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August 29, 2015 14:19
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The calculation of the checksum digit of the IMEI number according to Luhn formula.
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| -module(imei). | |
| -export([crc/1]). | |
| crc(IMEI) when is_list(IMEI), length(IMEI) =:= 14 -> | |
| calc(IMEI, 0). | |
| calc([], Acc) -> | |
| (10 - (Acc rem 10)) rem 10; | |
| calc(L = [X|Rest], Acc) when length(L) rem 2 =:= 0 -> | |
| calc(Rest, Acc + X - $0); | |
| calc([X|Rest], Acc) -> | |
| S = lists:sum([list_to_integer([Y]) || Y <- integer_to_list((X - $0) * 2)]), | |
| calc(Rest, Acc + S). |
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