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/*
* 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., 51 Franklin Street, Fifth Floor, Boston, MA
* 02110-1301, USA.
*/
FILE_LICENCE ( GPL2_OR_LATER );
/**
* @file
*
* I/O buffer padding
*
*/
#include <string.h>
#include <ipxe/iobuf.h>
/**
* Pad I/O buffer
*
* @v iobuf I/O buffer
* @v min_len Minimum length
*
* This function pads and aligns I/O buffers, for devices that
* aren't capable of padding in hardware, or that require specific
* alignment in TX buffers. The packet data will end up aligned to a
* multiple of @c IOB_ALIGN.
*
* @c min_len must not exceed @v IOB_ZLEN.
*/
void iob_pad ( struct io_buffer *iobuf, size_t min_len ) {
void *data;
size_t len;
size_t headroom;
signed int pad_len;
assert ( min_len <= IOB_ZLEN );
/* Move packet data to start of I/O buffer. This will both
* align the data (since I/O buffers are aligned to
* IOB_ALIGN) and give us sufficient space for the
* zero-padding
*/
data = iobuf->data;
len = iob_len ( iobuf );
headroom = iob_headroom ( iobuf );
iob_push ( iobuf, headroom );
memmove ( iobuf->data, data, len );
iob_unput ( iobuf, headroom );
/* Pad to minimum packet length */
pad_len = ( min_len - iob_len ( iobuf ) );
if ( pad_len > 0 )
memset ( iob_put ( iobuf, pad_len ), 0, pad_len );
}
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