class Fifo_mode

Class Fifo_mode that determines the mode of a fifo from the user's point of view.

Public Methods

constructors

Setting attributes of the Fifo_mode

Fifo::sFifo_mode getStructure()

To get the C structure sFifo_mode from the class Fifo_mode.

int checkValues()

Checks the values.

Documentation

Class Fifo_mode that determines the mode of a fifo from the user's point of view. Internally to the DD system it hides the details of the structure sFifo_mode from the user.

The reason for having Fifo_mode and the above mentioned structure sFifo_mode (defined in fifo.h) is that we do want to give the user all the advantages of a class, but we also want to have the fifos (which reside in shared memory) in the simplest possible form, hence the use of a structure.

The Fifo_mode has the following options:

• Fill_mode: Determines how the fifo is being filled, i.e.
  fill_all: every event is put into this fifo,
  fill_onreq: an event is only put into this fifo if a process is waiting for such an event
  fill_reqcnt: Put the event into the fifo if the count of the fifo is below the request count (see below)
  fill_prescaled: Put the event into the fifo if it is properly prescaled

• filter: Determines whether we filter the events according to the control words
  filter_on: filter is on,
  filter_off: no filter (i.e. no event selection)

• eWait: wait mode that determines what happens when a process is trying to read an empty fifo,
  sleep_mode: process falls asleep and wakes up when an event arrives
  async_mode: process returns with an error status

• iPrescale: integer that determines the prescale factor of the fifo

• iReqcnt: integer that determines the request count (i.e. an event is always put into this fifo if it has fewer than iReqcnt events in it).

• eSuser: Single user mode:
  multi_user: several processes are allowed to read from this fifo
  single_user: only one process is allowed to read from the fifo

• fctl: control words that determine the filter (see the section on the event distribution for details).

Modifications:

constructors

Fifo_mode( Fifo::eFifo_fill_mode eFill_mode = Fifo::fill_all, Fifo::eFifo_filter eFilter = Fifo::filter_off, Fifo::eFifo_wait_mode eWait = Fifo::sleep_mode, int iPrescale = -1, int iReqcnt = -1, Fifo::eFifo_user_mode user = Fifo::multi_user, Fifo_entry::fifo_ctl fctl = defaultCtl )

Constructor in which all arguments are specified and the default values are given. The arguments are defined in fifo.h, a description is given above.

Fifo_mode( const struct Fifo::sFifo_mode sMode )

Constructor with the fifo internal struture sFifo_mode.

Setting attributes of the Fifo_mode

inline void setFillMode( Fifo::eFifo_fill_mode mode )

To set the fill mode. This determines when an event is put into the fifo.

inline void setFilter( Fifo::eFifo_filter filter )

To set the filter (ie. enable/disable the selection of events based on the control words).

Parameters:

- filter = filter_on, filter_off

inline void setWaitMode( Fifo::eFifo_wait_mode mode )

To set the wait mode.

Parameters:

mode - = sleep_mode or async_mode

inline void setPrescale( int ps )

To set the prescale

inline void setReqCount( int rc )

To set the request count

inline void setSingleUserMode( Fifo::eFifo_user_mode user_mode )

To set single or multiple user mode.

Parameters:

user_mode - : multi_user or single_user

inline void setCtl( Fifo_entry::fifo_ctl ctl )

To set the control words with the fifo_ctl structure fifo_ctl has 4 members (iCtlw1, iCtlb1, iCtlw2, iCtlb2)

void setCtl( int w1=-1, int b1=-1, int w2=-1, int b2=-1 )

To set the control words individually

Fifo::sFifo_mode getStructure()

To get the C structure sFifo_mode from the class Fifo_mode. This should only be used for ease of conversion back and forth between the C structure and the C++ class. From the user's point of view there should only be a class Fifo_mode, i.e. he should not really use the structure itself.

int checkValues()

Checks the values. All private members are checked, whether they have a valid value. If not, the default is taken.

Returns:

: ddcSuccess if all values ok, ddcFailure otherwise

This class has no child classes.

Friends:

ostream& operator<<( ostream &os, Fifo_mode mode )

Author:

C.Witzig
Date: Nov 17, 1998

Version:

Last update: Nov 17, 1998

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