flags - How to decode hex into separate bits in Perl? -

a byte stored 2 hex numbers contains set of flags. need extract these flags, 0's , 1's. iterating on entries in file with:

foreach(<>) { @line = split(/ /,$_);  $torr = !!((hex $line[4]) & 0x3);  # bit 0 or 1 $tory = !!((hex $line[4]) & 0x4);  # bit 2 $torg = !!((hex $line[4]) & 0x8);  # bit 3  print "$torr,$tory,$torg\n"; } 

run on data file:

796.129 [1f/01] len:7<  02 01 d5 01 8b 0a 8e 796.224 [1f/01] len:7<  02 01 d4 03 09 a9 b8 796.320 [1f/01] len:7<  00 01 d4 03 07 49 5a 796.415 [1f/01] len:7<  00 01 d4 00 11 a0 ee 796.515 [1f/01] len:7<  00 01 d4 00 00 31 4c 796.627 [1f/01] len:7<  02 01 d4 01 89 c1 fd 796.724 [1f/01] len:7<  02 01 d3 03 06 39 fd 796.820 [1f/01] len:7<  08 01 d4 03 08 40 6f 796.915 [1f/01] len:7<  08 01 d5 00 13 3d a4 797.015 [1f/01] len:7<  08 01 d4 00 00 34 04 

actual result -

1,, 1,, ,, ,, ,, 1,, 1,, ,,1 ,,1 ,,1 

desired result:

1,0,0 1,0,0 0,0,0 0,0,0 0,0,0 1,0,0 1,0,0 0,0,1 0,0,1 0,0,1 

seems 'false' gets stored empty string instead of '0'.

is there neat trick right @ once, or need convert empty strings zeros "manually"?

if want true/false values numeric, need coerce them numeric:

$torr = 0 + !!((hex $line[4]) & 0x3);  # bit 0 or 1 $tory = 0 + !!((hex $line[4]) & 0x4);  # bit 2 $torg = 0 + !!((hex $line[4]) & 0x8);  # bit 3 

keep in mind empty string '' false value.

on other hand, might inclined write as:

my (@ryg) = map 0 + !!((hex $line[4]) & $_), 0x3, 0x4, 0x5; print join(', ', @ryg), "\n"; 

in addition, benefit not using plain numbers in program. consider, example, having %flag structure gives names these constants, , %col structure gives names columns interested in. using data posted:

use const::fast;  const %flag => (     torr => 0x3,     tory => 0x4,     torg => 0x5, );  const %col => (     # ...     tor => 4, );  while (my $line = <data>) {     @line = split ' ', $line;     %set_flags = map +($_ => 0 + !!((hex $line[$col{tor}]) & $flag{$_})), qw(torr tory torg);     print join(', ', @set_flags{qw(torr tory torg)}), "\n"; }  __data__ 796.129 [1f/01] len:7<  02 01 d5 01 8b 0a 8e 796.224 [1f/01] len:7<  02 01 d4 03 09 a9 b8 796.320 [1f/01] len:7<  00 01 d4 03 07 49 5a 796.415 [1f/01] len:7<  00 01 d4 00 11 a0 ee 796.515 [1f/01] len:7<  00 01 d4 00 00 31 4c 796.627 [1f/01] len:7<  02 01 d4 01 89 c1 fd 796.724 [1f/01] len:7<  02 01 d3 03 06 39 fd 796.820 [1f/01] len:7<  08 01 d4 03 08 40 6f 796.915 [1f/01] len:7<  08 01 d5 00 13 3d a4 797.015 [1f/01] len:7<  08 01 d4 00 00 34 04