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Assembly Source File | 1986-09-10 | 19.3 KB | 646 lines

page 59,120 title RX50DRVR -- RX50 Diskette Driver for IBM PC-AT ;-----------------------------------------------------------------------; ; ; ; RX50DRVR -- RX50 Diskette Driver for IBM PC-AT ; ; ; ;-----------------------------------------------------------------------; VERSION equ 05 ; 08-Dec-84 15:10 ; Copyright (c) 1984 by Robert F. Morse ; 17 Bowdoin Street ; Cambridge, MA 02138 ; ; This is an MS-DOS loadable block device driver to support reading and ; writing DEC RX50 diskettes in the high capacity diskette drive of an ; IBM PC-AT. It uses the drive which is known to the normal PC-DOS as ; drive A: but designates it by the letter assigned when this driver is ; loaded. Needless to say, attempting to use both letters at the same ; time will lead to unpredictable results. .286C ;enable 186/286 instructions NUNITS equ 1 ;number of units supported by this driver PHYS_DRIVE_0 equ 00h ;drive number for the HC drive A: PHYS_BLKSIZE equ 512 ;blocks always 512 bytes DOSRUPT equ 21h CR equ 0Dh LF equ 0Ah ;--------------------------------------------------------------- ; IBM ROM BIOS Definitions ;--------------------------------------------------------------- DKOP_RUPT equ 013h ;interrupt to call ROM BIOS DKOP_RESET equ 000h ; reset controller DKOP_STATUS equ 001h ; read status from last operation DKOP_READ equ 002h ; read sectors DKOP_WRITE equ 003h ; write sectors DKOP_VERIFY equ 004h ; verify sectors DKOP_CHANGE equ 016h ; test changed status DKOP_SETTYPE equ 017h ; set media type in drive DKST_TIMEOUT equ 080h ;drive not ready DKST_BADSEEK equ 040h ;seek failed DKST_BADNEC equ 020h ;NEC controller failed DKST_BADCRC equ 010h ;read CRC error DKST_BADDMA equ 009h ;attempt to DMA over 64K boundary DKST_OVERRUN equ 008h ;DMA overrun DKST_CHANGED equ 006h ;media changed DKST_RNF equ 004h ;sector not found DKST_WRPROT equ 003h ;write-protected diskette DKST_ADRMARK equ 002h ;address mark not found DKST_BADCMD equ 001h ;invalid command BIOS_DATA_SEG equ 0040h BIOSDATA segment at BIOS_DATA_SEG ;BIOS data segment-- org 0090h bios_dsk_state db ? ;drive 0 media state BIOS_DSK_360K equ 074h ; 360kb media established BIOS_DSK_RX50 equ 054h ; RX50 media established in drive ; (same as 360kb except single steps ; for 96 tpi media) BIOSDATA ends ;--------------------------------------------------------------- ; I/O Request Packet Definition ;--------------------------------------------------------------- iop_struc struc ;I/O request packet iop_len db ? ; packet length iop_unit db ? ; block device unit number iop_cmd db ? ; command code, 0..IOP_CMD_MAX iop_status dw ? ; status word, see IOPST... tags dd ? ; future queue link 1 dd ? ; future queue line 2 iop_media db ? ; media descriptor (or read-ahead byte) iop_bufoff dw ? ; buffer pointer offset iop_bufseg dw ? ; and segment iop_count dw ? ; byte/sector count iop_block dw ? ; starting block number iop_1stdrv db ? ; number of first block drive iop_struc ends iop_nextchar equ byte ptr iop_media ;next available input byte iop_nunits equ byte ptr iop_media ;number of units iop_bufptr equ dword ptr iop_bufoff ;buffer pointer iop_return equ byte ptr iop_bufoff ;disk-changed return code iop_ckvoloff equ word ptr iop_bufoff+1 ;pointer to iop_ckvolseg equ word ptr iop_bufoff+3 ; volume name for MEDIACHK iop_bpboff equ word ptr iop_count ;pointer to iop_bpbseg equ word ptr iop_count+2 ; BPB or BPB list iop_endoff equ word ptr iop_bufoff ;pointer to end of iop_endseg equ word ptr iop_bufoff+2 ; resident part of driver iop_rwvoloff equ word ptr iop_block+2 ;pointer to iop_rwvolseg equ word ptr iop_block+4 ; volume name for READ/WRITE IOP_CMD_MAX equ 15 ;highest valid command number IOPST_BUSY equ 0200h ;"busy" status IOPST_DONE equ 0100h ;"done" status IOPST_ERR equ 8000h ;"error" status, in combination with-- IOPST_WRPROT equ 0000h ; write-protect IOPST_BADUNIT equ 0001h ; invalid unit number IOPST_NOTRDY equ 0002h ; unit not ready IOPST_BADCMD equ 0003h ; invalid command IOPST_CRC equ 0004h ; CRC error IOPST_BADIOP equ 0005h ; bad IOP length IOPST_SEEK equ 0006h ; seek error IOPST_UNKMEDIA equ 0007h ; unknown media IOPST_RNF equ 0008h ; sector not found IOPST_NOPAPER equ 0009h ; printer out of paper IOPST_WRFAULT equ 000Ah ; write fault IOPST_RDFAULT equ 000Bh ; read fault IOPST_IOERR equ 000Ch ; general I/O failure IOPST_BADCHNG equ 000Fh ; invalid diskette change ;--------------------------------------------------------------- ; Bios Parameter Block Definition ;--------------------------------------------------------------- bpb_struc struc bpb_sectsiz dw ? ; sector size, in bytes bpb_sectalu db ? ; sectors per allocation unit bpb_reserved dw ? ; number of reserved sectors before 1st FAT bpb_numfats db ? ; number of FAT's bpb_dirents dw ? ; number of root directory entries bpb_totsects dw ? ; total number of sectors on disk bpb_media db ? ; media descriptor byte bpb_fatsects dw ? ; number of sectors in a FAT ; additional fields to describe media: bpb_sect_trk dw ? ; sectors per track bpb_head_cyl dw ? ; heads per cylinder bpb_hidden dw ? ; number of "hiden" sectors bpb_struc ends ;=======================================================================; ; Permanently Resident Code & Data ; ;=======================================================================; DRVRSEG segment word ;-------- I/O Device Header Block -------- ; ;This is at the first byte of the driver's code image. BLKDEV equ 0000h ;block device NONIBM equ 2000h ;non-IBM placement of FAT REMOVE equ 0800h ;has removable media header_rx50 label word dd -1 dw BLKDEV+NONIBM+REMOVE dw offset strategy dw offset service db NUNITS, 0,0,0,0,0,0,0 ;-------- Bios Parameter Blocks -------- init_bpblist dw NUNITS dup (offset bpb_rx50) bpb_rx50 bpb_struc <512, 1, 20, 2, 96, 800, 0FAh, 3, 10, 1, 0> ;-------- Working Storage -------- even io_packet_ptr dd ? ;save cell for IOP pointer drive_letter db 'A' ;letter for first drive supported vol_name db 'RX50DISK',0 bpb_pointer dw 0 ;pointer to currently valid BPB open_count dw 0 ;count of open files on device ;items for sector transfer loop: xx_oper db ? ; operation code xx_count dw ? ; block counter xx_block dw ? ; block number xx_buf dd ? ; buffer pointer: xx_offset equ word ptr xx_buf ; offset xx_seg equ word ptr xx_buf+2 ; and segment xx_status db ? ; diskette status code xx_retries db ? ; error retry counter ;--------------------------------------------------------------- ; IO_STRATEGY: strategy routine ;--------------------------------------------------------------- ; ;Simple strategy routine which merely saves the I/O packet pointer ;passed in ES:BX and returns. assume cs:DRVRSEG, ds:nothing strategy proc far mov word ptr cs:io_packet_ptr, bx mov word ptr cs:io_packet_ptr+2, es ret strategy endp ;--------------------------------------------------------------- ; IO_SERVICE: I/O request service routine ;--------------------------------------------------------------- ; ;Entry point to command dispatcher for all service requests. Validates ;the command and invokes the command execution routine with ES:DI ;pointing to the I/O packet. assume cs:DRVRSEG, ds:nothing, es:nothing service proc far pusha ;save caller's registers push ds push es cld ;be sure of direction mov ax, cs ;set up local data segment mov ds, ax assume ds:DRVRSEG les di, io_packet_ptr ;set ES:DI to I/O packet mov al, es:iop_cmd[di] ;load command code from IOP cmp al, IOP_CMD_MAX ; and test its value ja invalid_command cbw ;convert to word index add ax, ax xchg bx, ax ;put vector index into BX xor ax, ax ;start with AX=0 call drv_cmdtable [bx] ;call command executor ;Command routines return here with status flags in AX. Insert the ;"DONE" bit, store the status in the IOP, and exit from the driver. assume cs:DRVRSEG, ds:nothing epilogue: lds di, io_packet_ptr ;set DS:DI to IOP or ax, IOPST_DONE ;insert DONE flag mov ds:iop_status[di], ax ; and store status in IOP pop es ;restore caller's regs pop ds popa ret service endp ;-------- Command dispatch table -------- even drv_cmdtable label word dw init ; 0 -- initialize dw mediachk ; 1 -- media check dw makebpb ; 2 -- build BPB dw cmd_dummy ; 3 -- IOCTL input dw read ; 4 -- read sectors dw cmd_dummy ; 5 -- peek at next byte dw cmd_dummy ; 6 -- test input status dw cmd_dummy ; 7 -- flush input buffer dw write ; 8 -- write sectors dw writver ; 9 -- write and verify sectors dw cmd_dummy ;10 -- test output status dw cmd_dummy ;11 -- flush output buffer dw cmd_dummy ;12 -- IOCTL output dw open ;13 -- device open dw close ;14 -- device close dw removable ;15 -- removable media check ;-------- Invalid command -------- ; ;Load error status and jump to epilogue to return. invalid_command: mov ax, IOPST_ERR + IOPST_BADCMD jmp epilogue ;-------- Dummy command -------- ; ;Perform no operation and return with OK status. cmd_dummy: xor ax, ax ;no errors ret ;--------------------------------------------------------------- ; MEDIACHK -- Check for media change ;--------------------------------------------------------------- ; ;Test whether the diskette has been changed. If this is the first ;use of the unit or if the BPB pointer is 0 (indicating a non-DOS ;diskette), always reply CHANGED to force a new BPB build. ;Otherwise, call the IBM BIOS to test the disk drive's DISKETTE ;CHANGE line and respond CHANGED or NOCHANGE accordingly. NOCHANGE equ 1 DONTKNOW equ 0 CHANGED equ -1 assume cs:DRVRSEG, ds:DRVRSEG mediachk: mov si, bpb_pointer ;load pointer to BPB test si, si jz mediachk_changed ;reply CHANGED if non-DOS disk ;Call IBM ROM BIOS to get change status from drive. mov dl, PHYS_DRIVE_0 ;load drive number mov ah, DKOP_CHANGE ;BIOS op-code int DKOP_RUPT cmp ah, 00h je mediachk_nochange mediachk_changed: mov dl, CHANGED ;reply "changed" xor ax, ax ; with no error code mov open_count, ax ;zero count of open files jmp short mediachk_result mediachk_nochange: mov dl, NOCHANGE ;reply "no change" xor ax, ax ; with no error code mediachk_result: les di, io_packet_ptr ;get I/O packet pointer mov es:iop_ckvoloff[di], offset vol_name mov es:iop_ckvolseg[di], cs mov es:iop_return[di], dl ;store change return code ret ;--------------------------------------------------------------- ; MAKEBPB -- Set up BPB ;--------------------------------------------------------------- ; ;Set the ROM BIOS state for the drive to handle RX50 media and ;return a pointer to the RX50 BPB. assume cs:DRVRSEG, ds:DRVRSEG makebpb: mov open_count, 0 ;zero count of opened files mov dl, PHYS_DRIVE_0 ;load drive number mov al, 02h ;set up 360KB in 1.2m drive mov ah, DKOP_SETTYPE int DKOP_RUPT ;call BIOS to set up type mov xx_status, ah ; and store returned status test ah, DKST_TIMEOUT ;test for drive not ready jz makebpb_01 ;skip if no error mov ax, IOPST_ERR+IOPST_NOTRDY jmp short makebpb_ret makebpb_01: mov ax, BIOS_DATA_SEG ;change diskette status to mov es, ax ; single track stepping for 96 tpi mov es:bios_dsk_state, BIOS_DSK_RX50 mov si, offset bpb_rx50 ;set up RX50 BPB mov bpb_pointer, si ;save address of active BPB les di, io_packet_ptr ;point to I/O packet mov al, bpb_media[si] ;get media descriptor byte mov es:iop_media[di], al ; and put into IOP mov es:iop_bpboff[di], si ;put BPB pointer mov es:iop_bpbseg[di], ds ; into IOP xor ax, ax ;no error makebpb_ret: ret ;--------------------------------------------------------------- ; READ and WRITE: transfer sectors ;--------------------------------------------------------------- assume cs:DRVRSEG, ds:DRVRSEG read: mov al, DKOP_READ ;set up READ operation call do_readwrite ; and do it jmp short rwv_fini write: mov al, DKOP_WRITE ;set up WRITE operation call do_readwrite ; and do it jmp short rwv_fini writver: mov al, DKOP_WRITE ;set up WRITE operation call do_readwrite ; and do it test ax, ax ;if there is an error jnz rwv_fini ; then quit now les di, io_packet_ptr ;reload address of I/O packet mov al, DKOP_VERIFY ;set up VERIFY operation call do_readwrite ; and do it rwv_fini: les di, io_packet_ptr ;set ES:DI to I/O packet mov dx, xx_count ;load number of sectors NOT sub es:iop_count[di], dx ; transferred and adjust IOP count ret ;return with AX = error code ;Common routine for read, write and verify. ; ;Given: AL = operation code ; ES:DI = pointer to IOP, which contains ; iop_block = starting block number ; iop_bufptr = starting buffer address ; iop_count = number of blocks ;Returns: AX = IOP error code ; xx_count = number of requested blocks NOT transferred do_readwrite: mov es:iop_rwvoloff[di], offset vol_name mov es:iop_rwvolseg[di], cs mov xx_oper, al ;save operation code mov ax, es:iop_block[di] ;set starting block number mov xx_block, ax mov ax, es:iop_count[di] ;set block count mov xx_count, ax test ax, ax jz dorw_success ; quit if 0 sectors to do mov ax, es:iop_bufoff[di] ;set starting buffer offset mov xx_offset, ax ; and segment mov ax, es:iop_bufseg[di] mov xx_seg, ax dorw_loop: mov xx_retries, 5 ;set retry counter dorw_again: mov ax, BIOS_DATA_SEG ;set diskette status to single mov es, ax ; stepping for 96 tpi mov es:bios_dsk_state, BIOS_DSK_RX50 mov ax, xx_block ;load block number call makechs_rx50 ; and convert to CHS mov dl, PHYS_DRIVE_0 ;set drive number mov ah, xx_oper ;operation code mov al, 1 ;transfer 1 sector les bx, xx_buf ;set ES:BX to buffer address int DKOP_RUPT ;invoke ROM BIOS to do it mov xx_status, ah ; and save returned status test ah, ah ;test for error jnz dorw_error ; break loop on error inc xx_block ;advance to next block add xx_offset, PHYS_BLKSIZE ;advance buffer pointer dec xx_count ;count blocks jnz dorw_loop ; and continue until done dorw_success: xor ax, ax ;set no-error code ret ;Analyze read/write errors and either make another attempt or ;set the error code and return. dorw_error: mov al, IOPST_NOTRDY test ah, DKST_TIMEOUT jnz dorw_giveup mov al, IOPST_SEEK test ah, DKST_BADSEEK jnz dorw_retry mov al, IOPST_IOERR test ah, DKST_BADNEC jnz dorw_retry cmp ah, DKST_OVERRUN je dorw_retry mov al, IOPST_CRC cmp ah, DKST_BADCRC je dorw_retry mov al, IOPST_BADCMD cmp ah, DKST_BADDMA je dorw_giveup cmp ah, DKST_BADCMD je dorw_giveup mov al, IOPST_BADCHNG cmp ah, DKST_CHANGED jne dorw_nochange cmp open_count, 0 jg dorw_giveup ;error if change with any files open jmp short dorw_reset ; else do it again dorw_nochange: mov al, IOPST_RNF cmp ah, DKST_RNF je dorw_retry mov al, IOPST_WRPROT cmp ah, DKST_WRPROT je dorw_giveup mov al, IOPST_UNKMEDIA cmp ah, DKST_ADRMARK je dorw_retry mov al, IOPST_IOERR jmp short dorw_giveup dorw_retry: dec xx_retries ;count retries jle dorw_giveup dorw_reset: mov ah, DKOP_RESET ;reset the disk controller int DKOP_RUPT jmp dorw_again ; and try again dorw_giveup: mov ah, high IOPST_ERR ;complete the driver error return code ret ;-------- MAKECHS_RX50 -------- ; ;Convert block number to cylinder, head, sector for RX50. For cylinders ;2 through 79, the sectors are interleaved 2:1. ; ;Given: AX = block number. ;Returns: CH = cylinder, ; DH = head, ; CL = sector. ;Destroys: DL, AX. makechs_rx50: cwd ;set up block in DX:AX div secpertrk_rx50 ;AX=track, DX=sector xchg bx, dx ;get sector into BX cmp al, 2 ;test if cyls 0 or 1 jb makechs_rx50_a ; skip if so mov bl, interleave_rx50[bx] ; else interleave sectors makechs_rx50_a: inc bx ;shift to 1-origin sector # xchg dx, bx ;restore BX mov ch, al ;CH = cylinder mov dh, 0 ;DH = head mov cl, dl ;CL = sector ret secpertrk_rx50 dw 10 ;sectors per RX50 track interleave_rx50 db 0,2,4,6,8,1,3,5,7,9 ;0-origin sector interleave table ;--------------------------------------------------------------- ; OPEN -- Device Open ;--------------------------------------------------------------- ; ;Increment the count of opened files on the device. assume cs:DRVRSEG, ds:DRVRSEG open: inc open_count ret ;--------------------------------------------------------------- ; CLOSE -- Device Close ;--------------------------------------------------------------- ; ;Decrement the count of opened files on the device. assume cs:DRVRSEG, ds:DRVRSEG close: cmp open_count, 0 jle close_1 dec open_count close_1: ret ;--------------------------------------------------------------- ; REMOVABLE -- Report that Media are Removable ;--------------------------------------------------------------- ; ;Return with IOPST_BUSY = 0 to indicate that media can be removed ;from this device. assume cs:DRVRSEG, ds:DRVRSEG removable: ret ;=======================================================================; ; Initialization Code & Data ; ;=======================================================================; ; ;Code and data from here on are discarded after INIT is called. even end_permanent_code label byte init_msg_1 db CR,LF,'RX50DRVR version ' db (VERSION / 10) + '0' db (VERSION mod 10) + '0' db ' Copyright (c) 1984 by Robert F. Morse' db CR,LF,' Loaded at ' init_msg_seg db '0000' db '0 and refers to drive as ' init_msg_ltr db 'A:' db CR,LF,'$' ;--------------------------------------------------------------- ; INIT -- Driver Initialization ;--------------------------------------------------------------- assume cs:DRVRSEG, ds:DRVRSEG init: ;Put the drive letter and the segment at which the drive has been loaded ;into the signon message and display it. mov al, es:iop_1stdrv[di] ;get number to designate 1st drive add drive_letter, al ; save it add init_msg_ltr, al ; put in message mov bx, offset init_msg_seg ;put driver's address into msg mov cx, 4 mov dx, cs init_hex_loop: rol dx, 4 ;convert left digit of DX to mov al, dl ; hex and store at [BX]+ and al, 0Fh add al, '0' cmp al, '9' jbe init_hex_loop_1 add al, 'A'-'9'-1 init_hex_loop_1: mov [bx], al inc bx loop init_hex_loop ;do 4 digits mov dx, offset init_msg_1 ;display completed msg mov ah, 09h int DOSRUPT ;Fill in IOP with number of units, pointer to list of BPB's, and ;pointer to end of permanent code. assume ds:nothing lds di, io_packet_ptr ;set DS:DI to I/O packet mov ds:iop_nunits[di], NUNITS mov ds:iop_bpboff[di], offset init_bpblist mov ds:iop_bpbseg[di], cs mov ds:iop_endoff[di], offset end_permanent_code mov ds:iop_endseg[di], cs xor ax, ax ;return no error ret DRVRSEG ends end