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boot_fat32.h @ 664

Last change on this file since 664 was 521, checked in by viala@…, 6 years ago

[boot] Add const qualifier where it's possible.

Fix some gcc warning of "const qualifier discarded" warning.
Because litterals string are of type 'const char *'.

Property svn:executable set to *

File size: 23.6 KB

Line
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_kernel_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( void );
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( const char * pathname,
364	uint32_t buff_addr,
365	uint32_t buff_size );
366
367	#endif // BOOT_FAT32_H

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