;----------------------------------------------------------;
;---------------------------------------------;
- ; main FAT12 info structure ;
+ ; FAT12 calltable and structure pointer ;
;---------------------------------------------;
- struc fat12
+ FAT12:
+ .data_pointer dd 0 ; internal driver data
+ .FSname db 'FAT12' ; 5 char filesystem name
+ .init dd init_fat12 ; pointer to init
+ .deinit dd 0 ; remove driver
+ .format dd 0 ; format drive
+ .mount dd 0 ; mount drive
+ .unmount dd 0 ; unmount drive
+ .find dd 0 ; find file
+ .findnext dd 0 ; get next match
+ .open dd 0 ; open file, get handle
+ .close dd 0 ; close file from handle
+ .attrib dd 0 ; get/set attrib. and time
+ .read dd 0 ; read file from handle
+ .write dd 0 ; write file from handle
+ .seek dd 0 ; seek from handle
+ .rename dd 0 ; rename file
+ .remove dd 0 ; remove file/dir
+ .create dd 0 ; create file/dir
+ .ioctl dd 0 ; extra calls if exists
+
+ ;---------------------------------------------;
+ ; FAT12 main info structure ;
+ ;---------------------------------------------;
+ struc fat12_data
{
- .disk_number db 0 ; which VFS disk number
- .root_dir dw 0 ; position of rootdir
- .fat_1 dd 0 ; position of fat1
- .fat_2 dd 0 ; position of fat2
- .data_area dw 0 ; position of dataarea
- .disk_size dd 0 ; total storage size
- .free_space dd 0 ; free space available
- .boot bootsector
+ .disk_number db 0 ; which VFS disk number
+ .root_dir dw 0 ; position of rootdir
+ .disk_size dd 0 ; total storage size
+ .free_space dd 0 ; free space available
+ .fat_1 dd 0 ; position of fat1
+ .fat_2 dd 0 ; position of fat2
+ .data_area dw 0 ; position of dataarea
+ .boot: times sizeof.bootsector db 0 ; copy of FAT12 bootsector
.dir_entries:
- times 16 * sizeof.dir_entry db 0 ; 512b dir entry buffer
- .fat_buffer: times 512 db 0 ; 512b FAT cluster info buffer
+ times 16 * sizeof.dir_entry db 0 ; 512b dir entry buffer
+ .fat_buffer: times 512 db 0 ; 512b FAT cluster info buffer
+ .foundfile:
+ times 1 * sizeof.search db 0 ; "DTA" like structure
+ .filehandles: ; "System File Table"
+ times 32 * sizeof.filehandle db 0 ; for now, max opened files is 32
}
+ virtual at 0 ; could use "at esi" instead
+ fat12_data fat12_data
+ sizeof.fat12_data = $-$$
+ end virtual
+
;---------------------------------------------;
; FAT12 bootsector structure ;
;---------------------------------------------;
.jumper db 0,0,0
.oem db 0,0,0,0,0,0,0,0
.sectorsize dw 0
- .sect_per_clust db 0
+ .sect_per_clust db 0
.reserved_sect dw 0 ; reserved sectors, 1 for bootsector.
.fats_per_drive db 0
.root_entries dw 0
.disk_id dd 0 ; random ident number on format.
.volume_label db 0,0,0,0,0,0,0,0,0,0,0
.filesystem db 0,0,0,0,0,0,0,0 ; "FAT12 " or "FAT16 "
- .code: times 448 db 0
+ .code: times 448 db 0
.boot_signature db 0,0 ; 0x55,0xAA
}
+ virtual at 0
+ bootsector bootsector
+ sizeof.bootsector = $-$$
+ end virtual
+
;---------------------------------------------;
; FAT12 directory entry structure ;
;---------------------------------------------;
- struct dir_entry
+ struc dir_entry
{
.filename db 0,0,0,0,0,0,0,0
.extension db 0,0,0
.filesize dd 0
}
+ virtual at 0
+ dir_entry dir_entry
+ sizeof.dir_entry = $-$$
+ end virtual
+
;---------------------------------------------;
; FAT12 directory entry for LFN ;
;---------------------------------------------;
- struct lnf_entry
+ struc lfn_entry
{
.order db 0 ; LFN entry in sequence, never 0x00 or 0xE5.
.namefirst dw 0,0,0,0,0 ; 5 first unicode (2byte) chars
virtual at 0
lfn_entry lfn_entry
- sizeof.lfn_entry = $
+ sizeof.lfn_entry = $-$$
end virtual
- virtual at 0
- dir_entry dir_entry
- sizeof.dir_entry = $
- end virtual
+ ;---------------------------------------------;
+ ; FAT12 file search/DTA structure ;
+ ;---------------------------------------------;
+ struc search
+ {
+ .searchname:
+ times 255 db 0 ; file search pattern.
+ .attribute db 0 ; search attribute.
+ .direntry dw 0 ; directory entry number, 0 based
+ .dircluster dw 0 ; starting cluster of dir, 0 root
+ .foundattrib db 0 ; attribute of matching file
+ .foundtime dw 0 ; file time
+ .founddate dw 0 ; file date
+ .foundsize dw 0 ; file size
+ }
virtual at 0
- bootsector bootsector
- sizeof.bootsector = $
+ search search
+ sizeof.search = $-$$
end virtual
+ ;---------------------------------------------;
+ ; FAT12 file-handle structure ;
+ ;---------------------------------------------;
+ struc filehandle
+ {
+ .handles db 0 ; reference count or or zero for unused
+ .mode db 0 ; open mode. 0=read, 1=write, 2=r/w.
+ .lfn_entry dw 0 ; file LFN directory entry position
+ .direntry dw 0 ; file directory entry position
+ .cluster dw 0 ; file first cluster
+ .attribute db 0 ; file attributes
+ .filetime dw 0 ; last modified time
+ .filedate dw 0 ; last modified date
+ .filesize dd 0 ; filesize
+ .position dd 0 ; R/W position in file
+ .clusterpos dw 0 ; cluster number of last cluster read
+ .shortname:
+ times 11 db 0 ; short name
+ .fullname:
+ times 255 db 0 ; the full LFN
+ }
+
virtual at 0
- disk disk
- sizeof.disk = $
+ filehandle filehandle
+ sizeof.filehandle = $-$$
end virtual
;------------------------------------------;
attribute_lfn = 0x0F ; attrb. byte value for LFN dir entry
-
-
-
-fd0: fat12 ; define fd0 data.. tmp example.
-
-; TODO, alloc memory for struct and keep pointer only.
-; ---------------
-;drive dd 0
-;mov edi, drive+fat12into.boot
-
;--------------------------------------------------------------;
; init_fat12 - detect if drive fs is fat12 and init ;
;--------------------------------------------------------------;
push eax
;...
- ;-----------------------------;
- ; calculate root location ;
- ;-----------------------------;
- xor eax, eax
- mov al, byte [fd0.boot.fats_per_drive]
- mul word [fd0.boot.sectors_per_fat]
- add ax, word [fd0.boot.reserved_sect]
- mov [fd0.root_dir], ax
+ ;-----------------------------;
+ ; calculate root location ;
+ ;-----------------------------;
+ xor eax, eax
+ mov al, byte [fd0.boot.fats_per_drive]
+ mul word [fd0.boot.sectors_per_fat]
+ add ax, word [fd0.boot.reserved_sect]
+ mov [fd0.root_dir], ax
-; working with
-;mov si, [drive]
-;mov ax, [si+fat12.boot.sectorssize]
+; working with
+;mov si, [drive]
+;mov ax, [si+fat12.boot.sectorssize]
- ; a bit more code here
+ ; a bit more code here
pop eax
ret
mov cx, 11
xor ax, ax ; return value start with null
.l1:
- add ax, byte [esi] ; add next char to sum
+ push cx
+ movzx cx, byte [esi] ; add next char to sum
+ add ax, cx
+ pop cx
shr ax, 1 ; shift sum right by 1
inc esi ; prepare for next character
loop .l1
- pop esi
+ pop esi
pop cx
ret
projects / BOS.git / blobdiff