class Fifo

class Fifo_entry

Class Fifo_entry: Fifo_entries are the objects that the DD fifos contain and they represent the data in the data buffer.

Public Methods
constructors
Fifo_entry& deepCopy( const Fifo_entry &fev ): Deep copy member function.
inline BOOL is_valid() const: Returns true if there is a valid data in the Fifo_entry.
inline BOOL is_volatile() const: Returns true if the data buffer is volatile
inline BOOL is_broadcast() const: Returns true if the Fifo_entry is a broadcast event
void print( ostream &os = cout ) const: Prints the content of the Fifo_entry to the output stream os
accessor member functions
Member functions that set the internal data members.

Documentation

Class Fifo_entry: Fifo_entries are the objects that the DD fifos contain and they represent the data in the data buffer.
The DD works by passing Fifo_entries between independent processes. These Fifo_entries contain all the necessary information about the actual event, which is encapsulated in the class DataBuffer Db.
There are two types of Fifo_entries, which differ by the values of certain private data members: Fifo_entries that represent data buffers from the default DD event pool and Fifo_entries that represent volatile buffers (i.e. buffers that are allocated on the fly).
A Fifo_entry is fully characterized by the following values (see documentation of the private data members for details):

bValid: Boolean, is true once a Fifo_entry is associated with a valid data buffer.
iShmid: Identifier of the shared memory.
iDboff: offset to the data within the shared memory.
pData: Pointer to the actual data.
iLen: Length of the data in words (int).
sCtl: control structure that gives the characteristics of the event in the data buffer that the Fifo_entry represents.

Modifications:

constructors

Fifo_entry(int shmid, int dboff, int* p2da, int len, Fifo_entry::fifo_ctl ctl)
Constructor in which all arguments are specified.
Parameters:
shmid - identifier of the shared memory, -1 if the Fifo_entry is part of the DB pool, >0 if it is a volatile buffer
dboff - offset in the DB pool, -1 if volatile buffer
p2da - Pointer to the data
len - Length of the data buffer
ctl - structure fifo_ctl that gives the snapshot of the event

Fifo_entry(int shmid, int dboff, int* p2da, int len)
Constructor in which all arguments are specified but not the control words

Fifo_entry()
Default constructor which creates an unused Fifo_entry

~Fifo_entry()
Destructor

Fifo_entry& deepCopy( const Fifo_entry &fev )

Deep copy member function. For the (default) Fifo_entry( Fifo_entry& ) we use the default memberwise copy and for deepCopy we actually copy the Db data from one fev into another one.

inline BOOL is_valid() const

Returns true if there is a valid data in the Fifo_entry. If the Fifo_entry is created using the contructor Fifo_entry(), then we create an empty Fifo_entry, containing no valid data. In this case is_valid returns false until the Fifo_entry is filled.

inline BOOL is_volatile() const

Returns true if the data buffer is volatile

inline BOOL is_broadcast() const

Returns true if the Fifo_entry is a broadcast event

void print( ostream &os = cout ) const

Prints the content of the Fifo_entry to the output stream os

accessor member functions inline int get_shmid() const Return the identifier of the shared memory associated with this fifo_entry inline int get_dboff() const Return the data offset (with respect to the beginning of the shared memory. -1 for volatile buffers. inline int* get_pData() const Return the address where the data resides inline int get_len() const Return the length of the data. The length is the maximum length of the data buffer as long as there is no actual data associated with the Fifo_entry. Once the event is copied into the data buffer it is the length of the data itself (i.e. a number smaller than the length of the databuffer). inline int get_ctlw1() const Returns the first control word inline int get_ctlb1() const Returns the first (bitwise) control word inline int get_ctlw2() const Returns the second control word inline int get_ctlb2() const Returns the second (bitwise) control word inline fifo_ctl get_ctl() const Returns the entire control structure

Member functions that set the internal data members.

Note that not all the data members can be set.

void set_pdata( int* pInt )

Adjusts the pointer to the data. The address location where a process finds the data differs between processes as the shared memory can be attached at different addresses.

inline void set_len( const int new_len )

Sets the length of valid data in the data buffer that belongs to the Fifo_entry

inline void set_ctlw1( int iWord )

sets the first control word w1 of the fifo entry

inline void set_ctlb1( int iWord )

sets the first control bit-word b1 of the fifo entry

inline void set_ctlw2( int iWord )

sets the second control word w2 of the fifo entry

inline void set_ctlb2( int iWord )

sets the second control bit-word w2 of the fifo entry

inline void set_ctl( fifo_ctl new_ctl )

Sets the fifo control words

This class has no child classes.


Author:: C.Witzig
Date: Jan 11, 1998
Version:: Last update: Jan 11, 1998

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class Fifo_entry

Public Methods

Documentation