This is an approximate logic synthesis flow that automatically generates approximate circuits under a user-specified error constraint.

• Reference environment, Ubuntu 20.04 LTS with the following tools and libraries:

  • Tools: gcc 10.3.0 & g++ 10.3.0 & cmake 3.16.3

    You can install these tools with the following command:

    sudo apt install gcc-10
    sudo apt install g++-10
    sudo apt install cmake

    You also need to check whether the default versions of gcc and g++ are 10.3.0:

    gcc --version
    g++ --version

    If the default versions of gcc and g++ are not 10.3.0, please change them to 10.3.0.

  • Libraries: libboost 1.74.0, libreadline 8.0-4

    You can install these libraries with the following command:

    sudo apt install libboost1.74-all-dev
    sudo apt install libreadline-dev

  • Other tool: yosys

    sudo apt install yosys

• Alternatively, we prepare a docker image containing the dependencies:

  https://hub.docker.com/r/changmeng/als_min

This project contains a submodule: open-source logic synthesis and verification tool abc

To download the project:

git clone --recursive https://github.com/changmg/VACSEM.git

Please do add the parameter "--recursive", or the submodule will not be downloaded

• To build, go to the root directory of the project, and then execute:

mkdir build
cd build
cmake -DCMAKE_BUILD_TYPE=Release ..
make
cd ..

If you compile successfully, you will obtain the following executable program:

resubals.out

• To clean up, go to the root directory of the project, and then execute:

rm -rf build

To seek help, you can run:

./resubals.out -h

You will get the following illustration:

usage: ./resubals.out --accCirc=string [options] ... 
options:
      --accCirc              path to accurate circuit (string)
      --standCell            path to standard cell library (string [=./input/standard-cell/nangate_45nm_typ.lib])
      --outpPath             path to approximate circuits (string [=tmp])
      --metrType             error metric type: ER, MED, NMED, MSE, MHD, NMHD (string [=NMED])
      --distrType            error distribution type: UNIF, ENUM (string [=UNIF])
      --seed                 seed for randomness (unsigned int [=0])
      --errUppBound          error upper bound (double [=0.15])
      --nFrame               #Monte Carlo samples, nFrame should be an integer multiple of 64 (int [=102400])
      --nFrame4ResubGen      #patterns for AppResub Generation (int [=64])
      --maxCandResub         max #candidate AppResubs (int [=100000])
      --nThread              number of threads (int [=4])
      --enableFastErrEst     when this option is enabled, the program performs faster approximate error estimation;
                                otherwise, the program performs slower accurate error estimation
      --enableMeasureMode    when this option is enabled, the program measures the quality of the circuit specified by `appCirc' option;
                                otherwise, the program performs approximate logic synthesis
      --appCirc              path to approximate circuit,
                                this option is only used in the case when the `enableMeasureMode' option is active  (string [=])
  -h, --help                 print this message

Example command 1

./resubals.out --accCirc ./input/benchmark/iscas/c880.blif --standCell ./input/standard-cell/nangate_45nm_typ.lib --outpPath ./tmp/ --metrType ER --errUppBound 0.05 --nThread 4

In this example,

• The original circuit is "./input/benchmark/iscas/c880.blif"
• The stand cell library is "./input/standard-cell/nangate_45nm_typ.lib"
• The approximate circuits will be outputed to "./tmp/"
• The error metric is error rate (ER)
• The error upper bound is 0.05
• The applied CPU threads are 4