- my $c1 = ( ord(substr($card,$pos+0x37,1)) & 0xf0 ) >> 4;
- my $c2 = ( ord(substr($card,$pos+0x38,1)) & 0x0f );
- my $c3 = ( ord(substr($card,$pos+0x38,1)) & 0xf0 ) >> 4;
+ my $trailer_pos = $pos + $blocks * 0x10 - 0x10;
+ my $c1 = ( ord(substr($card,$trailer_pos+7,1)) & 0xf0 ) >> 4;
+ my $c2 = ( ord(substr($card,$trailer_pos+8,1)) & 0x0f );
+ my $c3 = ( ord(substr($card,$trailer_pos+8,1)) & 0xf0 ) >> 4;
+
+ printf "# trailer @%x c1:%d c2:%d c3:%d [%16b]\n"
+ , $trailer_pos, $c1, $c2, $c3
+ , unpack('n',(substr($card,$trailer_pos+7,2)))
+ ;