238 lines
9.1 KiB
Python
Executable File
238 lines
9.1 KiB
Python
Executable File
#!/usr/bin/env python
|
|
#
|
|
# This work is licensed under the Creative Attribution-NonCommercial-ShareAlike
|
|
# 3.0 Unported License.To view a copy of this license, visit
|
|
# http://creativecommons.org/licenses/by-nc-sa/3.0/ or send a letter to
|
|
# Creative Commons, 444 Castro Street, Suite 900, Mountain View,
|
|
# California, 94041, USA.
|
|
|
|
from __future__ import print_function
|
|
from bitarray import bitarray
|
|
import hamming
|
|
from time import time
|
|
|
|
# Does anybody read this stuff? There's a PEP somewhere that says I should do this.
|
|
__author__ = 'Cortney T. Buffington, N0MJS'
|
|
__copyright__ = 'Copyright (c) 2016 Cortney T. Buffington, N0MJS and the K0USY Group'
|
|
__credits__ = 'Jonathan Naylor, G4KLX; Ian Wraith'
|
|
__license__ = 'Creative Commons Attribution-NonCommercial-ShareAlike 3.0 Unported'
|
|
__maintainer__ = 'Cort Buffington, N0MJS'
|
|
__email__ = 'n0mjs@me.com'
|
|
|
|
|
|
#------------------------------------------------------------------------------
|
|
# Interleaver Index
|
|
#------------------------------------------------------------------------------
|
|
|
|
INDEX_181 = (
|
|
0, 181, 166, 151, 136, 121, 106, 91, 76, 61, 46, 31, 16, 1, 182, 167, 152, 137,
|
|
122, 107, 92, 77, 62, 47, 32, 17, 2, 183, 168, 153, 138, 123, 108, 93, 78, 63,
|
|
48, 33, 18, 3, 184, 169, 154, 139, 124, 109, 94, 79, 64, 49, 34, 19, 4, 185, 170,
|
|
155, 140, 125, 110, 95, 80, 65, 50, 35, 20, 5, 186, 171, 156, 141, 126, 111, 96,
|
|
81, 66, 51, 36, 21, 6, 187, 172, 157, 142, 127, 112, 97, 82, 67, 52, 37, 22, 7,
|
|
188, 173, 158, 143, 128, 113, 98, 83, 68, 53, 38, 23, 8, 189, 174, 159, 144, 129,
|
|
114, 99, 84, 69, 54, 39, 24, 9, 190, 175, 160, 145, 130, 115, 100, 85, 70, 55, 40,
|
|
25, 10, 191, 176, 161, 146, 131, 116, 101, 86, 71, 56, 41, 26, 11, 192, 177, 162,
|
|
147, 132, 117, 102, 87, 72, 57, 42, 27, 12, 193, 178, 163, 148, 133, 118, 103, 88,
|
|
73, 58, 43, 28, 13, 194, 179, 164, 149, 134, 119, 104, 89, 74, 59, 44, 29, 14,
|
|
195, 180, 165, 150, 135, 120, 105, 90, 75, 60, 45, 30, 15)
|
|
|
|
|
|
#------------------------------------------------------------------------------
|
|
# BPTC(196,96) Decoding Routings
|
|
#------------------------------------------------------------------------------
|
|
|
|
# Converts a DMR frame using 98-68-98 (info-sync/EMB-info) into 196 bit array
|
|
# Applies interleave indecies de-interleave 196 bit array
|
|
def deinterleave_19696(_data):
|
|
deint = bitarray(196, endian='big')
|
|
for index in xrange(196):
|
|
deint[index] = _data[INDEX_181[index]] # the real math is slower: deint[index] = _data[(index * 181) % 196]
|
|
return deint
|
|
|
|
# Applies BTPC error detection/correction routines
|
|
# This routine, in practice, will not be used in HBlink or DMRlink - it's only usefull for OTA direct data
|
|
def error_check_19696(_data):
|
|
count = 0
|
|
column = bitarray(13, endian='big')
|
|
|
|
while True:
|
|
errors = False
|
|
for col in xrange(15):
|
|
pos = col + 1
|
|
for index in xrange(13):
|
|
column[index] = _data[pos]
|
|
pos += 15
|
|
|
|
result_1393 = hamming.dec_1393(column)
|
|
if result_1393[1]:
|
|
pos = col + 1
|
|
for index in xrange(13):
|
|
_data[pos] = result_1393[0][index]
|
|
pos += 15
|
|
errors = True
|
|
|
|
for index in xrange(9):
|
|
pos = (index*15) + 1
|
|
result_15113 = hamming.dec_15113(_data[pos:(pos+15)])
|
|
if result_15113[1]:
|
|
errors = True
|
|
_data[pos:(pos+15)] = result_15113[0]
|
|
|
|
count += 1
|
|
if not errors or count > 4: break
|
|
return (errors)
|
|
|
|
#------------------------------------------------------------------------------
|
|
# BPTC(196,96) Encoding Routings
|
|
#------------------------------------------------------------------------------
|
|
|
|
def interleave_19696(_data):
|
|
inter = bitarray(196, endian='big')
|
|
for index in xrange(196):
|
|
inter[INDEX_181[index]] = _data[index] # the real math is slower: deint[index] = _data[(index * 181) % 196]
|
|
return inter
|
|
|
|
# Accepts 12 byte LC header + RS1293, converts to binary and pads for 196 bit
|
|
# encode hamming 15113 to rows and 1393 to columns
|
|
def encode_19696(_data):
|
|
# Create a bitarray from the 4 bytes of LC data (includes RS1293 ECC)
|
|
_bdata = bitarray(endian='big')
|
|
_bdata.frombytes(_data)
|
|
|
|
# Insert R0-R3 bits
|
|
for i in xrange(4):
|
|
_bdata.insert(0, 0)
|
|
|
|
# Get row hamming 15,11,3 and append. +1 is to account for R3 that makes an even 196bit string
|
|
for index in xrange(9):
|
|
spos = (index*15) + 1
|
|
epos= spos + 11
|
|
_rowp = hamming.enc_15113(_bdata[spos:epos])
|
|
for pbit in xrange(4):
|
|
_bdata.insert(epos+pbit,_rowp[pbit])
|
|
|
|
# Get column hamming 13,9,3 and append. +1 is to account for R3 that makes an even 196bit string
|
|
# Pad out the bitarray to a full 196 bits. Can't insert into 'columns'
|
|
for i in xrange(60):
|
|
_bdata.append(0)
|
|
|
|
column = bitarray(9, endian='big') # Temporary bitarray to hold column data
|
|
for col in xrange(15):
|
|
spos = col + 1
|
|
for index in xrange(9):
|
|
column[index] = _bdata[spos]
|
|
spos += 15
|
|
_colp = hamming.enc_1393(column)
|
|
|
|
# Insert bits into matrix...
|
|
cpar = 136 + col # Starting location in the matrix for column bits
|
|
for pbit in xrange(4):
|
|
_bdata[cpar] = _colp[pbit]
|
|
cpar += 15
|
|
|
|
return _bdata
|
|
|
|
|
|
#------------------------------------------------------------------------------
|
|
# BPTC Embedded LC Decoding Routines
|
|
#------------------------------------------------------------------------------
|
|
|
|
|
|
#------------------------------------------------------------------------------
|
|
# BPTC Embedded LC Encoding Routines
|
|
#------------------------------------------------------------------------------
|
|
|
|
|
|
# Accepts 12 byte LC header + 5-bit checksum, converts to binary and builts out the BPTC
|
|
# encoded result with hamming(16,11,4) and parity.
|
|
def encode_emblc(_lc, _csum5):
|
|
# Create a bitarray from the 4 bytes of LC data (includes 5-bit checksum).
|
|
_binlc = bitarray(endian='big')
|
|
_binlc.frombytes(_lc)
|
|
|
|
# Insert the checksum bits at the right location in the matrix (this is actually faster than with a for loop)
|
|
_binlc.insert(32, _csum5[0])
|
|
_binlc.insert(43,_csum5[1])
|
|
_binlc.insert(54,_csum5[2])
|
|
_binlc.insert(65,_csum5[3])
|
|
_binlc.insert(76,_csum5[4])
|
|
|
|
# Insert the hamming bits at the right location in the matrix
|
|
for index in xrange(0,112,16):
|
|
for hindex,hbit in zip(xrange(index+11,index+16), hamming.enc_16114(_binlc[index:index+11])):
|
|
_binlc.insert(hindex,hbit)
|
|
|
|
# TO DO NEXT:
|
|
# ADD PARITY BIT CALUCATIONS AND INTERLEAVE, RETURN A TUPLE OR LIBRARY OR EACH SEGMENT OF THE LC
|
|
|
|
|
|
#------------------------------------------------------------------------------
|
|
# Used to execute the module directly to run built-in tests
|
|
#------------------------------------------------------------------------------
|
|
|
|
if __name__ == '__main__':
|
|
|
|
from binascii import b2a_hex as h
|
|
from time import time
|
|
import crc
|
|
|
|
def to_bytes(_bits):
|
|
#add_bits = 8 - (len(_bits) % 8)
|
|
#if add_bits < 8:
|
|
# for bit in xrange(add_bits):
|
|
# _bits.insert(0,0)
|
|
_string = _bits.tobytes()
|
|
return _string
|
|
|
|
# Validation Example
|
|
|
|
orig_data = '\x00\x10\x20\x00\x0c\x30\x2f\x9b\xe5\xda\xd4\x5a'
|
|
t0 = time()
|
|
enc_data = encode_19696(orig_data)
|
|
inter_data = interleave_19696(enc_data)
|
|
t1 = time()
|
|
encode_time = t1-t0
|
|
|
|
# Good Data
|
|
dec_data = '\x2b\x60\x04\x10\x1f\x84\x2d\xd0\x0d\xf0\x7d\x41\x04\x6d\xff\x57\xd7\x5d\xf5\xde\x30\x15\x2e\x20\x70\xb2\x0f\x80\x3f\x88\xc6\x95\xe2'
|
|
# Bad Data
|
|
#dec_data = '\x2b\x60\xff\xff\xff\x85\x2d\xd0\x0d\xf0\x7d\x41\x04\x6d\xff\x57\xd7\x5d\xf5\xde\x30\x15\x2e\x20\x70\xb2\x0f\x80\x3f\x88\xc6\x95\xe2'
|
|
|
|
dec_bits = bitarray(endian='big')
|
|
dec_bits.frombytes(dec_data)
|
|
dec_bits = dec_bits[0:98] + dec_bits[166:264]
|
|
|
|
t0 = time()
|
|
deint_data = deinterleave_19696(dec_bits)
|
|
err_corrected = error_check_19696(deint_data) # This corrects deint_data in place -- it does not return a new array!!!
|
|
ext_data = to_bytes(deint_data)
|
|
t1 = time()
|
|
decode_time = t1-t0
|
|
|
|
|
|
print('VALIDATION ROUTINE:')
|
|
print()
|
|
print('ENCODER TEST:')
|
|
print('Original Data: {}, {} bytes'.format(h(orig_data), len(orig_data)))
|
|
print('Encoding time: {} seconds'.format(encode_time))
|
|
print('Encoded data: {}, {} bits'.format(enc_data, len(enc_data)))
|
|
print()
|
|
print('DECODER TEST:')
|
|
print('Encoded data: {}, {} bytes'.format(h(dec_data), len(dec_data)))
|
|
print('Decoding Time: {} seconds'.format(t1-t0))
|
|
if err_corrected:
|
|
print('WARNING DATA COULD NOT BE CORRECTED')
|
|
else:
|
|
print('Decoded Data: {}, {} bytes'.format(h(ext_data), len(ext_data)))
|
|
print()
|
|
|
|
print('ENCODED vs. DECODED:')
|
|
print('enc:', enc_data)
|
|
print('dec:', deint_data)
|
|
print(enc_data == deint_data)
|
|
|
|
orig_data = '\x00\x10\x20\x00\x0c\x30\x2f\x9b\xe5'
|
|
orig_csum = crc.csum5(orig_data)
|
|
emblc = encode_emblc(orig_data, orig_csum)
|
|
|