Merge branch 'master' into decoding-full-dmr
This commit is contained in:
Cort Buffington
commit
7745752742
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@ -9,6 +9,7 @@
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from __future__ import print_function
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from bitarray import bitarray
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import hamming
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from time import time
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# Does anybody read this stuff? There's a PEP somewhere that says I should do this.
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__author__ = 'Cortney T. Buffington, N0MJS'
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@ -43,7 +44,7 @@ INDEX_181 = (
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# Converts a DMR frame using 98-68-98 (info-sync/EMB-info) into 196 bit array
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# Applies interleave indecies de-interleave 196 bit array
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def deinterleave(_data):
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def deinterleave_19696(_data):
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deint = bitarray(196, endian='big')
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for index in xrange(196):
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deint[index] = _data[INDEX_181[index]] # the real math is slower: deint[index] = _data[(index * 181) % 196]
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@ -51,7 +52,7 @@ def deinterleave(_data):
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# Applies BTPC error detection/correction routines
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# This routine, in practice, will not be used in HBlink or DMRlink - it's only usefull for OTA direct data
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def error_check(_data):
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def error_check_19696(_data):
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count = 0
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column = bitarray(13, endian='big')
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@ -86,7 +87,7 @@ def error_check(_data):
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# BPTC(196,96) Encoding Routings
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#------------------------------------------------------------------------------
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def interleave(_data):
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def interleave_19696(_data):
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inter = bitarray(196, endian='big')
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for index in xrange(196):
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inter[INDEX_181[index]] = _data[index] # the real math is slower: deint[index] = _data[(index * 181) % 196]
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@ -94,7 +95,7 @@ def interleave(_data):
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# Accepts 12 byte LC header + RS1293, converts to binary and pads for 196 bit
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# encode hamming 15113 to rows and 1393 to columns
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def encode(_data):
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def encode_19696(_data):
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# Create a bitarray from the 4 bytes of LC data (includes RS1293 ECC)
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_bdata = bitarray(endian='big')
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_bdata.frombytes(_data)
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@ -133,6 +134,42 @@ def encode(_data):
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return _bdata
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#------------------------------------------------------------------------------
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# BPTC Embedded LC Decoding Routines
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#------------------------------------------------------------------------------
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#------------------------------------------------------------------------------
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# BPTC Embedded LC Encoding Routines
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#------------------------------------------------------------------------------
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# Accepts 12 byte LC header + 5-bit checksum, converts to binary and builts out the BPTC
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# encoded result with hamming(16,11,4) and parity.
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def encode_emblc(_lc, _csum5):
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# Create a bitarray from the 4 bytes of LC data (includes 5-bit checksum).
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_binlc = bitarray(endian='big')
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_binlc.frombytes(_lc)
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# Insert the checksum bits at the right location in the matrix (this is actually faster than with a for loop)
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_binlc.insert(32,_csum5[0])
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_binlc.insert(43,_csum5[1])
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_binlc.insert(54,_csum5[2])
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_binlc.insert(65,_csum5[3])
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_binlc.insert(76,_csum5[4])
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# Insert the hamming bits at the right location in the matrix
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for index in xrange(0,112,16):
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for hindex,hbit in zip(xrange(index+11,index+16), hamming.enc_16114(_binlc[index:index+11])):
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_binlc.insert(hindex,hbit)
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for index in xrange(0,16):
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_binlc.insert(index+112, _binlc[index+0] ^ _binlc[index+16] ^ _binlc[index+32] ^ _binlc[index+48] ^ _binlc[index+64] ^ _binlc[index+80] ^ _binlc[index+96])
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# TO DO NEXT:
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# INTERLEAVE, RETURN A TUPLE OR LIBRARY OR EACH SEGMENT OF THE LC
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# EACH SEGMENT IS 4 COLUMNS, TOP TO BOTTOM, LEFT TO RIGHT (PAGE 124 ETSI)
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#------------------------------------------------------------------------------
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# Used to execute the module directly to run built-in tests
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#------------------------------------------------------------------------------
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@ -141,6 +178,7 @@ if __name__ == '__main__':
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from binascii import b2a_hex as h
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from time import time
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import crc
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def to_bytes(_bits):
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#add_bits = 8 - (len(_bits) % 8)
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@ -154,8 +192,8 @@ if __name__ == '__main__':
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orig_data = '\x00\x10\x20\x00\x0c\x30\x2f\x9b\xe5\xda\xd4\x5a'
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t0 = time()
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enc_data = encode(orig_data)
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inter_data = interleave(enc_data)
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enc_data = encode_19696(orig_data)
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inter_data = interleave_19696(enc_data)
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t1 = time()
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encode_time = t1-t0
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@ -169,8 +207,8 @@ if __name__ == '__main__':
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dec_bits = dec_bits[0:98] + dec_bits[166:264]
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t0 = time()
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deint_data = deinterleave(dec_bits)
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err_corrected = error_check(deint_data) # This corrects deint_data in place -- it does not return a new array!!!
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deint_data = deinterleave_19696(dec_bits)
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err_corrected = error_check_19696(deint_data) # This corrects deint_data in place -- it does not return a new array!!!
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ext_data = to_bytes(deint_data)
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t1 = time()
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decode_time = t1-t0
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@ -195,4 +233,9 @@ if __name__ == '__main__':
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print('ENCODED vs. DECODED:')
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print('enc:', enc_data)
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print('dec:', deint_data)
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print(enc_data == deint_data)
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print(enc_data == deint_data)
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orig_data = '\x00\x10\x20\x00\x0c\x30\x2f\x9b\xe5'
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orig_csum = crc.csum5(orig_data)
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emblc = encode_emblc(orig_data, orig_csum)
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2
crc.py
2
crc.py
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@ -22,12 +22,14 @@ def csum5(_data):
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_data = bytearray(_data)
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accum = 0
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assert len(_data) == 9, 'csum5 expected 9 bytes of data and got something else'
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for i in xrange(9):
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accum += _data[i]
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accum = chr(accum % 31)
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csum = bitarray()
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csum.frombytes(accum)
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del csum[0:3]
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return csum
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@ -9,7 +9,7 @@
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from __future__ import print_function
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from bitarray import bitarray
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import bptc19696
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import bptc
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import constants as const
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# Does anybody read this stuff? There's a PEP somewhere that says I should do this.
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@ -37,7 +37,7 @@ def lc_data_9(_data):
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def voice_head_term(_string):
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burst = to_bits(_string)
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info = burst[0:98] + burst[166:264]
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de_int_info = bptc19696.deinterleave(info)
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de_int_info = bptc.deinterleave_19696(info)
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slot_type = burst[98:108] + burst[156:166]
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lc = to_bytes(lc_data_9(de_int_info))
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cc = to_bytes(slot_type[0:4])
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@ -117,6 +117,7 @@ def dec_1393(_data):
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# ENCODER - returns a bitarray object containing the hamming checksums
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def enc_16114(_data):
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assert len(_data) == 11, 'Hamming Encoder 16,11,4: Data not 11 bits long'
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csum = bitarray(5)
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csum[0] = _data[0] ^ _data[1] ^ _data[2] ^ _data[3] ^ _data[5] ^ _data[7] ^ _data[8]
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csum[1] = _data[1] ^ _data[2] ^ _data[3] ^ _data[4] ^ _data[6] ^ _data[8] ^ _data[9]
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