bsd/hfs/hfs_endian.h

   1 /*
   2  * Copyright (c) 2000 Apple Computer, Inc. All rights reserved.
   3  *
   4  * @APPLE_LICENSE_HEADER_START@
   5  *
   6  * This file contains Original Code and/or Modifications of Original Code
   7  * as defined in and that are subject to the Apple Public Source License
   8  * Version 2.0 (the 'License'). You may not use this file except in
   9  * compliance with the License. Please obtain a copy of the License at
  10  * http://www.opensource.apple.com/apsl/ and read it before using this
  11  * file.
  12  *
  13  * The Original Code and all software distributed under the License are
  14  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  15  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  16  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  17  * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
  18  * Please see the License for the specific language governing rights and
  19  * limitations under the License.
  20  *
  21  * @APPLE_LICENSE_HEADER_END@
  22  */
  23 #ifndef __HFS_ENDIAN_H__
  24 #define __HFS_ENDIAN_H__
  25
  26 #include <sys/appleapiopts.h>
  27
  28 #ifdef KERNEL
  29 #ifdef __APPLE_API_PRIVATE
  30 /*
  31  * hfs_endian.h
  32  *
  33  * This file prototypes endian swapping routines for the HFS/HFS Plus
  34  * volume format.
  35  */
  36 #include "hfs.h"
  37 #include "hfscommon/headers/BTreesInternal.h"
  38 #include <architecture/byte_order.h>
  39
  40 /*********************/
  41 /* BIG ENDIAN Macros */
  42 /*********************/
  43 #if BYTE_ORDER == BIG_ENDIAN
  44
  45     /* HFS is always big endian, make swaps into no-ops */
  46     #define SWAP_BE16(__a) (__a)
  47     #define SWAP_BE32(__a) (__a)
  48     #define SWAP_BE64(__a) (__a)
  49
  50     /* HFS is always big endian, no swapping needed */
  51     #define SWAP_HFS_PLUS_FORK_DATA(__a)
  52
  53 /************************/
  54 /* LITTLE ENDIAN Macros */
  55 /************************/
  56 #elif BYTE_ORDER == LITTLE_ENDIAN
  57
  58     /* HFS is always big endian, make swaps actually swap */
  59     #define SWAP_BE16(__a)                                                      NXSwapBigShortToHost (__a)
  60     #define SWAP_BE32(__a)                                                      NXSwapBigLongToHost (__a)
  61     #define SWAP_BE64(__a)                                                      NXSwapBigLongLongToHost (__a)
  62
  63     #define SWAP_HFS_PLUS_FORK_DATA(__a)                        hfs_swap_HFSPlusForkData ((__a))
  64
  65 #else
  66 #warning Unknown byte order
  67 #error
  68 #endif
  69
  70 #ifdef __cplusplus
  71 extern "C" {
  72 #endif
  73
  74 /*
  75  * Constants for the "unswap" argument to hfs_swap_BTNode:
  76  */
  77 enum HFSBTSwapDirection {
  78         kSwapBTNodeBigToHost            =       0,
  79         kSwapBTNodeHostToBig            =       1,
  80
  81         /*
  82          * kSwapBTNodeHeaderRecordOnly is used to swap just the header record
  83          * of a header node from big endian (on disk) to host endian (in memory).
  84          * It does not swap the node descriptor (forward/backward links, record
  85          * count, etc.).  It assumes the header record is at offset 0x000E.
  86          *
  87          * Since HFS Plus doesn't have fixed B-tree node sizes, we have to read
  88          * the header record to determine the actual node size for that tree
  89          * before we can set up the B-tree control block.  We read it initially
  90          * as 512 bytes, then re-read it once we know the correct node size.  Since
  91          * we may not have read the entire header node the first time, we can't
  92          * swap the record offsets, other records, or do most sanity checks.
  93          */
  94         kSwapBTNodeHeaderRecordOnly     =       3
  95 };
  96
  97 int  hfs_swap_BTNode (BlockDescriptor *src, vnode_t vp, enum HFSBTSwapDirection direction);
  98
  99 #ifdef __cplusplus
 100 }
 101 #endif
 102
 103 #endif /* __APPLE_API_PRIVATE */
 104 #endif /* KERNEL */
 105 #endif /* __HFS_FORMAT__ */