python4yahdlc/src/python4yahdlc.c at develop · recoord/python4yahdlc · GitHub

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#include <Python.h>

#include "yahdlc.h"

#define MAX_FRAME_PAYLOAD 512

#define HEADERS_LENGTH 8

#define TOTAL_FRAME_LENGTH MAX_FRAME_PAYLOAD + HEADERS_LENGTH

static PyObject *Yahdlc_MessageError;

static PyObject *Yahdlc_FCSError;

/* ---------- yahdlc functions ---------- */

/**

* Retrieves data from the specified buffer containing the HDLC frame.

static PyObject *get_data(PyObject *self, PyObject *args)

{

int ret;

const char *frame_data;

char recv_data[TOTAL_FRAME_LENGTH];

unsigned int buf_length = 0, recv_length = 0;

yahdlc_control_t control;

if (!PyArg_ParseTuple(args, "s#", &frame_data, &buf_length))

return NULL;

if (buf_length > TOTAL_FRAME_LENGTH)

{

PyErr_SetString(PyExc_ValueError, "buffer too long");

return NULL;

}

ret = yahdlc_get_data(&control, frame_data, buf_length, recv_data, &recv_length);

// If success.

if (ret >= 0)

{

PyObject *t;

t = PyTuple_New(4);

PyTuple_SetItem(t, 0, PyBytes_FromStringAndSize(recv_data, recv_length));

PyTuple_SetItem(t, 1, PyLong_FromUnsignedLong(control.frame));

PyTuple_SetItem(t, 2, PyLong_FromUnsignedLong(control.seq_no));

PyTuple_SetItem(t, 3, PyLong_FromUnsignedLong(ret));

return t;

}

else if (ret == -EINVAL)

{

PyErr_SetString(PyExc_ValueError, "invalid parameter");

return NULL;

}

else if (ret == -ENOMSG)

{

PyErr_SetString(Yahdlc_MessageError, "invalid message");

return NULL;

}

// If the FCS is not valid, we return the sequence number

// to be sent back as NACK.

else if (ret == -EIO)

{

PyErr_SetObject(Yahdlc_FCSError, PyLong_FromUnsignedLong(control.seq_no));

return NULL;

}

else

{

PyErr_SetString(PyExc_RuntimeError, "unknown error");

return NULL;

}

/**

* Resets the values used by the 'yahdlc_get_data' function

* to keep track of the received buffers.

static PyObject *get_data_reset(PyObject *self, PyObject *args)

{

yahdlc_get_data_reset();

Py_RETURN_NONE;

}

/**

* Creates an HDLC frame with the specified data buffer.

static PyObject *frame_data(PyObject *self, PyObject *args)

{

int ret;

const char *send_data;

char frame_data[TOTAL_FRAME_LENGTH];

unsigned int data_length = 0, frame_length = 0, frame_type = YAHDLC_FRAME_DATA, seq_no = 0;

yahdlc_control_t control;

if (!PyArg_ParseTuple(args, "s#|II", &send_data, &data_length, &frame_type, &seq_no))

return NULL;

if (data_length > MAX_FRAME_PAYLOAD)

{

PyErr_SetString(PyExc_ValueError, "data too long");

return NULL;

}

else if (frame_type != YAHDLC_FRAME_DATA && frame_type != YAHDLC_FRAME_ACK && frame_type != YAHDLC_FRAME_NACK)

{

PyErr_SetString(PyExc_ValueError, "bad frame type");

return NULL;

}

else if (seq_no > 7)

{

PyErr_SetString(PyExc_ValueError, "invalid sequence number");

return NULL;

}

control.frame = frame_type;

control.seq_no = seq_no;

ret = yahdlc_frame_data(&control, send_data, data_length, frame_data, &frame_length);

// If success.

if (ret == 0)

return PyBytes_FromStringAndSize(frame_data, frame_length);

else

{

PyErr_SetString(PyExc_ValueError, "invalid parameter");

return NULL;

}

/* ---------- Settings ---------- */

/**

* Python module's methods.

static PyMethodDef YahdlcMethods[] = {

{"get_data", get_data, METH_VARARGS, "Retrieves data from the specified buffer containing the HDLC frame."},

{"get_data_reset", get_data_reset, METH_VARARGS, "Resets the values used by the 'get_data' method to keep track of the received buffers."},

{"frame_data", frame_data, METH_VARARGS, "Creates an HDLC frame with the specified data buffer."},

{NULL, NULL, 0, NULL}

};

/**

* Python module itself.

static struct PyModuleDef yahdlc_module =

{

PyModuleDef_HEAD_INIT,

"yahdlc",

"HDLC implementation",

-1,

YahdlcMethods

};

/**

* Initialises the Python module.

PyMODINIT_FUNC PyInit_yahdlc(void)

{

PyObject *m;

m = PyModule_Create(&yahdlc_module);

if (m == NULL)

return NULL;

Yahdlc_MessageError = PyErr_NewException("yahdlc.MessageError", NULL, NULL);

Py_INCREF(Yahdlc_MessageError);

PyModule_AddObject(m, "MessageError", Yahdlc_MessageError);

Yahdlc_FCSError = PyErr_NewException("yahdlc.FCSError", NULL, NULL);

Py_INCREF(Yahdlc_FCSError);

PyModule_AddObject(m, "FCSError", Yahdlc_FCSError);

PyModule_AddIntConstant(m, "FRAME_DATA", YAHDLC_FRAME_DATA);

PyModule_AddIntConstant(m, "FRAME_ACK", YAHDLC_FRAME_ACK);

PyModule_AddIntConstant(m, "FRAME_NACK", YAHDLC_FRAME_NACK);

return m;

}

python4yahdlc/src/python4yahdlc.c at develop · recoord/python4yahdlc · GitHub

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