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   1  
   2  package IO::Compress::Zlib::Constants ;
   3  
   4  use strict ;
   5  use warnings;
   6  use bytes;
   7  
   8  require Exporter;
   9  
  10  our ($VERSION, @ISA, @EXPORT);
  11  
  12  $VERSION = '2.008';
  13  
  14  @ISA = qw(Exporter);
  15  
  16  @EXPORT= qw(
  17  
  18          ZLIB_HEADER_SIZE
  19          ZLIB_TRAILER_SIZE
  20  
  21          ZLIB_CMF_CM_OFFSET
  22          ZLIB_CMF_CM_BITS
  23          ZLIB_CMF_CM_DEFLATED
  24  
  25          ZLIB_CMF_CINFO_OFFSET
  26          ZLIB_CMF_CINFO_BITS 
  27          ZLIB_CMF_CINFO_MAX
  28  
  29          ZLIB_FLG_FCHECK_OFFSET
  30          ZLIB_FLG_FCHECK_BITS
  31  
  32          ZLIB_FLG_FDICT_OFFSET
  33          ZLIB_FLG_FDICT_BITS
  34  
  35          ZLIB_FLG_LEVEL_OFFSET
  36          ZLIB_FLG_LEVEL_BITS
  37  
  38          ZLIB_FLG_LEVEL_FASTEST
  39          ZLIB_FLG_LEVEL_FAST
  40          ZLIB_FLG_LEVEL_DEFAULT
  41          ZLIB_FLG_LEVEL_SLOWEST
  42  
  43          ZLIB_FDICT_SIZE
  44  
  45          );
  46  
  47  # Constant names derived from RFC1950
  48  
  49  use constant ZLIB_HEADER_SIZE       => 2;
  50  use constant ZLIB_TRAILER_SIZE      => 4;
  51  
  52  use constant ZLIB_CMF_CM_OFFSET     => 0;
  53  use constant ZLIB_CMF_CM_BITS       => 0xF ; # 0b1111
  54  use constant ZLIB_CMF_CM_DEFLATED   => 8;
  55  
  56  use constant ZLIB_CMF_CINFO_OFFSET  => 4;
  57  use constant ZLIB_CMF_CINFO_BITS    => 0xF ; # 0b1111;
  58  use constant ZLIB_CMF_CINFO_MAX     => 7;
  59  
  60  use constant ZLIB_FLG_FCHECK_OFFSET => 0;
  61  use constant ZLIB_FLG_FCHECK_BITS   => 0x1F ; # 0b11111;
  62  
  63  use constant ZLIB_FLG_FDICT_OFFSET  => 5;
  64  use constant ZLIB_FLG_FDICT_BITS    => 0x1 ; # 0b1;
  65  
  66  use constant ZLIB_FLG_LEVEL_OFFSET  => 6;
  67  use constant ZLIB_FLG_LEVEL_BITS    => 0x3 ; # 0b11;
  68  
  69  use constant ZLIB_FLG_LEVEL_FASTEST => 0;
  70  use constant ZLIB_FLG_LEVEL_FAST    => 1;
  71  use constant ZLIB_FLG_LEVEL_DEFAULT => 2;
  72  use constant ZLIB_FLG_LEVEL_SLOWEST => 3;
  73  
  74  use constant ZLIB_FDICT_SIZE        => 4;
  75  
  76  
  77  1;