fat.h

上一个上传的有问题,这个是好的。visopsys包括系统内核和GUI的全部SOURCE code ,还包括一些基本的docs文档。里面src子目录对应所有SOURCE code.对于想研究操作系统的朋

// 
//  Visopsys
//  Copyright (C) 1998-2007 J. Andrew McLaughlin
//  
//  This library is free software; you can redistribute it and/or modify it
//  under the terms of the GNU Lesser General Public License as published by
//  the Free Software Foundation; either version 2.1 of the License, or (at
//  your option) any later version.
//
//  This library 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 Lesser
//  General Public License for more details.
//
//  You should have received a copy of the GNU Lesser General Public License
//  along with this library; if not, write to the Free Software Foundation,
//  Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
//
//  fat.h
//

// This file contains definitions and structures for using and manipulating
// the Microsoft(R) FAT filesystems in Visopsys.

#if !defined(_FAT_H)

// FAT-specific Filesystem things
#define FAT_MAX_SECTORSIZE       4096
#define FAT_BYTES_PER_DIR_ENTRY  32
#define FAT_MAX_DIRTY_FATSECTS   32

// File attributes
#define FAT_ATTRIB_READONLY      0x01
#define FAT_ATTRIB_HIDDEN        0x02
#define FAT_ATTRIB_SYSTEM        0x04
#define FAT_ATTRIB_VOLUMELABEL   0x08
#define FAT_ATTRIB_SUBDIR        0x10
#define FAT_ATTRIB_ARCHIVE       0x20

typedef struct {
  unsigned char jmpBoot[3];
  char oemName[8];		        // 03 - 0A OEM Name
  unsigned short bytesPerSect;		// 0B - 0C Bytes per sector
  unsigned char sectsPerClust;		// 0D - 0D Sectors per cluster
  unsigned short rsvdSectCount;		// 0E - 0F Reserved sectors
  unsigned char numFats;		// 10 - 10 Copies of FAT
  unsigned short rootEntCount;		// 11 - 12 Max root directory entries
  unsigned short totalSects16;		// 13 - 14 Number of sectors
  unsigned char media;			// 15 - 15 Media descriptor byte
  unsigned short fatSize16;		// 16 - 17 Sectors per FAT
  unsigned short sectsPerTrack;		// 18 - 19 Sectors per track
  unsigned short numHeads;		// 1A - 1B Number of heads
  unsigned hiddenSects;			// 1C - 1F Hidden sectors
  unsigned totalSects32;		// 20 - 23 Number of sectors (32)
  // From here, the BPB for FAT and VFAT differ
  union {
    struct {
      unsigned char biosDriveNum;	// 24 - 24 BIOS drive number
      unsigned char reserved1; 		// 25 - 25 ?
      unsigned char bootSig;          	// 26 - 26 Signature
      unsigned volumeId;	    	// 27 - 2A Volume ID
      char volumeLabel[11];		// 2B - 35 Volume name
      char fileSysType[8];   		// 36 - 3D Filesystem type
      unsigned char bootCode[448];
    } __attribute__((packed)) fat;
    struct {
      unsigned fatSize32;		// 24 - 27 Sectors per FAT (32)
      unsigned short extFlags;		// 28 - 29 Flags
      unsigned short fsVersion;		// 2A - 2B FS version number
      unsigned rootClust;		// 2C - 2F Root directory cluster
      unsigned short fsInfo;		// 30 - 31 FSInfo struct sector
      unsigned short backupBootSect;	// 32 - 33 Backup boot sector
      unsigned char reserved[12];	// 34 - 3F ?
      unsigned char biosDriveNum;	// 40 - 40 BIOS drive number
      unsigned char reserved1; 		// 41 - 41 ?
      unsigned char bootSig;          	// 42 - 42 Signature
      unsigned volumeId;	    	// 43 - 46 Volume ID
      char volumeLabel[11];		// 47 - 51 Volume name
      char fileSysType[8];		// 52 - 59 Filesystem type
      unsigned char bootCode[414];
    } __attribute__((packed)) fat32;
  };
  unsigned short signature;

} __attribute__((packed)) fatBPB;

typedef struct {
  unsigned leadSig;
  unsigned char reserved1[480];
  unsigned structSig;
  unsigned freeCount;
  unsigned nextFree;
  unsigned char reserved2[12];
  unsigned trailSig;

} __attribute__((packed)) fatFsInfo;

#define _FAT_H
#endif