/* $NetBSD: efs_extent.h,v 1.3 2007/07/04 19:24:09 rumble Exp $ */
/*
* Copyright (c) 2006 Stephen M. Rumble <
[email protected]>
*
* Permission to use, copy, modify, and distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
* copyright notice and this permission notice appear in all copies.
*
* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*/
/*
* EFS extent descriptor format and sundry.
*
* See IRIX inode(4)
*/
#ifndef _FS_EFS_EFS_EXTENT_H_
#define _FS_EFS_EFS_EXTENT_H_
/*
* EFS on-disk extent descriptor (8 bytes)
*
* SGI smushed this structure's members into bit fields, but we have to
* be a little more portable. Therefore we use the efs_extent (see below)
* type for in-core manipulation and convert immediately to and from disk.
*/
struct efs_dextent {
union {
uint64_t ex_magic:8, /* magic number (always 0) */
ex_bn:24, /* bb number in filesystem */
ex_length:8, /* length of extent (in bb) */
ex_offset:24; /* logical file offset (in bb) */
uint8_t bytes[8];
uint32_t words[2];
} ex_muddle;
} __packed;
#define ex_bytes ex_muddle.bytes
#define ex_words ex_muddle.words
/*
* In-core, unsquished representation of an extent.
*/
struct efs_extent {
uint8_t ex_magic;
uint32_t ex_bn; /* NB: only 24 bits on disk */
uint8_t ex_length;
uint32_t ex_offset; /* NB: only 24 bits on disk */
};
#define EFS_EXTENT_MAGIC 0
#define EFS_EXTENT_BN_MASK 0x00ffffff
#define EFS_EXTENT_OFFSET_MASK 0x00ffffff
#define EFS_EXTENTS_PER_BB (EFS_BB_SIZE / sizeof(struct efs_dextent))
#endif /* !_FS_EFS_EFS_EXTENT_H_ */
