WebSVN – Kolibri OS – Blame – /kernel/trunk/sec_loader/trunk/boot/after_win/fat.inc

Rev	Author	Line No.	Line
2288	clevermous	1	; Copyright (c) 2008-2009, diamond
		2	; All rights reserved.
		3	;
		4	; Redistribution and use in source and binary forms, with or without
		5	; modification, are permitted provided that the following conditions are met:
		6	; * Redistributions of source code must retain the above copyright
		7	; notice, this list of conditions and the following disclaimer.
		8	; * Redistributions in binary form must reproduce the above copyright
		9	; notice, this list of conditions and the following disclaimer in the
		10	; documentation and/or other materials provided with the distribution.
		11	; * Neither the name of the nor the
		12	; names of its contributors may be used to endorse or promote products
		13	; derived from this software without specific prior written permission.
		14	;
		15	; THIS SOFTWARE IS PROVIDED BY Alexey Teplov aka ''AS IS'' AND ANY
		16	; EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
		17	; WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
		18	; DISCLAIMED. IN NO EVENT SHALL BE LIABLE FOR ANY
		19	; DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
		20	; (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
		21	; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
		22	; ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
		23	; (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
		24	; SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
		25	;*****************************************************************************
		26
		27	; in: ss:bp = 0:dat
		28	; in: es:bx = address to load file
		29	; in: ds:si -> ASCIIZ name
		30	; in: cx = limit in sectors
		31	; out: bx = status: bx=0 - ok, bx=1 - file is too big, only part of file has been loaded, bx=2 - file not found
		32	; out: dx:ax = file size (0xFFFFFFFF if file not found)
		33	load_file_fat:
		34	mov eax, [bp + root_clus - dat]
		35	mov [bp + cur_obj - dat], root_string
		36	push es
		37	push bx
		38	push cx
		39	.parse_dir_loop:
		40	; convert name to FAT name
		41	push [bp + cur_obj - dat]
		42	push ax
		43	mov [bp + cur_obj - dat], si
		44	push ss
		45	pop es
		46	; convert ASCIIZ filename to FAT name
		47	mov di, fat_filename
		48	push di
		49	mov cx, 8+3
		50	mov al, ' '
		51	rep stosb
		52	pop di
		53	mov cl, 8 ; 8 symbols per name
		54	mov bl, 1
		55	.nameloop:
		56	lodsb
		57	test al, al
		58	jz .namedone
		59	cmp al, '/'
		60	jz .namedone
		61	cmp al, '.'
		62	jz .namedot
		63	dec cx
		64	js .badname
		65	cmp al, 'a'
		66	jb @f
		67	cmp al, 'z'
		68	ja @f
		69	sub al, 'a'-'A'
		70	@@:
		71	stosb
		72	jmp .nameloop
		73	.namedot:
		74	inc bx
		75	jp .badname
		76	add di, cx
		77	mov cl, 3
		78	jmp .nameloop
		79	.badname:
		80	mov si, badname_msg
		81	jmp find_error_si
		82	.namedone:
		83	; scan directory
		84	pop ax ; eax = cluster of directory
		85	; high word of eax is preserved by operations above
		86	push ds
		87	push si
		88	; read a folder sector-by-sector and scan
		89	; first, try to use the cache
		90	push ss
		91	pop ds
		92	mov bx, -2
		93	mov cx, [bp + rootcache_size - dat]
		94	cmp [bp + root_clus - dat], eax
		95	jz .lookcache_root
		96	mov di, foldcache_mark
		97	xor bx, bx
		98	mov cx, [bp + cachelimit - dat]
		99	@@:
		100	lea si, [di+bx]
		101	mov edx, dword [foldcache_clus+si-foldcache_mark+bx]
		102	cmp edx, eax
		103	jz .cacheok
		104	test edx, edx
		105	jz .cacheadd ; the cache has place for new entry
		106	inc bx
		107	inc bx
		108	dec cx
		109	js @b
		110	; the folder is not present in the cache, so add it
		111	; the cache is full; find the oldest entry and replace it with the new one
		112	mov bx, -2
		113	mov dx, [bp + cachelimit - dat]
		114	@@:
		115	inc bx
		116	inc bx
		117	cmp word [di+bx], dx ; marks have values 0 through [cachelimit]
		118	jnz @b
		119	.cacheadd:
		120	or word [di+bx], 0xFFFF ; very big value, it will be changed soon
		121	and [foldcache_size+di-foldcache_mark+bx], 0 ; no folder items yet
		122	lea si, [di+bx]
		123	mov dword [foldcache_clus+si-foldcache_mark+bx], eax
		124	.cacheok:
		125	; update cache marks
		126	mov dx, [di+bx]
		127	mov cx, [foldcache_size+di-foldcache_mark+bx]
		128	mov di, [bp + cachelimit - dat]
		129	add di, di
		130	.cacheupdate:
		131	cmp [foldcache_mark+di], dx
		132	adc [foldcache_mark+di], 0
		133	dec di
		134	dec di
		135	jns .cacheupdate
		136	and [foldcache_mark+bx], 0
		137	; done, bx contains (position in cache)*2
		138	.lookcache_root:
		139	; bx = (position in cache)*2 for non-root folders; bx = -2 for root folder
		140	;mov dx, bx
		141	;shl dx, 8
		142	;add dx, 0x9200
		143	lea dx, [bx + 0x92]
		144	xchg dl, dh
		145	mov ds, dx
		146	mov si, fat_filename ; ss:si -> filename in FAT style
		147	call fat_scan_for_filename
		148	jz .lookup_done
		149	; cache miss, read folder data from disk
		150	; we are reading parent directory, it can result in disk read errors; restore [cur_obj]
		151	mov di, sp
		152	mov bx, [bp + cur_obj - dat]
		153	xchg bx, [ss:di+4]
		154	mov [bp + cur_obj - dat], bx
		155	mov bx, cx
		156	add bx, 0xF
		157	shr bx, 4
		158	shl cx, 5
		159	mov di, cx ; es:di -> free space in cache entry
		160	; external loop: scan clusters
		161	.folder_next_cluster:
		162	; internal loop: scan sectors in cluster
		163	movzx ecx, byte [ss:0x320D] ; BPB_SecPerClus
		164	push eax
		165	; FAT12/16 root - special handling
		166	test eax, eax
		167	jnz .folder_notroot
		168	mov cx, [ss:0x3211] ; BPB_RootEntCnt
		169	mov dx, cx
		170	add cx, 0xF
		171	rcr cx, 1
		172	shr cx, 3
		173	mov eax, [bp + root_start - dat]
		174	jmp .folder_next_sector
		175	.folder_notroot:
		176	mul ecx
		177	add eax, [bp + data_start - dat]
		178	.folder_next_sector:
		179	sub dx, 0x10
		180	; skip first bx sectors
		181	dec bx
		182	jns .folder_skip_sector
		183	push cx
		184	push es di
		185	push 0x8000
		186	pop es
		187	xor bx, bx
		188	mov cx, 1
		189	push es
		190	call read
		191	jc ..found_disk_error
		192	; copy data to the cache...
		193	pop ds
		194	pop di es
		195	cmp di, 0x2000 ; ...if there is free space, of course
		196	jae @f
		197	pusha
		198	mov cx, 0x100
		199	xor si, si
		200	rep movsw
		201	mov di, es
		202	shr di, 8
		203	cmp di, 0x90
		204	jz .update_rootcache_size
		205	add [ss:foldcache_size+di-0x92], 0x10 ; 0x10 new entries in the cache
		206	jmp .updated_cachesize
		207	.update_rootcache_size:
		208	mov cl, 0x10
		209	cmp cx, dx
		210	jb @f
		211	mov cx, dx
		212	@@:
		213	add [bp + rootcache_size - dat], cx
		214	.updated_cachesize:
		215	popa
		216	@@:
		217	push es
		218	mov cl, 0x10 ; ch=0 at this point
		219	cmp cx, dx
		220	jb @f
		221	mov cx, dx
		222	@@:
		223	call fat_scan_for_filename
		224	pop es
		225	pop cx
		226	jz .lookup_done_pop
		227	.folder_skip_sector:
		228	inc eax
		229	loop .folder_next_sector
		230	pop eax ; eax = current cluster
		231	test eax, eax
		232	jz @f
		233	call [bp + get_next_cluster_ptr - dat]
		234	jc .folder_next_cluster
		235	@@:
		236	stc
		237	push eax
		238	.lookup_done_pop:
		239	pop eax
		240	.lookup_done:
		241	pop si
		242	; CF=1 <=> failed
		243	jnc .found
		244	pop ds
		245	pop [bp + cur_obj - dat]
		246	mov si, error_not_found
		247	jmp find_error_si
		248	.found:
		249	mov eax, [di+20-2]
		250	mov edx, [di+28]
		251	mov ax, [di+26] ; get cluster
		252	test byte [di+11], 10h ; directory?
		253	pop ds
		254	pop [bp + cur_obj - dat] ; forget old [cur_obj]
		255	jz .regular_file
		256	cmp byte [si-1], 0
		257	jnz .parse_dir_loop
		258	..directory_error:
		259	mov si, directory_string
		260	jmp find_error_si
		261	.regular_file:
		262	cmp byte [si-1], 0
		263	jz @f
		264	..notdir_error:
		265	mov si, notdir_string
		266	jmp find_error_si
		267	@@:
		268	; ok, we have found a regular file and the caller requested it
		269	; parse FAT chunk
		270	push ss
		271	pop es
		272	push ss
		273	pop ds
		274	mov di, 0x4005
		275	mov byte [di-5], 1 ; non-resident attribute
		276	mov dword [di-4], 1
		277	stosd
		278	pop cx
		279	push cx
		280	.parsefat:
		281	call [bp + get_next_cluster_ptr - dat]
		282	jnc .done
		283	mov esi, [di-8]
		284	add esi, [di-4]
		285	cmp eax, esi
		286	jz .contc
		287	mov dword [di], 1
		288	scasd
		289	stosd
		290	jmp @f
		291	.contc:
		292	inc dword [di-8]
		293	@@:
		294	sub cl, [0x320D]
		295	sbb ch, 0
		296	ja .parsefat
		297	.done:
		298	xor eax, eax
		299	stosd
		300	mov si, 0x4000
		301	load_file_common_end:
		302	xor ecx, ecx
		303	pop cx
		304	pop bx
		305	pop es
		306	mov [bp + filesize - dat], edx
		307	mov [bp + sectors_read - dat], ecx
		308	add edx, 0x1FF
		309	shr edx, 9
		310	mov [bp + filesize_sectors - dat], edx
		311	cmp edx, ecx
		312	seta al
		313	mov ah, 0
		314	push ax
		315	call read_file_chunk
		316	continue_load_common_end:
		317	mov [bp + cur_chunk_ptr - dat], si
		318	pop bx
		319	mov ax, word [bp + filesize - dat]
		320	mov dx, word [bp + filesize+2 - dat]
		321	jnc @f
		322	mov bl, 3 ; read error
		323	@@:
		324	ret
		325
		326	continue_load_file:
		327	; es:bx -> buffer for output, ecx = cx = number of sectors
		328	mov si, [bp + cur_chunk_ptr - dat]
		329	push ecx
		330	add ecx, [bp + sectors_read - dat]
		331	mov [bp + sectors_read - dat], ecx
		332	cmp [bp + filesize_sectors - dat], ecx
		333	pop ecx
		334	seta al
		335	mov ah, 0
		336	push ax
		337	push continue_load_common_end
		338	push ss
		339	pop ds
		340	cmp [bp + cur_chunk_resident - dat], ah
		341	jnz .nonresident
		342	.resident:
		343	mov ax, word [bp + num_sectors - dat]
		344	jmp read_file_chunk.resident.continue
		345	.nonresident:
		346	mov eax, [bp + cur_cluster - dat]
		347	mov edx, [bp + num_sectors - dat]
		348	add eax, [bp + cur_delta - dat]
		349	jmp read_file_chunk.nonresident.continue
		350
		351	fat_scan_for_filename:
		352	; in: ss:si -> 11-bytes FAT name
		353	; in: ds:0 -> part of directory data
		354	; in: cx = number of entries
		355	; out: if found: CF=0, ZF=1, es:di -> directory entry
		356	; out: if not found, but continue required: CF=1 and ZF=0
		357	; out: if not found and zero item reached: CF=1 and ZF=1
		358	push ds
		359	pop es
		360	xor di, di
		361	push cx
		362	jcxz .noent
		363	.loop:
		364	cmp byte [di], 0
		365	jz .notfound
		366	test byte [di+11], 8 ; volume label?
		367	jnz .cont ; ignore volume labels
		368	pusha
		369	mov cx, 11
		370	repz cmps byte [ss:si], byte [es:di]
		371	popa
		372	jz .done
		373	.cont:
		374	add di, 0x20
		375	loop .loop
		376	.noent:
		377	inc cx ; clear ZF flag
		378	.notfound:
		379	stc
		380	.done:
		381	pop cx
		382	ret
		383
		384	fat12_get_next_cluster:
		385	; in: ax = cluster (high word of eax is zero)
		386	; out: if there is next cluster: CF=1, ax = next cluster
		387	; out: if there is no next cluster: CF=0
		388	push si
		389	push ds
		390	push 0x6000
		391	pop ds
		392	mov si, ax
		393	shr si, 1
		394	add si, ax
		395	test al, 1
		396	lodsw
		397	jz @f
		398	shr ax, 4
		399	@@:
		400	and ax, 0xFFF
		401	cmp ax, 0xFF7
		402	pop ds si
		403	ret
		404
		405	fat16_get_next_cluster:
		406	; in: ax = cluster (high word of eax is zero)
		407	; out: if there is next cluster: CF=1, ax = next cluster
		408	; out: if there is no next cluster: CF=0
		409	; each sector contains 200h bytes = 100h FAT entries
		410	; so ah = # of sector, al = offset in sector
		411	push si
		412	mov si, ax
		413	shr si, 8
		414	; calculate segment for this sector of FAT table
		415	; base for FAT table is 6000:0000, so the sector #si has to be loaded to (60000 + 200*si)
		416	; segment = 6000 + 20*si, offset = 0
		417	push es
		418	push si
		419	shl si, 5
		420	add si, 0x6000
		421	mov es, si
		422	pop si
		423	cmp byte [ss:0x3400+si], 0 ; sector already loaded?
		424	jnz .noread
		425	; load corresponding sector, try all FATs if disk read error detected
		426	pusha
		427	movzx di, byte [ss:0x3210] ; BPB_NumFATs
		428	xor bx, bx
		429	mov ax, [ss:0x320E] ; BPB_RsvdSecCnt
		430	xor dx, dx
		431	add ax, si
		432	adc dx, bx
		433	@@:
		434	push es
		435	push dx ax
		436	pop eax
		437	mov cx, 1 ; read 1 sector
		438	call read
		439	pop es
		440	jnc @f
		441	add ax, [ss:0x3216] ; BPB_FATSz16
		442	adc dx, bx
		443	dec di
		444	jnz @b
		445	..found_disk_error:
		446	mov si, disk_error_msg
		447	jmp find_error_si
		448	@@:
		449	popa
		450	.noread:
		451	mov si, ax
		452	and si, 0xFF
		453	add si, si
		454	mov ax, [es:si]
		455	pop es
		456	cmp ax, 0xFFF7
		457	pop si
		458	ret
		459
		460	fat32_get_next_cluster:
		461	; in: eax = cluster
		462	; out: if there is next cluster: CF=1, eax = next cluster
		463	; out: if there is no next cluster: CF=0
		464	push di
		465	push ax
		466	shr eax, 7
		467	; eax = FAT sector number; look in cache
		468	push si
		469	mov si, cache1head
		470	call cache_lookup
		471	pop si
		472	jnc .noread
		473	; read FAT, try all FATs if disk read error detected
		474	push es
		475	pushad
		476	movzx edx, word [ss:0x320E] ; BPB_RsvdSecCnt
		477	add eax, edx
		478	movzx si, byte [ss:0x3210] ; BPB_NumFATs
		479	@@:
		480	lea cx, [di - 0x3400 + (0x6000 shr (9-3))]
		481	shl cx, 9-3
		482	mov es, cx
		483	xor bx, bx
		484	mov cx, 1
		485	call read
		486	jnc @f
		487	add eax, [ss:0x3224] ; BPB_FATSz32
		488	dec si
		489	jnz @b
		490	jmp ..found_disk_error
		491	@@:
		492	popad
		493	pop es
		494	.noread:
		495	; get requested item
		496	lea ax, [di - 0x3400 + (0x6000 shr (9-3))]
		497	pop di
		498	and di, 0x7F
		499	shl di, 2
		500	shl ax, 9-3
		501	push ds
		502	mov ds, ax
		503	and byte [di+3], 0x0F
		504	mov eax, [di]
		505	pop ds
		506	pop di
		507	;and eax, 0x0FFFFFFF
		508	cmp eax, 0x0FFFFFF7
		509	ret

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(root)/kernel/trunk/sec_loader/trunk/boot/after_win/fat.inc – Rev 2288