccess are becoming available in industry, but resources for academic research are lacking Our project: OpenAccess Gear (OAGear) –Release useful tools and libraries to enable research –Make OpenAccess a useful platform for academia –Provide common infrastructure for research and benchmarking –Adopt an open source development model –Initiated and supported by Cadence Design Systems Overview Current focus on four main components –GUI: Layout and Schematic Viewer –Static Timing Analysis –Generic Standard Cell Placement Interface: Capo API –Benchmarks in OpenAccess Format Summary Planned Release Date: September 30, 2004 OAGear Home: http://oagear.sourceforge.net/ OpenAccess Home: http://openeda.si2.org/ Available as open source, free for any use –Open development model maximizes exchange of ideas and software between universities –Users encouraged to contribute bug reports, patches and functional components Ongoing development effort Possible future components: synthesis, routing, extraction GUI: Bazaar “Bazaar” = open market place where people bring their goods to sell Designed for easy to rework code and enhanced interoperability –Model-View-Controller design pattern Tool developers can bring their work to our “Bazaar” to contribute and promote them “Model-View-Controller” Design Pattern Applied to Bazaar OpenAccess (MODEL) Bazaar (VIEW) CONTROLLER Generic Placement Interface + Capo API Universal placer interface: –place(oaLib,oaCell,oaView) Routines to: –Import OpenAccess Designs and build Capo internal data structures –Run (potentially custom) Capo Placement Flows –Timing driven placement flows with prototypes “Strategy” design pattern, for placer interoperability –Pick and choose EDA algorithms –Compose new flows and combine tools in new ways previously too difficult! Future uses: –Designed to be extended for Incremental flows. –Contributions from other researchers OpenAccess Static Timing Analysis Place Block Capo Run Timer Weight Nets OpenAccess GUI Benchmarks Timer Placement API Capo Technical Capabilities Design Overview Static Timing Analysis: OAGear Timer