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      1 /*	$NetBSD: floppy_2d.c,v 1.5 2009/02/04 15:22:13 tsutsui Exp $	*/
      2 
      3 /*-
      4  * Copyright (c) 2004 The NetBSD Foundation, Inc.
      5  * All rights reserved.
      6  *
      7  * This code is derived from software contributed to The NetBSD Foundation
      8  * by UCHIYAMA Yasushi.
      9  *
     10  * Redistribution and use in source and binary forms, with or without
     11  * modification, are permitted provided that the following conditions
     12  * are met:
     13  * 1. Redistributions of source code must retain the above copyright
     14  *    notice, this list of conditions and the following disclaimer.
     15  * 2. Redistributions in binary form must reproduce the above copyright
     16  *    notice, this list of conditions and the following disclaimer in the
     17  *    documentation and/or other materials provided with the distribution.
     18  *
     19  * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
     20  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
     21  * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
     22  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
     23  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
     24  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
     25  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
     26  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
     27  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
     28  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
     29  * POSSIBILITY OF SUCH DAMAGE.
     30  */
     31 
     32 #include <sys/types.h>
     33 #include "common.h"
     34 
     35 bool
     36 blk_to_2d_position(uint32_t logical_block_number, uint32_t *position,
     37     int *count)
     38 {
     39 	int i, sector, side, cylinder;
     40 
     41 	/*
     42 	 * 2D: MFM format (cylinder 0 side 0 is FM format)
     43 	 *     77 cylinders/disk
     44 	 *	2 sides/disk
     45 	 *     26 sectors/track
     46 	 *    256 bytes/sector (cylinder 0 side 0 is 128 bytes/sector)
     47 	 *
     48 	 *    0-1988 : MFM
     49 	 * 1989-1995 : FM
     50 	 */
     51 	if (logical_block_number > 1988)
     52 		return false;	/* don't support FM track */
     53 
     54 	i = logical_block_number * 2 + 26;
     55 	cylinder = i / (26 * 2);
     56 	side = i - (cylinder * 26 * 2) > 25;
     57 	sector = i - (side + cylinder * 2) * 26;
     58 	if (position)
     59 		*position = (cylinder << 16) | (side << 8) | (sector + 1);
     60 	if (count)
     61 		*count = (26 - sector) / 2;
     62 
     63 	return true;
     64 }
     65 
     66