Using Cython is pretty good. You can write your C extension with a Python-like syntax and have it generate C code. Boilerplate included. Since you have the code already in python, you have to do just a few changes to your bottleneck code and C code will be generated from it.
Example. hello.pyx:
cdef int hello(int a, int b):
return a + b
That generates 601 lines of boilerplate code:
/* Generated by Cython 0.10.3 on Mon Jan 19 08:24:44 2009 */
#define PY_SSIZE_T_CLEAN
#include "Python.h"
#include "structmember.h"
#ifndef PY_LONG_LONG
#define PY_LONG_LONG LONG_LONG
#endif
#ifndef DL_EXPORT
#define DL_EXPORT(t) t
#endif
#if PY_VERSION_HEX < 0x02040000
#define METH_COEXIST 0
#endif
#if PY_VERSION_HEX < 0x02050000
typedef int Py_ssize_t;
#define PY_SSIZE_T_MAX INT_MAX
#define PY_SSIZE_T_MIN INT_MIN
#define PyInt_FromSsize_t(z) PyInt_FromLong(z)
#define PyInt_AsSsize_t(o) PyInt_AsLong(o)
#define PyNumber_Index(o) PyNumber_Int(o)
#define PyIndex_Check(o) PyNumber_Check(o)
#endif
#if PY_VERSION_HEX < 0x02060000
#define Py_REFCNT(ob) (((PyObject*)(ob))->ob_refcnt)
#define Py_TYPE(ob) (((PyObject*)(ob))->ob_type)
#define Py_SIZE(ob) (((PyVarObject*)(ob))->ob_size)
#define PyVarObject_HEAD_INIT(type, size) \
PyObject_HEAD_INIT(type) size,
#define PyType_Modified(t)
typedef struct {
void *buf;
PyObject *obj;
Py_ssize_t len;
Py_ssize_t itemsize;
int readonly;
int ndim;
char *format;
Py_ssize_t *shape;
Py_ssize_t *strides;
Py_ssize_t *suboffsets;
void *internal;
} Py_buffer;
#define PyBUF_SIMPLE 0
#define PyBUF_WRITABLE 0x0001
#define PyBUF_LOCK 0x0002
#define PyBUF_FORMAT 0x0004
#define PyBUF_ND 0x0008
#define PyBUF_STRIDES (0x0010 | PyBUF_ND)
#define PyBUF_C_CONTIGUOUS (0x0020 | PyBUF_STRIDES)
#define PyBUF_F_CONTIGUOUS (0x0040 | PyBUF_STRIDES)
#define PyBUF_ANY_CONTIGUOUS (0x0080 | PyBUF_STRIDES)
#define PyBUF_INDIRECT (0x0100 | PyBUF_STRIDES)
#endif
#if PY_MAJOR_VERSION < 3
#define __Pyx_BUILTIN_MODULE_NAME "__builtin__"
#else
#define __Pyx_BUILTIN_MODULE_NAME "builtins"
#endif
#if PY_MAJOR_VERSION >= 3
#define Py_TPFLAGS_CHECKTYPES 0
#define Py_TPFLAGS_HAVE_INDEX 0
#endif
#if (PY_VERSION_HEX < 0x02060000) || (PY_MAJOR_VERSION >= 3)
#define Py_TPFLAGS_HAVE_NEWBUFFER 0
#endif
#if PY_MAJOR_VERSION >= 3
#define PyBaseString_Type PyUnicode_Type
#define PyString_Type PyBytes_Type
#define PyInt_Type PyLong_Type
#define PyInt_Check(op) PyLong_Check(op)
#define PyInt_CheckExact(op) PyLong_CheckExact(op)
#define PyInt_FromString PyLong_FromString
#define PyInt_FromUnicode PyLong_FromUnicode
#define PyInt_FromLong PyLong_FromLong
#define PyInt_FromSize_t PyLong_FromSize_t
#define PyInt_FromSsize_t PyLong_FromSsize_t
#define PyInt_AsLong PyLong_AsLong
#define PyInt_AS_LONG PyLong_AS_LONG
#define PyInt_AsSsize_t PyLong_AsSsize_t
#define PyInt_AsUnsignedLongMask PyLong_AsUnsignedLongMask
#define PyInt_AsUnsignedLongLongMask PyLong_AsUnsignedLongLongMask
#define __Pyx_PyNumber_Divide(x,y) PyNumber_TrueDivide(x,y)
#else
#define __Pyx_PyNumber_Divide(x,y) PyNumber_Divide(x,y)
#define PyBytes_Type PyString_Type
#endif
#if PY_MAJOR_VERSION >= 3
#define PyMethod_New(func, self, klass) PyInstanceMethod_New(func)
#endif
#if !defined(WIN32) && !defined(MS_WINDOWS)
#ifndef __stdcall
#define __stdcall
#endif
#ifndef __cdecl
#define __cdecl
#endif
#else
#define _USE_MATH_DEFINES
#endif
#ifdef __cplusplus
#define __PYX_EXTERN_C extern "C"
#else
#define __PYX_EXTERN_C extern
#endif
#include <math.h>
#define __PYX_HAVE_API__helloworld
#ifdef __GNUC__
#define INLINE __inline__
#elif _WIN32
#define INLINE __inline
#else
#define INLINE
#endif
typedef struct
{PyObject **p; char *s; long n;
char is_unicode; char intern; char is_identifier;}
__Pyx_StringTabEntry; /*proto*/
static int __pyx_skip_dispatch = 0;
/* Type Conversion Predeclarations */
#if PY_MAJOR_VERSION < 3
#define __Pyx_PyBytes_FromString PyString_FromString
#define __Pyx_PyBytes_AsString PyString_AsString
#else
#define __Pyx_PyBytes_FromString PyBytes_FromString
#define __Pyx_PyBytes_AsString PyBytes_AsString
#endif
#define __Pyx_PyBool_FromLong(b) ((b) ? (Py_INCREF(Py_True), Py_True) : (Py_INCREF(Py_False), Py_False))
static INLINE int __Pyx_PyObject_IsTrue(PyObject* x);
static INLINE PY_LONG_LONG __pyx_PyInt_AsLongLong(PyObject* x);
static INLINE unsigned PY_LONG_LONG __pyx_PyInt_AsUnsignedLongLong(PyObject* x);
static INLINE Py_ssize_t __pyx_PyIndex_AsSsize_t(PyObject* b);
#define __pyx_PyInt_AsLong(x) (PyInt_CheckExact(x) ? PyInt_AS_LONG(x) : PyInt_AsLong(x))
#define __pyx_PyFloat_AsDouble(x) (PyFloat_CheckExact(x) ? PyFloat_AS_DOUBLE(x) : PyFloat_AsDouble(x))
static INLINE unsigned char __pyx_PyInt_unsigned_char(PyObject* x);
static INLINE unsigned short __pyx_PyInt_unsigned_short(PyObject* x);
static INLINE char __pyx_PyInt_char(PyObject* x);
static INLINE short __pyx_PyInt_short(PyObject* x);
static INLINE int __pyx_PyInt_int(PyObject* x);
static INLINE long __pyx_PyInt_long(PyObject* x);
static INLINE signed char __pyx_PyInt_signed_char(PyObject* x);
static INLINE signed short __pyx_PyInt_signed_short(PyObject* x);
static INLINE signed int __pyx_PyInt_signed_int(PyObject* x);
static INLINE signed long __pyx_PyInt_signed_long(PyObject* x);
static INLINE long double __pyx_PyInt_long_double(PyObject* x);
#ifdef __GNUC__
/* Test for GCC > 2.95 */
#if __GNUC__ > 2 || (__GNUC__ == 2 && (__GNUC_MINOR__ > 95))
#define likely(x) __builtin_expect(!!(x), 1)
#define unlikely(x) __builtin_expect(!!(x), 0)
#else /* __GNUC__ > 2 ... */
#define likely(x) (x)
#define unlikely(x) (x)
#endif /* __GNUC__ > 2 ... */
#else /* __GNUC__ */
#define likely(x) (x)
#define unlikely(x) (x)
#endif /* __GNUC__ */
static PyObject *__pyx_m;
static PyObject *__pyx_b;
static PyObject *__pyx_empty_tuple;
static int __pyx_lineno;
static int __pyx_clineno = 0;
static const char * __pyx_cfilenm= __FILE__;
static const char *__pyx_filename;
static const char **__pyx_f;
static void __Pyx_AddTraceback(const char *funcname); /*proto*/
/* Type declarations */
/* Module declarations from helloworld */
static int __pyx_f_10helloworld_hello(int, int); /*proto*/
/* Implementation of helloworld */
/* "/home/nosklo/devel/ctest/hello.pyx":1
* cdef int hello(int a, int b): # <<<<<<<<<<<<<<
* return a + b
*
*/
static int __pyx_f_10helloworld_hello(int __pyx_v_a, int __pyx_v_b) {
int __pyx_r;
/* "/home/nosklo/devel/ctest/hello.pyx":2
* cdef int hello(int a, int b):
* return a + b # <<<<<<<<<<<<<<
*
*/
__pyx_r = (__pyx_v_a + __pyx_v_b);
goto __pyx_L0;
__pyx_r = 0;
__pyx_L0:;
return __pyx_r;
}
static struct PyMethodDef __pyx_methods[] = {
{0, 0, 0, 0}
};
static void __pyx_init_filenames(void); /*proto*/
#if PY_MAJOR_VERSION >= 3
static struct PyModuleDef __pyx_moduledef = {
PyModuleDef_HEAD_INIT,
"helloworld",
0, /* m_doc */
-1, /* m_size */
__pyx_methods /* m_methods */,
NULL, /* m_reload */
NULL, /* m_traverse */
NULL, /* m_clear */
NULL /* m_free */
};
#endif
static int __Pyx_InitCachedBuiltins(void) {
return 0;
return -1;
}
static int __Pyx_InitGlobals(void) {
return 0;
return -1;
}
#if PY_MAJOR_VERSION < 3
PyMODINIT_FUNC inithelloworld(void); /*proto*/
PyMODINIT_FUNC inithelloworld(void)
#else
PyMODINIT_FUNC PyInit_helloworld(void); /*proto*/
PyMODINIT_FUNC PyInit_helloworld(void)
#endif
{
__pyx_empty_tuple = PyTuple_New(0);
if (unlikely(!__pyx_empty_tuple))
{__pyx_filename = __pyx_f[0]; __pyx_lineno = 1;
__pyx_clineno = __LINE__; goto __pyx_L1_error;}
/*--- Library function declarations ---*/
__pyx_init_filenames();
/*--- Initialize various global constants etc. ---*/
if (unlikely(__Pyx_InitGlobals() < 0))
{__pyx_filename = __pyx_f[0];
__pyx_lineno = 1;
__pyx_clineno = __LINE__;
goto __pyx_L1_error;}
/*--- Module creation code ---*/
#if PY_MAJOR_VERSION < 3
__pyx_m = Py_InitModule4("helloworld", __pyx_methods, 0, 0, PYTHON_API_VERSION);
#else
__pyx_m = PyModule_Create(&__pyx_moduledef);
#endif
if (!__pyx_m)
{__pyx_filename = __pyx_f[0];
__pyx_lineno = 1; __pyx_clineno = __LINE__;
goto __pyx_L1_error;};
#if PY_MAJOR_VERSION < 3
Py_INCREF(__pyx_m);
#endif
__pyx_b = PyImport_AddModule(__Pyx_BUILTIN_MODULE_NAME);
if (!__pyx_b)
{__pyx_filename = __pyx_f[0]; __pyx_lineno = 1;
__pyx_clineno = __LINE__; goto __pyx_L1_error;};
if (PyObject_SetAttrString(__pyx_m, "__builtins__", __pyx_b) < 0)
{__pyx_filename = __pyx_f[0]; __pyx_lineno = 1;
__pyx_clineno = __LINE__; goto __pyx_L1_error;};
/*--- Builtin init code ---*/
if (unlikely(__Pyx_InitCachedBuiltins() < 0))
{__pyx_filename = __pyx_f[0]; __pyx_lineno = 1;
__pyx_clineno = __LINE__; goto __pyx_L1_error;}
__pyx_skip_dispatch = 0;
/*--- Global init code ---*/
/*--- Function export code ---*/
/*--- Type init code ---*/
/*--- Type import code ---*/
/*--- Function import code ---*/
/*--- Execution code ---*/
/* "/home/nosklo/devel/ctest/hello.pyx":1
* cdef int hello(int a, int b): # <<<<<<<<<<<<<<
* return a + b
*
*/
#if PY_MAJOR_VERSION < 3
return;
#else
return __pyx_m;
#endif
__pyx_L1_error:;
__Pyx_AddTraceback("helloworld");
#if PY_MAJOR_VERSION >= 3
return NULL;
#endif
}
static const char *__pyx_filenames[] = {
"hello.pyx",
};
/* Runtime support code */
static void __pyx_init_filenames(void) {
__pyx_f = __pyx_filenames;
}
#include "compile.h"
#include "frameobject.h"
#include "traceback.h"
static void __Pyx_AddTraceback(const char *funcname) {
PyObject *py_srcfile = 0;
PyObject *py_funcname = 0;
PyObject *py_globals = 0;
PyObject *empty_string = 0;
PyCodeObject *py_code = 0;
PyFrameObject *py_frame = 0;
#if PY_MAJOR_VERSION < 3
py_srcfile = PyString_FromString(__pyx_filename);
#else
py_srcfile = PyUnicode_FromString(__pyx_filename);
#endif
if (!py_srcfile) goto bad;
if (__pyx_clineno) {
#if PY_MAJOR_VERSION < 3
py_funcname = PyString_FromFormat( "%s (%s:%d)", funcname,
__pyx_cfilenm, __pyx_clineno);
#else
py_funcname = PyUnicode_FromFormat( "%s (%s:%d)", funcname,
__pyx_cfilenm, __pyx_clineno);
#endif
}
else {
#if PY_MAJOR_VERSION < 3
py_funcname = PyString_FromString(funcname);
#else
py_funcname = PyUnicode_FromString(funcname);
#endif
}
if (!py_funcname) goto bad;
py_globals = PyModule_GetDict(__pyx_m);
if (!py_globals) goto bad;
#if PY_MAJOR_VERSION < 3
empty_string = PyString_FromStringAndSize("", 0);
#else
empty_string = PyBytes_FromStringAndSize("", 0);
#endif
if (!empty_string) goto bad;
py_code = PyCode_New(
0, /*int argcount,*/
#if PY_MAJOR_VERSION >= 3
0, /*int kwonlyargcount,*/
#endif
0, /*int nlocals,*/
0, /*int stacksize,*/
0, /*int flags,*/
empty_string, /*PyObject *code,*/
__pyx_empty_tuple, /*PyObject *consts,*/
__pyx_empty_tuple, /*PyObject *names,*/
__pyx_empty_tuple, /*PyObject *varnames,*/
__pyx_empty_tuple, /*PyObject *freevars,*/
__pyx_empty_tuple, /*PyObject *cellvars,*/
py_srcfile, /*PyObject *filename,*/
py_funcname, /*PyObject *name,*/
__pyx_lineno, /*int firstlineno,*/
empty_string /*PyObject *lnotab*/
);
if (!py_code) goto bad;
py_frame = PyFrame_New(
PyThreadState_GET(), /*PyThreadState *tstate,*/
py_code, /*PyCodeObject *code,*/
py_globals, /*PyObject *globals,*/
0 /*PyObject *locals*/
);
if (!py_frame) goto bad;
py_frame->f_lineno = __pyx_lineno;
PyTraceBack_Here(py_frame);
bad:
Py_XDECREF(py_srcfile);
Py_XDECREF(py_funcname);
Py_XDECREF(empty_string);
Py_XDECREF(py_code);
Py_XDECREF(py_frame);
}
/* Type Conversion Functions */
static INLINE Py_ssize_t __pyx_PyIndex_AsSsize_t(PyObject* b) {
Py_ssize_t ival;
PyObject* x = PyNumber_Index(b);
if (!x) return -1;
ival = PyInt_AsSsize_t(x);
Py_DECREF(x);
return ival;
}
static INLINE int __Pyx_PyObject_IsTrue(PyObject* x) {
if (x == Py_True) return 1;
else if (x == Py_False) return 0;
else return PyObject_IsTrue(x);
}
static INLINE PY_LONG_LONG __pyx_PyInt_AsLongLong(PyObject* x) {
if (PyInt_CheckExact(x)) {
return PyInt_AS_LONG(x);
}
else if (PyLong_CheckExact(x)) {
return PyLong_AsLongLong(x);
}
else {
PY_LONG_LONG val;
PyObject* tmp = PyNumber_Int(x); if (!tmp) return (PY_LONG_LONG)-1;
val = __pyx_PyInt_AsLongLong(tmp);
Py_DECREF(tmp);
return val;
}
}
static INLINE unsigned PY_LONG_LONG __pyx_PyInt_AsUnsignedLongLong(PyObject* x) {
if (PyInt_CheckExact(x)) {
long val = PyInt_AS_LONG(x);
if (unlikely(val < 0)) {
PyErr_SetString(PyExc_TypeError, "Negative assignment to unsigned type.");
return (unsigned PY_LONG_LONG)-1;
}
return val;
}
else if (PyLong_CheckExact(x)) {
return PyLong_AsUnsignedLongLong(x);
}
else {
PY_LONG_LONG val;
PyObject* tmp = PyNumber_Int(x); if (!tmp) return (PY_LONG_LONG)-1;
val = __pyx_PyInt_AsUnsignedLongLong(tmp);
Py_DECREF(tmp);
return val;
}
}
static INLINE unsigned char __pyx_PyInt_unsigned_char(PyObject* x) {
if (sizeof(unsigned char) < sizeof(long)) {
long long_val = __pyx_PyInt_AsLong(x);
unsigned char val = (unsigned char)long_val;
if (unlikely((val != long_val) || (long_val < 0))) {
PyErr_SetString(PyExc_OverflowError, "value too large to convert to unsigned char");
return (unsigned char)-1;
}
return val;
}
else {
return __pyx_PyInt_AsLong(x);
}
}
static INLINE unsigned short __pyx_PyInt_unsigned_short(PyObject* x) {
if (sizeof(unsigned short) < sizeof(long)) {
long long_val = __pyx_PyInt_AsLong(x);
unsigned short val = (unsigned short)long_val;
if (unlikely((val != long_val) || (long_val < 0))) {
PyErr_SetString(PyExc_OverflowError, "value too large to convert to unsigned short");
return (unsigned short)-1;
}
return val;
}
else {
return __pyx_PyInt_AsLong(x);
}
}
static INLINE char __pyx_PyInt_char(PyObject* x) {
if (sizeof(char) < sizeof(long)) {
long long_val = __pyx_PyInt_AsLong(x);
char val = (char)long_val;
if (unlikely((val != long_val) )) {
PyErr_SetString(PyExc_OverflowError, "value too large to convert to char");
return (char)-1;
}
return val;
}
else {
return __pyx_PyInt_AsLong(x);
}
}
static INLINE short __pyx_PyInt_short(PyObject* x) {
if (sizeof(short) < sizeof(long)) {
long long_val = __pyx_PyInt_AsLong(x);
short val = (short)long_val;
if (unlikely((val != long_val) )) {
PyErr_SetString(PyExc_OverflowError, "value too large to convert to short");
return (short)-1;
}
return val;
}
else {
return __pyx_PyInt_AsLong(x);
}
}
static INLINE int __pyx_PyInt_int(PyObject* x) {
if (sizeof(int) < sizeof(long)) {
long long_val = __pyx_PyInt_AsLong(x);
int val = (int)long_val;
if (unlikely((val != long_val) )) {
PyErr_SetString(PyExc_OverflowError, "value too large to convert to int");
return (int)-1;
}
return val;
}
else {
return __pyx_PyInt_AsLong(x);
}
}
static INLINE long __pyx_PyInt_long(PyObject* x) {
if (sizeof(long) < sizeof(long)) {
long long_val = __pyx_PyInt_AsLong(x);
long val = (long)long_val;
if (unlikely((val != long_val) )) {
PyErr_SetString(PyExc_OverflowError, "value too large to convert to long");
return (long)-1;
}
return val;
}
else {
return __pyx_PyInt_AsLong(x);
}
}
static INLINE signed char __pyx_PyInt_signed_char(PyObject* x) {
if (sizeof(signed char) < sizeof(long)) {
long long_val = __pyx_PyInt_AsLong(x);
signed char val = (signed char)long_val;
if (unlikely((val != long_val) )) {
PyErr_SetString(PyExc_OverflowError, "value too large to convert to signed char");
return (signed char)-1;
}
return val;
}
else {
return __pyx_PyInt_AsLong(x);
}
}
static INLINE signed short __pyx_PyInt_signed_short(PyObject* x) {
if (sizeof(signed short) < sizeof(long)) {
long long_val = __pyx_PyInt_AsLong(x);
signed short val = (signed short)long_val;
if (unlikely((val != long_val) )) {
PyErr_SetString(PyExc_OverflowError, "value too large to convert to signed short");
return (signed short)-1;
}
return val;
}
else {
return __pyx_PyInt_AsLong(x);
}
}
static INLINE signed int __pyx_PyInt_signed_int(PyObject* x) {
if (sizeof(signed int) < sizeof(long)) {
long long_val = __pyx_PyInt_AsLong(x);
signed int val = (signed int)long_val;
if (unlikely((val != long_val) )) {
PyErr_SetString(PyExc_OverflowError, "value too large to convert to signed int");
return (signed int)-1;
}
return val;
}
else {
return __pyx_PyInt_AsLong(x);
}
}
static INLINE signed long __pyx_PyInt_signed_long(PyObject* x) {
if (sizeof(signed long) < sizeof(long)) {
long long_val = __pyx_PyInt_AsLong(x);
signed long val = (signed long)long_val;
if (unlikely((val != long_val) )) {
PyErr_SetString(PyExc_OverflowError, "value too large to convert to signed long");
return (signed long)-1;
}
return val;
}
else {
return __pyx_PyInt_AsLong(x);
}
}
static INLINE long double __pyx_PyInt_long_double(PyObject* x) {
if (sizeof(long double) < sizeof(long)) {
long long_val = __pyx_PyInt_AsLong(x);
long double val = (long double)long_val;
if (unlikely((val != long_val) )) {
PyErr_SetString(PyExc_OverflowError, "value too large to convert to long double");
return (long double)-1;
}
return val;
}
else {
return __pyx_PyInt_AsLong(x);
}
}