TITLE 'ccb - cache functions for rxdos' PAGE 59, 132 .LALL ;'''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''; ; CCB Cache Manager for RxDOS ; ;...............................................................; ;'''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''; ; Real Time Dos ; ;- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -; ; ; ; This material was created as a published version of a DOS ; ; equivalent product. This program logically functions in ; ; the same way as MSDOS functions and it is internal data ; ; structure compliant with MSDOS 6.0 ; ; ; ; This product is distributed AS IS and contains no warranty ; ; whatsoever, including warranty of merchantability or ; ; fitness for a particular purpose. ; ; ; ; ; ; (c) Copyright 1990, 1997. Api Software and Mike Podanoffsky ; ; All Rights Reserved Worldwide. ; ; ; ; This product is protected under copyright laws and may not ; ; be reproduced in whole or in part, in any form or media, ; ; included but not limited to source listing, facsimile, data ; ; transmission, cd-rom, or floppy disk without the expressed ; ; written consent of the author. ; ; ; ; License for distribution for commercial use or resale ; ; required from: ; ; ; ; Api Software ; ; 12 South Walker Street ; ; Lowell, MA 01851 ; ; ; ; internet: mikep@world.std.com ; ; ; ;- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -; ; Compile with MASM 5.1 ; ;...............................................................; include rxdosmac.asm include rxdosdef.asm RxDOS SEGMENT PARA PUBLIC 'CODE' assume cs:RxDOS, ds:RxDOS, es:RxDOS, ss:RxDOS ;'''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''; ; Buffer Management ; ;...............................................................; public CCBChanged public invalidateBuffers public linkBegCCB public locateCCBPHeader public readBuffer public readSelBuffer public SelBuffer public unlinkCCB public updateAllChangedCCBBuffers public updateCCB public updateChangedCCB public updateDriveBuffers extrn DevRead : near extrn DevWrite : near extrn getAddrDPB : near extrn _RxDOS_BufferList : near extrn _RxDOS_pCDS : dword extrn _DebugInterruptTrap : near ;'''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''; ; Selected Buffer ; ;- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -; ; ; ; Input: ; ; ax drive ; ; cx:dx sector to read ; ; ; ; Output: ; ; es:di pointer to selected buffer ; ; nz buffer contains valid data ; ; all registers preserved ; ;...............................................................; SelBuffer: SaveRegisters ax, bx, cx, dx les di, dword ptr ss:[ _RxDOS_BufferList ] mov bx, -1 selBuffer_04: test byte ptr es:[ ccbStatus ][ di ], ( ccb_isVALID ) jz selBuffer_08 ; unallocated buffer --> cmp byte ptr es:[ ccbDrive ][ di ], al ; compare drives jnz selBuffer_08 ; not this block, try next --> cmp cx, word ptr es:[ ccbLBN. _high][ di ] ; compare logical block numbers jnz selBuffer_08 ; not this block, try next --> cmp dx, word ptr es:[ ccbLBN. _low ][ di ] ; compare logical block numbers jz selBuffer_36 ; buffer located --> selBuffer_08: test byte ptr es:[ ccbStatus ][ di ], ( ccb_isONHOLD ) jnz selBuffer_12 ; if on hold, don't use --> mov bx, di ; save last buffer address selBuffer_12: mov di, word ptr es:[ ccbNext ][ di ] cmp di, -1 jnz selBuffer_04 ;- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - ; if could not find a matching buffer, find an empty buffer ;- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - mov di, bx cmp di, -1 ; buffer address available ? jnz selBuffer_30 ; use the last referenced buffer --> les di, dword ptr ss:[ _RxDOS_BufferList ] ; else must seatch buffers again selBuffer_16: test byte ptr es:[ ccbStatus ][ di ], ( ccb_isVALID ) jz selBuffer_32 ; unallocated buffer --> cmp word ptr es:[ ccbNext ][ di ], -1 jz selBuffer_30 ; must write all, use least used --> mov di, word ptr es:[ ccbNext ][ di ] jmp selBuffer_16 ;- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - ; prep returned buffer ;- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - selBuffer_30: call updateCCB ; just in case update required selBuffer_32: mov byte ptr es:[ ccbDrive ][ di ], al ; set drive mov word ptr es:[ ccbLBN. _high][ di ], cx ; set logical block number mov word ptr es:[ ccbLBN. _low ][ di ], dx ; set logical block number mov byte ptr es:[ ccbStatus ][ di ], 00 ; clear status call setFlagIfDriveIsRemote ; sets remote flag push es push di call getAddrDPB ; pointer to dpb mov dx, es ; pointer was in [es:bx] pop di pop es mov word ptr es:[ ccbDPB. _segment ][ di ], dx mov word ptr es:[ ccbDPB. _pointer ][ di ], bx selBuffer_36: cmp di, word ptr ss:[ _RxDOS_BufferList. _pointer ] jz selBuffer_38 ; if already at beginning --> call unlinkCCB ; unlink CCB buffer call linkBegCCB ; link to front of CCB chain selBuffer_38: test byte ptr es:[ ccbStatus ][ di ], ( ccb_isVALID ) RestoreRegisters dx, cx, bx, ax ret ;'''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''; ; Is Drive Remote ; ;- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -; ; ; ; al drive ; ; es:di points to ccb buffer ; ;...............................................................; setFlagIfDriveIsRemote: push ax push di push es mov cl, sizeCDS mul cl ; ax contains current drive les di, dword ptr ss:[ _RxDOS_pCDS ] ; actual address of CDS add di, ax ; current drive test word ptr es:[ _cdsFlags ][ di ], _CDS_NETWORKEDDRIVE pop es pop di jz IfDriveIsRemote_12 ; if not remote --> or byte ptr es:[ ccbStatus ][ di ], ( ccb_isREMOTE ) IfDriveIsRemote_12: pop ax ret ;'''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''; ; Remove CCB Buffer from Linked List ; ;- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -; ; ; ; es:di points to ccb buffer ; ;...............................................................; unlinkCCB: pushf ; save current interrupt status push ax push di cli ; disable interrupts mov ax, word ptr es:[ ccbPrev ][ di ] mov di, word ptr es:[ ccbNext ][ di ] cmp ax, -1 ; no previous ? jnz unlinkCCB_06 ; no --> mov word ptr ss:[ _RxDOS_BufferList. _pointer ], di ; update beg of list if no previous unlinkCCB_06: cmp di, -1 ; no next pointer ? jz unlinkCCB_08 ; skip removing its Prev pointer -> mov word ptr es:[ ccbPrev ][ di ], ax ; next's prev fixed. unlinkCCB_08: cmp ax, -1 ; no previous ? jz unlinkCCB_12 ; no --> xchg di, ax mov word ptr es:[ ccbNext ][ di ], ax ; prev's next fixed. unlinkCCB_12: pop di mov word ptr es:[ ccbPrev ][ di ], -1 ; unlink current pointers mov word ptr es:[ ccbNext ][ di ], -1 pop ax popf ; restore interrupt status ret ;'''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''; ; Link CCB Buffer to Beginning of List ; ;- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -; ; ; ; es:di points to ccb buffer ; ;...............................................................; linkBegCCB: pushf ; save current interrupt status push ax cli ; disable interrupts mov ax, di les di, dword ptr ss:[ _RxDOS_BufferList ] cmp ax, di ; relinking ccb buffer to beg of list ? jz linkBegCCB_08 ; yes, don't do it --> mov word ptr es:[ ccbPrev ][ di ], ax ; previous to orig prev xchg di, ax mov word ptr es:[ ccbNext ][ di ], ax ; this next to old next mov word ptr es:[ ccbPrev ][ di ], -1 ; current no more previous mov word ptr ss:[ _RxDOS_BufferList. _pointer ], di linkBegCCB_08: pop ax popf ret ;'''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''; ; Mark CCB buffer changed. ; ;- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -; ; ; ; es:di pointer to selected buffer ; ;...............................................................; CCBChanged: or byte ptr es:[ ccbStatus ][ di ], ( ccb_isDIRTY + ccb_isVALID ) and byte ptr es:[ ccbStatus ][ di ], NOT ( ccb_isONHOLD ) ret ;'''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''; ; Locate from reference actual start of CCB buffer ; ;- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -; ; ; ; Input: ; ; si pointer into a CCB buffer ; ; ; ; Output: ; ; es:di pointer to CCB Header ; ; cx offset from start of data ; ;...............................................................; locateCCBPHeader: les di, dword ptr ss:[ _RxDOS_BufferList ] locateCCBPHeader_04: mov cx, si sub cx, di ; how far from start of buffer jl locateCCBPHeader_08 ; go to next --> cmp cx, sizeCCB ; within a CCB buffer ? jg locateCCBPHeader_08 ; go to next --> or cx, cx ; no carry (leave offset alone ) ret locateCCBPHeader_08: mov di, word ptr es:[ ccbNext ][ di ] cmp di, -1 jnz locateCCBPHeader_04 stc ret ;'''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''; ; Read Buffer ; ;- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -; ; ; ; Input: ; ; cx:dx sector to read ; ; ax drive ; ; bx attributes to claim buffer ; ; ; ; Output: ; ; es:di pointer to selected buffer ; ;...............................................................; readBuffer: call SelBuffer ; find a buffer jnz readBuffer_08 ; if buffer is valid --> call readSelBuffer ; else read buffer readBuffer_08: ret ;'''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''; ; Read Selected Buffer ; ;- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -; ; ; ; Input: ; ; es:di pointer to selected buffer ; ; cx:dx sector to read ; ; ax drive ; ; ; ; Output: ; ; es:di pointer to selected buffer ; ; cx:dx sector to read ; ;...............................................................; readSelBuffer: SaveAllRegisters push di push es mov byte ptr es:[ ccbDrive ][ di ], al ; set drive mov word ptr es:[ ccbLBN. _high][ di ], cx ; set logical block number mov word ptr es:[ ccbLBN. _low ][ di ], dx ; set logical block number mov byte ptr es:[ ccbStatus ][ di ], 00 ; kill entry's value, validity mov bx, 0001 lea di, offset ccbData [ di ] ; buffer address call DevRead ; read buffer pop es pop di jc readSelBuffer_08 ; if error --> mov byte ptr es:[ ccbStatus ][ di ], (ccb_isVALID) readSelBuffer_08: RestoreAllRegisters ret ;'''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''; ; Update CCB buffer, always. ; ;- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -; ; ; ; es:di pointer to selected buffer ; ; All Registers Preserved ; ;...............................................................; updateCCB: test byte ptr es:[ ccbStatus ][ di ], ( ccb_isVALID ) jz updateCCB_08 ; data not valid --> test byte ptr es:[ ccbStatus ][ di ], ( ccb_isDIRTY ) jnz updateChangedCCB ; data valid and changed --> updateCCB_08: ret ;'''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''; ; Update Changed CCB buffer. ; ;- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -; ; ; ; es:di pointer to selected buffer ; ; All Registers Preserved ; ; ; ; CY returned in fail in write ; ;...............................................................; updateChangedCCB: Entry ddef _buffer, es, di SaveAllRegisters mov bx, 0001 mov dx, word ptr es:[ ccbLBN. _low ][ di ] ; get sector mov cx, word ptr es:[ ccbLBN. _high ][ di ] mov al, byte ptr es:[ ccbDrive ][ di ] ; get drive number cbw lea di, offset ccbData [ di ] ; buffer address call DevWrite ; write t\disk jc updateCCB_12 ; if error/ fail --> les di, dword ptr [ _buffer ][ bp ] test byte ptr es:[ ccbStatus ][ di ], ( ccb_isFAT ) jz updateCCB_12 ; not a FAT buffer --> call updateAlternateFATTables ; update FAT tables ; jc updateCCB_12 ; if error/ fail --> updateCCB_12: pushf les di, dword ptr [ _buffer ][ bp ] and byte ptr es:[ ccbStatus ][ di ], NOT ( ccb_isDIRTY + ccb_isONHOLD ) popf ; keep flag, but kill error buffer RestoreAllRegisters Return ;'''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''; ; Update Alternate FAT Table ; ;- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -; ; ; ; Given a FAT sector address, copies the sector to the alter- ; ; nate FAT Table. ; ; ; ; Input: ; ; es:di pointer to a FAT CCB Buffer ; ;...............................................................; updateAlternateFATTables: Entry ddef _ccb, es, di def _dpbNumberFat def _dpbFATSectors test byte ptr es:[ ccbStatus ][ di ], ( ccb_isFAT ) jz updateAlternateFATTables_22 ; not a fat designated sector --> les bx, dword ptr es:[ ccbDPB ][ di ] ; get assigned DPB mov ax, word ptr es:[ _dpbSectorsPerFat ][ bx ] storarg _dpbFATSectors, ax mov ah, 0 mov al, byte ptr es:[ _dpbNumCopiesFAT ][ bx ] storarg _dpbNumberFat, ax getdarg es, di, _ccb mov dx, word ptr es:[ ccbLBN. _low ][ di ] ; get original sector mov cx, word ptr es:[ ccbLBN. _high ][ di ] mov al, byte ptr es:[ ccbDrive ][ di ] ; get drive number cbw lea di, offset ccbData [ di ] ; buffer address updateAlternateFATTables_08: dec word ptr [ _dpbNumberFat ][ bp ] jle updateAlternateFATTables_22 ; if not more than 1 --> mov bx, 0001 add dx, word ptr [ _dpbFATSectors ][ bp ] ; adjust for fat size adc cx, 0000 SaveRegisters es, di, dx, cx, ax call DevWrite RestoreRegisters ax, cx, dx, di, es jnc updateAlternateFATTables_08 updateAlternateFATTables_22: Return ;'''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''; ; Update All Drive Buffers ; ;- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -; ; ; ; Input: ; ; ax drive ; ;...............................................................; updateDriveBuffers: les di, dword ptr ss:[ _RxDOS_BufferList ] updDriveBuffer_04: test byte ptr es:[ ccbStatus ][ di ], ( ccb_isVALID ) jz updDriveBuffer_16 ; not a valid block --> cmp byte ptr es:[ ccbDrive ][ di ], al ; compare drives jnz updDriveBuffer_16 ; not this block, try next --> call updateCCB ; update block if changed updDriveBuffer_16: mov di, word ptr es:[ ccbNext ][ di ] cmp di, -1 jnz updDriveBuffer_04 ret ;'''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''; ; Update All Changed Buffers ; ;...............................................................; updateAllChangedCCBBuffers: pushf SaveAllRegisters les di, dword ptr ss:[ _RxDOS_BufferList ] updateAllChanged_04: test byte ptr es:[ ccbStatus ][ di ], ( ccb_isVALID ) jz updateAllChanged_16 ; not a valid buffer --> call updateCCB ; updated buffer if req'd updateAllChanged_16: mov di, word ptr es:[ ccbNext ][ di ] cmp di, -1 jnz updateAllChanged_04 RestoreAllRegisters popf ret ;'''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''; ; Invalidate Buffers for Specific Drive ; ;- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -; ; ; ; Input: ; ; ax drive ; ;...............................................................; invalidateBuffers: les di, dword ptr ss:[ _RxDOS_BufferList ] invBuffer_04: test byte ptr es:[ ccbStatus ][ di ], ( ccb_isVALID ) jz invBuffer_16 ; not a valid buffer --> cmp al, byte ptr es:[ ccbDrive ][ di ] ; same drive ? jnz invBuffer_16 ; if not --> and byte ptr es:[ ccbStatus ][ di ], NOT ( ccb_isVALID ) invBuffer_16: mov di, word ptr es:[ ccbNext ][ di ] cmp di, -1 jnz invBuffer_04 ret RxDOS ENDS END