Some simple one-liners for encoding and decoding binary-coded decimals (BCD).
    # Encode
    perl -le 'print join " ", map {ord pack "H2", $_} shift =~ /../g' 
+num

    # decode
    perl -le 'print unpack "H*", pack "C*", @ARGV'  num1 num2 ...

    perl -le 'print map {int($_/16).($_%16)} @ARGV' num1 num2 ...

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Some examples:

    # Encode

    $ perl -le 'print join " ", map {ord pack "H2", $_} shift =~ /../g
+' 019774
    1 151 116


    # decode

    $ perl -le 'print unpack "H*", pack "C*", @ARGV' 1 151 116
    019774

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You can use "h" instead of "H" for low nibble first encoding. Single digit components of the number to be encoded should be zero padded.

--
John.

Replies are listed 'Best First'.
Re: Encode and decode binary-coded decimals
by jryan (Vicar) on Oct 08, 2002 at 16:59 UTC

    I tried all of your snippets, and none seemed to work. For instance:

    perl -le 'print join " ", map {ord pack "H2", $_} shift =~ /../g' 396

    [download]

    I'd expect to get: 0011 1001 0110, but instead I get 57, which isn't very binary at all :)

    Similarly with decode: 

    perl -le 'print unpack "H*", pack "C*", @ARGV' 0011 1001 0110

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    Results in 0be96e (hex!) instead of 396.

    These should work: 

    # encode
perl -e 'print sprintf("%04b ",$_) for shift =~ /\d/g' decimal

#decode
perl -e '$p=1; map{$l+=oct("0b$_")*$p;$p*=10} reverse @ARGV; print $l'
+ bcddigit1 bcddigit2 etc

    [download]

    Update: Updated decoder to use 5.6.1's oct("0b") feature instead of the old perlfaq way to convery binary to decimal.

[reply]
[d/l]
[select]

      In the first case you need to use 0396 instead of 396. That's what the comment about "zero padding" refers to. 
          $ perl -le 'print join " ", map {ord pack "H2", $_} shift =~ /../g
+' 0396
    3 150

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      I'd expect to get: 0011 1001 011

      That is at odds with my expectation.:-) Nevertheless, it isn't too difficult to change these routines to support other ascii, hex or binary representations.

      --
      John.

[reply]
[d/l]

        My definition of BCD is similar to this, but maybe you are referring to something different? :)

[reply]

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