Add alloc_iob() and free_iob(). (Direct search-and-replace

equivalents for alloc_pkb() and free_pkb(), which will be retired in
due course).

src/core/iobuf.c

@@ -0,0 +1,74 @@
+/*
+ * Copyright (C) 2006 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 <stdint.h>
+#include <gpxe/malloc.h>
+#include <gpxe/iobuf.h>
+
+/** @file
+ *
+ * I/O buffers
+ *
+ */
+
+/**
+ * Allocate I/O buffer
+ *
+ * @v len	Required length of buffer
+ * @ret iobuf	I/O buffer, or NULL if none available
+ *
+ * The I/O buffer will be physically aligned to a multiple of
+ * @c IOBUF_SIZE.
+ */
+struct io_buffer * alloc_iob ( size_t len ) {
+	struct io_buffer *iobuf = NULL;
+	void *data;
+
+	/* Pad to minimum length */
+	if ( len < IOB_ZLEN )
+		len = IOB_ZLEN;
+
+	/* Align buffer length */
+	len = ( len + __alignof__( *iobuf ) - 1 ) &
+		~( __alignof__( *iobuf ) - 1 );
+	
+	/* Allocate memory for buffer plus descriptor */
+	data = malloc_dma ( len + sizeof ( *iobuf ), IOB_ALIGN );
+	if ( ! data )
+		return NULL;
+
+	iobuf = ( struct io_buffer * ) ( data + len );
+	iobuf->head = iobuf->data = iobuf->tail = data;
+	iobuf->end = iobuf;
+	return iobuf;
+}
+
+/**
+ * Free I/O buffer
+ *
+ * @v iobuf	I/O buffer
+ */
+void free_iob ( struct io_buffer *iobuf ) {
+	if ( iobuf ) {
+		assert ( iobuf->head <= iobuf->data );
+		assert ( iobuf->data <= iobuf->tail );
+		assert ( iobuf->tail <= iobuf->end );
+		free_dma ( iobuf->head,
+			   ( iobuf->end - iobuf->head ) + sizeof ( *iobuf ) );
+	}
+}