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This commit is contained in:
Cort Buffington 2016-09-07 20:02:06 -05:00
parent f9392ab032
commit 76b43f027a
1 changed files with 8 additions and 15 deletions
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23
RS129.py
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@ -93,15 +93,7 @@ def RS129_encode(_msg):
for j in range(NPAR - 1, 0, -1): for j in range(NPAR - 1, 0, -1):
parity[j] = parity[j - 1] ^ log_mult(POLY[j], dbyte) parity[j] = parity[j - 1] ^ log_mult(POLY[j], dbyte)
parity[0] = log_mult(POLY[0], dbyte) parity[0] = log_mult(POLY[0], dbyte)
return [parity[2], parity[1], parity[0]]
return parity
# Reed-Solomon (12,9) check
def RS129_check(_msg):
assert len(_msg) == 12, 'RS129_check error: Message not 12 bytes: %s' % print_hex(_msg)
parity = RS129_encode(_msg[:9])
return _msg[9] == parity[2] and msg[10] == parity[1] and msg[11] == parity[0];
# Apply DMR XOR MASK # Apply DMR XOR MASK
def xor_mask(_parity): def xor_mask(_parity):
@ -115,7 +107,7 @@ def DMR_RS129_LC_FEC(_message):
bin_message = bytearray(_message) bin_message = bytearray(_message)
parity = RS129_encode(bin_message) parity = RS129_encode(bin_message)
xor_parity = xor_mask(parity) xor_parity = xor_mask(parity)
return chr(xor_parity[2]) + chr(xor_parity[1]) + chr(xor_parity[0]) return chr(xor_parity[0]) + chr(xor_parity[1]) + chr(xor_parity[2])
# For testing the code # For testing the code
@ -123,9 +115,10 @@ def print_hex(_list):
print('[{}]'.format(', '.join(hex(x) for x in _list))) print('[{}]'.format(', '.join(hex(x) for x in _list)))
if __name__ == '__main__': if __name__ == '__main__':
message = '\x00\x10\x20\x00\x0c\x30\x2f\x9b\xe5'
parity = DMR_RS129_LC_FEC(message)
print(h(parity)) # Validation Example
message = '\x00\x10\x20\x00\x0c\x30\x2f\x9b\xe5'
parity_should_be = '\xda\x4d\x5a'
parity = DMR_RS129_LC_FEC(message)
print('Masked Parity Should be: {}'.format(h(parity_should_be)))
print('Calculated Masked Parity is: {}'.format(h(parity)))