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/*
* 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.
*/
FILE_LICENCE ( GPL2_OR_LATER );
#include <stdint.h>
#include <strings.h>
#include <errno.h>
#include <ipxe/malloc.h>
#include <ipxe/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;
size_t align;
void *data;
/* Pad to minimum length */
if ( len < IOB_ZLEN )
len = IOB_ZLEN;
/* Align buffer length to ensure that struct io_buffer is aligned */
len = ( len + __alignof__ ( *iobuf ) - 1 ) &
~( __alignof__ ( *iobuf ) - 1 );
/* Align buffer on its own size to avoid potential problems
* with boundary-crossing DMA.
*/
align = ( 1 << fls ( len - 1 ) );
/* Allocate buffer plus descriptor as a single unit, unless
* doing so will push the total size over the alignment
* boundary.
*/
if ( ( len + sizeof ( *iobuf ) ) <= align ) {
/* Allocate memory for buffer plus descriptor */
data = malloc_dma ( len + sizeof ( *iobuf ), align );
if ( ! data )
return NULL;
iobuf = ( data + len );
} else {
/* Allocate memory for buffer */
data = malloc_dma ( len, align );
if ( ! data )
return NULL;
/* Allocate memory for descriptor */
iobuf = malloc ( sizeof ( *iobuf ) );
if ( ! iobuf ) {
free_dma ( data, len );
return NULL;
}
}
/* Populate descriptor */
iobuf->head = iobuf->data = iobuf->tail = data;
iobuf->end = ( data + len );
return iobuf;
}
/**
* Free I/O buffer
*
* @v iobuf I/O buffer
*/
void free_iob ( struct io_buffer *iobuf ) {
size_t len;
/* Allow free_iob(NULL) to be valid */
if ( ! iobuf )
return;
/* Sanity checks */
assert ( iobuf->head <= iobuf->data );
assert ( iobuf->data <= iobuf->tail );
assert ( iobuf->tail <= iobuf->end );
/* Free buffer */
len = ( iobuf->end - iobuf->head );
if ( iobuf->end == iobuf ) {
/* Descriptor is inline */
free_dma ( iobuf->head, ( len + sizeof ( *iobuf ) ) );
} else {
/* Descriptor is detached */
free_dma ( iobuf->head, len );
free ( iobuf );
}
}
/**
* Ensure I/O buffer has sufficient headroom
*
* @v iobuf I/O buffer
* @v len Required headroom
*
* This function currently only checks for the required headroom; it
* does not reallocate the I/O buffer if required. If we ever have a
* code path that requires this functionality, it's a fairly trivial
* change to make.
*/
int iob_ensure_headroom ( struct io_buffer *iobuf, size_t len ) {
if ( iob_headroom ( iobuf ) >= len )
return 0;
return -ENOBUFS;
}
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