196 lines
6.5 KiB
PHP
196 lines
6.5 KiB
PHP
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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;; ;;
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;; Copyright (C) KolibriOS team 2013. All rights reserved. ;;
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;; Distributed under terms of the GNU General Public License ;;
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;; ;;
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;; RAMDISK functions ;;
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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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$Revision$
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iglobal
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align 4
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ramdisk_functions:
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dd .size
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dd 0 ; no close() function
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dd 0 ; no closemedia() function
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dd ramdisk_querymedia
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dd ramdisk_read
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dd ramdisk_write
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dd 0 ; no flush() function
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dd ramdisk_adjust_cache_size
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.size = $ - ramdisk_functions
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endg
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; See memmap.inc.
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; Currently size of memory allocated for the ramdisk is fixed.
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; This should be revisited when/if memory map would become more dynamic.
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RAMDISK_CAPACITY = 2880 ; in sectors
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iglobal
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align 4
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ramdisk_actual_size dd RAMDISK_CAPACITY
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endg
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; This function is called early in boot process.
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; It creates filesystem /rd/1 based on raw image data loaded by somebody before
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; to memory named as RAMDISK with max size RAMDISK_CAPACITY, may be less.
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proc ramdisk_init
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iglobal
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ramdisk_name db 'rd',0
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endg
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push ebx esi ; save used registers to be stdcall
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; 1. Register the device and the (always inserted) media in the disk subsystem.
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stdcall disk_add, ramdisk_functions, ramdisk_name, 0, 0
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test eax, eax
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jz .fail
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mov ebx, eax
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stdcall disk_media_changed, eax, 1
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; 2. We don't know actual size of loaded image,
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; so try to calculate it using partition structure,
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; assuming that file systems fill the real size based on contents of the partition.
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; 2a. Prepare for loop over partitions.
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xor ecx, ecx
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xor edx, edx
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; 2b. Check that at least one partition was recognized.
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cmp [ebx+DISK.NumPartitions], ecx
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jz .fail
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; 2c. Loop over partitions.
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.partitions:
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; For every partition, set edx to maximum between edx and end of partition.
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mov esi, [ebx+DISK.Partitions]
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mov esi, [esi+ecx*4]
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mov eax, dword [esi+PARTITION.FirstSector]
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add eax, dword [esi+PARTITION.Length]
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cmp eax, edx
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jb @f
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mov edx, eax
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@@:
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inc ecx
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cmp ecx, [ebx+DISK.NumPartitions]
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jb .partitions
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; 3. Reclaim unused memory, if any.
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mov [ramdisk_actual_size], edx
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add edx, 7 ; aligning up
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shr edx, 3 ; 512-byte sectors -> 4096-byte pages
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mov esi, RAMDISK_CAPACITY / 8 ; aligning down
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sub esi, edx
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jbe .no_reclaim
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shl edx, 12
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add edx, RAMDISK - OS_BASE
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@@:
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mov eax, edx
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call free_page
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add edx, 0x1000
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dec esi
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jnz @b
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.no_reclaim:
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pop esi ebx ; restore used registers to be stdcall
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ret
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.fail:
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dbgstr 'Failed to initialize ramdisk'
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pop esi ebx ; restore used registers to be stdcall
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ret
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endp
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; Returns information about disk media.
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proc ramdisk_querymedia
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virtual at esp+4
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.userdata dd ?
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.info dd ?
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end virtual
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; Media is always present, sector size is always 512 bytes.
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mov edx, [.userdata]
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mov ecx, [.info]
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mov [ecx+DISKMEDIAINFO.Flags], 0
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mov [ecx+DISKMEDIAINFO.SectorSize], 512
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mov eax, [ramdisk_actual_size]
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mov dword [ecx+DISKMEDIAINFO.Capacity], eax
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mov dword [ecx+DISKMEDIAINFO.Capacity+4], 0
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; Return zero as an indicator of success.
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xor eax, eax
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retn 8
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endp
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; Common procedure for reading and writing.
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; operation = 0 for reading, operation = 1 for writing.
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; Arguments of ramdisk_read and ramdisk_write are the same.
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macro ramdisk_read_write operation
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{
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push esi edi ; save used registers to be stdcall
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mov esi, [userdata]
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mov edi, [numsectors_ptr]
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; 1. Determine number of sectors to be transferred.
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; This is either the requested number of sectors or number of sectors
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; up to the disk boundary, depending of what is less.
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xor ecx, ecx
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; 1a. Test whether [start_sector] is less than RAMDISK_CAPACITY.
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; If so, calculate number of sectors between [start_sector] and RAMDISK_CAPACITY.
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; Otherwise, the actual number of sectors is zero.
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cmp dword [start_sector+4], ecx
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jnz .got_number
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mov eax, [ramdisk_actual_size]
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sub eax, dword [start_sector]
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jbe .got_number
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; 1b. Get the requested number of sectors.
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mov ecx, [edi]
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; 1c. If it is greater than number of sectors calculated in 1a, use the value
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; from 1a.
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cmp ecx, eax
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jb .got_number
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mov ecx, eax
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.got_number:
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; 2. Compare the actual number of sectors with requested. If they are
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; equal, set eax (it will be the returned value) to zero. Otherwise,
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; use DISK_STATUS_END_OF_MEDIA.
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xor eax, eax
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cmp ecx, [edi]
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jz @f
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mov al, DISK_STATUS_END_OF_MEDIA
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@@:
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; 3. Store the actual number of sectors.
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mov [edi], ecx
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; 4. Calculate source and destination addresses.
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if operation = 0 ; reading?
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mov esi, dword [start_sector]
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shl esi, 9
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add esi, RAMDISK
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mov edi, [buffer]
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else ; writing?
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mov edi, dword [start_sector]
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shl edi, 9
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add edi, RAMDISK
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mov esi, [buffer]
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end if
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; 5. Calculate number of dwords to be transferred.
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shl ecx, 9-2
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; 6. Copy data.
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rep movsd
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; 7. Return. The value in eax was calculated in step 2.
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pop edi esi ; restore used registers to be stdcall
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}
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; Reads one or more sectors from the device.
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proc ramdisk_read userdata:dword, buffer:dword, start_sector:qword, numsectors_ptr:dword
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ramdisk_read_write 0
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ret
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endp
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; Writes one or more sectors to the device.
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proc ramdisk_write userdata:dword, buffer:dword, start_sector:qword, numsectors_ptr:dword
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ramdisk_read_write 1
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ret
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endp
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; The kernel calls this function when initializing cache subsystem for
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; the media. This call allows the driver to adjust the cache size.
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proc ramdisk_adjust_cache_size
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virtual at esp+4
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.userdata dd ?
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.suggested_size dd ?
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end virtual
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; Since ramdisk does not need cache, just return 0.
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xor eax, eax
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retn 8
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endp
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