NAME

       Device::Modem::Protocol::Xmodem - XModem protocol implementation

Xmodem::Block

       Class that represents a single Xmodem data block.

   Synopsis
               my $b = Xmodem::Block->new( 1, 'My Data...<until-128-chars>...' );
               if( defined $b ) {
                       # Ok, block instanced, verify its checksum
                       if( $b->verify( 'checksum', <my_chksum> ) ) {
                               ...
                       } else {
                               ...
                       }
               } else {
                       # No block
               }

               # Calculate checksum, crc16, 32, ...
               $crc16 = $b->crc16();
               $crc32 = $b->crc32();
               $chksm = $b->checksum();

Xmodem::Buffer

       Class that implements an Xmodem receive buffer of data blocks. Every block of data is
       represented by a "Xmodem::Block" object.

       Blocks can be pushed and popped from the buffer. You can retrieve the last block, or the
       list of blocks from buffer.

   Synopsis
               my $buf = Xmodem::Buffer->new();
               my $b1  = Xmodem::Block->new(1, 'Data...');

               $buf->push($b1);

               my $b2  = Xmodem::Block->new(2, 'More data...');
               $buf->push($b2);

               my $last_block = $buf->last();

               print 'now I have ', scalar($buf->blocks()), ' in the buffer';

               # TODO document replace() function ???

Xmodem::Constants

       Package that contains all useful Xmodem protocol constants used in handshaking and data
       blocks encoding procedures

   Synopsis
               Xmodem::Constants::soh ........... 'start of header'
               Xmodem::Constants::eot ........... 'end of trasmission'
               Xmodem::Constants::ack ........... 'acknowlegded'
               Xmodem::Constants::nak ........... 'not acknowledged'
               Xmodem::Constants::can ........... 'cancel'
               Xmodem::Constants::C   ........... `C' ASCII char

               Xmodem::Constants::XMODEM ........ basic xmodem protocol
               Xmodem::Constants::XMODEM_1K ..... xmodem protocol with 1k blocks
               Xmodem::Constants::XMODEM_CRC .... xmodem protocol with CRC checks

               Xmodem::Constants::CHECKSUM ...... type of block checksum
               Xmodem::Constants::CRC16 ......... type of block crc16
               Xmodem::Constants::CRC32 ......... type of block crc32

Xmodem::Receiver

       Control class to initiate and complete a "X-modem" file transfer in receive mode

   Synopsis
               my $recv = Xmodem::Receiver->new(
                       modem    => {Device::Modem object},
                       filename => 'name of file',
                       XXX protocol => 'xmodem' | 'xmodem-crc', | 'xmodem-1k'
               );

               $recv->run();

   Object methods
       abort_transfer()
           Sends a cancel char ("can"), that signals to sender that transfer is aborted. This is
           issued if we receive a bad block number, which usually means we got a bad line.

       modem()
           Returns the underlying Device::Modem object.

       receive_message()
           Retreives message from modem and if a block is detected it breaks it into appropriate
           parts.

       run()
           Starts a new transfer until file receive is complete. The only parameter accepted is
           the (optional) local filename to be written.

       send_ack()
           Sends an acknowledge ("ack") char, to signal that we received and stored a correct
           block Resets count of timeouts and returns the "Xmodem::Block" object of the data
           block received.

       send_timeout()
           Sends a timeout ("nak") char, to signal that we received a bad block header (either a
           bad start char or a bad block number), or a bad data checksum. Increments count of
           timeouts and at ten timeouts, aborts transfer.

   See also
       - Device::Modem