Buffers - System Buffer Pool

Topics
	Buffer Ownership States
	Buffer State Flags

Classes
struct	pool_buffer
	Main buffer structure for network and serial communication. More...
class	buffer_list
	Doubly-linked list management for buffers. More...
class	fifo_buffer_storage
	FIFO buffer storage using linked pool buffers. More...
class	SMPoolPtr
	Smart pointer wrapper for automatic buffer management. More...

Functions
PoolPtr	GetBuffer ()
	Allocate a software buffer for general use.
PoolPtr	GetFastBuffer ()
	Allocate a software buffer, preferring the fast memory pool.
void	FreeBuffer (PoolPtr nbuf)
	Free a buffer and return it to the unused pool.
void	FreeBufferList (PoolPtr nbuf)
	Free a linked list of buffers.
void	IncUsageCount (PoolPtr pp)
	Increment the usage count of a buffer.
uint16_t	GetFreeCount ()
	Returns the number of free buffers in the system. Buffers are used for both serial and network interfaces.
void	InitBuffers ()
	Initialize the buffer system.
void	ShowBuffer (PoolPtr p)
	Display buffer contents and state information.

Detailed Description

#include< buffers.h>


Functions associated with the buffers allocated for use by network interfaces and serial ports. If a system runs out of buffers it will no longer be able to send or receive network data.

Function Documentation

FreeBuffer()

void FreeBuffer

(

PoolPtr

nbuf

)

#include <buffers.h>

Free a buffer and return it to the unused pool.

Decrements the buffer's usage count and returns it to the free pool when the count reaches zero. This allows safe sharing of buffers between multiple system components.

Parameters

nbuf	Buffer to free

See also

GetBuffer(), IncUsageCount()

FreeBufferList()

void FreeBufferList

(

PoolPtr

nbuf

)

#include <buffers.h>

Free a linked list of buffers.

Frees a chain of buffers linked by their pNextFifo_El pointers. Each buffer in the list will be returned to the unused pool.

Parameters

nbuf	First buffer in the linked list to free

See also

FreeBuffer()

GetBuffer()

PoolPtr GetBuffer

(

)

#include <buffers.h>

Allocate a software buffer for general use.

Allocates a buffer from the system buffer pool for use by application software. The buffer will be marked with ownership state BO_SOFTWARE.

Returns

Pointer to allocated buffer, or NULL if no buffers available

See also

FreeBuffer(), GetFastBuffer()

GetFastBuffer()

PoolPtr GetFastBuffer

(

)

#include <buffers.h>

Allocate a software buffer, preferring the fast memory pool.

Similar to GetBuffer(), but attempts to allocate from the fast buffer pool first before falling back to the standard pool. Fast buffers may provide better performance for time-critical operations.

Returns

Pointer to allocated buffer, or NULL if no buffers available

See also

GetBuffer(), FreeBuffer()

GetFreeCount()

uint16_t GetFreeCount

(

)

#include <buffers.h>

Returns the number of free buffers in the system. Buffers are used for both serial and network interfaces.

This function returns the number of free pool buffers, which are used for network and serial communication. The maximum number of buffers is defined in \nburn\nbrtos\include\constants.h:

#define BUFFER_POOL_SIZE (128) 

The size of each buffer is defined as:

#define ETHER_BUFFER_SIZE 1548 

If the number of free buffers reaches zero, then no further network communication will be possible until some buffers are freed. This is a good function to use as a debug tool for detecting buffer leaks in your application.

Serial ports also use buffers, which are allocated in constants.h:

#define SERIAL_TX_BUFFERS (2)
#define SERIAL_RX_BUFFERS (2)

Each serial port buffer is equal in size to an Ethernet buffer.

Returns

The number of free buffers in the system.

IncUsageCount()

void IncUsageCount

(

PoolPtr

pp

)

#include <buffers.h>

Increment the usage count of a buffer.

Increases the reference count for shared buffer usage. The buffer will not be freed until FreeBuffer() is called once for each reference (usage count reaches zero).

Parameters

pp	Buffer to increment usage count

See also

FreeBuffer()

InitBuffers()

void InitBuffers

(

)

#include <buffers.h>

Initialize the buffer system.

Sets up the buffer pools and free lists. This function is called during system initialization and should not be called by application code.

See also

GetFreeCount()

ShowBuffer()

void ShowBuffer

(

PoolPtr

p

)

#include <buffers.h>

Display buffer contents and state information.

Prints detailed information about a buffer including its state, size, and data contents to stdout. Useful for debugging.

Parameters

p	Buffer to display