Re: Problems Getting the Template Correct when Using unpack()

[ozboomer]

One thing that may not be clear... is that the '$data' item is not always going to be a string, hence my attempt to use 'C' in the template.

For some values of the '$rec_type_idx', the '$data' item may contain text (as in the original example) but it can be actual binary data (including NULs) that needs further decoding.

[BillKSmith]

Your specification of C33 returns a list of 33 unsigned numbers. You need an array to hold them. Another option is to use the array, but fill it with a list of characters ( use (a)33 ).

C:\Users\Bill\forums\monks>type ozboomer.pl
use strict;
use warnings;

my @data = ( 0x2E, 0x75, 0x0A, 0x04, 0x00, 0x00, 0x00, 0x10, 0x57, 0x5
+6,
             0x32, 0x20, 0x20, 0x20, 0x80, 0x49, 0x3D, 0x34, 0x32, 0x3
+7,
             0x20, 0x4C, 0x61, 0x6D, 0x70, 0x20, 0x64, 0x69, 0x6D, 0x2
+0,
             0x73, 0x74, 0x61, 0x74, 0x65, 0x3D, 0x32, 0x20, 0x5B, 0x5
+3,
             0x43, 0x41, 0x54, 0x53, 0x3D, 0x30, 0x5D, 0x2E );


my @formats = (  "C8a6C33C1",  "C8A6(A)33C1" );

my $inbuf = join('', map { chr($_) } @data);  # Input buffer


printf("\$inbuf: >%s<\n", $inbuf);
printf("\n");

foreach my $fmt (@formats) {
   my $tmpbuf = $inbuf;  # In case something's being corrupted
   my ($event_len, $tail_len);
   my ($year, $mon, $day);
   my ($hour, $min, $sec);
   my $rec_type_idx;
   my $source_name;
   my @data;

   ($event_len, $year, $mon, $day, $hour, $min, $sec,
       $rec_type_idx, $source_name, @data[0..32], $tail_len) = unpack(
+$fmt, $tmp
buf);

   my $date_str = sprintf("%s/%s/%s", $day, $mon, $year+1900);
   my $time_str = sprintf("%02d:%02d:%02d", $hour, $min, $sec);
      $rec_type_idx &= 0x1F;      # Only use b0-b6

   printf("        Format: %s\n", $fmt);
   printf("   \$event_len: %02Xx = %d\n", $event_len, $event_len);
   printf("    \$date_str: %s\n", $date_str);
   printf("    \$time_str: %s\n", $time_str);
   printf("\$rec_type_idx: %02Xx = %d\n", $rec_type_idx, $rec_type_idx
+);
   printf(" \$source_name: !%s!\n", $source_name);
   printf("        \$data: !%s!\n", join(' ', @data));
   printf("    \$tail_len: %02Xx = %d\n", $tail_len, $tail_len);
   printf("\n");

}


C:\Users\Bill\forums\monks>perl ozboomer.pl
$inbuf: >.u
&#9830;   &#9658;WV2   ÇI=427 Lamp dim state=2 [SCATS=0].<

        Format: C8a6C33C1
   $event_len: 2Ex = 46
    $date_str: 4/10/2017
    $time_str: 00:00:00
$rec_type_idx: 10x = 16
 $source_name: !WV2   !
        $data: !128 73 61 52 50 55 32 76 97 109 112 32 100 105 109 32 
[phone]
 116 101 61 50 32 91 83 67 65 84 83 61 48 93!
    $tail_len: 2Ex = 46

        Format: C8A6(A)33C1
   $event_len: 2Ex = 46
    $date_str: 4/10/2017
    $time_str: 00:00:00
$rec_type_idx: 10x = 16
 $source_name: !WV2!
        $data: !Ç I = 4 2 7  L a m p  d i m  s t a t e = 2  [ S C A T 
+S = 0 ]!
    $tail_len: 2Ex = 46

I recommend that you do return $data as a string (use a33). Yes, you do need additional processing, but string processing is what perl does best.