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clean up

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This commit is contained in:
Cort Buffington 2016-09-21 16:38:58 -05:00
parent a1c77141d6
commit 779b54f21e
1 changed files with 28 additions and 12 deletions
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40
RS129.py
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@ -14,7 +14,8 @@ from __future__ import print_function
from binascii import b2a_hex as h
from binascii import a2b_hex as a2b
MASK = [0x96, 0x96, 0x96]
START_MASK = [0x96, 0x96, 0x96]
END_MASK = [0x99, 0x99, 0x99]
NUM_BYTES = 9
NPAR = 3;
POLY= [64, 56, 14, 1, 0, 0, 0, 0, 0, 0, 0, 0]
@ -83,7 +84,7 @@ def log_mult(a, b):
return z
# Reed-Solomon (12,9) encoder
def RS129_encode(_msg):
def encode(_msg):
assert len(_msg) == 9, 'RS129_encode error: Message not 9 bytes: %s' % print_hex(_msg)
parity = [0x00, 0x00, 0x00]
@ -95,30 +96,45 @@ def RS129_encode(_msg):
parity[0] = log_mult(POLY[0], dbyte)
return [parity[2], parity[1], parity[0]]
# Apply DMR XOR MASK
def RS129_mask(_parity):
# Apply DMR XOR LC start MASK
def lc_start_mask(_parity):
xor = [0,0,0]
for i in range(len(_parity)):
xor[i] = _parity[i] ^ MASK[i]
xor[i] = _parity[i] ^ START_MASK[i]
return xor
# Apply DMR XOR LC end MASK
def lc_end_mask(_parity):
xor = [0,0,0]
for i in range(len(_parity)):
xor[i] = _parity[i] ^ END_MASK[i]
return xor
# All Inclusive function to take an LC string and provide the RS129 string to append
def DMR_RS129_LC_FEC(_message):
def lc_start_encode(_message):
bin_message = bytearray(_message)
parity = RS129_encode(bin_message)
masked_parity = RS129_mask(parity)
parity = encode(bin_message)
masked_parity = lc_start_mask(parity)
return chr(masked_parity[0]) + chr(masked_parity[1]) + chr(masked_parity[2])
# All Inclusive function to take an LC string and provide the RS129 string to append
def lc_end_encode(_message):
bin_message = bytearray(_message)
parity = encode(bin_message)
masked_parity = lc_end_mask(parity)
return chr(masked_parity[0]) + chr(masked_parity[1]) + chr(masked_parity[2])
# For testing the code
def print_hex(_list):
print('[{}]'.format(', '.join(hex(x) for x in _list)))
if __name__ == '__main__':
# For testing the code
def print_hex(_list):
print('[{}]'.format(', '.join(hex(x) for x in _list)))
# Validation Example
message = '\x00\x10\x20\x00\x0c\x30\x2f\x9b\xe5'
parity_should_be = '\xda\x4d\x5a'
parity = DMR_RS129_LC_FEC(message)
parity = lc_start_encode(message)
print('Masked Parity Should be: {}'.format(h(parity_should_be)))
print('Calculated Masked Parity is: {}'.format(h(parity)))