added stuff for the Extensions class

Author: PythonCHB

Examples/week-08-extensions/c-api/add.c

@@ -0,0 +1,29 @@
+#include <Python.h>
+
+static PyObject *
+add(PyObject *self, PyObject *args)
+{
+    int x;
+    int y;
+    int sts;
+
+    if (!PyArg_ParseTuple(args, "ii", &x, &y))
+        return NULL;
+    sts = x+y;
+    return Py_BuildValue("i", sts);
+}
+
+// Module's method table and initialization function
+// see: https://docs.python.org/2/extending/extending.html#the-module-s-method-table-and-initialization-function
+static PyMethodDef AddMethods[] = {
+    {"add", add, METH_VARARGS, "add two numbers"},
+    {NULL, NULL, 0, NULL} // sentinel
+};
+
+
+PyMODINIT_FUNC
+initadd(void) {
+    // Module's initialization function
+    // Will be called again if you use Python's reload()
+    (void) Py_InitModule("add", AddMethods);
+}

Examples/week-08-extensions/c-api/divide/divide.c

@@ -0,0 +1,30 @@
+#include <Python.h>
+
+static PyObject *
+divide(PyObject *self, PyObject *args)
+{
+    double x;
+    double y;
+    double sts;
+
+    if (!PyArg_ParseTuple(args, "dd", &x, &y))
+        return NULL;
+    sts = x/y;
+    return Py_BuildValue("d", sts);
+}
+
+// Module's method table and initialization function
+// See: http://docs.python.org/extending/extending.html#the-module-s-method-table-and-initialization-function
+static PyMethodDef DivideMethods[] = {
+    {"divide", divide, METH_VARARGS, "divide two numbers"},
+    {NULL, NULL, 0, NULL}
+};
+
+PyMODINIT_FUNC // does the right thing on Windows, Linux, etc.
+initdivide(void) {
+    // Module's initialization function
+    // Will be called again if you use Python's reload()
+
+    Py_InitModule("divide", DivideMethods);
+}
+

Examples/week-08-extensions/c-api/divide/setup.py

@@ -0,0 +1,11 @@
+#!/usr/bin/env python
+
+from distutils.core import setup, Extension
+
+setup(
+    name='Cdiv',
+    version='1.0',
+    description='sample method that does exceptions',
+    ext_modules=[Extension('divide', sources=['divide.c'])],
+)
+

Examples/week-08-extensions/c-api/setup.py

@@ -0,0 +1,10 @@
+#!/usr/bin/env python
+
+from setuptools import setup, Extension
+
+setup(
+    name='Cadd',
+    version='1.0',
+    description='simple c extension for an example',
+    ext_modules=[Extension('add', sources=['add.c'])],
+)

Examples/week-08-extensions/c-api/test_add.py

@@ -0,0 +1,21 @@
+#!/usr/bin/env python
+
+"""
+simple test for the add C extension
+"""
+
+import pytest
+
+import add
+
+def test_basic():
+    assert add.add(3,4) == 7
+
+def test_negative():
+    assert add.add(-12, 5) == -7
+
+def test_float():
+    with pytest.raises(TypeError):
+        add.add(3, 4.0)
+
+

Examples/week-08-extensions/ctypes/Makefile

@@ -0,0 +1 @@
+all: add; gcc -shared -o add.so add.c

Examples/week-08-extensions/ctypes/add.c

@@ -0,0 +1,10 @@
+#include <stdio.h>
+
+int add(int x, int y) {
+    return x+y;
+}
+int main(void) {
+    int w = 3;
+    int q = 2;
+    printf("%d + %d = %d\n\n", w, q, add(w,q));
+}

Examples/week-08-extensions/ctypes/pointers.py

@@ -0,0 +1,12 @@
+#!/usr/bin/env python
+
+from ctypes import *
+
+libc = CDLL("libc.dylib")
+
+i = c_int()
+f = c_float()
+s = create_string_buffer('\000' * 32)
+print i.value, f.value, repr(s.value)
+libc.sscanf("1 3.14 Hello", "%d %f %s",byref(i), byref(f), s)
+print i.value, f.value, repr(s.value)

Examples/week-08-extensions/ctypes/qsort_test.py

@@ -0,0 +1,26 @@
+#!/usr/bin/env python
+
+from ctypes import *
+
+libc = CDLL("libc.dylib")
+
+TenInts = c_int * 10
+data = TenInts(*range(10,0,-1))
+
+# http://www.gnu.org/software/libc/manual/html_node/Array-Sort-Function.html
+# void qsort (void *array, size_t count, size_t size, comparison_fn_t compare)
+
+# http://docs.python.org/2/library/ctypes.html#ctypes.CFUNCTYPE
+CMPFUNC = CFUNCTYPE(c_int, POINTER(c_int), POINTER(c_int))
+
+def py_cmp_func(a, b):
+    # print "py_cmp_func", a[0], b[0]
+    return a[0] - b[0]
+
+for i in data:
+    print i
+
+libc.qsort(data, len(data), sizeof(c_int), CMPFUNC(py_cmp_func))
+
+for i in data:
+    print i

Examples/week-08-extensions/ctypes/test_add.py

@@ -0,0 +1,67 @@
+#!/usr/bin/env python
+
+import sys
+
+lib_ext = ('.so' if ('darwin' in sys.platform or
+                    'linux' in sys.platform)
+                else ".dll")
+
+import ctypes
+
+# now load our own shared library
+add = ctypes.cdll.LoadLibrary("add"+lib_ext)
+
+print "This should be 7:",
+print add.add(3,4)
+
+# Using an already-loaded shared library:
+## loading libc and libm (math)
+if 'darwin' in sys.platform:
+    # OS-X likes full paths...
+    libc = ctypes.CDLL("/usr/lib/libc.dylib")
+    libm = ctypes.CDLL("/usr/lib/libm.dylib")
+elif 'linux' in sys.platform:
+    # linux uses the shared lib search path 
+    libc = ctypes.CDLL("libc.so")
+    libm = ctypes.CDLL("libm.so")
+elif 'win' in sys.platform:
+    # Windows can find already loaded dlls by name
+    libc = ctypes.cdll.msvcrt # lib c and libm are in msvcrt
+    libm = ctypes.cdll.msvcrt
+
+libc.printf("printed via libc printf()\n")
+
+print "passing different types to printf:"
+#libc.printf("An int %d, a double %f\n", 1234, 3.14)
+libc.printf("An int %d, a double %f\n", 1234, ctypes.c_double(3.14))
+
+
+## Calling libm
+## prototype for pow():
+## double pow ( double x, double y )   
+
+print "This should be 81.0:",
+print libm.pow(ctypes.c_double(3), ctypes.c_double(4))
+
+## need to set the return type!
+libm.pow.restype = ctypes.c_double
+print "This should be 81.0:",
+print libm.pow(ctypes.c_double(3), ctypes.c_double(4))
+
+## if you are going to call the same function a lot,
+## you can specify the arument types:
+
+libm.pow.restype = ctypes.c_double
+libm.pow.argtypes = [ctypes.c_double, ctypes.c_double]
+print "This should be 81.0:",
+print libm.pow(3, 4.0)
+
+## much easier!
+
+
+
+
+
+
+
+