in reply to Testing & Using Bits

FunkyMonk, thanks for the insite- I read the posting tips & appreciate the heads up. My last post WAS rather ugly. My problem seems to be threefold-
1. Finding things in the man pages. Where is the Bits:: etc. functions defined & do I need use statements at the beginning of my code to use things like Bits:: or File:: etc.?
2. I've been learning new languages for over 3 decades & it grinds me to have to ask someone else to do my work, but alas "seeking devine guidence", can save time. Thanks for the tip on the tutorials. There was a segment that I stumbled onto that caused me some grief... 
print join(" ", map { sprintf "%#02x", $_ } unpack("C*",pack("L",0x123
+45678))), "\n";

print join(" ", map { sprintf "%#02x", $_ } unpack("C*",pack("L",$Byte
+s))), "\n";

[download]
This first line works, it prints the 0x12 0x34 etc., but the second just prints 0x00 0x00 etc. I know the 6 hex bytes are in $Bytes because printing it yeilds the proper graphics on the screen. Can you explain the "%#02x"? I've read the printf doc but the light just isn't comming on.
3. See, sorry to ramble on, but when I finally do ask for help, I just want to give you as much info as possible. I work in support, so I know all too well the headaches associated with getting bits (no pun) of info on a "need to know" basis. I guess the next post will have to be "a sample of my script", but I'm trying to avoid burdening you with the laughter. Thanks again.
By the way, I don't plan on spending time here, but if you folks would prefer I sign up, I'd be happy to. At my age, I just try to avoid having to remember additional IDs & passwords. Thanks.
'le Dufois.

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Re^2: Testing & Using Bits
by FunkyMonk (Bishop) on May 31, 2007 at 17:46 UTC
    Your code works here:

    my $bytes = 0x123456;
print join(" ", map { sprintf "%#02x", $_ } unpack("C*",pack("L",0x123
+45678))), "\n";
print join(" ", map { sprintf "%#02x", $_ } unpack("C*",pack("L",$byte
+s))), "\n";

#output:
#0x78 0x56 0x34 0x12
#0x56 0x34 0x12 00

    [download]

    What did you expect it to do?

[reply]
[d/l]
      That's exactly what I expected. I'll recheck my code, but I was getting all zeroes. I even cut/pasted the line & THEN substituted the scalar for the string. Also where can I fine the doc on the sprintf codes %#02x, etc. Thanks.
[reply]
        %#02x means:

        • % A format code
        • # prefix with "0x"
        • 02 2 digits wide, padded with a leading zero if necessary
        • x hexadecimal

        You can read the full documentation here.

[reply]
[d/l]
[select]
        OK, I guess there's just no getting around it... ;-) Here's my code... 
         # !perl      DebugBCD.pl
open (inFILE, "<C:/Dev/Perl_Dev/ItemExp/TESTFILE.DAT") || 
                    die "Cannot open file\n";

# The first 6 bytes of my test file contain the 12 digit UPC Barcode 1
+23456789910

binmode (inFILE);
seek (inFILE,0,0);
read (inFILE,$inBuf,6);
print "Len=".length($inBuf)."  Raw Data = $inBuf \n";  # This prints t
+he graphics 

$Test = DecodeBCD($inBuf);
print $Test;                    # This prints   48 48 52 48 I expected
+ 1 2 3 4

close inFile;

sub DecodeBCD {
   my ($i,@lo,@hi,$Byte,$Bits,@pairs);
   my $Hi,$Low;
   my $LoMask = 15;
   my $HiMask = 240;
   my $Zone = 0x30;
   for ($i = 0; $i < 2; $i++) 
   {
      $Byte = substr($_[0],$i,1);
      $lo[$i] = ($Byte & $LoMask) | $Zone;        # These OR statement
+s seem to
      $hi[$i] = (($Byte & $HiMask) >> 4) | $Zone; # result in JUST the
+ $Zone piece,
      $pairs[$i] = join("",$lo[$i],$hi[$i]);      # Implying that the 
+& result is Zero.
      print "\nLo $i=".$lo[$i]."    Hi $i=".$hi[$i]."     $pairs[$i]\n
+";
   }  
   print "(@pairs)\n";
   chomp ($Dummy = <STDIN>);
   join('',@pairs);
}

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        Please try to keep the laughter to a dull roar.
[reply]
[d/l]

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