WebSVN – Kolibri OS – Diff – /kernel/trunk/blkdev/disk.inc


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;;                                                              ;;
;; Copyright (C) KolibriOS team 2011. All rights reserved.      ;;
;; Distributed under terms of the GNU General Public License    ;;
;;                                                              ;;
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$Revision: 2288 $
 
; =============================================================================
; ================================= Constants =================================
; =============================================================================
; Error codes for callback functions.
DISK_STATUS_OK              = 0 ; success
DISK_STATUS_GENERAL_ERROR   = -1; if no other code is suitable
DISK_STATUS_INVALID_CALL    = 1 ; invalid input parameters
DISK_STATUS_NO_MEDIA        = 2 ; no media present
DISK_STATUS_END_OF_MEDIA    = 3 ; end of media while reading/writing data
; Driver flags. Represent bits in DISK.DriverFlags.
DISK_NO_INSERT_NOTIFICATION = 1
; Media flags. Represent bits in DISKMEDIAINFO.Flags.
DISK_MEDIA_READONLY = 1
 
; If too many partitions are detected,there is probably an error on the disk.
; 256 partitions should be enough for any reasonable use.
; Also, the same number is limiting the number of MBRs to process; if
; too many MBRs are visible,there probably is a loop in the MBR structure.
MAX_NUM_PARTITIONS = 256
 
; =============================================================================
; ================================ Structures =================================
; =============================================================================
; This structure defines all callback functions for working with the physical
; device. They are implemented by a driver. Objects with this structure reside
; in a driver.
struct DISKFUNC
.strucsize      dd      ?
; Size of the structure. This field is intended for possible extensions of
; this structure. If a new function is added to this structure and a driver
; implements an old version, the caller can detect this by checking .strucsize,
; so the driver remains compatible.
.close          dd      ?
; The pointer to the function which frees all driver-specific resources for
; the disk.
; Optional, may be NULL.
; void close(void* userdata);
.closemedia     dd      ?
; The pointer to the function which informs the driver that the kernel has
; finished all processing with the current media. If media is removed, the
; driver should decline all requests to that media with DISK_STATUS_NO_MEDIA,
; even if new media is inserted, until this function is called. If media is
; removed, a new call to 'disk_media_changed' is not allowed until this
; function is called.
; Optional, may be NULL (if media is not removable).
; void closemedia(void* userdata);
.querymedia     dd      ?
; The pointer to the function which determines capabilities of the media.
; int querymedia(void* userdata, DISKMEDIAINFO* info);
; Return value: one of DISK_STATUS_*
.read           dd      ?
; The pointer to the function which reads data from the device.
; int read(void* userdata, void* buffer, __int64 startsector, int* numsectors);
; input: *numsectors = number of sectors to read
; output: *numsectors = number of sectors which were successfully read
; Return value: one of DISK_STATUS_*
.write          dd      ?
; The pointer to the function which writes data to the device.
; Optional, may be NULL.
; int write(void* userdata, void* buffer, __int64 startsector, int* numsectors);
; input: *numsectors = number of sectors to write
; output: *numsectors = number of sectors which were successfully written
; Return value: one of DISK_STATUS_*
.flush          dd      ?
; The pointer to the function which flushes the internal device cache.
; Optional, may be NULL.
; int flush(void* userdata);
; Return value: one of DISK_STATUS_*
; Note that read/write are called by the cache manager, so a driver should not
; create a software cache. This function is implemented for flushing a hardware
; cache, if it exists.
.adjust_cache_size      dd      ?
; The pointer to the function which returns the cache size for this device.
; Optional, may be NULL.
; unsigned int adjust_cache_size(unsigned int suggested_size);
; Return value: 0 = disable cache, otherwise = used cache size in bytes.
ends
 
; This structure holds information on a medium.
; Objects with this structure are allocated by the kernel as a part of the DISK
; structure and are filled by a driver in the 'querymedia' callback.
struct DISKMEDIAINFO
.Flags          dd      ?
; Combination of DISK_MEDIA_* bits.
.SectorSize     dd      ?
; Size of the sector.
.Capacity       dq      ?
; Size of the media in sectors.
ends
 
; This structure represents the disk cache. To follow the old implementation,
; there are two distinct caches for a disk, one for "system" data,and the other
; for "application" data.
struct DISKCACHE
.Lock           MUTEX
; Lock to protect the cache.
; The following fields are inherited from data32.inc:cache_ideX.
.pointer     rd 1
.data_size   rd 1   ; not use
.data        rd 1
.sad_size    rd 1
.search_start       rd 1
ends
 
; This structure represents a disk device and its media for the kernel.
; This structure is allocated by the kernel in the 'disk_add' function,
; freed in the 'disk_dereference' function.
struct DISK
; Fields of disk object
.Next           dd      ?
.Prev           dd      ?
; All disk devices are linked in one list with these two fields.
; Head of the list is the 'disk_list' variable.
.Functions      dd      ?
; Pointer to the 'DISKFUNC' structure with driver functions.
.Name           dd      ?
; Pointer to the string used for accesses through the global filesystem.
.UserData       dd      ?
; This field is passed to all callback functions so a driver can decide which
; physical device is addressed.
.DriverFlags    dd      ?
; Bitfield. Currently only DISK_NO_INSERT_NOTIFICATION bit is defined.
; If it is set, the driver will never issue 'disk_media_changed' notification
; with argument set to true, so the kernel must try to detect media during
; requests from the file system.
.RefCount       dd      ?
; Count of active references to this structure. One reference is kept during
; the lifetime of the structure between 'disk_add' and 'disk_del'.
; Another reference is taken during any filesystem operation for this disk.
; One reference is added if media is inserted.
; The structure is destroyed when the reference count decrements to zero:
; this usually occurs in 'disk_del', but can be delayed to the end of last
; filesystem operation, if one is active.
.MediaLock              MUTEX
; Lock to protect the MEDIA structure. See the description after
; 'disk_list_mutex' for the locking strategy.
; Fields of media object
.MediaInserted          db      ?
; 0 if media is not inserted, nonzero otherwise.
.MediaUsed              db      ?
; 0 if media fields are not used, nonzero otherwise. If .MediaRefCount is
; nonzero, this field is nonzero too; however, when .MediaRefCount goes
; to zero, there is some time interval during which media object is still used.
                align 4
; The following fields are not valid unless either .MediaInserted is nonzero
; or they are accessed from a code which has obtained the reference when
; .MediaInserted was nonzero.
.MediaRefCount          dd      ?
; Count of active references to the media object. One reference is kept during
; the lifetime of the media between two calls to 'disk_media_changed'.
; Another reference is taken during any filesystem operation for this media.
; The callback 'closemedia' is called when the reference count decrements to
; zero: this usually occurs in 'disk_media_changed', but can be delayed to the
; end of the last filesystem operation, if one is active.
.MediaInfo              DISKMEDIAINFO
; This field keeps information on the current media.
.NumPartitions  dd      ?
; Number of partitions on this media.
.Partitions     dd      ?
; Pointer to array of .NumPartitions pointers to PARTITION structures.
.cache_size     dd      ?
; inherited from cache_ideX_size
.SysCache       DISKCACHE
.AppCache       DISKCACHE
; Two caches for the disk.
ends
 
; This structure represents one partition for the kernel. This is a base
; template, the actual contents after common fields is determined by the
; file system code for this partition.
struct PARTITION
.FirstSector    dq      ?
; First sector of the partition.
.Length         dq      ?
; Length of the partition in sectors.
.Disk           dd      ?
; Pointer to parent DISK structure.
.FSUserFunctions        dd      ?
; Handlers for the sysfunction 70h. This field is a pointer to the following
; array. The first dword is a number of supported subfunctions, other dwords
; point to handlers of corresponding subfunctions.
; This field is 0 if file system is not recognized.
; ...fs-specific data may follow...
ends
 
; This is an external structure, it represents an entry in the partition table.
struct PARTITION_TABLE_ENTRY
.Bootable       db      ?
; 80h = bootable partition, 0 = non-bootable partition, other values = invalid
.FirstHead      db      ?
.FirstSector    db      ?
.FirstTrack     db      ?
; Coordinates of first sector in CHS.
.Type           db      ?
; Partition type, one of predefined constants. 0 = empty, several types denote
; extended partition (see process_partition_table_entry), we are not interested
; in other values.
.LastHead       db      ?
.LastSector     db      ?
.LastTrack      db      ?
; Coordinates of last sector in CHS.
.FirstAbsSector dd      ?
; Coordinate of first sector in LBA.
.Length         dd      ?
; Length of the partition in sectors.
ends
 
; =============================================================================
; ================================ Global data ================================
; =============================================================================
iglobal
; The pseudo-item for the list of all DISK structures.
; Initialized to the empty list.
disk_list:
        dd      disk_list
        dd      disk_list
endg
uglobal
; This mutex guards all operations with the global list of DISK structures.
disk_list_mutex MUTEX
; * There are two dependent objects, a disk and a media. In the simplest case,
;   disk and media are both non-removable. However, in the general case both
;   can be removed at any time, simultaneously or only media,and this makes things
;   complicated.
; * For efficiency, both disk and media objects are located in the one
;   structure named DISK. However, logically they are different.
; * The following operations use data of disk object: adding (disk_add);
;   deleting (disk_del); filesystem (fs_lfn which eventually calls
;   dyndisk_handler or dyndisk_enum_root).
; * The following operations use data of media object: adding/removing
;   (disk_media_changed); filesystem (fs_lfn which eventually calls
;   dyndisk_handler; dyndisk_enum_root doesn't work with media).
; * Notifications disk_add, disk_media_changed, disk_del are synchronized
;   between themselves, this is a requirement for the driver. However, file
;   system operations are asynchronous, can be issued at any time by any
;   thread.
; * We must prevent a situation when a filesystem operation thinks that the
;   object is still valid but in fact the notification has destroyed the
;   object. So we keep a reference counter for both disk and media and destroy
;   the object when this counter goes to zero.
; * The driver must know when it is safe to free driver-allocated resources.
;   The object can be alive even after death notification has completed.
;   We use special callbacks to satisfy both assertions: 'close' for the disk
;   and 'closemedia' for the media. The destruction of the object includes
;   calling the corresponding callback.
; * Each filesystem operation keeps one reference for the disk and one
;   reference for the media. Notification disk_del forces notification on the
;   media death, so the reference counter for the disk is always not less than
;   the reference counter for the media.
; * Two operations "get the object" and "increment the reference counter" can
;   not be done simultaneously. We use a mutex to guard the consistency here.
;   It must be a part of the container for the object, so that this mutex can
;   be acquired as a part of getting the object from the container. The
;   container for disk object is the global list, and this list is guarded by
;   'disk_list_mutex'. The container for media object is the disk object, and
;   the corresponding mutex is DISK.MediaLock.
; * Notifications do not change the data of objects, they can only remove
;   objects. Thus we don't need another synchronization at this level. If two
;   filesystem operations are referencing the same filesystem data, this is
;   better resolved at the level of the filesystem.
endg
 
iglobal
; The function 'disk_scan_partitions' needs three 512-byte buffers for
; MBR, bootsector and fs-temporary sector data. It can not use the static
; buffers always, since it can be called for two or more disks in parallel.
; However, this case is not typical. We reserve three static 512-byte buffers
; and a flag that these buffers are currently used. If 'disk_scan_partitions'
; detects that the buffers are currently used, it allocates buffers from the
; heap.
; The flag is implemented as a global dword variable. When the static buffers
; are not used, the value is -1. When the static buffers are used, the value
; is normally 0 and temporarily can become greater. The function increments
; this value. If the resulting value is zero, it uses the buffers and
; decrements the value when the job is done. Otherwise, it immediately
; decrements the value and uses buffers from the heap, allocated in the
; beginning and freed in the end.
partition_buffer_users  dd      -1
endg
uglobal
; The static buffers for MBR, bootsector and fs-temporary sector data.
align 16
mbr_buffer      rb      512
bootsect_buffer rb      512
fs_tmp_buffer   rb      512
endg
 
iglobal
; This is the array of default implementations of driver callbacks.
; Same as DRIVERFUNC structure except for the first field; all functions must
; have the default implementations.
align 4
disk_default_callbacks:
        dd      disk_default_close
        dd      disk_default_closemedia
        dd      disk_default_querymedia
        dd      disk_default_read
        dd      disk_default_write
        dd      disk_default_flush
        dd      disk_default_adjust_cache_size
endg
 
; =============================================================================
; ================================= Functions =================================
; =============================================================================
 
; This function registers a disk device.
; This includes:
; - allocating an internal structure describing this device;
; - registering this structure in the global filesystem.
; The function initializes the disk as if there is no media. If a media is
; present, the function 'disk_media_changed' should be called after this
; function succeeds.
; Parameters:
; [esp+4] = pointer to DISKFUNC structure with the callbacks
; [esp+8] = pointer to name (ASCIIZ string)
; [esp+12] = userdata to be passed to the callbacks as is.
; [esp+16] = flags, bitfield. Currently only DISK_NO_INSERT_NOTIFICATION bit
;            is defined.
; Return value:
; NULL = operation has failed
; non-NULL = handle of the disk. This handle can be used
; in the operations with other Disk* functions.
; The handle is the pointer to the internal structure DISK.
disk_add:
        push    ebx esi         ; save used registers to be stdcall
; 1. Allocate the DISK structure.
; 1a. Call the heap manager.
        push    sizeof.DISK
        pop     eax
        call    malloc
; 1b. Check the result. If allocation failed, return (go to 9) with eax = 0.
        test    eax, eax
        jz      .nothing
; 2. Copy the disk name to the DISK structure.
; 2a. Get length of the name, including the terminating zero.
        mov     ebx, [esp+8+8]  ; ebx = pointer to name
        push    eax             ; save allocated pointer to DISK
        xor     eax, eax        ; the argument of malloc() is in eax
@@:
        inc     eax
        cmp     byte [ebx+eax-1], 0
        jnz     @b
; 2b. Call the heap manager.
        call    malloc
; 2c. Check the result. If allocation failed, go to 7.
        pop     esi             ; restore allocated pointer to DISK
        test    eax, eax
        jz      .free
; 2d. Store the allocated pointer to the DISK structure.
        mov     [esi+DISK.Name], eax
; 2e. Copy the name.
@@:
        mov     dl, [ebx]
        mov     [eax], dl
        inc     ebx
        inc     eax
        test    dl, dl
        jnz     @b
; 3. Copy other arguments of the function to the DISK structure.
        mov     eax, [esp+4+8]
        mov     [esi+DISK.Functions], eax
        mov     eax, [esp+12+8]
        mov     [esi+DISK.UserData], eax
        mov     eax, [esp+16+8]
        mov     [esi+DISK.DriverFlags], eax
; 4. Initialize other fields of the DISK structure.
; Media is not inserted, reference counter is 1.
        lea     ecx, [esi+DISK.MediaLock]
        call    mutex_init
        xor     eax, eax
        mov     dword [esi+DISK.MediaInserted], eax
        inc     eax
        mov     [esi+DISK.RefCount], eax
; The DISK structure is initialized.
; 5. Insert the new structure to the global list.
; 5a. Acquire the mutex.
        mov     ecx, disk_list_mutex
        call    mutex_lock
; 5b. Insert item to the tail of double-linked list.
        mov     edx, disk_list
        list_add_tail esi, edx     ;esi= new edx= list head
; 5c. Release the mutex.
        call    mutex_unlock
; 6. Return with eax = pointer to DISK.
        xchg    eax, esi
        jmp     .nothing
.free:
; Memory allocation for DISK structure succeeded, but for disk name failed.
; 7. Free the DISK structure.
        xchg    eax, esi
        call    free
; 8. Return with eax = 0.
        xor     eax, eax
.nothing:
; 9. Return.
        pop     esi ebx         ; restore used registers to be stdcall
        ret     16              ; purge 4 dword arguments to be stdcall
 
; This function deletes a disk device from the global filesystem.
; This includes:
; - removing a media including all partitions;
; - deleting this structure from the global filesystem;
; - dereferencing the DISK structure and possibly destroying it.
; Parameters:
; [esp+4] = handle of the disk, i.e. the pointer to the DISK structure.
; Return value: none.
disk_del:
        push    esi         ; save used registers to be stdcall
; 1. Force media to be removed. If the media is already removed, the
; call does nothing.
        mov     esi, [esp+4+8]  ; esi = handle of the disk
        stdcall disk_media_changed, esi, 0
; 2. Delete the structure from the global list.
; 2a. Acquire the mutex.
        mov     ecx, disk_list_mutex
        call    mutex_lock
; 2b. Delete item from double-linked list.
        mov     eax, [esi+DISK.Next]
        mov     edx, [esi+DISK.Prev]
        mov     [eax+DISK.Prev], edx
        mov     [edx+DISK.Next], eax
; 2c. Release the mutex.
        call    mutex_unlock
; 3. The structure still has one reference created in disk_add. Remove this
; reference. If there are no other references, disk_dereference will free the
; structure.
        call    disk_dereference
; 4. Return.
        pop     esi             ; restore used registers to be stdcall
        ret     4               ; purge 1 dword argument to be stdcall
 
; This is an internal function which removes a previously obtained reference
; to the disk. If this is the last reference, this function lets the driver
; finalize all associated data, and afterwards frees the DISK structure.
; esi = pointer to DISK structure
disk_dereference:
; 1. Decrement reference counter. Use atomic operation to correctly handle
; possible simultaneous calls.
        lock dec [esi+DISK.RefCount]
; 2. If the result is nonzero, there are other references, so nothing to do.
; In this case, return (go to 4).
        jnz     .nothing
; 3. If we are here, we just removed the last reference and must destroy the
; disk object.
; 3a. Call the driver.
        mov     al, DISKFUNC.close
        stdcall disk_call_driver
; 3b. Free the structure.
        xchg    eax, esi
        call    free
; 4. Return.
.nothing:
        ret
 
; This is an internal function which removes a previously obtained reference
; to the media. If this is the last reference, this function calls 'closemedia'
; callback to signal the driver that the processing has finished and it is safe
; to inform about a new media.
; esi = pointer to DISK structure
disk_media_dereference:
; 1. Decrement reference counter. Use atomic operation to correctly handle
; possible simultaneous calls.
        lock dec [esi+DISK.MediaRefCount]
; 2. If the result is nonzero, there are other references, so nothing to do.
; In this case, return (go to 4).
        jnz     .nothing
; 3. If we are here, we just removed the last reference and must destroy the
; media object.
; Note that the same place inside the DISK structure is reused for all media
; objects, so we must guarantee that reusing does not happen while freeing.
; Reusing is only possible when someone processes a new media. There are two
; mutually exclusive variants:
; * driver issues media insert notifications (DISK_NO_INSERT_NOTIFICATION bit
;   in DISK.DriverFlags is not set). In this case, we require from the driver
;   that such notification (except for the first one) can occur only after a
;   call to 'closemedia' callback.
; * driver does not issue media insert notifications. In this case, the kernel
;   itself must sometimes check whether media is inserted. We have the flag
;   DISK.MediaUsed, visible to the kernel. This flag signals to the other parts
;   of kernel that the way is free.
; In the first case other parts of the kernel do not use DISK.MediaUsed, so it
; does not matter when this flag is cleared. In the second case this flag must
; be cleared after all other actions, including call to 'closemedia'.
; 3a. Free all partitions.
        push    esi edi
        mov     edi, [esi+DISK.NumPartitions]
        mov     esi, [esi+DISK.Partitions]
        test    edi, edi
        jz      .nofree
.freeloop:
        lodsd
        call    free
        dec     edi
        jnz     .freeloop
.nofree:
        pop     edi esi
; 3b. Free the cache.
        call    disk_free_cache
; 3c. Call the driver.
        mov     al, DISKFUNC.closemedia
        stdcall disk_call_driver
; 3d. Clear the flag.
        mov     [esi+DISK.MediaUsed], 0
.nothing:
        ret
 
; This function is called by the driver and informs the kernel that the media
; has changed. If the media is non-removable, it is called exactly once
; immediately after 'disk_add' and once from 'disk_del'.
; Parameters:
; [esp+4] = handle of the disk, i.e. the pointer to the DISK structure.
; [esp+8] = new status of the media: zero = no media, nonzero = media inserted.
disk_media_changed:
        push    ebx esi edi             ; save used registers to be stdcall
; 1. Remove the existing media, if it is present.
        mov     esi, [esp+4+12]         ; esi = pointer to DISK
; 1a. Check whether it is present. Since DISK.MediaInserted is changed only
; in this function and calls to this function are synchronized, no lock is
; required for checking.
        cmp     [esi+DISK.MediaInserted], 0
        jz      .noremove
; We really need to remove the media.
; 1b. Acquire mutex.
        lea     ecx, [esi+DISK.MediaLock]
        call    mutex_lock
; 1c. Clear the flag.
        mov     [esi+DISK.MediaInserted], 0
; 1d. Release mutex.
        call    mutex_unlock
; 1e. Remove the "lifetime" reference and possibly destroy the structure.
        call    disk_media_dereference
.noremove:
; 2. Test whether there is new media.
        cmp     dword [esp+8+12], 0
        jz      .noinsert
; Yep, there is.
; 3. Process the new media. We assume that all media fields are available to
; use, see comments in 'disk_media_dereference' (this covers using by previous
; media referencers) and note that calls to this function are synchronized
; (this covers using by new media referencers).
; 3a. Call the 'querymedia' callback.
; .Flags are set to zero for possible future extensions.
        lea     edx, [esi+DISK.MediaInfo]
        and     [edx+DISKMEDIAINFO.Flags], 0
        mov     al, DISKFUNC.querymedia
        stdcall disk_call_driver, edx
; 3b. Check the result of the callback. Abort if it failed.
        test    eax, eax
        jnz     .noinsert
; 3c. Allocate the cache unless disabled by the driver. Abort if failed.
        call    disk_init_cache
        test    al, al
        jz      .noinsert
; 3d. Acquire the lifetime reference for the media object.
        inc     [esi+DISK.MediaRefCount]
; 3e. Scan for partitions. Ignore result; the list of partitions is valid even
; on errors.
        call    disk_scan_partitions
; 3f. Media is inserted and available for use.
        inc     [esi+DISK.MediaInserted]
.noinsert:
; 4. Return.
        pop     edi esi ebx             ; restore used registers to be stdcall
        ret     8                       ; purge 2 dword arguments to be stdcall
 
; This function is a thunk for all functions of a disk driver.
; It checks whether the referenced function is implemented in the driver.
; If so, this function jumps to the function in the driver.
; Otherwise, it jumps to the default implementation.
; al = offset of function in the DISKFUNC structure;
; esi = pointer to the DISK structure;
; stack is the same as for the corresponding function except that the
; first parameter (void* userdata) is prepended automatically.
disk_call_driver:
        movzx   eax, al ; eax = offset of function in the DISKFUNC structure
; 1. Prepend the first argument to the stack.
        pop     ecx     ; ecx = return address
        push    [esi+DISK.UserData]     ; add argument
        push    ecx     ; save return address
; 2. Check that the required function is inside the table. If not, go to 5.
        mov     ecx, [esi+DISK.Functions]
        cmp     eax, [ecx+DISKFUNC.strucsize]
        jae     .default
; 3. Check that the required function is implemented. If not, go to 5.
        mov     ecx, [ecx+eax]
        test    ecx, ecx
        jz      .default
; 4. Jump to the required function.
        jmp     ecx
.default:
; 5. Driver does not implement the required function; use default implementation.
        jmp     dword [disk_default_callbacks+eax-4]
 
; The default implementation of DISKFUNC.querymedia.
disk_default_querymedia:
        push    DISK_STATUS_INVALID_CALL
        pop     eax
        ret     8
 
; The default implementation of DISKFUNC.read and DISKFUNC.write.
disk_default_read:
disk_default_write:
        push    DISK_STATUS_INVALID_CALL
        pop     eax
        ret     20
 
; The default implementation of DISKFUNC.close, DISKFUNC.closemedia and
; DISKFUNC.flush.
disk_default_close:
disk_default_closemedia:
disk_default_flush:
        xor     eax, eax
        ret     4
 
; The default implementation of DISKFUNC.adjust_cache_size.
disk_default_adjust_cache_size:
        mov     eax, [esp+4]
        ret     4
 
; This is an internal function called from 'disk_media_changed' when a new media
; is detected. It creates the list of partitions for the media.
; If media is not partitioned, then the list consists of one partition which
; covers all the media.
; esi = pointer to the DISK structure.
disk_scan_partitions:
; 1. Initialize .NumPartitions and .Partitions fields as zeros: empty list.
        and     [esi+DISK.NumPartitions], 0
        and     [esi+DISK.Partitions], 0
; 2. Currently we can work only with 512-bytes sectors. Check this restriction.
; The only exception is 2048-bytes CD/DVD, but they are not supported yet by
; this code.
        cmp     [esi+DISK.MediaInfo.SectorSize], 512
        jz      .doscan
        DEBUGF 1,'K : sector size is %d, only 512 is supported\n',[esi+DISK.MediaInfo.SectorSize]
        ret
.doscan:
; 3. Acquire the buffer for MBR and bootsector tests. See the comment before
; the 'partition_buffer_users' variable.
        mov     ebx, mbr_buffer         ; assume the global buffer is free
        lock inc [partition_buffer_users]
        jz      .buffer_acquired        ; yes, it is free
        lock dec [partition_buffer_users]       ; no, we must allocate
        stdcall kernel_alloc, 512*3
        test    eax, eax
        jz      .nothing
        xchg    eax, ebx
.buffer_acquired:
; MBR/EBRs are organized in the chain. We use a loop over MBR/EBRs, but no
; more than MAX_NUM_PARTITION times.
; 4. Prepare things for the loop.
; ebp will hold the sector number for current MBR/EBR.
; [esp] will hold the sector number for current extended partition, if there
; is one.
; [esp+4] will hold the counter that prevents long loops.
        push    ebp             ; save ebp
        push    MAX_NUM_PARTITIONS      ; the counter of max MBRs to process
        xor     ebp, ebp        ; start from sector zero
        push    ebp             ; no extended partition yet
.new_mbr:
; 5. Read the current sector.
; Note that 'read' callback operates with 64-bit sector numbers, so we must
; push additional zero as a high dword of sector number.
        mov     al, DISKFUNC.read
        push    1
        stdcall disk_call_driver, ebx, ebp, 0, esp
        pop     ecx
; 6. If the read has failed, abort the loop.
        dec     ecx
        jnz     .mbr_failed
; 7. Check the MBR/EBR signature. If it is wrong, abort the loop.
; Soon we will access the partition table which starts at ebx+0x1BE,
; so we can fill its address right now. If we do it now, then the addressing
; [ecx+0x40] is shorter than [ebx+0x1fe]: one-byte offset vs 4-bytes offset.
        lea     ecx, [ebx+0x1be]        ; ecx -> partition table
        cmp     word [ecx+0x40], 0xaa55
        jnz     .mbr_failed
; 8. The MBR is treated differently from EBRs. For MBR we additionally need to
; execute step 9 and possibly step 10.
        test    ebp, ebp
        jnz     .mbr
; The partition table can be present or not present. In the first case, we just
; read the MBR. In the second case, we just read the bootsector for a
; filesystem.
; The following algorithm is used to distinguish between these cases.
; A. If at least one entry of the partition table is invalid, this is
;    a bootsector. See the description of 'is_partition_table_entry' for
;    definition of validity.
; B. If all entries are empty (filesystem type field is zero) and the first
;    byte is jmp opcode (0EBh or 0E9h), this is a bootsector which happens to
;    have zeros in the place of partition table.
; C. Otherwise, this is an MBR.
; 9. Test for MBR vs bootsector.
; 9a. Check entries. If any is invalid, go to 10 (rule A).
        call    is_partition_table_entry
        jc      .notmbr
        add     ecx, 10h
        call    is_partition_table_entry
        jc      .notmbr
        add     ecx, 10h
        call    is_partition_table_entry
        jc      .notmbr
        add     ecx, 10h
        call    is_partition_table_entry
        jc      .notmbr
; 9b. Check types of the entries. If at least one is nonzero, go to 11 (rule C).
        mov     al, [ecx-30h+PARTITION_TABLE_ENTRY.Type]
        or      al, [ecx-20h+PARTITION_TABLE_ENTRY.Type]
        or      al, [ecx-10h+PARTITION_TABLE_ENTRY.Type]
        or      al, [ecx+PARTITION_TABLE_ENTRY.Type]
        jnz     .mbr
; 9c. Empty partition table or bootsector with many zeroes? (rule B)
        cmp     byte [ebx], 0EBh
        jz      .notmbr
        cmp     byte [ebx], 0E9h
        jnz     .mbr
.notmbr:
; 10. This is not an  MBR. The media is not partitioned. Create one partition
; which covers all the media and abort the loop.
        stdcall disk_add_partition, 0, 0, \
                dword [esi+DISK.MediaInfo.Capacity], dword [esi+DISK.MediaInfo.Capacity+4]
        jmp     .done
.mbr:
; 11. Process all entries of the new MBR/EBR
        lea     ecx, [ebx+0x1be]        ; ecx -> partition table
        push    0       ; assume no extended partition
        call    process_partition_table_entry
        add     ecx, 10h
        call    process_partition_table_entry
        add     ecx, 10h
        call    process_partition_table_entry
        add     ecx, 10h
        call    process_partition_table_entry
        pop     ebp
; 12. Test whether we found a new EBR and should continue the loop.
; 12a. If there was no next EBR, return.
        test    ebp, ebp
        jz      .done
; Ok, we have EBR.
; 12b. EBRs addresses are relative to the start of extended partition.
; For simplicity, just abort if an 32-bit overflow occurs; large disks
; are most likely partitioned with GPT, not MBR scheme, since the precise
; calculation here would increase limit just twice at the price of big
; compatibility problems.
        pop     eax     ; load extended partition
        add     ebp, eax
        jc      .mbr_failed
; 12c. If extended partition has not yet started, start it.
        test    eax, eax
        jnz     @f
        mov     eax, ebp
@@:
; 12c. If the limit is not exceeded, continue the loop.
        dec     dword [esp]
        push    eax     ; store extended partition
        jnz     .new_mbr
.mbr_failed:
.done:
; 13. Cleanup after the loop.
        pop     eax     ; not important anymore
        pop     eax     ; not important anymore
        pop     ebp     ; restore ebp
; 14. Release the buffer.
; 14a. Test whether it is the global buffer or we have allocated it.
        cmp     ebx, mbr_buffer
        jz      .release_partition_buffer
; 14b. If we have allocated it, free it.
        xchg    eax, ebx
        call    free
        jmp     .nothing
; 14c. Otherwise, release reference.
.release_partition_buffer:
        lock dec [partition_buffer_users]
.nothing:
; 15. Return.
        ret
 
; This is an internal function called from disk_scan_partitions. It checks
; whether the entry pointed to by ecx is a valid entry of partition table.
; The entry is valid if the first byte is 0 or 80h, the first sector plus the
; length is less than twice the size of media. Multiplication by two is
; required since the size mentioned in the partition table can be slightly
; greater than the real size.
is_partition_table_entry:
; 1. Check .Bootable field.
        mov     al, [ecx+PARTITION_TABLE_ENTRY.Bootable]
        and     al, 7Fh
        jnz     .invalid
; 3. Calculate first sector + length. Note that .FirstAbsSector is relative
; to the MBR/EBR, so the real sum is ebp + .FirstAbsSector + .Length.
        mov     eax, ebp
        xor     edx, edx
        add     eax, [ecx+PARTITION_TABLE_ENTRY.FirstAbsSector]
        adc     edx, 0
        add     eax, [ecx+PARTITION_TABLE_ENTRY.Length]
        adc     edx, 0
; 4. Divide by two.
        shr     edx, 1
        rcr     eax, 1
; 5. Compare with capacity. If the subtraction (edx:eax) - .Capacity does not
; overflow, this is bad.
        sub     eax, dword [esi+DISK.MediaInfo.Capacity]
        sbb     edx, dword [esi+DISK.MediaInfo.Capacity+4]
        jnc     .invalid
.valid:
; 5. Return success: CF is cleared.
        clc
        ret
.invalid:
; 6. Return fail: CF is set.
        stc
        ret
 
; This is an internal function called from disk_scan_partitions. It processes
; the entry pointed to by ecx.
; * If the entry is invalid, just ignore this entry.
; * If the type is zero, just ignore this entry.
; * If the type is one of types for extended partition, store the address
;   of this partition as the new MBR in [esp+4].
; * Otherwise, add the partition to the list of partitions for this disk.
;   We don't use the type from the entry to identify the file system;
;   fs-specific checks do this more reliably.
process_partition_table_entry:
; 1. Check for valid entry. If invalid, return (go to 5).
        call    is_partition_table_entry
        jc      .nothing
; 2. Check for empty entry. If invalid, return (go to 5).
        mov     al, [ecx+PARTITION_TABLE_ENTRY.Type]
        test    al, al
        jz      .nothing
; 3. Check for extended partition. If extended, go to 6.
irp type,\
    0x05,\                 ; DOS: extended partition
    0x0f,\                 ; WIN95: extended partition, LBA-mapped
    0xc5,\                 ; DRDOS/secured: extended partition
    0xd5                   ; Old Multiuser DOS secured: extended partition
{
        cmp     al, type
        jz      .extended
}
; 4. If we are here, that is a normal partition. Add it to the list.
; Note that the first sector is relative to MBR/EBR.
        mov     eax, ebp
        xor     edx, edx
        add     eax, [ecx+PARTITION_TABLE_ENTRY.FirstAbsSector]
        adc     edx, 0
        push    ecx
        stdcall disk_add_partition, eax, edx, \
                [ecx+PARTITION_TABLE_ENTRY.Length], 0
        pop     ecx
.nothing:
; 5. Return.
        ret
.extended:
; 6. If we are here, that is an extended partition. Store the address.
        mov     eax, [ecx+PARTITION_TABLE_ENTRY.FirstAbsSector]
        mov     [esp+4], eax
        ret
 
; This is an internal function called from disk_scan_partitions and
; process_partition_table_entry. It adds one partition to the list of
; partitions for the media.
proc disk_add_partition stdcall uses ebx edi, start:qword, length:qword
; 1. Check that this partition will not exceed the limit on total number.
        cmp     [esi+DISK.NumPartitions], MAX_NUM_PARTITIONS
        jae     .nothing
; 2. Check that this partition does not overlap with any already registered
; partition. Since any file system assumes that the disk data will not change
; outside of its control, such overlap could be destructive.
; Since the number of partitions is usually very small and is guaranteed not
; to be large, the simple linear search is sufficient.
; 2a. Prepare the loop: edi will point to the current item of .Partitions
; array, ecx will be the current item, ebx will hold number of items left.
        mov     edi, [esi+DISK.Partitions]
        mov     ebx, [esi+DISK.NumPartitions]
        test    ebx, ebx
        jz      .partitionok
.scan_existing:
; 2b. Get the next partition.
        mov     ecx, [edi]
        add     edi, 4
; The range [.FirstSector, .FirstSector+.Length) must be either entirely to
; the left of [start, start+length) or entirely to the right.
; 2c. Subtract .FirstSector - start. The possible overflow distinguish between
; cases "to the left" (2e) and "to the right" (2d).
        mov     eax, dword [ecx+PARTITION.FirstSector]
        mov     edx, dword [ecx+PARTITION.FirstSector+4]
        sub     eax, dword [start]
        sbb     edx, dword [start+4]
        jb      .less
; 2d. .FirstSector is greater than or equal to start. Check that .FirstSector
; is greater than or equal to start+length; the subtraction
; (.FirstSector-start) - length must not cause overflow. Go to 2g if life is
; good or to 2f in the other case.
        sub     eax, dword [length]
        sbb     edx, dword [length+4]
        jb      .overlap
        jmp     .next_existing
.less:
; 2e. .FirstSector is less than start. Check that .FirstSector+.Length is less
; than or equal to start. If the addition (.FirstSector-start) + .Length does
; not cause overflow, then .FirstSector + .Length is strictly less than start;
; since the equality is also valid, use decrement preliminarily. Go to 2g or
; 2f depending on the overflow.
        sub     eax, 1
        sbb     edx, 0
        add     eax, dword [ecx+PARTITION.Length]
        adc     edx, dword [ecx+PARTITION.Length+4]
        jnc     .next_existing
.overlap:
; 2f. The partition overlaps with previously registered partition. Say warning
; and return with nothing done.
        dbgstr 'two partitions overlap, ignoring the last one'
        jmp     .nothing
.next_existing:
; 2g. The partition does not overlap with the current partition. Continue the
; loop.
        dec     ebx
        jnz     .scan_existing
.partitionok:
; 3. The partition has passed tests. Reallocate the partitions array for a new
; entry.
; 3a. Call the allocator.
        mov     eax, [esi+DISK.NumPartitions]
        inc     eax     ; one more entry
        shl     eax, 2  ; each entry is dword
        call    malloc
; 3b. Test the result. If failed, return with nothing done.
        test    eax, eax
        jz      .nothing
; 3c. Copy the old array to the new array.
        mov     edi, eax
        push    esi
        mov     ecx, [esi+DISK.NumPartitions]
        mov     esi, [esi+DISK.Partitions]
        rep movsd
        pop     esi
; 3d. Set the field in the DISK structure to the new array.
        xchg    [esi+DISK.Partitions], eax
; 3e. Free the old array.
        call    free
; 4. Recognize the file system.
; 4a. Call the filesystem recognizer. It will allocate the PARTITION structure
; with possible filesystem-specific fields.
        call    disk_detect_partition
; 4b. Check return value. If zero, return with list not changed; so far only
; the array was reallocated, this is ok for other code.
        test    eax, eax
        jz      .nothing
; 5. Insert the new partition to the list.
        stosd
        inc     [esi+DISK.NumPartitions]
; 6. Return.
.nothing:
        ret
endp
 
; This is an internal function called from disk_add_partition.
; It tries to recognize the file system on the partition and allocates the
; corresponding PARTITION structure with filesystem-specific fields.
disk_detect_partition:
; This function inherits the stack frame from disk_add_partition. In stdcall
; with ebp-based frame arguments start from ebp+8, since [ebp]=saved ebp
; and [ebp+4]=return address.
virtual at ebp+8
.start  dq      ?
.length dq      ?
end virtual
; Currently no file systems are supported, so just allocate the PARTITION
; structure without extra fields.
; 1. Allocate and check result.
        push    sizeof.PARTITION
        pop     eax
        call    malloc
        test    eax, eax
        jz      .nothing
; 2. Fill the common fields: copy .start and .length.
        mov     edx, dword [.start]
        mov     dword [eax+PARTITION.FirstSector], edx
        mov     edx, dword [.start+4]
        mov     dword [eax+PARTITION.FirstSector+4], edx
        mov     edx, dword [.length]
        mov     dword [eax+PARTITION.Length], edx
        mov     edx, dword [.length+4]
        mov     dword [eax+PARTITION.Length+4], edx
.nothing:
; 3. Return with eax = pointer to PARTITION or NULL.
        ret
 
; This function is called from file_system_lfn.
; This handler gets the control each time when fn 70 is called
; with unknown item of root subdirectory.
; in: esi -> name
;     ebp = 0 or rest of name relative to esi
; out: if the handler processes path, it must not return in file_system_lfn,
;      but instead pop return address and return directly to the caller
;      otherwise simply return
dyndisk_handler:
        push    ebx edi         ; save registers used in file_system_lfn
; 1. Acquire the mutex.
        mov     ecx, disk_list_mutex
        call    mutex_lock
; 2. Loop over the list of DISK structures.
; 2a. Initialize.
        mov     ebx, disk_list
.scan:
; 2b. Get the next item.
        mov     ebx, [ebx+DISK.Next]
; 2c. Check whether the list is done. If so, go to 3.
        cmp     ebx, disk_list
        jz      .notfound
; 2d. Compare names. If names match, go to 5.
        mov     edi, [ebx+DISK.Name]
        push    esi
@@:
; esi points to the name from fs operation; it is terminated by zero or slash.
        lodsb
        test    al, al
        jz      .eoin_dec
        cmp     al, '/'
        jz      .eoin
; edi points to the disk name.
        inc     edi
; edi points to lowercase name, this is a requirement for the driver.
; Characters at esi can have any register. Lowercase the current character.
; This lowercasing works for latin letters and digits; since the disk name
; should not contain other symbols, this is ok.
        or      al, 20h
        cmp     al, [edi-1]
        jz      @b
.wrongname:
; 2f. Names don't match. Continue the loop.
        pop     esi
        jmp     .scan
.notfound:
; The loop is done and no name matches.
; 3. Release the mutex.
        call    mutex_unlock
; 4. Return normally.
        pop     edi ebx         ; restore registers used in file_system_lfn
        ret
; part of 2d: the name matches partially, but we must check that this is full
; equality.
.eoin_dec:
        dec     esi
.eoin:
        cmp     byte [edi], 0
        jnz     .wrongname
; We found the addressed DISK structure.
; 5. Reference the disk.
        lock inc [ebx+DISK.RefCount]
; 6. Now we are sure that the DISK structure is not going to die at least
; while we are working with it, so release the global mutex.
        call    mutex_unlock
; 7. Acquire the mutex for media object.
        pop     edi             ; restore edi
        lea     ecx, [ebx+DISK.MediaLock]
        call    mutex_lock
; 8. Get the media object. If it is not NULL, reference it.
        xor     edx, edx
        cmp     [ebx+DISK.MediaInserted], dl
        jz      @f
        mov     edx, ebx
        inc     [ebx+DISK.MediaRefCount]
@@:
; 9. Now we are sure that the media object, if it exists, is not going to die
; at least while we are working with it, so release the mutex for media object.
        call    mutex_unlock
        mov     ecx, ebx
        pop     ebx eax         ; restore ebx, pop return address
; 10. Check whether the fs operation wants to enumerate partitions (go to 11)
; or work with some concrete partition (go to 12).
        cmp     byte [esi], 0
        jnz     .haspartition
; 11. The fs operation wants to enumerate partitions.
; 11a. Only "list directory" operation is applicable to / path. Check
; the operation code. If wrong, go to 13.
        cmp     dword [ebx], 1
        jnz     .access_denied
; 11b. If the media is inserted, use 'fs_dyndisk_next' as an enumeration
; procedure. Otherwise, use 'fs_dyndisk_next_nomedia'.
        mov     esi, fs_dyndisk_next_nomedia
        test    edx, edx
        jz      @f
        mov     esi, fs_dyndisk_next
@@:
; 11c. Let the procedure from fs_lfn.inc do the job.
        jmp     file_system_lfn.maindir_noesi
.haspartition:
; 12. The fs operation has specified some partition.
; 12a. Store parameters for callback functions.
        push    edx
        push    ecx
; 12b. Store callback functions.
        push    dyndisk_cleanup
        push    fs_dyndisk
        mov     edi, esp
; 12c. Let the procedure from fs_lfn.inc do the job.
        jmp     file_system_lfn.found2
.access_denied:
; 13. Fail the operation with the appropriate code.
        mov     dword [esp+32], ERROR_ACCESS_DENIED
.cleanup:
; 14. Cleanup.
        mov     esi, ecx        ; disk*dereference assume that esi points to DISK
.cleanup_esi:
        test    edx, edx        ; if there are no media, we didn't reference it
        jz      @f
        call    disk_media_dereference
@@:
        call    disk_dereference
; 15. Return.
        ret
 
; This is a callback for cleaning up things called from file_system_lfn.found2.
dyndisk_cleanup:
        mov     esi, [edi+8]
        mov     edx, [edi+12]
        jmp     dyndisk_handler.cleanup_esi
 
; This is a callback for enumerating partitions called from
; file_system_lfn.maindir in the case of inserted media.
; It just increments eax until DISK.NumPartitions reached and then
; cleans up.
fs_dyndisk_next:
        cmp     eax, [ecx+DISK.NumPartitions]
        jae     .nomore
        inc     eax
        clc
        ret
.nomore:
        pusha
        mov     esi, ecx
        call    disk_media_dereference
        call    disk_dereference
        popa
        stc
        ret
 
; This is a callback for enumerating partitions called from
; file_system_lfn.maindir in the case of missing media.
; In this case we create one pseudo-partition.
fs_dyndisk_next_nomedia:
        cmp     eax, 1
        jae     .nomore
        inc     eax
        clc
        ret
.nomore:
        pusha
        mov     esi, ecx
        call    disk_dereference
        popa
        stc
        ret
 
; This is a callback for doing real work with selected partition.
; Currently this is just placeholder, since no file systems are supported.
; edi = esp -> {dd fs_dyndisk, dd dyndisk_cleanup, dd pointer to DISK, dd media object}
; ecx = partition number, esi+ebp = ASCIIZ name
fs_dyndisk:
        dec     ecx     ; convert to zero-based partition index
        pop     edx edx edx eax ; edx = pointer to DISK, eax = NULL or edx
        test    eax, eax
        jz      .nomedia
.main:
        cmp     ecx, [edx+DISK.NumPartitions]
        jae     .notfound
        mov     dword [esp+32], ERROR_UNKNOWN_FS
.cleanup:
        mov     esi, edx
        call    disk_media_dereference
        call    disk_dereference
        ret
.notfound:
        mov     dword [esp+32], ERROR_FILE_NOT_FOUND
        jmp     .cleanup
.nomedia:
        test    ecx, ecx
        jnz     .notfound
        test    byte [edx+DISK.DriverFlags], DISK_NO_INSERT_NOTIFICATION
        jz      .deverror
; if the driver does not support insert notifications and we are the only fs
; operation with this disk, issue the fake insert notification; if media is
; still not inserted, 'disk_media_changed' will detect this and do nothing
;;;        push    ebx
        lea     ecx, [edx+DISK.MediaLock]
        call    mutex_lock
        cmp     [edx+DISK.MediaRefCount], 1
        jnz     .noluck
        call    mutex_unlock
        push    edx
        stdcall disk_media_changed, edx, 1
        pop     edx
        lea     ecx, [edx+DISK.MediaLock]
        call    mutex_lock
        cmp     [edx+DISK.MediaInserted], 0
        jz      .noluck
        lock inc [edx+DISK.MediaRefCount]
        call    mutex_unlock
        xor     ecx, ecx
        jmp     .main
.noluck:
        call    mutex_unlock
.deverror:
        mov     dword [esp+32], ERROR_DEVICE
        mov     esi, edx
        call    disk_dereference
        ret
 
; This function is called from file_system_lfn.
; This handler is called when virtual root is enumerated
; and must return all items which can be handled by this.
; It is called several times, first time with eax=0
; in: eax = 0 for first call, previously returned value for subsequent calls
; out: eax = 0 => no more items
;      eax != 0 => buffer pointed to by edi contains name of item
dyndisk_enum_root:
        push    edx             ; save register used in file_system_lfn
        mov     ecx, disk_list_mutex    ; it will be useful
; 1. If this is the first call, acquire the mutex and initialize.
        test    eax, eax
        jnz     .notfirst
        call    mutex_lock
        mov     eax, disk_list
.notfirst:
; 2. Get next item.
        mov     eax, [eax+DISK.Next]
; 3. If there are no more items, go to 6.
        cmp     eax, disk_list
        jz      .last
; 4. Copy name from the DISK structure to edi.
        push    eax esi
        mov     esi, [eax+DISK.Name]
@@:
        lodsb
        stosb
        test    al, al
        jnz     @b
        pop     esi eax
; 5. Return with eax = item.
        pop     edx             ; restore register used in file_system_lfn
        ret
.last:
; 6. Release the mutex and return with eax = 0.
        call    mutex_unlock
        xor     eax, eax
        pop     edx             ; restore register used in file_system_lfn
        ret

Rev 2257	Rev 2288
1	;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;	1	;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
2	;; ;;	2	;; ;;
3	;; Copyright (C) KolibriOS team 2011. All rights reserved. ;;	3	;; Copyright (C) KolibriOS team 2011. All rights reserved. ;;
4	;; Distributed under terms of the GNU General Public License ;;	4	;; Distributed under terms of the GNU General Public License ;;
5	;; ;;	5	;; ;;
6	;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;	6	;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
7		7
8	$Revision: 2257 $	8	$Revision: 2288 $
9		9
10	; =============================================================================	10	; =============================================================================
11	; ================================= Constants =================================	11	; ================================= Constants =================================
12	; =============================================================================	12	; =============================================================================
13	; Error codes for callback functions.	13	; Error codes for callback functions.
14	DISK_STATUS_OK = 0 ; success	14	DISK_STATUS_OK = 0 ; success
15	DISK_STATUS_GENERAL_ERROR = -1; if no other code is suitable	15	DISK_STATUS_GENERAL_ERROR = -1; if no other code is suitable
16	DISK_STATUS_INVALID_CALL = 1 ; invalid input parameters	16	DISK_STATUS_INVALID_CALL = 1 ; invalid input parameters
17	DISK_STATUS_NO_MEDIA = 2 ; no media present	17	DISK_STATUS_NO_MEDIA = 2 ; no media present
18	DISK_STATUS_END_OF_MEDIA = 3 ; end of media while reading/writing data	18	DISK_STATUS_END_OF_MEDIA = 3 ; end of media while reading/writing data
19	; Driver flags. Represent bits in DISK.DriverFlags.	19	; Driver flags. Represent bits in DISK.DriverFlags.
20	DISK_NO_INSERT_NOTIFICATION = 1	20	DISK_NO_INSERT_NOTIFICATION = 1
21	; Media flags. Represent bits in DISKMEDIAINFO.Flags.	21	; Media flags. Represent bits in DISKMEDIAINFO.Flags.
22	DISK_MEDIA_READONLY = 1	22	DISK_MEDIA_READONLY = 1
23		23
24	; If too many partitions are detected,there is probably an error on the disk.	24	; If too many partitions are detected,there is probably an error on the disk.
25	; 256 partitions should be enough for any reasonable use.	25	; 256 partitions should be enough for any reasonable use.
26	; Also, the same number is limiting the number of MBRs to process; if	26	; Also, the same number is limiting the number of MBRs to process; if
27	; too many MBRs are visible,there probably is a loop in the MBR structure.	27	; too many MBRs are visible,there probably is a loop in the MBR structure.
28	MAX_NUM_PARTITIONS = 256	28	MAX_NUM_PARTITIONS = 256
29		29
30	; =============================================================================	30	; =============================================================================
31	; ================================ Structures =================================	31	; ================================ Structures =================================
32	; =============================================================================	32	; =============================================================================
33	; This structure defines all callback functions for working with the physical	33	; This structure defines all callback functions for working with the physical
34	; device. They are implemented by a driver. Objects with this structure reside	34	; device. They are implemented by a driver. Objects with this structure reside
35	; in a driver.	35	; in a driver.
36	struct DISKFUNC	36	struct DISKFUNC
37	.strucsize dd ?	37	.strucsize dd ?
38	; Size of the structure. This field is intended for possible extensions of	38	; Size of the structure. This field is intended for possible extensions of
39	; this structure. If a new function is added to this structure and a driver	39	; this structure. If a new function is added to this structure and a driver
40	; implements an old version, the caller can detect this by checking .strucsize,	40	; implements an old version, the caller can detect this by checking .strucsize,
41	; so the driver remains compatible.	41	; so the driver remains compatible.
42	.close dd ?	42	.close dd ?
43	; The pointer to the function which frees all driver-specific resources for	43	; The pointer to the function which frees all driver-specific resources for
44	; the disk.	44	; the disk.
45	; Optional, may be NULL.	45	; Optional, may be NULL.
46	; void close(void* userdata);	46	; void close(void* userdata);
47	.closemedia dd ?	47	.closemedia dd ?
48	; The pointer to the function which informs the driver that the kernel has	48	; The pointer to the function which informs the driver that the kernel has
49	; finished all processing with the current media. If media is removed, the	49	; finished all processing with the current media. If media is removed, the
50	; driver should decline all requests to that media with DISK_STATUS_NO_MEDIA,	50	; driver should decline all requests to that media with DISK_STATUS_NO_MEDIA,
51	; even if new media is inserted, until this function is called. If media is	51	; even if new media is inserted, until this function is called. If media is
52	; removed, a new call to 'disk_media_changed' is not allowed until this	52	; removed, a new call to 'disk_media_changed' is not allowed until this
53	; function is called.	53	; function is called.
54	; Optional, may be NULL (if media is not removable).	54	; Optional, may be NULL (if media is not removable).
55	; void closemedia(void* userdata);	55	; void closemedia(void* userdata);
56	.querymedia dd ?	56	.querymedia dd ?
57	; The pointer to the function which determines capabilities of the media.	57	; The pointer to the function which determines capabilities of the media.
58	; int querymedia(void* userdata, DISKMEDIAINFO* info);	58	; int querymedia(void* userdata, DISKMEDIAINFO* info);
59	; Return value: one of DISK_STATUS_*	59	; Return value: one of DISK_STATUS_*
60	.read dd ?	60	.read dd ?
61	; The pointer to the function which reads data from the device.	61	; The pointer to the function which reads data from the device.
62	; int read(void* userdata, void* buffer, __int64 startsector, int* numsectors);	62	; int read(void* userdata, void* buffer, __int64 startsector, int* numsectors);
63	; input: *numsectors = number of sectors to read	63	; input: *numsectors = number of sectors to read
64	; output: *numsectors = number of sectors which were successfully read	64	; output: *numsectors = number of sectors which were successfully read
65	; Return value: one of DISK_STATUS_*	65	; Return value: one of DISK_STATUS_*
66	.write dd ?	66	.write dd ?
67	; The pointer to the function which writes data to the device.	67	; The pointer to the function which writes data to the device.
68	; Optional, may be NULL.	68	; Optional, may be NULL.
69	; int write(void* userdata, void* buffer, __int64 startsector, int* numsectors);	69	; int write(void* userdata, void* buffer, __int64 startsector, int* numsectors);
70	; input: *numsectors = number of sectors to write	70	; input: *numsectors = number of sectors to write
71	; output: *numsectors = number of sectors which were successfully written	71	; output: *numsectors = number of sectors which were successfully written
72	; Return value: one of DISK_STATUS_*	72	; Return value: one of DISK_STATUS_*
73	.flush dd ?	73	.flush dd ?
74	; The pointer to the function which flushes the internal device cache.	74	; The pointer to the function which flushes the internal device cache.
75	; Optional, may be NULL.	75	; Optional, may be NULL.
76	; int flush(void* userdata);	76	; int flush(void* userdata);
77	; Return value: one of DISK_STATUS_*	77	; Return value: one of DISK_STATUS_*
78	; Note that read/write are called by the cache manager, so a driver should not	78	; Note that read/write are called by the cache manager, so a driver should not
79	; create a software cache. This function is implemented for flushing a hardware	79	; create a software cache. This function is implemented for flushing a hardware
80	; cache, if it exists.	80	; cache, if it exists.
81	.adjust_cache_size dd ?	81	.adjust_cache_size dd ?
82	; The pointer to the function which returns the cache size for this device.	82	; The pointer to the function which returns the cache size for this device.
83	; Optional, may be NULL.	83	; Optional, may be NULL.
84	; unsigned int adjust_cache_size(unsigned int suggested_size);	84	; unsigned int adjust_cache_size(unsigned int suggested_size);
85	; Return value: 0 = disable cache, otherwise = used cache size in bytes.	85	; Return value: 0 = disable cache, otherwise = used cache size in bytes.
86	ends	86	ends
87		87
88	; This structure holds information on a medium.	88	; This structure holds information on a medium.
89	; Objects with this structure are allocated by the kernel as a part of the DISK	89	; Objects with this structure are allocated by the kernel as a part of the DISK
90	; structure and are filled by a driver in the 'querymedia' callback.	90	; structure and are filled by a driver in the 'querymedia' callback.
91	struct DISKMEDIAINFO	91	struct DISKMEDIAINFO
92	.Flags dd ?	92	.Flags dd ?
93	; Combination of DISK_MEDIA_* bits.	93	; Combination of DISK_MEDIA_* bits.
94	.SectorSize dd ?	94	.SectorSize dd ?
95	; Size of the sector.	95	; Size of the sector.
96	.Capacity dq ?	96	.Capacity dq ?
97	; Size of the media in sectors.	97	; Size of the media in sectors.
98	ends	98	ends
99		99
100	; This structure represents the disk cache. To follow the old implementation,	100	; This structure represents the disk cache. To follow the old implementation,
101	; there are two distinct caches for a disk, one for "system" data,and the other	101	; there are two distinct caches for a disk, one for "system" data,and the other
102	; for "application" data.	102	; for "application" data.
103	struct DISKCACHE	103	struct DISKCACHE
104	.Lock MUTEX	104	.Lock MUTEX
105	; Lock to protect the cache.	105	; Lock to protect the cache.
106	; The following fields are inherited from data32.inc:cache_ideX.	106	; The following fields are inherited from data32.inc:cache_ideX.
107	.pointer rd 1	107	.pointer rd 1
108	.data_size rd 1 ; not use	108	.data_size rd 1 ; not use
109	.data rd 1	109	.data rd 1
110	.sad_size rd 1	110	.sad_size rd 1
111	.search_start rd 1	111	.search_start rd 1
112	ends	112	ends
113		113
114	; This structure represents a disk device and its media for the kernel.	114	; This structure represents a disk device and its media for the kernel.
115	; This structure is allocated by the kernel in the 'disk_add' function,	115	; This structure is allocated by the kernel in the 'disk_add' function,
116	; freed in the 'disk_dereference' function.	116	; freed in the 'disk_dereference' function.
117	struct DISK	117	struct DISK
118	; Fields of disk object	118	; Fields of disk object
119	.Next dd ?	119	.Next dd ?
120	.Prev dd ?	120	.Prev dd ?
121	; All disk devices are linked in one list with these two fields.	121	; All disk devices are linked in one list with these two fields.
122	; Head of the list is the 'disk_list' variable.	122	; Head of the list is the 'disk_list' variable.
123	.Functions dd ?	123	.Functions dd ?
124	; Pointer to the 'DISKFUNC' structure with driver functions.	124	; Pointer to the 'DISKFUNC' structure with driver functions.
125	.Name dd ?	125	.Name dd ?
126	; Pointer to the string used for accesses through the global filesystem.	126	; Pointer to the string used for accesses through the global filesystem.
127	.UserData dd ?	127	.UserData dd ?
128	; This field is passed to all callback functions so a driver can decide which	128	; This field is passed to all callback functions so a driver can decide which
129	; physical device is addressed.	129	; physical device is addressed.
130	.DriverFlags dd ?	130	.DriverFlags dd ?
131	; Bitfield. Currently only DISK_NO_INSERT_NOTIFICATION bit is defined.	131	; Bitfield. Currently only DISK_NO_INSERT_NOTIFICATION bit is defined.
132	; If it is set, the driver will never issue 'disk_media_changed' notification	132	; If it is set, the driver will never issue 'disk_media_changed' notification
133	; with argument set to true, so the kernel must try to detect media during	133	; with argument set to true, so the kernel must try to detect media during
134	; requests from the file system.	134	; requests from the file system.
135	.RefCount dd ?	135	.RefCount dd ?
136	; Count of active references to this structure. One reference is kept during	136	; Count of active references to this structure. One reference is kept during
137	; the lifetime of the structure between 'disk_add' and 'disk_del'.	137	; the lifetime of the structure between 'disk_add' and 'disk_del'.
138	; Another reference is taken during any filesystem operation for this disk.	138	; Another reference is taken during any filesystem operation for this disk.
139	; One reference is added if media is inserted.	139	; One reference is added if media is inserted.
140	; The structure is destroyed when the reference count decrements to zero:	140	; The structure is destroyed when the reference count decrements to zero:
141	; this usually occurs in 'disk_del', but can be delayed to the end of last	141	; this usually occurs in 'disk_del', but can be delayed to the end of last
142	; filesystem operation, if one is active.	142	; filesystem operation, if one is active.
143	.MediaLock MUTEX	143	.MediaLock MUTEX
144	; Lock to protect the MEDIA structure. See the description after	144	; Lock to protect the MEDIA structure. See the description after
145	; 'disk_list_mutex' for the locking strategy.	145	; 'disk_list_mutex' for the locking strategy.
146	; Fields of media object	146	; Fields of media object
147	.MediaInserted db ?	147	.MediaInserted db ?
148	; 0 if media is not inserted, nonzero otherwise.	148	; 0 if media is not inserted, nonzero otherwise.
149	.MediaUsed db ?	149	.MediaUsed db ?
150	; 0 if media fields are not used, nonzero otherwise. If .MediaRefCount is	150	; 0 if media fields are not used, nonzero otherwise. If .MediaRefCount is
151	; nonzero, this field is nonzero too; however, when .MediaRefCount goes	151	; nonzero, this field is nonzero too; however, when .MediaRefCount goes
152	; to zero, there is some time interval during which media object is still used.	152	; to zero, there is some time interval during which media object is still used.
153	align 4	153	align 4
154	; The following fields are not valid unless either .MediaInserted is nonzero	154	; The following fields are not valid unless either .MediaInserted is nonzero
155	; or they are accessed from a code which has obtained the reference when	155	; or they are accessed from a code which has obtained the reference when
156	; .MediaInserted was nonzero.	156	; .MediaInserted was nonzero.
157	.MediaRefCount dd ?	157	.MediaRefCount dd ?
158	; Count of active references to the media object. One reference is kept during	158	; Count of active references to the media object. One reference is kept during
159	; the lifetime of the media between two calls to 'disk_media_changed'.	159	; the lifetime of the media between two calls to 'disk_media_changed'.
160	; Another reference is taken during any filesystem operation for this media.	160	; Another reference is taken during any filesystem operation for this media.
161	; The callback 'closemedia' is called when the reference count decrements to	161	; The callback 'closemedia' is called when the reference count decrements to
162	; zero: this usually occurs in 'disk_media_changed', but can be delayed to the	162	; zero: this usually occurs in 'disk_media_changed', but can be delayed to the
163	; end of the last filesystem operation, if one is active.	163	; end of the last filesystem operation, if one is active.
164	.MediaInfo DISKMEDIAINFO	164	.MediaInfo DISKMEDIAINFO
165	; This field keeps information on the current media.	165	; This field keeps information on the current media.
166	.NumPartitions dd ?	166	.NumPartitions dd ?
167	; Number of partitions on this media.	167	; Number of partitions on this media.
168	.Partitions dd ?	168	.Partitions dd ?
169	; Pointer to array of .NumPartitions pointers to PARTITION structures.	169	; Pointer to array of .NumPartitions pointers to PARTITION structures.
170	.cache_size dd ?	170	.cache_size dd ?
171	; inherited from cache_ideX_size	171	; inherited from cache_ideX_size
172	.SysCache DISKCACHE	172	.SysCache DISKCACHE
173	.AppCache DISKCACHE	173	.AppCache DISKCACHE
174	; Two caches for the disk.	174	; Two caches for the disk.
175	ends	175	ends
176		176
177	; This structure represents one partition for the kernel. This is a base	177	; This structure represents one partition for the kernel. This is a base
178	; template, the actual contents after common fields is determined by the	178	; template, the actual contents after common fields is determined by the
179	; file system code for this partition.	179	; file system code for this partition.
180	struct PARTITION	180	struct PARTITION
181	.FirstSector dq ?	181	.FirstSector dq ?
182	; First sector of the partition.	182	; First sector of the partition.
183	.Length dq ?	183	.Length dq ?
184	; Length of the partition in sectors.	184	; Length of the partition in sectors.
185	.Disk dd ?	185	.Disk dd ?
186	; Pointer to parent DISK structure.	186	; Pointer to parent DISK structure.
187	.FSUserFunctions dd ?	187	.FSUserFunctions dd ?
188	; Handlers for the sysfunction 70h. This field is a pointer to the following	188	; Handlers for the sysfunction 70h. This field is a pointer to the following
189	; array. The first dword is a number of supported subfunctions, other dwords	189	; array. The first dword is a number of supported subfunctions, other dwords
190	; point to handlers of corresponding subfunctions.	190	; point to handlers of corresponding subfunctions.
191	; This field is 0 if file system is not recognized.	191	; This field is 0 if file system is not recognized.
192	; ...fs-specific data may follow...	192	; ...fs-specific data may follow...
193	ends	193	ends
194		194
195	; This is an external structure, it represents an entry in the partition table.	195	; This is an external structure, it represents an entry in the partition table.
196	struct PARTITION_TABLE_ENTRY	196	struct PARTITION_TABLE_ENTRY
197	.Bootable db ?	197	.Bootable db ?
198	; 80h = bootable partition, 0 = non-bootable partition, other values = invalid	198	; 80h = bootable partition, 0 = non-bootable partition, other values = invalid
199	.FirstHead db ?	199	.FirstHead db ?
200	.FirstSector db ?	200	.FirstSector db ?
201	.FirstTrack db ?	201	.FirstTrack db ?
202	; Coordinates of first sector in CHS.	202	; Coordinates of first sector in CHS.
203	.Type db ?	203	.Type db ?
204	; Partition type, one of predefined constants. 0 = empty, several types denote	204	; Partition type, one of predefined constants. 0 = empty, several types denote
205	; extended partition (see process_partition_table_entry), we are not interested	205	; extended partition (see process_partition_table_entry), we are not interested
206	; in other values.	206	; in other values.
207	.LastHead db ?	207	.LastHead db ?
208	.LastSector db ?	208	.LastSector db ?
209	.LastTrack db ?	209	.LastTrack db ?
210	; Coordinates of last sector in CHS.	210	; Coordinates of last sector in CHS.
211	.FirstAbsSector dd ?	211	.FirstAbsSector dd ?
212	; Coordinate of first sector in LBA.	212	; Coordinate of first sector in LBA.
213	.Length dd ?	213	.Length dd ?
214	; Length of the partition in sectors.	214	; Length of the partition in sectors.
215	ends	215	ends
216		216
217	; =============================================================================	217	; =============================================================================
218	; ================================ Global data ================================	218	; ================================ Global data ================================
219	; =============================================================================	219	; =============================================================================
220	iglobal	220	iglobal
221	; The pseudo-item for the list of all DISK structures.	221	; The pseudo-item for the list of all DISK structures.
222	; Initialized to the empty list.	222	; Initialized to the empty list.
223	disk_list:	223	disk_list:
224	dd disk_list	224	dd disk_list
225	dd disk_list	225	dd disk_list
226	endg	226	endg
227	uglobal	227	uglobal
228	; This mutex guards all operations with the global list of DISK structures.	228	; This mutex guards all operations with the global list of DISK structures.
229	disk_list_mutex MUTEX	229	disk_list_mutex MUTEX
230	; * There are two dependent objects, a disk and a media. In the simplest case,	230	; * There are two dependent objects, a disk and a media. In the simplest case,
231	; disk and media are both non-removable. However, in the general case both	231	; disk and media are both non-removable. However, in the general case both
232	; can be removed at any time, simultaneously or only media,and this makes things	232	; can be removed at any time, simultaneously or only media,and this makes things
233	; complicated.	233	; complicated.
234	; * For efficiency, both disk and media objects are located in the one	234	; * For efficiency, both disk and media objects are located in the one
235	; structure named DISK. However, logically they are different.	235	; structure named DISK. However, logically they are different.
236	; * The following operations use data of disk object: adding (disk_add);	236	; * The following operations use data of disk object: adding (disk_add);
237	; deleting (disk_del); filesystem (fs_lfn which eventually calls	237	; deleting (disk_del); filesystem (fs_lfn which eventually calls
238	; dyndisk_handler or dyndisk_enum_root).	238	; dyndisk_handler or dyndisk_enum_root).
239	; * The following operations use data of media object: adding/removing	239	; * The following operations use data of media object: adding/removing
240	; (disk_media_changed); filesystem (fs_lfn which eventually calls	240	; (disk_media_changed); filesystem (fs_lfn which eventually calls
241	; dyndisk_handler; dyndisk_enum_root doesn't work with media).	241	; dyndisk_handler; dyndisk_enum_root doesn't work with media).
242	; * Notifications disk_add, disk_media_changed, disk_del are synchronized	242	; * Notifications disk_add, disk_media_changed, disk_del are synchronized
243	; between themselves, this is a requirement for the driver. However, file	243	; between themselves, this is a requirement for the driver. However, file
244	; system operations are asynchronous, can be issued at any time by any	244	; system operations are asynchronous, can be issued at any time by any
245	; thread.	245	; thread.
246	; * We must prevent a situation when a filesystem operation thinks that the	246	; * We must prevent a situation when a filesystem operation thinks that the
247	; object is still valid but in fact the notification has destroyed the	247	; object is still valid but in fact the notification has destroyed the
248	; object. So we keep a reference counter for both disk and media and destroy	248	; object. So we keep a reference counter for both disk and media and destroy
249	; the object when this counter goes to zero.	249	; the object when this counter goes to zero.
250	; * The driver must know when it is safe to free driver-allocated resources.	250	; * The driver must know when it is safe to free driver-allocated resources.
251	; The object can be alive even after death notification has completed.	251	; The object can be alive even after death notification has completed.
252	; We use special callbacks to satisfy both assertions: 'close' for the disk	252	; We use special callbacks to satisfy both assertions: 'close' for the disk
253	; and 'closemedia' for the media. The destruction of the object includes	253	; and 'closemedia' for the media. The destruction of the object includes
254	; calling the corresponding callback.	254	; calling the corresponding callback.
255	; * Each filesystem operation keeps one reference for the disk and one	255	; * Each filesystem operation keeps one reference for the disk and one
256	; reference for the media. Notification disk_del forces notification on the	256	; reference for the media. Notification disk_del forces notification on the
257	; media death, so the reference counter for the disk is always not less than	257	; media death, so the reference counter for the disk is always not less than
258	; the reference counter for the media.	258	; the reference counter for the media.
259	; * Two operations "get the object" and "increment the reference counter" can	259	; * Two operations "get the object" and "increment the reference counter" can
260	; not be done simultaneously. We use a mutex to guard the consistency here.	260	; not be done simultaneously. We use a mutex to guard the consistency here.
261	; It must be a part of the container for the object, so that this mutex can	261	; It must be a part of the container for the object, so that this mutex can
262	; be acquired as a part of getting the object from the container. The	262	; be acquired as a part of getting the object from the container. The
263	; container for disk object is the global list, and this list is guarded by	263	; container for disk object is the global list, and this list is guarded by
264	; 'disk_list_mutex'. The container for media object is the disk object, and	264	; 'disk_list_mutex'. The container for media object is the disk object, and
265	; the corresponding mutex is DISK.MediaLock.	265	; the corresponding mutex is DISK.MediaLock.
266	; * Notifications do not change the data of objects, they can only remove	266	; * Notifications do not change the data of objects, they can only remove
267	; objects. Thus we don't need another synchronization at this level. If two	267	; objects. Thus we don't need another synchronization at this level. If two
268	; filesystem operations are referencing the same filesystem data, this is	268	; filesystem operations are referencing the same filesystem data, this is
269	; better resolved at the level of the filesystem.	269	; better resolved at the level of the filesystem.
270	endg	270	endg
271		271
272	iglobal	272	iglobal
273	; The function 'disk_scan_partitions' needs three 512-byte buffers for	273	; The function 'disk_scan_partitions' needs three 512-byte buffers for
274	; MBR, bootsector and fs-temporary sector data. It can not use the static	274	; MBR, bootsector and fs-temporary sector data. It can not use the static
275	; buffers always, since it can be called for two or more disks in parallel.	275	; buffers always, since it can be called for two or more disks in parallel.
276	; However, this case is not typical. We reserve three static 512-byte buffers	276	; However, this case is not typical. We reserve three static 512-byte buffers
277	; and a flag that these buffers are currently used. If 'disk_scan_partitions'	277	; and a flag that these buffers are currently used. If 'disk_scan_partitions'
278	; detects that the buffers are currently used, it allocates buffers from the	278	; detects that the buffers are currently used, it allocates buffers from the
279	; heap.	279	; heap.
280	; The flag is implemented as a global dword variable. When the static buffers	280	; The flag is implemented as a global dword variable. When the static buffers
281	; are not used, the value is -1. When the static buffers are used, the value	281	; are not used, the value is -1. When the static buffers are used, the value
282	; is normally 0 and temporarily can become greater. The function increments	282	; is normally 0 and temporarily can become greater. The function increments
283	; this value. If the resulting value is zero, it uses the buffers and	283	; this value. If the resulting value is zero, it uses the buffers and
284	; decrements the value when the job is done. Otherwise, it immediately	284	; decrements the value when the job is done. Otherwise, it immediately
285	; decrements the value and uses buffers from the heap, allocated in the	285	; decrements the value and uses buffers from the heap, allocated in the
286	; beginning and freed in the end.	286	; beginning and freed in the end.
287	partition_buffer_users dd -1	287	partition_buffer_users dd -1
288	endg	288	endg
289	uglobal	289	uglobal
290	; The static buffers for MBR, bootsector and fs-temporary sector data.	290	; The static buffers for MBR, bootsector and fs-temporary sector data.
291	align 16	291	align 16
292	mbr_buffer rb 512	292	mbr_buffer rb 512
293	bootsect_buffer rb 512	293	bootsect_buffer rb 512
294	fs_tmp_buffer rb 512	294	fs_tmp_buffer rb 512
295	endg	295	endg
296		296
297	iglobal	297	iglobal
298	; This is the array of default implementations of driver callbacks.	298	; This is the array of default implementations of driver callbacks.
299	; Same as DRIVERFUNC structure except for the first field; all functions must	299	; Same as DRIVERFUNC structure except for the first field; all functions must
300	; have the default implementations.	300	; have the default implementations.
301	align 4	301	align 4
302	disk_default_callbacks:	302	disk_default_callbacks:
303	dd disk_default_close	303	dd disk_default_close
304	dd disk_default_closemedia	304	dd disk_default_closemedia
305	dd disk_default_querymedia	305	dd disk_default_querymedia
306	dd disk_default_read	306	dd disk_default_read
307	dd disk_default_write	307	dd disk_default_write
308	dd disk_default_flush	308	dd disk_default_flush
309	dd disk_default_adjust_cache_size	309	dd disk_default_adjust_cache_size
310	endg	310	endg
311		311
312	; =============================================================================	312	; =============================================================================
313	; ================================= Functions =================================	313	; ================================= Functions =================================
314	; =============================================================================	314	; =============================================================================
315		315
316	; This function registers a disk device.	316	; This function registers a disk device.
317	; This includes:	317	; This includes:
318	; - allocating an internal structure describing this device;	318	; - allocating an internal structure describing this device;
319	; - registering this structure in the global filesystem.	319	; - registering this structure in the global filesystem.
320	; The function initializes the disk as if there is no media. If a media is	320	; The function initializes the disk as if there is no media. If a media is
321	; present, the function 'disk_media_changed' should be called after this	321	; present, the function 'disk_media_changed' should be called after this
322	; function succeeds.	322	; function succeeds.
323	; Parameters:	323	; Parameters:
324	; [esp+4] = pointer to DISKFUNC structure with the callbacks	324	; [esp+4] = pointer to DISKFUNC structure with the callbacks
325	; [esp+8] = pointer to name (ASCIIZ string)	325	; [esp+8] = pointer to name (ASCIIZ string)
326	; [esp+12] = userdata to be passed to the callbacks as is.	326	; [esp+12] = userdata to be passed to the callbacks as is.
327	; [esp+16] = flags, bitfield. Currently only DISK_NO_INSERT_NOTIFICATION bit	327	; [esp+16] = flags, bitfield. Currently only DISK_NO_INSERT_NOTIFICATION bit
328	; is defined.	328	; is defined.
329	; Return value:	329	; Return value:
330	; NULL = operation has failed	330	; NULL = operation has failed
331	; non-NULL = handle of the disk. This handle can be used	331	; non-NULL = handle of the disk. This handle can be used
332	; in the operations with other Disk* functions.	332	; in the operations with other Disk* functions.
333	; The handle is the pointer to the internal structure DISK.	333	; The handle is the pointer to the internal structure DISK.
334	disk_add:	334	disk_add:
335	push ebx esi ; save used registers to be stdcall	335	push ebx esi ; save used registers to be stdcall
336	; 1. Allocate the DISK structure.	336	; 1. Allocate the DISK structure.
337	; 1a. Call the heap manager.	337	; 1a. Call the heap manager.
338	push sizeof.DISK	338	push sizeof.DISK
339	pop eax	339	pop eax
340	call malloc	340	call malloc
341	; 1b. Check the result. If allocation failed, return (go to 9) with eax = 0.	341	; 1b. Check the result. If allocation failed, return (go to 9) with eax = 0.
342	test eax, eax	342	test eax, eax
343	jz .nothing	343	jz .nothing
344	; 2. Copy the disk name to the DISK structure.	344	; 2. Copy the disk name to the DISK structure.
345	; 2a. Get length of the name, including the terminating zero.	345	; 2a. Get length of the name, including the terminating zero.
346	mov ebx, [esp+8+8] ; ebx = pointer to name	346	mov ebx, [esp+8+8] ; ebx = pointer to name
347	push eax ; save allocated pointer to DISK	347	push eax ; save allocated pointer to DISK
348	xor eax, eax ; the argument of malloc() is in eax	348	xor eax, eax ; the argument of malloc() is in eax
349	@@:	349	@@:
350	inc eax	350	inc eax
351	cmp byte [ebx+eax-1], 0	351	cmp byte [ebx+eax-1], 0
352	jnz @b	352	jnz @b
353	; 2b. Call the heap manager.	353	; 2b. Call the heap manager.
354	call malloc	354	call malloc
355	; 2c. Check the result. If allocation failed, go to 7.	355	; 2c. Check the result. If allocation failed, go to 7.
356	pop esi ; restore allocated pointer to DISK	356	pop esi ; restore allocated pointer to DISK
357	test eax, eax	357	test eax, eax
358	jz .free	358	jz .free
359	; 2d. Store the allocated pointer to the DISK structure.	359	; 2d. Store the allocated pointer to the DISK structure.
360	mov [esi+DISK.Name], eax	360	mov [esi+DISK.Name], eax
361	; 2e. Copy the name.	361	; 2e. Copy the name.
362	@@:	362	@@:
363	mov dl, [ebx]	363	mov dl, [ebx]
364	mov [eax], dl	364	mov [eax], dl
365	inc ebx	365	inc ebx
366	inc eax	366	inc eax
367	test dl, dl	367	test dl, dl
368	jnz @b	368	jnz @b
369	; 3. Copy other arguments of the function to the DISK structure.	369	; 3. Copy other arguments of the function to the DISK structure.
370	mov eax, [esp+4+8]	370	mov eax, [esp+4+8]
371	mov [esi+DISK.Functions], eax	371	mov [esi+DISK.Functions], eax
372	mov eax, [esp+12+8]	372	mov eax, [esp+12+8]
373	mov [esi+DISK.UserData], eax	373	mov [esi+DISK.UserData], eax
374	mov eax, [esp+16+8]	374	mov eax, [esp+16+8]
375	mov [esi+DISK.DriverFlags], eax	375	mov [esi+DISK.DriverFlags], eax
376	; 4. Initialize other fields of the DISK structure.	376	; 4. Initialize other fields of the DISK structure.
377	; Media is not inserted, reference counter is 1.	377	; Media is not inserted, reference counter is 1.
378	lea ecx, [esi+DISK.MediaLock]	378	lea ecx, [esi+DISK.MediaLock]
379	call mutex_init	379	call mutex_init
380	xor eax, eax	380	xor eax, eax
381	mov dword [esi+DISK.MediaInserted], eax	381	mov dword [esi+DISK.MediaInserted], eax
382	inc eax	382	inc eax
383	mov [esi+DISK.RefCount], eax	383	mov [esi+DISK.RefCount], eax
384	; The DISK structure is initialized.	384	; The DISK structure is initialized.
385	; 5. Insert the new structure to the global list.	385	; 5. Insert the new structure to the global list.
386	; 5a. Acquire the mutex.	386	; 5a. Acquire the mutex.
387	mov ecx, disk_list_mutex	387	mov ecx, disk_list_mutex
388	call mutex_lock	388	call mutex_lock
389	; 5b. Insert item to the tail of double-linked list.	389	; 5b. Insert item to the tail of double-linked list.
390	mov edx, disk_list	390	mov edx, disk_list
391	list_add_tail esi, edx ;esi= new edx= list head	391	list_add_tail esi, edx ;esi= new edx= list head
392	; 5c. Release the mutex.	392	; 5c. Release the mutex.
393	call mutex_unlock	393	call mutex_unlock
394	; 6. Return with eax = pointer to DISK.	394	; 6. Return with eax = pointer to DISK.
395	xchg eax, esi	395	xchg eax, esi
396	jmp .nothing	396	jmp .nothing
397	.free:	397	.free:
398	; Memory allocation for DISK structure succeeded, but for disk name failed.	398	; Memory allocation for DISK structure succeeded, but for disk name failed.
399	; 7. Free the DISK structure.	399	; 7. Free the DISK structure.
400	xchg eax, esi	400	xchg eax, esi
401	call free	401	call free
402	; 8. Return with eax = 0.	402	; 8. Return with eax = 0.
403	xor eax, eax	403	xor eax, eax
404	.nothing:	404	.nothing:
405	; 9. Return.	405	; 9. Return.
406	pop esi ebx ; restore used registers to be stdcall	406	pop esi ebx ; restore used registers to be stdcall
407	ret 16 ; purge 4 dword arguments to be stdcall	407	ret 16 ; purge 4 dword arguments to be stdcall
408		408
409	; This function deletes a disk device from the global filesystem.	409	; This function deletes a disk device from the global filesystem.
410	; This includes:	410	; This includes:
411	; - removing a media including all partitions;	411	; - removing a media including all partitions;
412	; - deleting this structure from the global filesystem;	412	; - deleting this structure from the global filesystem;
413	; - dereferencing the DISK structure and possibly destroying it.	413	; - dereferencing the DISK structure and possibly destroying it.
414	; Parameters:	414	; Parameters:
415	; [esp+4] = handle of the disk, i.e. the pointer to the DISK structure.	415	; [esp+4] = handle of the disk, i.e. the pointer to the DISK structure.
416	; Return value: none.	416	; Return value: none.
417	disk_del:	417	disk_del:
418	push esi ; save used registers to be stdcall	418	push esi ; save used registers to be stdcall
419	; 1. Force media to be removed. If the media is already removed, the	419	; 1. Force media to be removed. If the media is already removed, the
420	; call does nothing.	420	; call does nothing.
421	mov esi, [esp+4+8] ; esi = handle of the disk	421	mov esi, [esp+4+8] ; esi = handle of the disk
422	stdcall disk_media_changed, esi, 0	422	stdcall disk_media_changed, esi, 0
423	; 2. Delete the structure from the global list.	423	; 2. Delete the structure from the global list.
424	; 2a. Acquire the mutex.	424	; 2a. Acquire the mutex.
425	mov ecx, disk_list_mutex	425	mov ecx, disk_list_mutex
426	call mutex_lock	426	call mutex_lock
427	; 2b. Delete item from double-linked list.	427	; 2b. Delete item from double-linked list.
428	mov eax, [esi+DISK.Next]	428	mov eax, [esi+DISK.Next]
429	mov edx, [esi+DISK.Prev]	429	mov edx, [esi+DISK.Prev]
430	mov [eax+DISK.Prev], edx	430	mov [eax+DISK.Prev], edx
431	mov [edx+DISK.Next], eax	431	mov [edx+DISK.Next], eax
432	; 2c. Release the mutex.	432	; 2c. Release the mutex.
433	call mutex_unlock	433	call mutex_unlock
434	; 3. The structure still has one reference created in disk_add. Remove this	434	; 3. The structure still has one reference created in disk_add. Remove this
435	; reference. If there are no other references, disk_dereference will free the	435	; reference. If there are no other references, disk_dereference will free the
436	; structure.	436	; structure.
437	call disk_dereference	437	call disk_dereference
438	; 4. Return.	438	; 4. Return.
439	pop esi ; restore used registers to be stdcall	439	pop esi ; restore used registers to be stdcall
440	ret 4 ; purge 1 dword argument to be stdcall	440	ret 4 ; purge 1 dword argument to be stdcall
441		441
442	; This is an internal function which removes a previously obtained reference	442	; This is an internal function which removes a previously obtained reference
443	; to the disk. If this is the last reference, this function lets the driver	443	; to the disk. If this is the last reference, this function lets the driver
444	; finalize all associated data, and afterwards frees the DISK structure.	444	; finalize all associated data, and afterwards frees the DISK structure.
445	; esi = pointer to DISK structure	445	; esi = pointer to DISK structure
446	disk_dereference:	446	disk_dereference:
447	; 1. Decrement reference counter. Use atomic operation to correctly handle	447	; 1. Decrement reference counter. Use atomic operation to correctly handle
448	; possible simultaneous calls.	448	; possible simultaneous calls.
449	lock dec [esi+DISK.RefCount]	449	lock dec [esi+DISK.RefCount]
450	; 2. If the result is nonzero, there are other references, so nothing to do.	450	; 2. If the result is nonzero, there are other references, so nothing to do.
451	; In this case, return (go to 4).	451	; In this case, return (go to 4).
452	jnz .nothing	452	jnz .nothing
453	; 3. If we are here, we just removed the last reference and must destroy the	453	; 3. If we are here, we just removed the last reference and must destroy the
454	; disk object.	454	; disk object.
455	; 3a. Call the driver.	455	; 3a. Call the driver.
456	mov al, DISKFUNC.close	456	mov al, DISKFUNC.close
457	stdcall disk_call_driver	457	stdcall disk_call_driver
458	; 3b. Free the structure.	458	; 3b. Free the structure.
459	xchg eax, esi	459	xchg eax, esi
460	call free	460	call free
461	; 4. Return.	461	; 4. Return.
462	.nothing:	462	.nothing:
463	ret	463	ret
464		464
465	; This is an internal function which removes a previously obtained reference	465	; This is an internal function which removes a previously obtained reference
466	; to the media. If this is the last reference, this function calls 'closemedia'	466	; to the media. If this is the last reference, this function calls 'closemedia'
467	; callback to signal the driver that the processing has finished and it is safe	467	; callback to signal the driver that the processing has finished and it is safe
468	; to inform about a new media.	468	; to inform about a new media.
469	; esi = pointer to DISK structure	469	; esi = pointer to DISK structure
470	disk_media_dereference:	470	disk_media_dereference:
471	; 1. Decrement reference counter. Use atomic operation to correctly handle	471	; 1. Decrement reference counter. Use atomic operation to correctly handle
472	; possible simultaneous calls.	472	; possible simultaneous calls.
473	lock dec [esi+DISK.MediaRefCount]	473	lock dec [esi+DISK.MediaRefCount]
474	; 2. If the result is nonzero, there are other references, so nothing to do.	474	; 2. If the result is nonzero, there are other references, so nothing to do.
475	; In this case, return (go to 4).	475	; In this case, return (go to 4).
476	jnz .nothing	476	jnz .nothing
477	; 3. If we are here, we just removed the last reference and must destroy the	477	; 3. If we are here, we just removed the last reference and must destroy the
478	; media object.	478	; media object.
479	; Note that the same place inside the DISK structure is reused for all media	479	; Note that the same place inside the DISK structure is reused for all media
480	; objects, so we must guarantee that reusing does not happen while freeing.	480	; objects, so we must guarantee that reusing does not happen while freeing.
481	; Reusing is only possible when someone processes a new media. There are two	481	; Reusing is only possible when someone processes a new media. There are two
482	; mutually exclusive variants:	482	; mutually exclusive variants:
483	; * driver issues media insert notifications (DISK_NO_INSERT_NOTIFICATION bit	483	; * driver issues media insert notifications (DISK_NO_INSERT_NOTIFICATION bit
484	; in DISK.DriverFlags is not set). In this case, we require from the driver	484	; in DISK.DriverFlags is not set). In this case, we require from the driver
485	; that such notification (except for the first one) can occur only after a	485	; that such notification (except for the first one) can occur only after a
486	; call to 'closemedia' callback.	486	; call to 'closemedia' callback.
487	; * driver does not issue media insert notifications. In this case, the kernel	487	; * driver does not issue media insert notifications. In this case, the kernel
488	; itself must sometimes check whether media is inserted. We have the flag	488	; itself must sometimes check whether media is inserted. We have the flag
489	; DISK.MediaUsed, visible to the kernel. This flag signals to the other parts	489	; DISK.MediaUsed, visible to the kernel. This flag signals to the other parts
490	; of kernel that the way is free.	490	; of kernel that the way is free.
491	; In the first case other parts of the kernel do not use DISK.MediaUsed, so it	491	; In the first case other parts of the kernel do not use DISK.MediaUsed, so it
492	; does not matter when this flag is cleared. In the second case this flag must	492	; does not matter when this flag is cleared. In the second case this flag must
493	; be cleared after all other actions, including call to 'closemedia'.	493	; be cleared after all other actions, including call to 'closemedia'.
494	; 3a. Free all partitions.	494	; 3a. Free all partitions.
495	push esi edi	495	push esi edi
496	mov edi, [esi+DISK.NumPartitions]	496	mov edi, [esi+DISK.NumPartitions]
497	mov esi, [esi+DISK.Partitions]	497	mov esi, [esi+DISK.Partitions]
498	test edi, edi	498	test edi, edi
499	jz .nofree	499	jz .nofree
500	.freeloop:	500	.freeloop:

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(root)/kernel/trunk/blkdev/disk.inc – Rev 2257 → 2288