linux-imx

/*

 *  linux/fs/hfs/extent.c

 *

 * Copyright (C) 1995-1997  Paul H. Hargrove

 * (C) 2003 Ardis Technologies <roman@ardistech.com>

 * This file may be distributed under the terms of the GNU General Public License.

 *

 * This file contains the functions related to the extents B-tree.

 */

​

#include <linux/pagemap.h>

​

#include "hfs_fs.h"

#include "btree.h"

​

/*================ File-local functions ================*/

​

/*

 * build_key

 */

static void hfs_ext_build_key(hfs_btree_key *key, u32 cnid, u16 block, u8 type)

{

    key->key_len = 7;

    key->ext.FkType = type;

    key->ext.FNum = cpu_to_be32(cnid);

    key->ext.FABN = cpu_to_be16(block);

}

​

/*

 * hfs_ext_compare()

 *

 * Description:

 *   This is the comparison function used for the extents B-tree.  In

 *   comparing extent B-tree entries, the file id is the most

 *   significant field (compared as unsigned ints); the fork type is

 *   the second most significant field (compared as unsigned chars);

 *   and the allocation block number field is the least significant

 *   (compared as unsigned ints).

 * Input Variable(s):

 *   struct hfs_ext_key *key1: pointer to the first key to compare

 *   struct hfs_ext_key *key2: pointer to the second key to compare

 * Output Variable(s):

 *   NONE

 * Returns:

 *   int: negative if key1<key2, positive if key1>key2, and 0 if key1==key2

 * Preconditions:

 *   key1 and key2 point to "valid" (struct hfs_ext_key)s.

 * Postconditions:

 *   This function has no side-effects */

int hfs_ext_keycmp(const btree_key *key1, const btree_key *key2)

{

    __be32 fnum1, fnum2;

    __be16 block1, block2;

​

    fnum1 = key1->ext.FNum;

    fnum2 = key2->ext.FNum;

    if (fnum1 != fnum2)

        return be32_to_cpu(fnum1) < be32_to_cpu(fnum2) ? -1 : 1;

    if (key1->ext.FkType != key2->ext.FkType)

        return key1->ext.FkType < key2->ext.FkType ? -1 : 1;

​

    block1 = key1->ext.FABN;

    block2 = key2->ext.FABN;