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source: trunk/boot/tsar_mips32/boot_fat32.h @ 452

Last change on this file since 452 was 439, checked in by satin@…, 7 years ago
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[439]	1	/****************************************************************************
	2	* This file defines the implementation of a simplified FAT32 file system *
	3	* supported by the ALMOS-MKH boot-loader. *
	4	* *
	5	* This implementation only supports block devices with block (sector) *
	6	* size of 512 bytes (value stored in BPB_BYTSPERSEC, see below). The *
	7	* max size for a single file is 4Gb - 1. *
	8	* *
	9	* A cluster is a smallest storage allocatable unit on the block device: *
	10	* any file (or directory) occupies at least one cluster, and a given *
	11	* cluster cannot be shared by 2 different files. This implementation *
	12	* supports cluster size of 4Kb (8 sectors, value stored in *
	13	* BPB_SECPERCLUS, see below). *
	14	* *
	15	* For partitioned devices such as hard drives, the first sector of the *
	16	* drive is the Master Boot Record defining partitions, while the first *
	17	* sector of partitions formatted with a FAT file system is the boot *
	18	* sector (Volume Boot Record). *
	19	* *
	20	* Here is the layout of a partition formatted with a FAT32 file system: *
	21	* +--------------------------------------------------------------------+ *
	22	* \| Reserved Region, composed of: \| *
	23	* \| - Boot Sector (i.e VBR, logical sector 0), \| *
	24	* \| - FS Information Sector (logical sector 1, value stored in \| *
	25	* \| BPB_FSINFO, see below), \| *
	26	* \| - Other reserved sectors (optional). \| *
	27	* \|--------------------------------------------------------------------\| *
	28	* \| FAT Region: contains the File Allocation Table which are maps \| *
	29	* \| of the Data Region, indicating which clusters are used by files \| *
	30	* \| and directories. \| *
	31	* \| This may contains two copies of the FAT data structure (value \| *
	32	* \| stored in BPB_NUMFATS, see below) for the sake of redundancy \| *
	33	* \| checking, although rarely used. \| *
	34	* \|--------------------------------------------------------------------\| *
	35	* \| Data Region: this is where the actual file and directory data \| *
	36	* \| stored. The Root Directory Table is stored in the first cluster \| *
	37	* \| of the Data Region (value stored in BPB_ROOTCLUS, see below). \| *
	38	* +--------------------------------------------------------------------+ *
	39	****************************************************************************/
	40
	41	#ifndef BOOT_FAT32_H
	42	#define BOOT_FAT32_H
	43
	44	/****************************************************************************
	45	* Various signature values. *
	46	* Warning: don't forget that little-endian representation must be assumed *
	47	****************************************************************************/
	48
	49	#define BOOT_SIGNATURE 0xAA55
	50	#define FSI_SIGNATURE1 0x41615252
	51	#define FSI_SIGNATURE2 0x61417272
	52	#define FSI_SIGNATURE3 0xAA550000
	53
	54	/****************************************************************************
	55	* Master Boot Record structure. *
	56	****************************************************************************/
	57
	58	/* Boot code (first 446 bytes). */
	59
	60	/* Partition table (64 bytes). */
	61	/* offset \| size (both in bytes) */
	62	#define FIRST_ENTRY_ACTIVE 446, 1 /* Status of first partition. */
	63	#define FIRST_ENTRY_CHSFRST 447, 3 /* CHS address of first sector. */
	64	#define FIRST_ENTRY_TYPE 450, 1 /* First partition type. */
	65	#define FIRST_ENTRY_CHSLST 451, 3 /* CHS address of last sector. */
	66	#define FIRST_ENTRY_LBAFRST 454, 4 /* LBA of first sector. */
	67	#define FIRST_ENTRY_SIZE 458, 4 /* Count of sectors in partition. */
	68
	69	#define SECOND_ENTRY_ACTIVE 462, 1 /* Status of second partition. */
	70	#define SECOND_ENTRY_CHSFRST 463, 3 /* CHS address of first sector. */
	71	#define SECOND_ENTRY_TYPE 466, 1 /* Second partition type. */
	72	#define SECOND_ENTRY_CHSLST 467, 3 /* CHS address of last sector. */
	73	#define SECOND_ENTRY_LBAFRST 470, 4 /* LBA of first sector. */
	74	#define SECOND_ENTRY_SIZE 474, 4 /* Count of sectors in partition. */
	75
	76	#define THIRD_ENTRY_ACTIVE 478, 1 /* Status of third partition. */
	77	#define THIRD_ENTRY_CHSFRST 479, 3 /* CHS address of first sector. */
	78	#define THIRD_ENTRY_TYPE 482, 1 /* Third partition type. */
	79	#define THIRD_ENTRY_CHSLST 483, 3 /* CHS address of last sector. */
	80	#define THIRD_ENTRY_LBAFRST 486, 4 /* LBA of first sector. */
	81	#define THIRD_ENTRY_SIZE 490, 4 /* Count of sectors in partition. */
	82
	83	#define FOURTH_ENTRY_ACTIVE 494, 1 /* Status of fourth partition. */
	84	#define FOURTH_ENTRY_CHSFRST 495, 3 /* CHS address of first sector. */
	85	#define FOURTH_ENTRY_TYPE 498, 1 /* Fourth partition type. */
	86	#define FOURTH_ENTRY_CHSLST 499, 3 /* CHS address of last sector. */
	87	#define FOURTH_ENTRY_LBAFRST 502, 4 /* LBA of first sector. */
	88	#define FOURTH_ENTRY_SIZE 506, 4 /* Count of sectors in partition. */
	89
	90	/* Signature (last 2 bytes). */
	91	/* offset \| size (both in bytes) */
	92	#define MBR_SIGNATURE_POS 510, 2 /* Boot signature. */
	93
	94	/****************************************************************************
	95	* Boot Sector structure. *
	96	****************************************************************************/
	97
	98	/* First 11 bytes. */
	99	/* offset \| size (both in bytes) */
	100	#define BS_JMPBOOT 0, 3 /* Jump instruction to boot code. */
	101	#define BS_OEMNAME 3, 8 /* OEM identifier (meaningless). */
	102
	103	/* BIOS Parameter Block (next 25 bytes). */
	104	/* offset \| size (both in bytes) */
	105	#define BPB_BYTSPERSEC 11, 2 /* Bytes per logical sector. */
	106	#define BPB_SECPERCLUS 13, 1 /* Logical sectors per cluster. */
	107	#define BPB_RSVDSECCNT 14, 2 /* Count of reserved sectors. */
	108	#define BPB_NUMFATS 16, 1 /* Count of File Allocation Tables. */
	109	#define BPB_ROOTENTCNT 17, 2 /* Must be 0 for FAT32. */
	110	#define BPB_TOTSEC16 19, 2 /* Total sectors count on 16 bits. */
	111	#define BPB_MEDIA 21, 1 /* Media descriptor. */
	112	#define BPB_FATSZ16 22, 2 /* Must be 0 for FAT32. */
	113	#define BPB_SECPERTRK 24, 2 /* Sectors per track for INT 0x13. */
	114	#define BPB_NUMHEADS 26, 2 /* Number of heads for INT 0x13. */
	115	#define BPB_HIDDSEC 28, 2 /* Hidden sectors preceding the
	116	partition that contains this FAT
	117	volume. */
	118	#define BPB_TOTSEC32 32, 4 /* Total sectors count on 32 bits. */
	119
	120	/* FAT32 Extended BIOS Parameter Block (next 28 bytes). */
	121	/* offset \| size (both in bytes) */
	122	#define BPB_FATSZ32 36, 4 /* Sectors per FAT on 32 bits. */
	123	#define BPB_EXTFLAGS 40, 2 /* Mirroring flags. */
	124	#define BPB_FSVER 42, 2 /* Version. */
	125	#define BPB_ROOTCLUS 44, 4 /* Number of first cluster of the
	126	root directory. */
	127	#define BPB_FSINFO 48, 2 /* Logical sector number of FS
	128	Information Sector. */
	129	#define BPB_BKBOOTSEC 50, 2 /* Logical sector of Backup Boot
	130	Sector. */
	131	#define BPB_RESERVED 52, 12 /* Reserved for future expansion. */
	132
	133	/* FAT12/FAT16 Extended BIOS Parameter Block (next 26 bytes). */
	134	/* offset \| size (both in bytes) */
	135	#define BS_DRVNUM 64, 1 /* INT 0x13 drive number. */
	136	#define BS_RESERVED1 65, 1 /* Reserved. */
	137	#define BS_BOOTSIG 66, 1 /* Extended boot signature. */
	138	#define BS_VOLID 67, 4 /* Volume ID (serial number). */
	139	#define BS_VOLLAB 71, 11 /* Volume label. */
	140	#define BS_FILSYSTYPE 82, 8 /* File system type: "FAT12 ",
	141	"FAT16 " or "FAT " */
	142
	143	/* File system and operating system specific boot code (next 420 bytes). */
	144	/* offset \| size (both in bytes) */
	145	#define BS_CODE 90, 420 /* Executable code. */
	146
	147	/* Signature (last 2 bytes). */
	148	/* offset \| size (both in bytes) */
	149	#define BS_SIGNATURE 510, 2 /* Boot signature. */
	150
	151	/****************************************************************************
	152	* FS Information Sector structure. *
	153	* This sector is used for speeding up access times of certain operations. *
	154	****************************************************************************/
	155
	156	/* offset \| size (both in bytes) */
	157	#define FSI_LEADSIG 0, 4 /* Lead signature. */
	158	#define FSI_RESERVED1 4, 480 /* Reserved. */
	159	#define FSI_STRUCSIG 484, 4 /* Another signature. */
	160	#define FSI_FREE_COUNT 488, 4 /* Number of free clusters. */
	161	#define FSI_NXT_FREE 492, 4 /* Most recently allocated cluster. */
	162	#define FSI_RESERVED2 496, 12 /* Reserved. */
	163	#define FSI_TRAILSIG 508, 4 /* Trail signature. */
	164
	165	/****************************************************************************
	166	* File Allocation Table. *
	167	* The File Allocation Table is a table that indicates the status and *
	168	* location of all data clusters on the disk. It can be *
	169	* considered the "table of contents" of a disk. The cluster may be *
	170	* available for use, it may be reserved by the operating system, it may *
	171	* be unavailable due to a bad sector on the disk, or it may be in use *
	172	* by a file. The clusters of a file need not to be right next to each *
	173	* other on the disk. The FAT allows the operating system to follow the *
	174	* chain of clusters in a file. *
	175	* *
	176	* Since the first cluster of the Data Region is cluster #2, the first 2 *
	177	* entries of the FAT are unused. *
	178	* *
	179	* Note that despite its name FAT32 uses only 28 bits of the 32 possible *
	180	* bits to address the clusters on the disk: the upper 4 bits should be *
	181	* left untouched. *
	182	****************************************************************************/
	183
	184	#define FAT_ENTRY_SIZE 4 /* Size of a FAT entry (in bytes) */
	185
	186	/* FAT entry values. */
	187	#define FREE 0x00000000 /* Free cluster. */
	188	#define RESERVED 0x00000001 /* Reserved for internal purposes. */
	189	#define BAD 0x0FFFFFF7 /* Bad sector in cluster. */
	190
	191	// Value in this range should be interpreted as next cluster number.
	192	#define USED_MIN 0x00000002 /* Minimum value to be considered
	193	as used for data clusters. */
	194	#define USED_MAX 0x0FFFFFEF /* Maximum value to be considered
	195	as used for data clusters. */
	196
	197	// Value in this range means this is the last cluster in file.
	198	#define EOC_MIN 0x0FFFFFF8 /* Minimum value to be considered
	199	as end-of-chain marker. */
	200	#define EOC_MAX 0x0FFFFFFF /* Maximum value to be considered
	201	as end-of-chain marker. */
	202
	203	/****************************************************************************
	204	* Directory table. *
	205	* A directory table is a special type of file that represents a directory. *
	206	* Each file or subdirectory stored within it is represented by a 32-byte *
	207	* entry in the table. All directory tables are stored in the Data Region. *
	208	* The actual number of entries in a directory stored in the Data Region *
	209	* can grow by adding another cluster to the chain in the FAT. *
	210	* *
	211	* A directory entry simply stores the information needed to know where *
	212	* a file's data or a folder's children are stored on the disk. *
	213	* *
	214	* The only special directory which must always be present is the root *
	215	* directory. For FAT32, it can be of variable size and is a cluster, *
	216	* just like any other directory is (this is not true for FAT12/FAT16). *
	217	* The first cluster of the root directory on a FAT32 volume is stored in *
	218	* BPB_ROOTCLUS. *
	219	* *
	220	* Each entry can be preceded by "fake entries" to support a VFAT long *
	221	* filename (LFN, see further below). When such a directory entry is *
	222	* encountered, it is given special treatment by the file system. *
	223	****************************************************************************/
	224
	225	#define DIR_ENTRY_SIZE 32 /* Directory entry size (in bytes) */
	226	#define PATH_MAX_SIZE 260 /* Max file path length (bytes) */
	227	#define NAME_MAX_SIZE 256 /* Max file/dir name length (bytes) */
	228
	229	/****************************************************************************
	230	* Standard 8.3 format. *
	231	* For a classic 8.3 filename entry, the DIR_NAME field is actually broken *
	232	* in 2 parts: the 8-characters main part of the name and the 3-characters *
	233	* extension. These 2 parts are "trailing space padded". *
	234	* *
	235	* Furthermore, all classic 8.3 filenames are uppercase. *
	236	****************************************************************************/
	237
	238	/* offset \| size (both in bytes) */
	239	#define DIR_NAME 0, 11 /* Short file name. */
	240	#define DIR_ATTR 11, 1 /* File attributes. */
	241	#define DIR_NTRES 12, 1 /* Reserved for use by WINDOWS NT. */
	242	#define DIR_CRTTIMETENTH 13, 1 /* Millisecond stamp at file
	243	creation time. */
	244	#define DIR_CRTTIME 14, 2 /* Time file was created. */
	245	#define DIR_CRTDATE 16, 2 /* Date file was created. */
	246	#define DIR_LSTACCDATE 18, 2 /* Last access date. */
	247	#define DIR_FSTCLUSHI 20, 2 /* High 16 bits of this entry's
	248	first cluster number. */
	249	#define DIR_WRTTIME 22, 2 /* Time of last write. */
	250	#define DIR_WRTDATE 24, 2 /* Date of last write. */
	251	#define DIR_FSTCLUSLO 26, 2 /* Low 16 bits of this entry's
	252	first cluster number. */
	253	#define DIR_FILESIZE 28, 4 /* This file's size in bytes. */
	254
	255	/* File attributes (DIR_ATTR values). */
	256	#define ATTR_READ_ONLY 0x01 /* Writes to file should fail. */
	257	#define ATTR_HIDDEN 0x02 /* Normal directory listings should
	258	not show this file. */
	259	#define ATTR_SYSTEM 0x04 /* File belongs to the system, must
	260	not be physically moved. */
	261	#define ATTR_VOLUME_ID 0x08 /* Volume label. */
	262	#define ATTR_DIRECTORY 0x10 /* Container for other files. */
	263	#define ATTR_ARCHIVE 0x20 /* Archive (file marked as dirty). */
	264	#define ATTR_LONG_NAME 0x0F /* The file is part of the long
	265	long entry for some other file. */
	266
	267	/* Special values of the first byte DIR_NAME[0] of a FAT directory entry. */
	268	#define FREE_ENTRY 0xE5 /* Directory entry is free. */
	269	#define LAST_ENTRY 0x00 /* No subsequent entry in use. */
	270
	271	/****************************************************************************
	272	* Long File Name format. *
	273	* Long File Names are stored on FAT file system using a trick: adding *
	274	* (possibly multiple) additional entries to the directory before the *
	275	* normal file entry. This means that long file name entries is always *
	276	* associated with a regular 8.3 entry that they always immediately *
	277	* precede (this because only short directory entries are visible to *
	278	* previous versions of MS-DOS). *
	279	* *
	280	* Note 1: every member of a set of long entries is uniquely numbered and *
	281	* the LDIR_ORD field of the last member of the set is or'd with a flag *
	282	* indicating that it is in fact the last member of the set. On the other *
	283	* hand, this field cannot have values of 0xE5 or 0x00 (see above). *
	284	* *
	285	* Note 2: an 8-bit checksum is computed on the name contained in the *
	286	* short directory entry at the time the short and long directory entries *
	287	* are created. This checksum is then placed in every long entry. All 11 *
	288	* characters of the name in the short entry are used in the checksum *
	289	* calculation. *
	290	* *
	291	* Note 3: if there are multiple LFN entries, firstly comes the LAST LFN *
	292	* entry (the last part of the file name). *
	293	****************************************************************************/
	294
	295	/* offset \| size (both in bytes) */
	296	#define LDIR_ORD 0, 1 /* Order of this entry in the
	297	sequence of long directory
	298	entries. */
	299	#define LDIR_NAME1 1, 10 /* Characters 1-5 of the long name
	300	sub-component in this entry. */
	301	#define LDIR_ATTR 11, 1 /* Must be ATTR_LONG_NAME. */
	302	#define LDIR_TYPE 12, 1 /* Always 0. */
	303	#define LDIR_CHKSUM 13, 1 /* Checksum of name in the short
	304	directory entry at the end of
	305	the long directory set. */
	306	#define LDIR_NAME2 14, 12 /* Characters 6-11 of the long name
	307	sub-component in this entry. */
	308	#define LDIR_FSTCLUSLO 26, 2 /* Must be 0. */
	309	#define LDIR_NAME3 28, 4 /* Characters 12-13 of the long name
	310	sub-component in this entry. */
	311
	312	/* Last long directory entry mask. */
	313	#define LAST_LONG_ENTRY 0x40
	314
	315
	316	/****************************************************************************
	317	* This structure defines a FAT32 File System descriptor. *
	318	****************************************************************************/
	319
	320	#include <hal_types.h>
	321
	322	typedef struct fat_desc_s
	323	{
	324	unsigned char block_buffer[512]; /* Buffer for FS Information. */
	325	uint32_t block_buffer_lba; /* LBA of block_buffer. */
	326	uint32_t initialized; /* Status of the FAT32 File System. */
	327	uint32_t sector_size; /* Must be 512 bytes. */
	328	uint32_t cluster_size; /* Must be 4096 bytes. */
	329	uint32_t fat_sectors; /* Count of sectors in FAT Region. */
	330	uint32_t fat_lba; /* LBA of first FAT sector. */
	331	uint32_t data_sectors; /* Count of sectors in Data Region. */
	332	uint32_t data_lba; /* LBA of first data sector. */
	333	uint32_t root_cluster; /* first cluster of root directory. */
	334	uint32_t fsi_lba; /* LBA of FS Information. */
	335	uint32_t free_cluster_hint; /* Start point for free cluster */
	336	uint32_t free_clusters_nr; /* Total number of free clusters. */
	337	}
	338	fat_desc_t;
	339
	340	/****************************************************************************
	341	* Basic operations of FAT32 File System. *
	342	****************************************************************************/
	343
	344	extern fat_desc_t boot_fat;
	345
	346	/****************************************************************************
	347	* This function initializes the FAT32 File System. *
	348	* *
	349	* @ returns 0 on success, -1 on error. *
	350	****************************************************************************/
	351	int boot_fat32_init();
	352
	353	/****************************************************************************
	354	* This function loads the 'pathname' file into the memory buffer at base *
	355	* address 'buff_addr' of 'buff_size'. It uses the 512-byte buffer defined *
	356	* in the FAT32 descriptor. *
	357	* @ pathname : file to be loaded pathname. *
	358	* @ buff_addr : memory address of file containing buffer. *
	359	* @ buff_size : size of file containing buffer (in bytes). *
	360	* *
	361	* @ returns 0 on success, -1 on error. *
	362	****************************************************************************/
	363	int boot_fat32_load( char* pathname,
	364	uint32_t buff_addr,
	365	uint32_t buff_size );
	366
	367	#endif // BOOT_FAT32_H

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