Initial sketch for the generic data-transfer interface.

diff --git a/src/core/interface.c b/src/core/interface.c
new file mode 100644 (file)
index 0000000..15df49d
--- /dev/null
+++ b/src/core/interface.c
@@ -0,0 +1,81 @@
+/*
+ * Copyright (C) 2007 Michael Brown <mbrown@fensystems.co.uk>.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 of the
+ * License, or any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+ */
+
+#include <assert.h>
+#include <gpxe/interface.h>
+
+/** @file
+ *
+ * Object communication interfaces
+ *
+ */
+
+/**
+ * Obtain reference to interface
+ *
+ * @v intf             Interface
+ * @ret intf           Interface
+ *
+ * Increases the reference count on the interface.
+ */
+static struct interface * intf_get ( struct interface *intf ) {
+       intf->refcnt ( intf, +1 );
+       return intf;
+}
+
+/**
+ * Drop reference to interface
+ *
+ * @v intf             Interface
+ *
+ * Decreases the reference count on the interface.
+ */
+static void intf_put ( struct interface *intf ) {
+       intf->refcnt ( intf, -1 );
+}
+
+/**
+ * Plug an interface into a new destination interface
+ *
+ * @v intf             Interface
+ * @v dest             New destination interface
+ *
+ * The reference to the existing destination interface is dropped, a
+ * reference to the new destination interface is obtained, and the
+ * interface is updated to point to the new destination interface.
+ *
+ * Note that there is no "unplug" call; instead you must plug the
+ * interface into a null interface.
+ */
+void plug ( struct interface *intf, struct interface *dest ) {
+       intf_put ( intf->dest );
+       intf->dest = intf_get ( dest );
+}
+
+/**
+ * Null update reference count
+ *
+ * @v intf             Interface
+ * @v delta            Change to apply to reference count
+ *
+ * Use this as the refcnt() method for an interface that does not need
+ * to support reference counting.
+ */
+void null_refcnt ( struct interface *intf __unused, int delta __unused ) {
+       /* Do nothing */
+}

diff --git a/src/core/xfer.c b/src/core/xfer.c
new file mode 100644 (file)
index 0000000..d08b3b8
--- /dev/null
+++ b/src/core/xfer.c
@@ -0,0 +1,74 @@
+/*
+ * Copyright (C) 2007 Michael Brown <mbrown@fensystems.co.uk>.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 of the
+ * License, or any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+ */
+
+#include <errno.h>
+#include <gpxe/xfer.h>
+
+/** @file
+ *
+ * Data transfer interfaces
+ *
+ */
+
+/**
+ * Deliver datagram
+ *
+ * @v xfer             Data-transfer interface
+ * @v iobuf            Datagram I/O buffer
+ * @ret rc             Return status code
+ */
+int deliver ( struct xfer_interface *xfer, struct io_buffer *iobuf ) {
+       struct xfer_interface *dest = xfer_dest ( xfer );
+
+       return dest->op->deliver ( dest, xfer, iobuf );
+}
+
+/**
+ * Null deliver datagram
+ *
+ * @v xfer             Data-transfer interface
+ * @v src              Source interface
+ * @v iobuf            Datagram I/O buffer
+ * @ret rc             Return status code
+ */
+static int null_deliver ( struct xfer_interface *xfer __unused,
+                         struct xfer_interface *src __unused,
+                         struct io_buffer *iobuf ) {
+       free_iob ( iobuf );
+       return -EPIPE;
+}
+
+/** Null data transfer interface operations */
+struct xfer_interface_operations null_xfer_ops = {
+       .deliver = null_deliver,
+};
+
+/**
+ * Null data transfer interface
+ *
+ * This is the interface to which data transfer interfaces are
+ * connected when unplugged.  It will never generate messages, and
+ * will silently absorb all received messages.
+ */
+struct xfer_interface null_xfer = {
+       .intf = {
+               .dest = &null_xfer.intf,
+               .refcnt = null_refcnt,
+       },
+       .op = &null_xfer_ops,
+};

diff --git a/src/include/gpxe/interface.h b/src/include/gpxe/interface.h
new file mode 100644 (file)
index 0000000..38e6272
--- /dev/null
+++ b/src/include/gpxe/interface.h
@@ -0,0 +1,36 @@
+#ifndef _GPXE_INTERFACE_H
+#define _GPXE_INTERFACE_H
+
+/** @file
+ *
+ * Object communication interfaces
+ *
+ */
+
+/** An object communication interface */
+struct interface {
+       /** Destination interface
+        *
+        * When messages are sent via this interface, they will be
+        * delivered to the destination interface.
+        *
+        * This pointer may never be NULL.  When the interface is
+        * unplugged, it should point to a null interface.
+        */
+       struct interface *dest;
+       /** Update reference count
+        *
+        * @v intf              Interface
+        * @v delta             Change to apply to reference count
+        *
+        * This method updates the reference count for the object
+        * containing the interface.
+        */
+       void ( * refcnt ) ( struct interface *intf, int delta );
+};
+
+extern void plug ( struct interface *intf, struct interface *dest );
+
+extern void null_refcnt ( struct interface *intf, int delta );
+
+#endif /* _GPXE_INTERFACE_H */

diff --git a/src/include/gpxe/iobuf.h b/src/include/gpxe/iobuf.h
new file mode 100644 (file)
index 0000000..cf99050
--- /dev/null
+++ b/src/include/gpxe/iobuf.h
@@ -0,0 +1,148 @@
+#ifndef _GPXE_IOBUF_H
+#define _GPXE_IOBUF_H
+
+/** @file
+ *
+ * I/O buffers
+ *
+ */
+
+#include <stdint.h>
+#include <assert.h>
+#include <gpxe/list.h>
+
+/**
+ * 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 iob      I/O buffer
+ * @v len      Length to reserve
+ * @ret data   Pointer to new start of buffer
+ */
+static inline void * iob_reserve ( struct io_buffer *iob, size_t len ) {
+       iob->data += len;
+       iob->tail += len;
+       assert ( iob->tail <= iob->end );
+       return iob->data;
+}
+
+/**
+ * Add data to start of I/O buffer
+ *
+ * @v iob      I/O buffer
+ * @v len      Length to add
+ * @ret data   Pointer to new start of buffer
+ */
+static inline void * iob_push ( struct io_buffer *iob, size_t len ) {
+       iob->data -= len;
+       assert ( iob->data >= iob->head );
+       return iob->data;
+}
+
+/**
+ * Remove data from start of I/O buffer
+ *
+ * @v iob      I/O buffer
+ * @v len      Length to remove
+ * @ret data   Pointer to new start of buffer
+ */
+static inline void * iob_pull ( struct io_buffer *iob, size_t len ) {
+       iob->data += len;
+       assert ( iob->data <= iob->tail );
+       return iob->data;
+}
+
+/**
+ * Add data to end of I/O buffer
+ *
+ * @v iob      I/O buffer
+ * @v len      Length to add
+ * @ret data   Pointer to newly added space
+ */
+static inline void * iob_put ( struct io_buffer *iob, size_t len ) {
+       void *old_tail = iob->tail;
+       iob->tail += len;
+       assert ( iob->tail <= iob->end );
+       return old_tail;
+}
+
+/**
+ * Remove data from end of I/O buffer
+ *
+ * @v iob      I/O buffer
+ * @v len      Length to remove
+ */
+static inline void iob_unput ( struct io_buffer *iob, size_t len ) {
+       iob->tail -= len;
+       assert ( iob->tail >= iob->data );
+}
+
+/**
+ * Empty an I/O buffer
+ *
+ * @v iob      I/O buffer
+ */
+static inline void iob_empty ( struct io_buffer *iob ) {
+       iob->tail = iob->data;
+}
+
+/**
+ * Calculate length of data in an I/O buffer
+ *
+ * @v iob      I/O buffer
+ * @ret len    Length of data in buffer
+ */
+static inline size_t iob_len ( struct io_buffer *iob ) {
+       return ( iob->tail - iob->data );
+}
+
+/**
+ * Calculate available space at start of an I/O buffer
+ *
+ * @v iob      I/O buffer
+ * @ret len    Length of data available at start of buffer
+ */
+static inline size_t iob_headroom ( struct io_buffer *iob ) {
+       return ( iob->data - iob->head );
+}
+
+/**
+ * Calculate available space at end of an I/O buffer
+ *
+ * @v iob      I/O buffer
+ * @ret len    Length of data available at end of buffer
+ */
+static inline size_t iob_tailroom ( struct io_buffer *iob ) {
+       return ( iob->end - iob->tail );
+}
+
+extern struct io_buffer * alloc_iob ( size_t len );
+extern void free_iob ( struct io_buffer *iob );
+extern void iob_pad ( struct io_buffer *iob, size_t min_len );
+
+#endif /* _GPXE_IOBUF_H */

diff --git a/src/include/gpxe/xfer.h b/src/include/gpxe/xfer.h
new file mode 100644 (file)
index 0000000..0e577e9
--- /dev/null
+++ b/src/include/gpxe/xfer.h
@@ -0,0 +1,78 @@
+#ifndef _GPXE_XFER_H
+#define _GPXE_XFER_H
+
+/** @file
+ *
+ * Data transfer interfaces
+ *
+ */
+
+#include <stddef.h>
+#include <gpxe/interface.h>
+#include <gpxe/iobuf.h>
+
+struct xfer_interface;
+
+/** Data transfer interface operations */
+struct xfer_interface_operations {
+       /** Deliver datagram
+        *
+        * @v xfer              Data-transfer interface
+        * @v src               Source  interface
+        * @v iobuf             Datagram I/O buffer
+        * @ret rc              Return status code
+        */
+       int ( * deliver ) ( struct xfer_interface *xfer,
+                           struct xfer_interface *src,
+                           struct io_buffer *iobuf );
+};
+
+/** A data transfer interface */
+struct xfer_interface {
+       /** Generic object communication interface */
+       struct interface intf;
+       /** Operations for received messages */
+       struct xfer_interface_operations *op;
+};
+
+extern struct xfer_interface null_xfer;
+extern struct xfer_interface_operations null_xfer_ops;
+
+static inline struct xfer_interface *
+xfer_dest ( struct xfer_interface *xfer ) {
+       return container_of ( xfer->intf.dest, struct xfer_interface, intf );
+}
+
+/**
+ * Plug a data-transfer interface into a new destination interface
+ *
+ * @v xfer             Data-transfer interface
+ * @v dest             New destination interface
+ */
+static inline void xfer_plug ( struct xfer_interface *xfer,
+                              struct xfer_interface *dest ) {
+       plug ( &xfer->intf, &dest->intf );
+}
+
+/**
+ * Unplug a data-transfer interface
+ *
+ * @v xfer             Data-transfer interface
+ */
+static inline void xfer_unplug ( struct xfer_interface *xfer ) {
+       plug ( &xfer->intf, &null_xfer.intf );
+}
+
+/**
+ * Terminate a data-transfer interface
+ *
+ * @v xfer             Data-transfer interface
+ *
+ * After calling this method, no further messages will be received via
+ * the interface.
+ */
+static inline void xfer_terminate ( struct xfer_interface *xfer ) {
+       xfer->op = &null_xfer_ops;
+};
+
+#endif /* _GPXE_XFER_H */