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#ifndef _GPXE_PKBUFF_H
#define _GPXE_PKBUFF_H
/** @file
*
* Packet buffers
*
* Packet buffers are used to contain network packets. Methods are
* provided for appending, prepending, etc. data.
*
*/
#include <stdint.h>
#include <assert.h>
#include <gpxe/list.h>
/**
* Packet buffer alignment
*
* Packet buffers allocated via alloc_pkb() are guaranteed to be
* physically aligned to this boundary. Some cards cannot DMA across
* a 4kB boundary. With a standard Ethernet MTU, aligning to a 2kB
* boundary is sufficient to guarantee no 4kB boundary crossings. For
* a jumbo Ethernet MTU, a packet may be larger than 4kB anyway.
*/
#define PKBUFF_ALIGN 2048
/**
* Minimum packet buffer length
*
* alloc_pkb() will round up the allocated length to this size if
* necessary. This is used on behalf of hardware that is not capable
* of auto-padding.
*/
#define PKB_ZLEN 64
/** A packet buffer
*
* This structure is used to represent a network packet within gPXE.
*/
struct pk_buff {
/** List of which this buffer is a member */
struct list_head list;
/** Start of the buffer */
void *head;
/** Start of data */
void *data;
/** End of data */
void *tail;
/** End of the buffer */
void *end;
};
/**
* Reserve space at start of packet buffer
*
* @v pkb Packet buffer
* @v len Length to reserve
* @ret data Pointer to new start of buffer
*/
static inline void * pkb_reserve ( struct pk_buff *pkb, size_t len ) {
pkb->data += len;
pkb->tail += len;
assert ( pkb->tail <= pkb->end );
return pkb->data;
}
/**
* Add data to start of packet buffer
*
* @v pkb Packet buffer
* @v len Length to add
* @ret data Pointer to new start of buffer
*/
static inline void * pkb_push ( struct pk_buff *pkb, size_t len ) {
pkb->data -= len;
assert ( pkb->data >= pkb->head );
return pkb->data;
}
/**
* Remove data from start of packet buffer
*
* @v pkb Packet buffer
* @v len Length to remove
* @ret data Pointer to new start of buffer
*/
static inline void * pkb_pull ( struct pk_buff *pkb, size_t len ) {
pkb->data += len;
assert ( pkb->data <= pkb->tail );
return pkb->data;
}
/**
* Add data to end of packet buffer
*
* @v pkb Packet buffer
* @v len Length to add
* @ret data Pointer to newly added space
*/
static inline void * pkb_put ( struct pk_buff *pkb, size_t len ) {
void *old_tail = pkb->tail;
pkb->tail += len;
assert ( pkb->tail <= pkb->end );
return old_tail;
}
/**
* Remove data from end of packet buffer
*
* @v pkb Packet buffer
* @v len Length to remove
*/
static inline void pkb_unput ( struct pk_buff *pkb, size_t len ) {
pkb->tail -= len;
assert ( pkb->tail >= pkb->data );
}
/**
* Empty a packet buffer
*
* @v pkb Packet buffer
*/
static inline void pkb_empty ( struct pk_buff *pkb ) {
pkb->tail = pkb->data;
}
/**
* Calculate length of data in a packet buffer
*
* @v pkb Packet buffer
* @ret len Length of data in buffer
*/
static inline size_t pkb_len ( struct pk_buff *pkb ) {
return ( pkb->tail - pkb->data );
}
/**
* Calculate available space in a packet buffer
*
* @v pkb Packet buffer
* @ret len Length of data available in buffer
*/
static inline size_t pkb_available ( struct pk_buff *pkb ) {
return ( pkb->end - pkb->tail );
}
extern struct pk_buff * alloc_pkb ( size_t len );
extern void free_pkb ( struct pk_buff *pkb );
#endif /* _GPXE_PKBUFF_H */
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