2 * Copyright (C) 2007 Michael Brown <mbrown@fensystems.co.uk>.
4 * This program is free software; you can redistribute it and/or
5 * modify it under the terms of the GNU General Public License as
6 * published by the Free Software Foundation; either version 2 of the
7 * License, or any later version.
9 * This program is distributed in the hope that it will be useful, but
10 * WITHOUT ANY WARRANTY; without even the implied warranty of
11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
12 * General Public License for more details.
14 * You should have received a copy of the GNU General Public License
15 * along with this program; if not, write to the Free Software
16 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
19 * You can also choose to distribute this program under the terms of
20 * the Unmodified Binary Distribution Licence (as given in the file
21 * COPYING.UBDL), provided that you have satisfied its requirements.
24 FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
34 #include <ipxe/iobuf.h>
40 * @v min_len Minimum length
42 * This function pads and aligns I/O buffers, for devices that
43 * aren't capable of padding in hardware, or that require specific
44 * alignment in TX buffers. The packet data will end up aligned to a
45 * multiple of @c IOB_ALIGN.
47 * @c min_len must not exceed @v IOB_ZLEN.
49 void iob_pad ( struct io_buffer *iobuf, size_t min_len ) {
55 assert ( min_len <= IOB_ZLEN );
57 /* Move packet data to start of I/O buffer. This will both
58 * align the data (since I/O buffers are aligned to
59 * IOB_ALIGN) and give us sufficient space for the
63 len = iob_len ( iobuf );
64 headroom = iob_headroom ( iobuf );
65 iob_push ( iobuf, headroom );
66 memmove ( iobuf->data, data, len );
67 iob_unput ( iobuf, headroom );
69 /* Pad to minimum packet length */
70 pad_len = ( min_len - iob_len ( iobuf ) );
72 memset ( iob_put ( iobuf, pad_len ), 0, pad_len );