boost.python 1

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background

in OEM’s ADS team, there are bunch of model-based design engineers, who build the ADAS features based on Matlab/Simulink tools, which is good to build quick demos, when comes to massive data verification, we can’t really depends on Matlab solver, which is so slow and licensed.

so a common idea is to recompile the Matlab/Simulink model to C/C++ code, which can further embedded to more open envs, e.g. python or C++.

as previously mentioned, we had designed a rq based massive data driven test framework, so the gap from C++ ADAS code to this python test framework is fixed in this blog.

there are a few wasy to integrate C++ code to Python, one is Boost.Python:

setup

install boost

configuring Boost.BUild

python env : 3.6 (from conda env aeb)
gcc: 4.5.0 

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export BOOST_BUILD_PATH=`pwd`   #where we keep `user-config.jam`

user-config.jam

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using gcc : 5.4.0 : /usr/bin/g++ ;
using python : 3.6
        : "/home/anaconda3/envs/aeb/bin/python"
        : "/home/anaconda3/envs/aeb/include"
        : "/home/anaconda3/envs/aeb/include/python3.6m" ; 
``` 
bootstrap will find `user-config.jam` from $BOOST_BUILD_PATH. 
```sh 
cd  /path/to/boost_1_73_0
./bootstrap.sh --help
./bootstrap.sh --prefix=/usr/local/ --show-libraries
b2 --with-python --prefix="/usr/local/" install variant=release link=static address-model=64 
b2 --clean

a sample of user-config.jam

  • error fixing 
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fatal error: pyconfig.h: No such file or directory
compilation terminated.

need export CPATH=~/anaconda/envs/aeb/include/python3.6m/, where located pyconfig.h and other headers

finally report: boost.python build successfully !

demo run

the following is simple sample of how to use boost_python wrapper to wrapping an AEB model(in c++) to python

aeb.h

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#include <iostream>
#include <string>
typedef struct {
	float time; 
	float dx ;
	float dy ;
} AEB;
typedef struct {
	AEB out1 ;
} OP;
class aeb {
    public:
        Student() {}
	OP op_out ;
        void test_op(){
            (void) memset((void *)&op_out, 0, sizeof(OP)); 
            op_out.out1.time = 1.0 ; 
            op_out.out1.dx = 2.0 ;
            op_out.out1.dy = 3.0 ; 
            AEB o1 = op_out.out1 ;
            std::cout << o1.time << std::endl ;
        }
};

wrap_aeb.cpp

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#include <Python.h>
#include <boost/python.hpp>
#include <boost/python/suite/indexing/vector_indexing_suite.hpp>
#include "aeb.h"
using namespace boost::python;
BOOST_PYTHON_MODULE(aeb) {
    scope().attr("__version__") = "1.0.0";
    scope().attr("__doc__") = "a demo module to use boost_python.";
    class_<aeb>("aeb", "a class of aeb")
        .def(init<>())
        .def("test_op", &aeb::test_op, "test op")
        .def_readonly("op_out", &aeb::op_out)
}
``` 
tips, if aeb.h and aeb.cpp are separated files, it's better to merge them first;  for nested structure in wrapper is another topic later.
#### build and python import 
* check header location
      Python.h @ `/home/anaconda3/envs/aeb/include/python3.6m`
      boost/python @ `/usr/local/include/boost`
* check .so lib location
     
       /usr/local/lib/
tips, if there is duplicated `boost lib` in system, e.g. `/usr/lib/x86_64-linxu-gnu/libboost_python.so` which maybe conflict with `boost_python` install location at `/usr/local/lib/libboost_python36.so`
* build 
```sh
g++ -I/home/anaconda3/envs/aeb/include/python3.6m -I/usr/local/include/boost -fPIC wrap_aeb.cpp -L/usr/local/lib/ -lboost_python36 -shared -o aeb.so
  • test 
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import aeb
t = aeb.aeb
t.test_op()

summary

this blog gives the basic idea how to use boost.python to integrate c++ to python test framework. there are plenty details need fixed, e.g. nested structures, share_pointers. maybe share in next blog.

refere

boost.python tutorial