CCirBufBase Class Reference

#include <e32base.h>

Link against: euser_v5.lib

class CCirBufBase : public CBase

Inherits from

CCirBufBase
- CBase

Protected Attributes
TInt	iCount
TUint8 *	iHead
TInt	iLength
TUint8 *	iPtr
TUint8 *	iPtrE
TInt	iSize
TUint8 *	iTail

Public Member Functions
	~CCirBufBase()
TInt	Count()
TInt	Length()
IMPORT_C void	Reset()
IMPORT_C void	SetLengthL(TInt)

Protected Member Functions
	CCirBufBase(TInt)
IMPORT_C TInt	DoAdd(const TUint8 *)
IMPORT_C TInt	DoAdd(const TUint8 *, TInt)
IMPORT_C TInt	DoRemove(TUint8 *)
IMPORT_C TInt	DoRemove(TUint8 *, TInt)

Inherited Functions
	CBase::CBase()
	CBase::Delete(CBase *)
	CBase::Extension_(TUint,TAny &,TAny )
	CBase::operator new(TUint)
	CBase::operator new(TUint,TAny *)
	CBase::operator new(TUint,TLeave)
	CBase::operator new(TUint,TLeave,TUint)
	CBase::operator new(TUint,TUint)
	CBase::~CBase()

Detailed Description

Base class for circular buffers.

The class is part of the implementation of circular buffers and is never instantiated.

The class provides member functions that form part of the interface.

Member Attribute Documentation

iCount

TInt

iCount

[protected]

iHead

TUint8 *

iHead

[protected]

iLength

TInt

iLength

[protected]

iPtr

TUint8 *

iPtr

[protected]

iPtrE

TUint8 *

iPtrE

[protected]

iSize

TInt

iSize

[protected]

iTail

TUint8 *

iTail

[protected]

Constructor & Destructor Documentation

CCirBufBase ( TInt )

IMPORT_C

CCirBufBase

(

TInt

aSize

)

[protected]

Constructor taking the size of an object within the buffer.

Parameters
aSize	The size of an object in the buffer.

Panic Codes
E32USER-CBase	72, if aSize is zero or negative.

~CCirBufBase ( )

IMPORT_C

~CCirBufBase

(

)

Destructor.

This frees the memory allocated to the buffer.

Member Function Documentation

Count ( )

TInt

Count

(

)

const [inline]

Gets the current number of objects in this circular buffer.

Return Value: The number of objects in this circular buffer. This value can never be greater than the maximum capacity.

DoAdd ( const TUint8 * )

IMPORT_C TInt

DoAdd

(

const TUint8 *

aPtr

)

[protected]

Implementation function for CCirBuf::Add(const T*)

Adds a single object to the circular buffer, but only if there is space available.

Parameters
aPtr	A pointer to the object to be added.

Return Value: 1 if the object is successfully added. 0 if the object cannot be added because the circular buffer is full.

Panic Codes
E32USER-CBase	74, if a call to

DoAdd ( const TUint8 *, TInt )

IMPORT_C TInt	DoAdd	(	const TUint8 *	aPtr,
			TInt	aCount
		)	[protected]

Implementation function for CCirBuf::Add(const T*,TInt)

Adds multiple objects to the circular buffer, but only if there is space available.

Parameters
aPtr	A pointer to a set of contiguous objects to be added.
aCount	The number of objects to be added.

Return Value: The number of objects successfully added to the buffer. This value may be less than the number requested and can range from 0 to aCount.

Panic Codes
E32USER-CBase	74, if a call to
E32USER-CBase	75, if aCount is not a positive value.

DoRemove ( TUint8 * )

IMPORT_C TInt

DoRemove

(

TUint8 *

aPtr

)

[protected]

Implementation function for CCirBuf::Remove(T*)

Removes a single object from the circular buffer, but only if there are objects in the buffer.

A binary copy of the object is made to aPtr.

Parameters
aPtr	A pointer to a location supplied by the caller.

DoRemove ( TUint8 *, TInt )

IMPORT_C TInt	DoRemove	(	TUint8 *	aPtr,
			TInt	aCount
		)	[protected]

Implementation function for CCirBuf::Remove(T*,TInt)

Attempts to remove aCount objects from the circular buffer, but only if there are objects in the buffer.

A binary copy of the objects is made to aPtr.

Parameters
aPtr	A pointer to a location supplied by the caller capable of holding aCount objects.
aCount	The number of objects to be removed from the circular buffer.

Panic Codes
E32USER-CBase	76, if aCount is not a positive value.

Length ( )

TInt

Length

(

)

const [inline]

Gets the maximum capacity of this circular buffer.

The capacity is the maximum number of elements that the buffer can hold.

Use SetLengthL() to change the capacity of the circular buffer.

Reset ( )

IMPORT_C void

Reset

(

)

Empties the buffer.

SetLengthL ( TInt )

IMPORT_C void

SetLengthL

(

TInt

aLength

)

Sets the maximum capacity of this circular buffer, and resets all of the buffer pointers.

The capacity is the maximum number of elements that the buffer can hold.

The buffer itself is allocated as a result of a call to this function. If the function has previously been called, then any existing buffer is freed and any information in it is lost.

Notes:

1. This function must be called before attempting to add any objects to the buffer.

2. The function can leave if there is insufficient memory available to allocate the buffer.

Parameters
aLength	The maximum capacity of the circular buffer.

Panic Codes
E32USER-CBase	73, if aLength is zero or negative.