kernel/vfs/vfs.asm

   1 ;----------------------------------------------------------;
   2 ; BOS kernel                Christoffer Bubach, 2012-2015. ;
   3 ;----------------------------------------------------------;
   4 ;                                                          ;
   5 ;        VFS handling all devices and filesystems.         ;
   6 ;                                                          ;
   7 ;----------------------------------------------------------;
   8
   9
  10     ; file handles need to be dword, where the high
  11     ; word contains drive number, and the low word
  12     ; is the drive/FS specific handle. limits FS to
  13     ; a max of 65535 opened files. should be alright. ;)
  14
  15
  16     ;---------------------------------------------;
  17     ;   VFS main structure                        ;
  18     ;---------------------------------------------;
  19     struc VFS
  20     {
  21         .number:                times 255      db 0   ; 00=FD, 0x10=HD, 0x60=CD, 0x80=VD, 90=RD, B0=ND
  22         .storage:
  23             times 255 * sizeof.VFS_storage     db 0   ; storage driver structure
  24         .filesystem:
  25             times 255 * sizeof.VFS_filesystem  db 0   ; filesystem driver structure
  26         .mounted                               db 0   ; 1/0 switch if mounted
  27         .current_path:          times 255      db 0   ; drive opened path (increase max path size?)
  28     }
  29
  30     virtual at 0                                      ; could use "at esi" instead
  31         VFS VFS
  32         sizeof.VFS = $-$$
  33     end virtual
  34
  35     ;---------------------------------------------;
  36     ;   VFS storage driver structure              ;
  37     ;---------------------------------------------;
  38     struc VFS_storage
  39     {
  40         .data_pointer         dd  0                   ; internal driver data
  41         .init                 dd  0                   ; pointer to init
  42         .deinit               dd  0                   ; remove driver
  43         .read                 dd  0                   ; read device
  44         .write                dd  0                   ; write device
  45         .ioctl                dd  0                   ; handle device specific extras
  46     }
  47
  48     virtual at 0
  49         VFS_storage VFS_storage
  50         sizeof.VFS_storage = $-$$
  51     end virtual
  52
  53     ;---------------------------------------------;
  54     ;   VFS filesystem structure                  ;
  55     ;---------------------------------------------;
  56     struc VFS_filesystem
  57     {
  58         .data_pointer         dd  0                   ; internal driver data
  59         .init                 dd  0                   ; pointer to init
  60         .deinit               dd  0                   ; remove driver
  61         .format               dd  0                   ; format drive
  62         .mount                dd  0                   ; mount drive
  63         .unmount              dd  0                   ; unmount drive
  64         .find                 dd  0                   ; find file
  65         .findnext             dd  0                   ; get next match
  66         .open                 dd  0                   ; open file, get handle
  67         .read                 dd  0                   ; read file from handle
  68         .write                dd  0                   ; write file from handle
  69         .seek                 dd  0                   ; seek from handle
  70         .remove               dd  0                   ; remove file/dir
  71         .create               dd  0                   ; create file/dir
  72         .ioctl                dd  0                   ; extra calls if exists
  73     }
  74
  75     virtual at 0
  76         VFS_filesystem VFS_filesystem
  77         sizeof.VFS_filesystem = $-$$
  78     end virtual
  79
  80     ;---------------------------------------------;
  81     ;   VFS structure pointer                     ;
  82     ;---------------------------------------------;
  83     VFS_structure             dd 0
  84
  85
  86 ;--------------------------------------------------------------;
  87 ;   init_vfs  -  detect connected drives                       ;
  88 ;--------------------------------------------------------------;
  89 ;                                                              ;
  90 ;       out:                    cf = set if failed             ;
  91 ;                                                              ;
  92 ;--------------------------------------------------------------;
  93 init_vfs:
  94         push   eax
  95         push   ebx
  96
  97         mov    ebx, sizeof.VFS                        ; allocate structure size
  98         call   allocate_mem
  99         cmp    eax, 0
 100         jne    .ok
 101         stc                                           ; if error, set carry
 102         mov    ebx, 0
 103
 104     .ok:
 105         mov    dword [VFS_structure], ebx
 106
 107         pop    ebx
 108         pop    eax
 109         ret
 110
 111 ;--------------------------------------------------------------;
 112 ;   add_media  -  add media driver                             ;
 113 ;--------------------------------------------------------------;
 114 ;                                                              ;
 115 ;       in:  reg = pointer to VFS drive info                   ;
 116 ;                                                              ;
 117 ;       out: reg = pointer to struct(s) if FAT12 found         ;
 118 ;                                                              ;
 119 ;--------------------------------------------------------------;
 120 add_media:
 121         push   eax
 122         ;...
 123         pop    eax
 124         ret
 125
 126 ;--------------------------------------------------------------;
 127 ;   add_fs  -  add filesystem driver                           ;
 128 ;--------------------------------------------------------------;
 129 ;                                                              ;
 130 ;       in:  reg = pointer to VFS drive info                   ;
 131 ;                                                              ;
 132 ;       out: reg = pointer to struct(s) if FAT12 found         ;
 133 ;                                                              ;
 134 ;--------------------------------------------------------------;
 135 add_fs:
 136         push   eax
 137         ;...
 138         pop    eax
 139         ret