Aw: Decoding an extravagant binary format 46 06 09 21 43 65 87 F9

[Oliver Korpilla]

Hi,
 
instead of matching out each byte, you could use binary_to_list, I think it would give you a list of octets, IIRC, skipping building the list of elements by hand. Then you could map.
 

 
string:join([ << Y, Z >> || <<X:4, Y:4>> <= <<IMSI_CODED:64>> ], "").
 
Could somehing like this work?

I have no Erlang interpreter to test it.
 
Oliver
 
 

Gesendet: Montag, 13. Juli 2020 um 18:46 Uhr
Von: "Papa Tana" <papa.tana101@REDACTED>
An: "erlang-questions" <erlang-questions@REDACTED>
Betreff: Decoding an extravagant binary format 46 06 09 21 43 65 87 F9
Hi All,

I receive binaries in my application:

IMSI_CODED in hex_dump
0000 46 06 09 21 43 65 87 F9

In reality, the peer is sending me this IMSI : (64 60 90 12 34 56 78 9F).

I hard-decode this IMSI_CODED like below:

<<R1:8, R2:8, R3:8, R4:8, R5:8, R6:8, R7:8, R8:8>> = <<IMSI_CODED:64>>,

Elements = [
string:right(integer_to_list(R1,16), 2, $0),
string:right(integer_to_list(R2,16), 2, $0),
string:right(integer_to_list(R3,16), 2, $0),
string:right(integer_to_list(R4,16), 2, $0),
string:right(integer_to_list(R5,16), 2, $0),
string:right(integer_to_list(R6,16), 2, $0),
string:right(integer_to_list(R7,16), 2, $0),
string:right(integer_to_list(R8,16), 2, $0)
],
R = [[B,A] || [A,B] <-Elements ], %% here, I need to revert each element :-/
L = list_to_tuple(R),
Z = tuple_to_list(L),
Real_IMSI = string:join(Z,"")


=> Real_IMSI = "646090123456789F"

I'm using the same hard-coding style to decode some SMS payload in
binary format..

But I can feel that there is a much more elegant way to do it, because
as you can see, despite it's working, it's really dirty etc...

Can anyone advice please?

Thanks,

Best Regards,