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- #ifndef _GPXE_IOBUF_H
- #define _GPXE_IOBUF_H
-
- /** @file
- *
- * I/O buffers
- *
- */
-
- #include <stdint.h>
- #include <assert.h>
- #include <gpxe/list.h>
-
- /**
- * I/O buffer alignment
- *
- * I/O buffers allocated via alloc_iob() 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 IOB_ALIGN 2048
-
- /**
- * Minimum I/O buffer length
- *
- * alloc_iob() 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 IOB_ZLEN 64
-
- /**
- * A persistent I/O buffer
- *
- * This data structure encapsulates a long-lived I/O buffer. The
- * buffer may be passed between multiple owners, queued for possible
- * retransmission, etc.
- */
- struct io_buffer {
- /** List of which this buffer is a member
- *
- * The list must belong to the current owner of the buffer.
- * Different owners may maintain different lists (e.g. a
- * retransmission list for TCP).
- */
- 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 I/O buffer
- *
- * @v iobuf I/O buffer
- * @v len Length to reserve
- * @ret data Pointer to new start of buffer
- */
- static inline void * iob_reserve ( struct io_buffer *iobuf, size_t len ) {
- iobuf->data += len;
- iobuf->tail += len;
- return iobuf->data;
- }
- #define iob_reserve( iobuf, len ) ( { \
- void *__result; \
- __result = iob_reserve ( (iobuf), (len) ); \
- assert ( (iobuf)->tail <= (iobuf)->end ); \
- __result; } )
-
- /**
- * Add data to start of I/O buffer
- *
- * @v iobuf I/O buffer
- * @v len Length to add
- * @ret data Pointer to new start of buffer
- */
- static inline void * iob_push ( struct io_buffer *iobuf, size_t len ) {
- iobuf->data -= len;
- return iobuf->data;
- }
- #define iob_push( iobuf, len ) ( { \
- void *__result; \
- __result = iob_push ( (iobuf), (len) ); \
- assert ( (iobuf)->data >= (iobuf)->head ); \
- __result; } )
-
- /**
- * Remove data from start of I/O buffer
- *
- * @v iobuf I/O buffer
- * @v len Length to remove
- * @ret data Pointer to new start of buffer
- */
- static inline void * iob_pull ( struct io_buffer *iobuf, size_t len ) {
- iobuf->data += len;
- assert ( iobuf->data <= iobuf->tail );
- return iobuf->data;
- }
- #define iob_pull( iobuf, len ) ( { \
- void *__result; \
- __result = iob_pull ( (iobuf), (len) ); \
- assert ( (iobuf)->data <= (iobuf)->tail ); \
- __result; } )
-
- /**
- * Add data to end of I/O buffer
- *
- * @v iobuf I/O buffer
- * @v len Length to add
- * @ret data Pointer to newly added space
- */
- static inline void * iob_put ( struct io_buffer *iobuf, size_t len ) {
- void *old_tail = iobuf->tail;
- iobuf->tail += len;
- return old_tail;
- }
- #define iob_put( iobuf, len ) ( { \
- void *__result; \
- __result = iob_put ( (iobuf), (len) ); \
- assert ( (iobuf)->tail <= (iobuf)->end ); \
- __result; } )
-
- /**
- * Remove data from end of I/O buffer
- *
- * @v iobuf I/O buffer
- * @v len Length to remove
- */
- static inline void iob_unput ( struct io_buffer *iobuf, size_t len ) {
- iobuf->tail -= len;
- }
- #define iob_unput( iobuf, len ) do { \
- iob_unput ( (iobuf), (len) ); \
- assert ( (iobuf)->tail >= (iobuf)->data ); \
- } while ( 0 )
-
- /**
- * Empty an I/O buffer
- *
- * @v iobuf I/O buffer
- */
- static inline void iob_empty ( struct io_buffer *iobuf ) {
- iobuf->tail = iobuf->data;
- }
-
- /**
- * Calculate length of data in an I/O buffer
- *
- * @v iobuf I/O buffer
- * @ret len Length of data in buffer
- */
- static inline size_t iob_len ( struct io_buffer *iobuf ) {
- return ( iobuf->tail - iobuf->data );
- }
-
- /**
- * Calculate available space at start of an I/O buffer
- *
- * @v iobuf I/O buffer
- * @ret len Length of data available at start of buffer
- */
- static inline size_t iob_headroom ( struct io_buffer *iobuf ) {
- return ( iobuf->data - iobuf->head );
- }
-
- /**
- * Calculate available space at end of an I/O buffer
- *
- * @v iobuf I/O buffer
- * @ret len Length of data available at end of buffer
- */
- static inline size_t iob_tailroom ( struct io_buffer *iobuf ) {
- return ( iobuf->end - iobuf->tail );
- }
-
- extern struct io_buffer * __malloc alloc_iob ( size_t len );
- extern void free_iob ( struct io_buffer *iobuf );
- extern void iob_pad ( struct io_buffer *iobuf, size_t min_len );
- extern int iob_ensure_headroom ( struct io_buffer *iobuf, size_t len );
-
- #endif /* _GPXE_IOBUF_H */
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