embedded gcc and awk

Feel free to break this code, which is using the power of embedded gcc and awk.

#!/usr/bin/perl
$_='gcc 92 !$* % "awk in I$: ar& $:a"';
foreach(/(\S)/g){$;.=substr(unpack("B*"
,pack(n,unpack("c",$_))),-4);$;.="\n"if
!(++$i%5);}$_=$;;y;0;\40;;y;1;#;;print;
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Note: If you use Windows, you can use the windows compiler wcc instead of gcc.
If you don't have awk available, agk should work fine although I haven't test it myself.

Len ;-)

Comment on embedded gcc and awk Download Code

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Re: embedded gcc and awk
by jmcnamara (Monsignor) on Mar 28, 2002 at 13:14 UTC

gcc

awk

;-)

Anyway here is a breakdown of the code. With reformatting it looks like this:

    $_='gcc 92 !$* % "awk in I$: ar& $:a"';

    foreach (/(\S)/g) {
        $;.= substr(unpack("B*",pack(n,unpack("c",$_))),-4);
        $;.= "\n" if !(++$i%5);
    }

    $_=$;;
    y;0;\40;;
    y;1;#;;
    print;
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Substituting $str for $; and making some other changes:

    $_='gcc 92 !$* % "awk in I$: ar& $:a"';

    foreach $char (/\S/g) { # Capturing parens not needed
        $str.= substr(unpack("B*",pack(n,unpack("c",$char))),-4);
        $str.= "\n" if !(++$i%5);
    }

    $_=$str;
    tr/0/\40/;
    tr/1/#/;
    print $_;
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Looking at the main substution in detail for the first character "g":

    $str.= substr(unpack("B*",pack(n,unpack("c",$char))),-4);
    
    unpack("c",$char) # is the same as
    ord $char         # 103

    pack(n, ...       # packs 103 as a little-endian int

    unpack("B*", ...  # Packs it as a binary string: 0000000001100111

    substr(..., -4)   # Get the last 4 chars:        0111
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After these substitutions $str looks like this:

    01110011001110010010
    00010100101001010010
    00010111101110011110
    10010100101000010010
    01100100101000010010
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The transliteration could be done in one pass: tr/01/ #/; Applying the transliterations gives:

     ###  ##  ###  #  # 
       # #  # #  # #  # 
       # #### ###  #### 
    #  # #  # #    #  # 
     ##  #  # #    #  #
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I liked the joke about wcc and agk. :-) There is an example of a JAPH that does use an embedded awk (of sorts) here: JAAH

--
John.

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