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用C扩展Python

时间:2017-03-22 21:13:06      阅读:280      评论:0      收藏:0      [点我收藏+]

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参考

python扩展实现方法--python与c混和编程

编写Python扩展(Extending Python with C or C++)

https://docs.python.org/2.7/extending/embedding.html

 

环境

主机: ubuntu14.04 64bit

开发板: qemu + aarch64 (参考: http://www.cnblogs.com/pengdonglin137/p/6442583.html

 

工具链: aarch64-linux-gnu-gcc  (gcc version 4.9.1 20140529)

Python版本: Python-2.7.13

 

概述

上面参考列表中的文章已经说的很全了,这里仅作一些补充。分为三个:

1、交叉编译扩展模块到aarch64上面

2、编译扩展模块到Qemu模拟的x86_64上面

3、编译扩展模块到PC(x86_64)上面

采用的测试模块是Extend_wrap.c,这个在python扩展实现方法--python与c混和编程中有说明,源码如下:

 1 #include <stdio.h>
 2 #include <stdlib.h>
 3 #include <string.h>
 4 #include <Python.h>
 5 
 6 #define BUFSIZE 10
 7 
 8 int fac(int n) {
 9     if (n < 2)
10         return 1;
11     return n * fac(n - 1);
12 }
13 
14 static PyObject * Extest_fac(PyObject *self, PyObject *args) {
15     int res;//计算结果值
16     int num;//参数
17     PyObject* retval;//返回值
18 
19     //i表示需要传递进来的参数类型为整型,如果是,就赋值给num,如果不是,返回NULL;
20     res = PyArg_ParseTuple(args, "i", &num);
21     if (!res) {
22         //包装函数返回NULL,就会在Python调用中产生一个TypeError的异常
23         return NULL;
24     }
25     res = fac(num);
26     //需要把c中计算的结果转成python对象,i代表整数对象类型。
27     retval = (PyObject *)Py_BuildValue("i", res);
28     return retval;
29 }
30 
31 char *reverse(char *s) {
32     register char t;
33     char *p = s;
34     char *q = (s + (strlen(s) - 1));
35     while (p < q) {
36         t = *p;
37         *p++ = *q;
38         *q-- = t;
39     }
40     return s;
41 }
42 
43 static PyObject *
44 Extest_reverse(PyObject *self, PyObject *args) {
45     char *orignal;
46     if (!(PyArg_ParseTuple(args, "s", &orignal))) {
47         return NULL;
48     }
49     return (PyObject *)Py_BuildValue("s", reverse(orignal));
50 }
51 
52 static PyObject *
53 Extest_doppel(PyObject *self, PyObject *args) {
54     char *orignal;
55     char *reversed;
56     PyObject * retval;
57     if (!(PyArg_ParseTuple(args, "s", &orignal))) {
58         return NULL;
59     }
60     retval = (PyObject *)Py_BuildValue("ss", orignal, reversed=reverse(strdup(orignal)));
61     free(reversed);
62     return retval;
63 }
64 
65 static PyMethodDef
66 ExtestMethods[] = {
67     {"fac", Extest_fac, METH_VARARGS},
68     {"doppel", Extest_doppel, METH_VARARGS},
69     {"reverse", Extest_reverse, METH_VARARGS},
70     {NULL, NULL},
71 };
72 
73 void initExtest() {
74     Py_InitModule("Extest", ExtestMethods);
75 }
76 
77 int main() {
78     char s[BUFSIZE];
79     printf("4! == %d\n", fac(4));
80     printf("8! == %d\n", fac(8));
81     printf("12! == %d\n", fac(12));
82     strcpy(s, "abcdef");
83     printf("reversing ‘abcdef‘, we get ‘%s‘\n", reverse(s));
84     strcpy(s, "madam");
85     printf("reversing ‘madam‘, we get ‘%s‘\n", reverse(s));
86     return 0;
87 }

关于这段代码的解释,请参考python扩展实现方法--python与c混和编程

正文

1、交叉编译扩展模块到aarch64上面

这里介绍两种方法:

第一种: 将这个文件拷贝到Python2.7.3的Modules目录下面编译

拷贝:

    cp Extest_wrap.c ../../Python-2.7.13/Modules/

修改Python-2.7.13/setup.py,添加模块:

 1 diff --git a/setup.py b/setup.py
 2 index 81355c7..5083c3d 100644
 3 --- a/setup.py
 4 +++ b/setup.py
 5 @@ -1743,6 +1743,7 @@ class PyBuildExt(build_ext):
 6                                       -framework, Carbon]) )
 7  
 8  
 9 +        exts.append(Extension(Extest, [Extest_wrap.c]))
10          self.extensions.extend(exts)
11  
12          # Call the method for detecting whether _tkinter can be compiled

然后执行aarch64/mk2_make.sh,可以看到build/lib.linux2-aarch64-2.7/下面已经有Extest.so了:

1 $ls build/lib.linux2-aarch64-2.7/Extest.so -l
2 -rwxrwxr-x 1 pengdonglin pengdonglin 22121 Mar 22 14:47 build/lib.linux2-aarch64-2.7/Extest.so*

然后执行aarch64/mk3_install.sh,就会将Extest.so安装到lib/python2.7/lib-dynload/下面。

最后重新制作ramdisk文件,重启板子,测试Extest.so能否使用:

 1 [root@aarch64 root]# python
 2 Python 2.7.13 (default, Mar 22 2017, 10:39:43) 
 3 [GCC 4.9.1 20140529 (prerelease)] on linux2
 4 Type "help", "copyright", "credits" or "license" for more information.
 5 >>> import Extest
 6 >>> Extest.fac(4)
 7 24
 8 >>> Extest.reverse("abc") 
 9 cba
10 >>> Extest.doppel("abc")
11 (abc, cba)
12 >>> 

第二种: 手动编译

我们需要指定编译用的库以及头文件的搜索路径即可,下面是编译命令:

 1 #!/bin/bash
 2 export PATH=/home/pengdonglin/src/qemu/aarch64/gcc-linaro-aarch64-linux-gnu-4.9-2014.07_linux/bin:$PATH
 3 
 4 CFLAGS="-I/home/pengdonglin/src/qemu/python_cross_compile/Python2/aarch64/include/python2.7 -fno-strict-aliasing -g -O2 -DNDEBUG -g -fwrapv -O3 -Wall -Wstrict-prototypes"
 5 
 6 LDFLAGS="-L/home/pengdonglin/src/qemu/python_cross_compile/Python2/aarch64/lib -lpython2.7 -lpthread -ldl -lutil -lm -Xlinker -export-dynamic"
 7 
 8 aarch64-linux-gnu-gcc -c ../Extest_wrap.c ${CFLAGS} -o Extest.o
 9 
10 aarch64-linux-gnu-gcc --shared Extest.o ${LDFLAGS} -o Extest.so

其中CFLAGS和LDFLAGS的值可以用下面的命令获得

1 $/usr/local/bin/python2-config --cflags
2 -I/usr/local/include/python2.7 -I/usr/local/include/python2.7 -fno-strict-aliasing -g -O2 -DNDEBUG -g -fwrapv -O3 -Wall -Wstrict-prototypes
3 
4 $/usr/local/bin/python2-config --ldflags
5 -L/usr/local/lib/python2.7/config -lpython2.7 -lpthread -ldl -lutil -lm -Xlinker -export-dynamic

然后编译,就会在当前目录下面生成一个Extest.so,然后拷贝到板子的/usr/lib/python2.7/site-packages/下面,这个目录下存放的是一些第三方的扩展模块,而/usr/lib/python2.7/lib-dynload/存放的一般是内建模块。

2、编译扩展模块到Qemu模拟的x86_64上面

这里也有三种方法:

第一种:将Extend_wrap.c拷贝到Python源码的Modules目录下,这个前面说过,不再重复

第二种:手动编译,编译命令如下

1 #!/bin/bash
2 CFLAGS="-I/home/pengdonglin/src/qemu/python_cross_compile/Python2/x86_64/include/python2.7 -fPIC"
3 
4 LDFLAGS="-L/home/pengdonglin/src/qemu/python_cross_compile/Python2/x86_64/lib -fPIC"
5 
6 gcc -c ../Extest_wrap.c ${CFLAGS} -o Extest.o
7 
8 gcc --shared Extest.o ${LDFLAGS} -o Extest.so

编译完成后,将Extest.so拷贝到板子上面的相应目录下即可(如/usr/lib/python2.7/site-packages

第三种:手动编写setup.py

setup.py:

1 #!/usr/bin/env python
2 
3 from distutils.core import setup, Extension
4 
5 MOD = Extest_x86_64
6 setup(name=MOD, ext_modules=[Extension(MOD, sources=[Extest_wrap.c])])

这里模块名是Extest_x86_64,同时需要注意的是需要将setup.py跟Extest_wrap.c放到同一个目录下面。

编译:

/home/pengdonglin/src/qemu/python_cross_compile/Python2/x86_64/bin/python ./setup.py build

从log看执行的其实就是下面两条命令:

gcc -pthread -fno-strict-aliasing -g -O2 -DNDEBUG -g -fwrapv -O3 -Wall -Wstrict-prototypes -fPIC -I/home/pengdonglin/src/qemu/python_cross_compile/Python2/x86_64/include/python2.7 -c Extest_wrap.c -o build/temp.linux-x86_64-2.7/Extest_wrap.o

creating build/lib.linux-x86_64-2.7
gcc -pthread -shared build/temp.linux-x86_64-2.7/Extest_wrap.o -o build/lib.linux-x86_64-2.7/Extest_x86_64.so

安装:

/home/pengdonglin/src/qemu/python_cross_compile/Python2/x86_64/bin/python ./setup.py  install

从log看,Extest_x86_64.so会被安装到/home/pengdonglin/src/qemu/python_cross_compile/Python2/x86_64/lib/python2.7/site-packages下面

1 running install
2 running build
3 running build_ext
4 running install_lib
5 copying build/lib.linux-x86_64-2.7/Extest_x86_64.so -> /home/pengdonglin/src/qemu/python_cross_compile/Python2/x86_64/lib/python2.7/site-packages
6 running install_egg_info
7 Writing /home/pengdonglin/src/qemu/python_cross_compile/Python2/x86_64/lib/python2.7/site-packages/Extest_x86_64-0.0.0-py2.7.egg-info

然后从新制作ramdisk就可以了

3、编译扩展模块到PC(x86_64)上面

在操作之前PC上面应该用Python源码编译安装一次,方法很简单:

#!/bin/bash
../Python-2.7.13/configure
make -j8
sudo make install

默认会被安装到/usr/local下面

方法一: 将Extend_wrap.c拷贝到Python源码的Modules目录下,这个前面说过,不再重复

方法二: 手动编译,编译命令如下

1 #!/bin/bash
2 CFLAGS="-I/usr/local/include/python2.7 -fPIC"
3 LDFLAGS="-L/usr/local/lib -fPIC"
4 gcc -c ../Extest_wrap.c ${CFLAGS} -o Extest.o
5 gcc --shared Extest.o ${LDFLAGS} -o Extest.so

将生成的Extest.so拷贝到/usr/local/lib/python2.7/site-packages/即可

测试:

1 $sudo cp Extest.so /usr/local/lib/python2.7/site-packages/
2 $/usr/local/bin/python
3 Python 2.7.13 (default, Mar 22 2017, 13:18:43) 
4 [GCC 4.8.4] on linux2
5 Type "help", "copyright", "credits" or "license" for more information.
6 >>> import Extest
7 >>> Extest.reverse("peng")
8 gnep

方法三: 编写setup.py

setup.py:

1 $cat setup.py 
2 #!/usr/bin/env python
3 from distutils.core import setup, Extension
4 MOD = Extest
5 setup(name=MOD, ext_modules=[Extension(MOD, sources=[Extest_wrap.c])])

编译:

/usr/local/bin/python ./setup.py build

从log看,执行的是下面的命令:

1 running build
2 running build_ext
3 building Extest extension
4 creating build
5 creating build/temp.linux-x86_64-2.7
6 gcc -pthread -fno-strict-aliasing -g -O2 -DNDEBUG -g -fwrapv -O3 -Wall -Wstrict-prototypes -fPIC -I/usr/local/include/python2.7 -c Extest_wrap.c -o build/temp.linux-x86_64-2.7/Extest_wrap.o
7 gcc -pthread -shared build/temp.linux-x86_64-2.7/Extest_wrap.o -o build/lib.linux-x86_64-2.7/Extest.so

安装:

sudo /usr/local/bin/python ./setup.py install
从log看,Extest.so被安装到了/usr/local/lib/python2.7/site-packages下面
1 running install
2 running build
3 running build_ext
4 running install_lib
5 copying build/lib.linux-x86_64-2.7/Extest.so -> /usr/local/lib/python2.7/site-packages
6 running install_egg_info
7 Removing /usr/local/lib/python2.7/site-packages/Extest-0.0.0-py2.7.egg-info
8 Writing /usr/local/lib/python2.7/site-packages/Extest-0.0.0-py2.7.egg-info

 

用C扩展Python

标签:share   微软   生成   core   tuple   html   strlen   post   介绍   

原文地址:http://www.cnblogs.com/pengdonglin137/p/6601431.html

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