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/* State for an I/O stream.
Copyright (C) 1995 Free Software Foundation, Inc.
Written by Miles Bader <miles@gnu.ai.mit.edu>
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, or (at
your option) 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. */
#ifndef __IOSTATE_H__
#define __IOSTATE_H__
/* ---------------------------------------------------------------- */
enum io_state_buffer_use
{
/* 0 means nothing */
IO_STATE_BUFFERED_WRITE = 1, IO_STATE_BUFFERED_READ = 2
};
struct io_state {
/* What we think the current position is. */
vm_offset_t location;
/* The buffer in which we accumulate buffered i/o. */
vm_address_t buffer;
/* The size of BUFFER. */
vm_size_t buffer_size;
/* If LOCATION is not a multiple of the block size (and so points somewhere
in the middle of BUFFER), this indicates why. */
enum io_state_buffer_use buffer_use;
/* Lock this if you want to read/modify LOCATION or BUFFER. */
struct mutex lock;
};
#define io_state_lock(ios) mutex_lock(&(ios)->lock)
#define io_state_unlock(ios) mutex_unlock(&(ios)->lock)
/* Declare this to keep the parameter scope below sane. */
struct dev;
/* Initialize the io_state structure IOS to be used with the device DEV. If
a memory allocation error occurs, ENOMEM is returned, otherwise 0. */
error_t io_state_init(struct io_state *ios, struct dev *dev);
/* Frees all resources used by IOS. */
void io_state_finalize(struct io_state *ios);
/* If IOS's location isn't block aligned because writes have been buffered
there, then sync the whole buffer out to the device. Any error that
occurs while writing is returned, otherwise 0. */
error_t io_state_sync(struct io_state *ios, struct dev *dev);
#endif /* !__IOSTATE_H__ */
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