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Device::Modem::Protocol::Xmodem.3pm

NAME

Device::Modem::Protocol::Xmodem

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