In this project, some changes have been made to the open-source tool OpenSTA to accommodate any custom model for delay calculation. These changes allow the user to use any of the models that they want (their own custom model or the inbuilt model) and generate the report according to that model.
- For testing the changes sample files have been added to the experiment directory.
- We use the "use_custom_delay_model" variable to set the choice if we want to use the custom delay model or the Gate Table Delay model.
- If we assign the value 1 to the variable then the custom model is used, else if 0 is assigned then an inbuilt model is used.
- From the experiment directory if sta1.tcl is used then we get the results with delay=1, and if we use sta0.tcl then the inbuilt delay is used.
A final report on OpenSTA which consists of a detailed analysis of how the software works and in particular how the delay calculation model works is attached by the name of "REPORT ON OPENSTA.pdf". This report also describes the changes that have been made to accommodate a custom delay model.
OpenSTA is built with CMake.
The build dependency versions are show below. Other versions may work, but these are the versions used for development.
from Ubuntu Xcode
22.04.2 11.3
cmake 3.10.2 3.24.2 3.16.2
clang 9.1.0 14.0.3
gcc 3.3.2 11.3.0
tcl 8.4 8.6 8.6.6
swig 1.3.28 4.1.0 4.0.1
bison 1.35 3.0.2 3.8.2
flex 2.5.4 2.6.4 2.6.4
Note that flex versions before 2.6.4 contain 'register' declarations that are illegal in c++17.
These packages are optional:
tclreadline 2.3.8
libz 1.1.4 1.2.5 1.2.8
cudd 2.4.1 3.0.0
The TCL readline library links the GNU readline library to the TCL interpreter for command line editing On OSX, Homebrew does not support tclreadline, but the macports system does (see https://www.macports.org). To enable TCL readline support use the following Cmake option:
cmake .. -DUSE_TCL_READLINE=ON
The Zlib library is an optional. If CMake finds libz, OpenSTA can read Verilog, SDF, SPF, and SPEF files compressed with gzip.
CUDD is a binary decision diageram (BDD) package that is used to improve conditional timing arc handling. OpenSTA does not require it to be installed. It is available here or here.
Note that the file hierarchy of the CUDD installation changed with version 3.0. Some changes to CMakeLists.txt are required to support older versions.
Use the USE_CUDD option to look for the cudd library. Use the CUDD_DIR option to set the install directory if it is not in one of the normal install directories.
When building CUDD you may use the --prefix option to configure to
install in a location other than the default (/usr/local/lib).
cd $HOME/cudd-3.0.0
mkdir $HOME/cudd
./configure --prefix $HOME/cudd
make
make install
cd <opensta>/build
cmake .. -DUSE_CUDD=ON -DCUDD_DIR=$HOME/cudd
Use the following commands to checkout the git repository and build the OpenSTA library and excutable.
git clone https://github.com/The-OpenROAD-Project/OpenSTA.git
cd OpenSTA
mkdir build
cd build
cmake ..
make
The default build type is release to compile optimized code.
The resulting executable is in app/sta.
The library without a main() procedure is app/libSTA.a.
Optional CMake variables passed as -D= arguments to CMake are show below.
CMAKE_BUILD_TYPE DEBUG|RELEASE
CMAKE_CXX_FLAGS - additional compiler flags
TCL_LIBRARY - path to tcl library
TCL_HEADER - path to tcl.h
CUDD - path to cudd installation
ZLIB_ROOT - path to zlib
CMAKE_INSTALL_PREFIX
If TCL_LIBRARY is specified the CMake script will attempt to locate
the header from the library path.
The default install directory is /usr/local.
To install in a different directory with CMake use:
cmake .. -DCMAKE_INSTALL_PREFIX=<prefix_path>
If you make changes to CMakeLists.txt you may need to clean out
existing CMake cached variable values by deleting all of the
files in the build directory.