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#!/usr/bin/env python
# -*- coding: utf-8 -*-
#
# Copyright 2021 Naoki Pross.
from functools import reduce
import operator as op
import numpy as np
from gnuradio import gr
class frame_obj(gr.basic_block):
"""
Frame Object: Contains informations about a data frame.
-------------------------------------------------------------------------------
| Preamble | Padding | ID | Data Length | Parity | Payload | Padding |
| k bytes | 1 bit | 4 bits | 22 bits | 5 bits | | if necessary |
-------------------------------------------------------------------------------
| (31, 26) Hamming code EC |
-----------------------------------
- The preamble is user defined.
- The ID (11 bits) + Data length (22 bits) together are a 31 bits, followed
by 26 parity bits computed using a (31,26) hamming code.
This constraints the maximum payload size to 64 MB and the number IDs to
1024 (i.e. max file size is 1 GB, more than enough for many thing)
"""
def __init__(self, preamble, payload_len):
gr.basic_block.__init__(self, name="frame_obj",
in_sig=None, out_sig=None)
self.preamble = np.array(preamble, dtype=np.uint8)
self.preamble_len = len(self.preamble)
self.payload_len = payload_len
@property
def length(self):
"""Frame lenght in bytes"""
return self.preamble_len + self.payload_len + 8
def parity(self, bits):
"""Compute the 5 parity bits for an unpacked array of 26 bits"""
assert(len(bits) == 26)
# FIXME: does not work
# gen = np.array(
# [[1, 0, 0, 0, 0, 1, 0, 0, 1, 0, 1, 1, 0, 0, 1, 1, 1, 1, 1, 0, 0, 0, 1, 1, 0, 1, 1, 1, 0, 1, 0],
# [0, 1, 0, 0, 0, 0, 1, 0, 0, 1, 0, 1, 1, 0, 0, 1, 1, 1, 1, 1, 0, 0, 0, 1, 1, 0, 1, 1, 1, 0, 1],
# [0, 0, 1, 0, 0, 1, 0, 1, 1, 0, 0, 1, 1, 1, 1, 1, 0, 0, 0, 1, 1, 0, 1, 1, 1, 0, 1, 0, 1, 0, 0],
# [0, 0, 0, 1, 0, 0, 1, 0, 1, 1, 0, 0, 1, 1, 1, 1, 1, 0, 0, 0, 1, 1, 0, 1, 1, 1, 0, 1, 0, 1, 0],
# [0, 0, 0, 0, 1, 0, 0, 1, 0, 1, 1, 0, 0, 1, 1, 1, 1, 1, 0, 0, 0, 1, 1, 0, 1, 1, 1, 0, 1, 0, 1]],
# dtype=np.uint8)
# return np.matmul(bits, gen) % 2
return np.array([0, 0, 0, 0, 0])
def make(self, idv, data_len, data):
"""Make a frame"""
return np.concatenate(self.preamble, np.packbits(hamming), data)
def syndrome(self, bits):
"""Compute the syndrome (check Hamming code) for an unpacked array of 31 bits"""
assert(len(bits) == 31)
return reduce(op.xor, [i for i, bit in enumerate(bits) if bit])
def general_work(self, input_items, output_items):
"""
This block has no inputs or output
"""
return 0;
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