Atmel Software Framework

lwip-1.3.2/src/include/lwip/pbuf.h File Reference
#include "lwip/opt.h"
#include "lwip/err.h"

Data Structures

struct  pbuf
 

Macros

#define PBUF_FLAG_PUSH   0x01U
 indicates this packet's data should be immediately passed to the application More...
 
#define pbuf_init()
 
#define PBUF_IP_HLEN   20
 
#define PBUF_TRANSPORT_HLEN   20
 

Enumerations

enum  pbuf_layer {
  PBUF_TRANSPORT,
  PBUF_IP,
  PBUF_LINK,
  PBUF_RAW,
  PBUF_TRANSPORT,
  PBUF_IP,
  PBUF_LINK,
  PBUF_RAW,
  PBUF_TRANSPORT,
  PBUF_IP,
  PBUF_LINK,
  PBUF_RAW
}
 
enum  pbuf_type {
  PBUF_RAM,
  PBUF_ROM,
  PBUF_REF,
  PBUF_POOL,
  PBUF_RAM,
  PBUF_ROM,
  PBUF_REF,
  PBUF_POOL,
  PBUF_RAM,
  PBUF_ROM,
  PBUF_REF,
  PBUF_POOL
}
 

Functions

struct pbufpbuf_alloc (pbuf_layer l, u16_t size, pbuf_type type)
 Allocates a pbuf of the given type (possibly a chain for PBUF_POOL type). More...
 
void pbuf_cat (struct pbuf *head, struct pbuf *tail)
 Concatenate two pbufs (each may be a pbuf chain) and take over the caller's reference of the tail pbuf. More...
 
void pbuf_chain (struct pbuf *head, struct pbuf *tail)
 Chain two pbufs (or pbuf chains) together. More...
 
u8_t pbuf_clen (struct pbuf *p)
 Count number of pbufs in a chain. More...
 
struct pbufpbuf_coalesce (struct pbuf *p, pbuf_layer layer)
 Creates a single pbuf out of a queue of pbufs. More...
 
err_t pbuf_copy (struct pbuf *p_to, struct pbuf *p_from)
 Create PBUF_RAM copies of pbufs. More...
 
u16_t pbuf_copy_partial (struct pbuf *p, void *dataptr, u16_t len, u16_t offset)
 Copy (part of) the contents of a packet buffer to an application supplied buffer. More...
 
struct pbufpbuf_dechain (struct pbuf *p)
 Dechains the first pbuf from its succeeding pbufs in the chain. More...
 
u8_t pbuf_free (struct pbuf *p)
 Dereference a pbuf chain or queue and deallocate any no-longer-used pbufs at the head of this chain or queue. More...
 
u8_t pbuf_header (struct pbuf *p, s16_t header_size)
 Adjusts the payload pointer to hide or reveal headers in the payload. More...
 
void pbuf_realloc (struct pbuf *p, u16_t size)
 Shrink a pbuf chain to a desired length. More...
 
void pbuf_ref (struct pbuf *p)
 Increment the reference count of the pbuf. More...
 
void pbuf_ref_chain (struct pbuf *p)
 
err_t pbuf_take (struct pbuf *buf, const void *dataptr, u16_t len)
 Copy application supplied data into a pbuf. More...
 

#define PBUF_FLAG_PUSH   0x01U

indicates this packet's data should be immediately passed to the application

#define pbuf_init ( )
#define PBUF_IP_HLEN   20
#define PBUF_TRANSPORT_HLEN   20

enum pbuf_layer
Enumerator
PBUF_TRANSPORT 
PBUF_IP 
PBUF_LINK 
PBUF_RAW 
PBUF_TRANSPORT 
PBUF_IP 
PBUF_LINK 
PBUF_RAW 
PBUF_TRANSPORT 
PBUF_IP 
PBUF_LINK 
PBUF_RAW 
enum pbuf_type
Enumerator
PBUF_RAM 
PBUF_ROM 
PBUF_REF 
PBUF_POOL 
PBUF_RAM 
PBUF_ROM 
PBUF_REF 
PBUF_POOL 
PBUF_RAM 
PBUF_ROM 
PBUF_REF 
PBUF_POOL 

struct pbuf* pbuf_alloc ( pbuf_layer  layer,
u16_t  length,
pbuf_type  type 
)

Allocates a pbuf of the given type (possibly a chain for PBUF_POOL type).

The actual memory allocated for the pbuf is determined by the layer at which the pbuf is allocated and the requested size (from the size parameter).

Parameters
layerflag to define header size
lengthsize of the pbuf's payload
typethis parameter decides how and where the pbuf should be allocated as follows:
  • PBUF_RAM: buffer memory for pbuf is allocated as one large chunk. This includes protocol headers as well.
  • PBUF_ROM: no buffer memory is allocated for the pbuf, even for protocol headers. Additional headers must be prepended by allocating another pbuf and chain in to the front of the ROM pbuf. It is assumed that the memory used is really similar to ROM in that it is immutable and will not be changed. Memory which is dynamic should generally not be attached to PBUF_ROM pbufs. Use PBUF_REF instead.
  • PBUF_REF: no buffer memory is allocated for the pbuf, even for protocol headers. It is assumed that the pbuf is only being used in a single thread. If the pbuf gets queued, then pbuf_take should be called to copy the buffer.
  • PBUF_POOL: the pbuf is allocated as a pbuf chain, with pbufs from the pbuf pool that is allocated during pbuf_init().
Returns
the allocated pbuf. If multiple pbufs where allocated, this is the first pbuf of a pbuf chain.
void pbuf_cat ( struct pbuf h,
struct pbuf t 
)

Concatenate two pbufs (each may be a pbuf chain) and take over the caller's reference of the tail pbuf.

Note
The caller MAY NOT reference the tail pbuf afterwards. Use pbuf_chain() for that purpose.
See Also
pbuf_chain()
void pbuf_chain ( struct pbuf h,
struct pbuf t 
)

Chain two pbufs (or pbuf chains) together.

The caller MUST call pbuf_free(t) once it has stopped using it. Use pbuf_cat() instead if you no longer use t.

Parameters
hhead pbuf (chain)
ttail pbuf (chain)
Note
The pbufs MUST belong to the same packet.
MAY NOT be called on a packet queue.

The ->tot_len fields of all pbufs of the head chain are adjusted. The ->next field of the last pbuf of the head chain is adjusted. The ->ref field of the first pbuf of the tail chain is adjusted.

u8_t pbuf_clen ( struct pbuf p)

Count number of pbufs in a chain.

Parameters
pfirst pbuf of chain
Returns
the number of pbufs in a chain
struct pbuf* pbuf_coalesce ( struct pbuf p,
pbuf_layer  layer 
)

Creates a single pbuf out of a queue of pbufs.

Remarks
: Either the source pbuf 'p' is freed by this function or the original pbuf 'p' is returned, therefore the caller has to check the result!
Parameters
pthe source pbuf
layerpbuf_layer of the new pbuf
Returns
a new, single pbuf (p->next is NULL) or the old pbuf if allocation fails
Remarks
: The source pbuf 'p' is not freed by this function because that can be illegal in some places!
Parameters
pthe source pbuf
layerpbuf_layer of the new pbuf
Returns
a new, single pbuf (p->next is NULL) or the old pbuf if allocation fails
err_t pbuf_copy ( struct pbuf p_to,
struct pbuf p_from 
)

Create PBUF_RAM copies of pbufs.

Used to queue packets on behalf of the lwIP stack, such as ARP based queueing.

Note
You MUST explicitly use p = pbuf_take(p);
Only one packet is copied, no packet queue!
Parameters
p_topbuf destination of the copy
p_frompbuf source of the copy
Returns
ERR_OK if pbuf was copied ERR_ARG if one of the pbufs is NULL or p_to is not big enough to hold p_from
u16_t pbuf_copy_partial ( struct pbuf buf,
void *  dataptr,
u16_t  len,
u16_t  offset 
)

Copy (part of) the contents of a packet buffer to an application supplied buffer.

Parameters
bufthe pbuf from which to copy data
dataptrthe application supplied buffer
lenlength of data to copy (dataptr must be big enough). No more than buf->tot_len will be copied, irrespective of len
offsetoffset into the packet buffer from where to begin copying len bytes
Returns
the number of bytes copied, or 0 on failure
struct pbuf* pbuf_dechain ( struct pbuf p)

Dechains the first pbuf from its succeeding pbufs in the chain.

Makes p->tot_len field equal to p->len.

Parameters
ppbuf to dechain
Returns
remainder of the pbuf chain, or NULL if it was de-allocated.
Note
May not be called on a packet queue.
u8_t pbuf_free ( struct pbuf p)

Dereference a pbuf chain or queue and deallocate any no-longer-used pbufs at the head of this chain or queue.

Decrements the pbuf reference count. If it reaches zero, the pbuf is deallocated.

For a pbuf chain, this is repeated for each pbuf in the chain, up to the first pbuf which has a non-zero reference count after decrementing. So, when all reference counts are one, the whole chain is free'd.

Parameters
pThe pbuf (chain) to be dereferenced.
Returns
the number of pbufs that were de-allocated from the head of the chain.
Note
MUST NOT be called on a packet queue (Not verified to work yet).
the reference counter of a pbuf equals the number of pointers that refer to the pbuf (or into the pbuf).

examples:

Assuming existing chains a->b->c with the following reference counts, calling pbuf_free(a) results in:

1->2->3 becomes ...1->3 3->3->3 becomes 2->3->3 1->1->2 becomes ......1 2->1->1 becomes 1->1->1 1->1->1 becomes .......

u8_t pbuf_header ( struct pbuf p,
s16_t  header_size_increment 
)

Adjusts the payload pointer to hide or reveal headers in the payload.

Adjusts the ->payload pointer so that space for a header (dis)appears in the pbuf payload.

The ->payload, ->tot_len and ->len fields are adjusted.

Parameters
ppbuf to change the header size.
header_size_incrementNumber of bytes to increment header size which increases the size of the pbuf. New space is on the front. (Using a negative value decreases the header size.) If hdr_size_inc is 0, this function does nothing and returns succesful.

PBUF_ROM and PBUF_REF type buffers cannot have their sizes increased, so the call will fail. A check is made that the increase in header size does not move the payload pointer in front of the start of the buffer.

Returns
non-zero on failure, zero on success.
void pbuf_realloc ( struct pbuf p,
u16_t  new_len 
)

Shrink a pbuf chain to a desired length.

Parameters
ppbuf to shrink.
new_lendesired new length of pbuf chain

Depending on the desired length, the first few pbufs in a chain might be skipped and left unchanged. The new last pbuf in the chain will be resized, and any remaining pbufs will be freed.

Note
If the pbuf is ROM/REF, only the ->tot_len and ->len fields are adjusted.
May not be called on a packet queue.
Despite its name, pbuf_realloc cannot grow the size of a pbuf (chain).
void pbuf_ref ( struct pbuf p)

Increment the reference count of the pbuf.

Parameters
ppbuf to increase reference counter of
void pbuf_ref_chain ( struct pbuf p)
err_t pbuf_take ( struct pbuf buf,
const void *  dataptr,
u16_t  len 
)

Copy application supplied data into a pbuf.

This function can only be used to copy the equivalent of buf->tot_len data.

Parameters
bufpbuf to fill with data
dataptrapplication supplied data buffer
lenlength of the application supplied data buffer
Returns
ERR_OK if successful, ERR_MEM if the pbuf is not big enough