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/* Window management routines for buffered I/O using VM.
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 __WINDOW_H__
#define __WINDOW_H__
#include <mach.h>
/* ---------------------------------------------------------------- */
/* A structure describing a memory window used to do buffered random access
device i/o through the device pager. */
struct window
{
/* The currently allocated vm window backed by the device pager. */
vm_address_t buffer;
/* The device offset of the window. */
vm_offset_t location;
/* The length of the window (should be a multiple of __vm_page_size). If
this is 0, this window isn't allocated. */
vm_size_t size;
/* If SIZE < MIN_SIZE we won't shrink the window. */
vm_size_t min_size;
/* If SIZE > MAX_SIZE, we'll try and shrink the window to fit. */
vm_size_t max_size;
/* The device pager providing backing store for this window. */
mach_port_t memobj;
/* True if the mapping should be read_only. */
int read_only;
/* Lock this if you want to read/write some field(s) here. */
struct mutex lock;
};
/* Create a VM window onto the memory object MEMOBJ, and return it in WIN.
MIN_SIZE and MAX_SIZE are the minimum and maximum sizes that the window
will shrink/grow to. */
error_t window_create(mach_port_t memobj,
vm_size_t min_size, vm_size_t max_size, int read_only,
struct window **win);
/* Free WIN and any resources it holds. */
void window_free(struct window *win);
/* Write up to BUF_LEN bytes from BUF to the device that WIN is a window on,
at offset *OFFS, using memory-mapped buffered I/O. If successful, 0 is
returned, otherwise an error code is returned. *OFFS is incremented by
the amount sucessfully written. */
error_t window_write(struct window *win,
vm_address_t buf, vm_size_t buf_len, vm_size_t *amount,
vm_offset_t *offs);
/* Read up to AMOUNT bytes from the device that WIN is a window on, at offset
*OFFS, into BUF and BUF_LEN (using the standard mach out-array
conventions), using memory-mapped buffered I/O. If successful, 0 is
returned, otherwise an error code is returned. *OFFS is incremented by
the amount sucessfully written. */
error_t window_read(struct window *win,
vm_address_t *buf, vm_size_t *buf_len,
vm_size_t amount, vm_offset_t *offs);
#endif /* !__WINDOW_H__ */
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