/*
   * collate.c - NTFS kernel collation handling.  Part of the Linux-NTFS project.
   *
   * Copyright (c) 2004 Anton Altaparmakov
   *
   * This program/include file 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 of the License, or
   * (at your option) any later version.
   *
   * This program/include file 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 (in the main directory of the Linux-NTFS
   * distribution in the file COPYING); if not, write to the Free Software
   * Foundation,Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
   */
  
  #include "collate.h"
  #include "debug.h"
  #include "ntfs.h"
  
  static int ntfs_collate_binary(ntfs_volume *vol,
  		const void *data1, const int data1_len,
  		const void *data2, const int data2_len)
  {
  	int rc;
  
  	ntfs_debug("Entering.");
  	rc = memcmp(data1, data2, min(data1_len, data2_len));
  	if (!rc && (data1_len != data2_len)) {
  		if (data1_len < data2_len)
  			rc = -1;
  		else
  			rc = 1;
  	}
  	ntfs_debug("Done, returning %i", rc);
  	return rc;
  }
  
  static int ntfs_collate_ntofs_ulong(ntfs_volume *vol,
  		const void *data1, const int data1_len,
  		const void *data2, const int data2_len)
  {
  	int rc;
  	u32 d1, d2;
  
  	ntfs_debug("Entering.");
  	// FIXME:  We don't really want to bug here.
  	BUG_ON(data1_len != data2_len);
  	BUG_ON(data1_len != 4);
  	d1 = le32_to_cpup(data1);
  	d2 = le32_to_cpup(data2);
  	if (d1 < d2)
  		rc = -1;
  	else {
  		if (d1 == d2)
  			rc = 0;
  		else
  			rc = 1;
  	}
  	ntfs_debug("Done, returning %i", rc);
  	return rc;
  }
  
  typedef int (*ntfs_collate_func_t)(ntfs_volume *, const void *, const int,
  		const void *, const int);
  
  static ntfs_collate_func_t ntfs_do_collate0x0[3] = {
  	ntfs_collate_binary,
  	NULL/*ntfs_collate_file_name*/,
  	NULL/*ntfs_collate_unicode_string*/,
  };
  
  static ntfs_collate_func_t ntfs_do_collate0x1[4] = {
  	ntfs_collate_ntofs_ulong,
  	NULL/*ntfs_collate_ntofs_sid*/,
  	NULL/*ntfs_collate_ntofs_security_hash*/,
  	NULL/*ntfs_collate_ntofs_ulongs*/,
  };
  
  /**
   * ntfs_collate - collate two data items using a specified collation rule
   * @vol:	ntfs volume to which the data items belong
   * @cr:		collation rule to use when comparing the items
   * @data1:	first data item to collate
   * @data1_len:	length in bytes of @data1
   * @data2:	second data item to collate
   * @data2_len:	length in bytes of @data2
   *
   * Collate the two data items @data1 and @data2 using the collation rule @cr
   * and return -1, 0, ir 1 if @data1 is found, respectively, to collate before,
   * to match, or to collate after @data2.
   *
   * For speed we use the collation rule @cr as an index into two tables of
   * function pointers to call the appropriate collation function.
   */
  int ntfs_collate(ntfs_volume *vol, COLLATION_RULE cr,
  		const void *data1, const int data1_len,
  		const void *data2, const int data2_len) {
  	int i;
  
  	ntfs_debug("Entering.");
  	/*
  	 * FIXME:  At the moment we only support COLLATION_BINARY and
  	 * COLLATION_NTOFS_ULONG, so we BUG() for everything else for now.
  	 */
  	BUG_ON(cr != COLLATION_BINARY && cr != COLLATION_NTOFS_ULONG);
  	i = le32_to_cpu(cr);
  	BUG_ON(i < 0);
  	if (i <= 0x02)
  		return ntfs_do_collate0x0[i](vol, data1, data1_len,
  				data2, data2_len);
  	BUG_ON(i < 0x10);
  	i -= 0x10;
  	if (likely(i <= 3))
  		return ntfs_do_collate0x1[i](vol, data1, data1_len,
  				data2, data2_len);
  	BUG();
  	return 0;
  }