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