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;; ;;
;; Copyright (C) KolibriOS team 2013-2015. All rights reserved. ;;
;; Distributed under terms of the GNU General Public License ;;
;; ;;
;; RAMDISK functions ;;
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$Revision: 8064 $
iglobal
align 4
ramdisk_functions:
dd .size
dd 0 ; no close() function
dd 0 ; no closemedia() function
dd ramdisk_querymedia
dd ramdisk_read
dd ramdisk_write
dd 0 ; no flush() function
dd ramdisk_adjust_cache_size
.size = $ - ramdisk_functions
endg
iglobal
align 4
ramdisk_actual_size dd RAMDISK_CAPACITY
endg
; This function is called early in boot process.
; It creates filesystem /rd/1 based on raw image data loaded by somebody before
; to memory named as RAMDISK with max size RAMDISK_CAPACITY, may be less.
proc ramdisk_init
iglobal
ramdisk_name db 'rd',0
endg
push ebx esi ; save used registers to be stdcall
; 1. Register the device and the (always inserted) media in the disk subsystem.
stdcall disk_add, ramdisk_functions, ramdisk_name, 0, 0
test eax, eax
jz .fail
mov ebx, eax
stdcall disk_media_changed, eax, 1
; 2. We don't know actual size of loaded image,
; so try to calculate it using partition structure,
; assuming that file systems fill the real size based on contents of the partition.
; 2a. Prepare for loop over partitions.
xor eax, eax
xor ecx, ecx
xor edx, edx
; 2b. Check that at least one partition was recognized.
cmp [ebx+DISK.NumPartitions], ecx
jz .fail
; 2c. Loop over partitions.
.partitions:
; For every partition, set edx to maximum between edx and end of partition.
mov esi, [ebx+DISK.Partitions]
mov esi, [esi+ecx*4]
mov eax, dword [esi+PARTITION.FirstSector]
add eax, dword [esi+PARTITION.Length]
cmp eax, edx
jb @f
mov edx, eax
@@:
inc ecx
cmp ecx, [ebx+DISK.NumPartitions]
jb .partitions
; 3. Reclaim unused memory, if any.
mov [ramdisk_actual_size], edx
add edx, 7 ; aligning up
shr edx, 3 ; 512-byte sectors -> 4096-byte pages
mov esi, RAMDISK_CAPACITY / 8 ; aligning down
sub esi, edx
jbe .no_reclaim
shl edx, 12
add edx, RAMDISK - OS_BASE
@@:
mov eax, edx
call free_page
add edx, 0x1000
dec esi
jnz @b
.no_reclaim:
mov eax, ebx
pop esi ebx ; restore used registers to be stdcall
ret
.fail:
dbgstr 'Failed to initialize ramdisk'
pop esi ebx ; restore used registers to be stdcall
ret
endp
; Returns information about disk media.
proc ramdisk_querymedia
virtual at esp+4
.userdata dd ?
.info dd ?
end virtual
; Media is always present, sector size is always 512 bytes.
mov edx, [.userdata]
mov ecx, [.info]
mov [ecx+DISKMEDIAINFO.Flags], 0
mov [ecx+DISKMEDIAINFO.SectorSize], 512
mov eax, [ramdisk_actual_size]
mov dword [ecx+DISKMEDIAINFO.Capacity], eax
mov dword [ecx+DISKMEDIAINFO.Capacity+4], 0
; Return zero as an indicator of success.
xor eax, eax
retn 8
endp
; Common procedure for reading and writing.
; operation = 0 for reading, operation = 1 for writing.
; Arguments of ramdisk_read and ramdisk_write are the same.
macro ramdisk_read_write operation
{
push esi edi ; save used registers to be stdcall
mov esi, [userdata]
mov edi, [numsectors_ptr]
; 1. Determine number of sectors to be transferred.
; This is either the requested number of sectors or number of sectors
; up to the disk boundary, depending of what is less.
xor ecx, ecx
; 1a. Test whether [start_sector] is less than RAMDISK_CAPACITY.
; If so, calculate number of sectors between [start_sector] and RAMDISK_CAPACITY.
; Otherwise, the actual number of sectors is zero.
cmp dword [start_sector+4], ecx
jnz .got_number
mov eax, [ramdisk_actual_size]
sub eax, dword [start_sector]
jbe .got_number
; 1b. Get the requested number of sectors.
mov ecx, [edi]
; 1c. If it is greater than number of sectors calculated in 1a, use the value
; from 1a.
cmp ecx, eax
jb .got_number
mov ecx, eax
.got_number:
; 2. Compare the actual number of sectors with requested. If they are
; equal, set eax (it will be the returned value) to zero. Otherwise,
; use DISK_STATUS_END_OF_MEDIA.
xor eax, eax
cmp ecx, [edi]
jz @f
mov al, DISK_STATUS_END_OF_MEDIA
@@:
; 3. Store the actual number of sectors.
mov [edi], ecx
; 4. Calculate source and destination addresses.
if operation = 0 ; reading?
mov esi, dword [start_sector]
shl esi, 9
add esi, RAMDISK
mov edi, [buffer]
else ; writing?
mov edi, dword [start_sector]
shl edi, 9
add edi, RAMDISK
mov esi, [buffer]
end if
; 5. Calculate number of dwords to be transferred.
shl ecx, 9-2
; 6. Copy data.
rep movsd
; 7. Return. The value in eax was calculated in step 2.
pop edi esi ; restore used registers to be stdcall
}
; Reads one or more sectors from the device.
proc ramdisk_read userdata:dword, buffer:dword, start_sector:qword, numsectors_ptr:dword
ramdisk_read_write 0
ret
endp
; Writes one or more sectors to the device.
proc ramdisk_write userdata:dword, buffer:dword, start_sector:qword, numsectors_ptr:dword
ramdisk_read_write 1
ret
endp
; The kernel calls this function when initializing cache subsystem for
; the media. This call allows the driver to adjust the cache size.
proc ramdisk_adjust_cache_size
virtual at esp+4
.userdata dd ?
.suggested_size dd ?
end virtual
; Since ramdisk does not need cache, just return 0.
xor eax, eax
retn 8
endp