Initial sketch for the generic data-transfer interface.
This commit is contained in:
Michael Brown
parent
95206577a7
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/*
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* Copyright (C) 2007 Michael Brown <mbrown@fensystems.co.uk>.
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License as
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* published by the Free Software Foundation; either version 2 of the
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* License, or any later version.
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*
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* This program is distributed in the hope that it will be useful, but
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* WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
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*/
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#include <assert.h>
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#include <gpxe/interface.h>
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/** @file
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*
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* Object communication interfaces
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*
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*/
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/**
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* Obtain reference to interface
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*
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* @v intf Interface
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* @ret intf Interface
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*
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* Increases the reference count on the interface.
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*/
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static struct interface * intf_get ( struct interface *intf ) {
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intf->refcnt ( intf, +1 );
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return intf;
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}
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/**
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* Drop reference to interface
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*
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* @v intf Interface
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*
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* Decreases the reference count on the interface.
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*/
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static void intf_put ( struct interface *intf ) {
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intf->refcnt ( intf, -1 );
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}
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/**
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* Plug an interface into a new destination interface
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*
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* @v intf Interface
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* @v dest New destination interface
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*
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* The reference to the existing destination interface is dropped, a
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* reference to the new destination interface is obtained, and the
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* interface is updated to point to the new destination interface.
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*
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* Note that there is no "unplug" call; instead you must plug the
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* interface into a null interface.
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*/
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void plug ( struct interface *intf, struct interface *dest ) {
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intf_put ( intf->dest );
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intf->dest = intf_get ( dest );
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}
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/**
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* Null update reference count
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*
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* @v intf Interface
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* @v delta Change to apply to reference count
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*
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* Use this as the refcnt() method for an interface that does not need
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* to support reference counting.
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*/
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void null_refcnt ( struct interface *intf __unused, int delta __unused ) {
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/* Do nothing */
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}
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@ -0,0 +1,74 @@
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/*
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* Copyright (C) 2007 Michael Brown <mbrown@fensystems.co.uk>.
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License as
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* published by the Free Software Foundation; either version 2 of the
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* License, or any later version.
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*
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* This program is distributed in the hope that it will be useful, but
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* WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
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*/
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#include <errno.h>
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#include <gpxe/xfer.h>
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/** @file
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*
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* Data transfer interfaces
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*
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*/
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/**
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* Deliver datagram
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*
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* @v xfer Data-transfer interface
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* @v iobuf Datagram I/O buffer
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* @ret rc Return status code
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*/
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int deliver ( struct xfer_interface *xfer, struct io_buffer *iobuf ) {
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struct xfer_interface *dest = xfer_dest ( xfer );
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return dest->op->deliver ( dest, xfer, iobuf );
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}
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/**
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* Null deliver datagram
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*
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* @v xfer Data-transfer interface
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* @v src Source interface
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* @v iobuf Datagram I/O buffer
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* @ret rc Return status code
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*/
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static int null_deliver ( struct xfer_interface *xfer __unused,
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struct xfer_interface *src __unused,
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struct io_buffer *iobuf ) {
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free_iob ( iobuf );
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return -EPIPE;
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}
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/** Null data transfer interface operations */
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struct xfer_interface_operations null_xfer_ops = {
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.deliver = null_deliver,
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};
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/**
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* Null data transfer interface
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*
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* This is the interface to which data transfer interfaces are
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* connected when unplugged. It will never generate messages, and
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* will silently absorb all received messages.
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*/
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struct xfer_interface null_xfer = {
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.intf = {
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.dest = &null_xfer.intf,
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.refcnt = null_refcnt,
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},
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.op = &null_xfer_ops,
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};
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#ifndef _GPXE_INTERFACE_H
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#define _GPXE_INTERFACE_H
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/** @file
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*
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* Object communication interfaces
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*
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*/
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/** An object communication interface */
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struct interface {
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/** Destination interface
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*
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* When messages are sent via this interface, they will be
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* delivered to the destination interface.
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*
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* This pointer may never be NULL. When the interface is
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* unplugged, it should point to a null interface.
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*/
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struct interface *dest;
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/** Update reference count
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*
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* @v intf Interface
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* @v delta Change to apply to reference count
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*
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* This method updates the reference count for the object
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* containing the interface.
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*/
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void ( * refcnt ) ( struct interface *intf, int delta );
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};
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extern void plug ( struct interface *intf, struct interface *dest );
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extern void null_refcnt ( struct interface *intf, int delta );
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#endif /* _GPXE_INTERFACE_H */
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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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#ifndef _GPXE_XFER_H
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#define _GPXE_XFER_H
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/** @file
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*
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* Data transfer interfaces
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*
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*/
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#include <stddef.h>
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#include <gpxe/interface.h>
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#include <gpxe/iobuf.h>
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struct xfer_interface;
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/** Data transfer interface operations */
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struct xfer_interface_operations {
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/** Deliver datagram
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*
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* @v xfer Data-transfer interface
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* @v src Source interface
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* @v iobuf Datagram I/O buffer
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* @ret rc Return status code
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*/
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int ( * deliver ) ( struct xfer_interface *xfer,
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struct xfer_interface *src,
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struct io_buffer *iobuf );
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};
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/** A data transfer interface */
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struct xfer_interface {
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/** Generic object communication interface */
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struct interface intf;
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/** Operations for received messages */
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struct xfer_interface_operations *op;
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};
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extern struct xfer_interface null_xfer;
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extern struct xfer_interface_operations null_xfer_ops;
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static inline struct xfer_interface *
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xfer_dest ( struct xfer_interface *xfer ) {
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return container_of ( xfer->intf.dest, struct xfer_interface, intf );
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}
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/**
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* Plug a data-transfer interface into a new destination interface
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*
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* @v xfer Data-transfer interface
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* @v dest New destination interface
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*/
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static inline void xfer_plug ( struct xfer_interface *xfer,
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struct xfer_interface *dest ) {
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plug ( &xfer->intf, &dest->intf );
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}
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/**
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* Unplug a data-transfer interface
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*
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* @v xfer Data-transfer interface
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*/
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static inline void xfer_unplug ( struct xfer_interface *xfer ) {
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plug ( &xfer->intf, &null_xfer.intf );
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}
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/**
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* Terminate a data-transfer interface
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*
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* @v xfer Data-transfer interface
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*
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* After calling this method, no further messages will be received via
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* the interface.
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*/
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static inline void xfer_terminate ( struct xfer_interface *xfer ) {
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xfer->op = &null_xfer_ops;
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};
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#endif /* _GPXE_XFER_H */
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