Default header formatter for digital packet transmission. More...

#include <packet_header_default.h>

Inheritance diagram for gr::digital::packet_header_default:

Public Types
typedef boost::shared_ptr < packet_header_default >	sptr
Public Member Functions
	packet_header_default (long header_len, const std::string &len_tag_key="packet_len", const std::string &num_tag_key="packet_num", int bits_per_byte=1)
	~packet_header_default ()
sptr	base ()
sptr	formatter ()
void	set_header_num (unsigned header_num)
long	header_len ()
pmt::pmt_t	len_tag_key ()
virtual bool	header_formatter (long packet_len, unsigned char *out, const std::vector< gr_tag_t > &tags=std::vector< gr_tag_t >())
	Encodes the header information in the given tags into bits and places them into `out`.
virtual bool	header_parser (const unsigned char *header, std::vector< gr_tag_t > &tags)
	Inverse function to header_formatter().
Static Public Member Functions
static sptr	make (long header_len, const std::string &len_tag_key="packet_len", const std::string &num_tag_key="packet_num", int bits_per_byte=1)
Protected Attributes
long	d_header_len
pmt::pmt_t	d_len_tag_key
pmt::pmt_t	d_num_tag_key
int	d_bits_per_byte
unsigned	d_header_number
unsigned	d_mask

Detailed Description

Default header formatter for digital packet transmission.

For bursty/packetized digital transmission, packets are usually prepended with a packet header, containing the number of bytes etc. This class is not a block, but a tool to create these packet header.

This is a default packet header (see header_formatter()) for a description on the header format). To create other header, derive packet header creator classes from this function.

gr::digital::packet_headergenerator_bb uses header generators derived from this class to create packet headers from data streams.

Member Typedef Documentation

typedef boost::shared_ptr<packet_header_default> gr::digital::packet_header_default::sptr

Reimplemented in gr::digital::packet_header_ofdm.

Constructor & Destructor Documentation

gr::digital::packet_header_default::packet_header_default	(	long	header_len,
		const std::string &	len_tag_key = `"packet_len"`,
		const std::string &	num_tag_key = `"packet_num"`,
		int	bits_per_byte = `1`
	)

gr::digital::packet_header_default::~packet_header_default ( )

Member Function Documentation

sptr gr::digital::packet_header_default::base ( ) [inline]

sptr gr::digital::packet_header_default::formatter ( ) [inline]

virtual bool gr::digital::packet_header_default::header_formatter	(	long	packet_len,
		unsigned char *	out,
		const std::vector< gr_tag_t > &	tags = `std::vector< gr_tag_t >()`
	)		`[virtual]`

Encodes the header information in the given tags into bits and places them into out.

Uses the following header format: Bits 0-11: The packet length (what was stored in the tag with key len_tag_key) Bits 12-27: The header number (counts up everytime this function is called) Bit 28: Even parity bit All other bits: Are set to zero

If the header length is smaller than 29, bits are simply left out. For this reason, they always start with the LSB.

long gr::digital::packet_header_default::header_len ( ) [inline]

virtual bool gr::digital::packet_header_default::header_parser	(	const unsigned char *	header,
		std::vector< gr_tag_t > &	tags
	)		`[virtual]`

Inverse function to header_formatter().

Reads the bit stream in header and writes a corresponding tag into tags.

Reimplemented in gr::digital::packet_header_ofdm.

pmt::pmt_t gr::digital::packet_header_default::len_tag_key ( ) [inline]

static sptr gr::digital::packet_header_default::make	(	long	header_len,
		const std::string &	len_tag_key = `"packet_len"`,
		const std::string &	num_tag_key = `"packet_num"`,
		int	bits_per_byte = `1`
	)		`[static]`