这个都是过去DOS时代的汇编源码，虽然已经过去了，但是对于学习汇编还是有帮助的，汇编语言只是程序员一门基础语言，大多人掌握即可，不一定要深入研究.......
name driver
page 55,132
title 'DRIVER --- installable driver template'
;
; This is a "template" for a MS-DOS installable device driver.
; The actual driver subroutines are stubs only and have
; no effect but to return a non-error "done" status.
;
; Ray Duncan
; Laboratory Microsystems Inc.
; April 1985
code segment public 'CODE'
driver proc far
assume cs:code,ds:code,es:code
org 0
Max_Cmd equ 15 ; MS-DOS command code maximum
; this is 15 for MS-DOS 3.x
; and 12 for MS-DOS 2.x
cr equ 0dh ; ASCII carriage return
lf equ 0ah ; ASCII line feed
eom equ '$' ; end of message signal
page
;
; Device Driver Header
;
Header dd -1 ;link to next device,-1= end of list
dw 8000h ;attribute word
;bit 15=1 for character devices
dw Strat ;device "Strategy" entry point
dw Intr ;device "Interrupt" entry point
db 'DRIVER ' ;char device name, 8 char, or
;if block device, no. of units
;in first byte followed by
;7 don't care bytes
; Interpretation of Attribute word:
;
; Bit Significance
;
; 15 =1 for character drivers
; 14 =1 if driver can handle IOCTL
; 13 =1 if block device & non-IBM format
; 12 0
; 11 open/close/RM supported (DOS 3.x)
; 10 0
; 9 0
; 8 0
; 7 0
; 6 0
; 5 0
; 4 0
; 3 =1 if CLOCK device
; 2 =1 if NUL device
; 1 =1 if Standard Output
; 0 =1 if Standard Input
page
;
; local variables for use by driver
;
RH_Ptr dd ? ; pointer to request header
; passed to Strat by BDOS
Ident db cr,lf,lf
db 'LMI Example Device Driver 1.0'
db cr,lf
db 'Copyright (c) 1985 '
db 'Laboratory Microsystems Inc.'
db cr,lf,lf,eom
;
; MS-DOS Command Codes dispatch table.
; The "Interrupt" routine uses this table and the
; Command Code supplied in the Request Header to
; transfer to the appropriate driver subroutine.
Dispatch:
dw Init ; 0 = init driver into system
dw Media_Chk ; 1 = media check on blk dev
dw Build_Bpb ; 2 = build BIOS param block
dw Ioctl_Inp ; 3 = I/O ctrl read from dev
dw Input ; 4 = normal destructive read
dw Nd_Input ; 5 = non-destructive read,no wait
dw Inp_Stat ; 6 = return current input status
dw Inp_Flush ; 7 = flush device input buffers
dw Output ; 8 = normal output to device
dw Outp_Vfy ; 9 = output with verify
dw Outp_Stat ; 10 = return current output status
dw Outp_Flush ; 11 = flush output buffers
dw Ioctl_Outp ; 12 = I/O control output
dw Dev_Open ; 13 = device open (MS-DOS 3.x)
dw Dev_Close ; 14 = device close (MS-DOS 3.x)
dw Rem_Media ; 15 = removeable media (MS-DOS 3.x)
page
;
; MS-DOS Request Header structure definition
;
; The first 13 bytes of all Request Headers are the same
; and are referred to as the "Static" part of the Header.
; The number and meaning of the following bytes varies.
; In this "Struc" definition we show the Request Header
; contents for Read and Write calls.
;
Request struc ; request header template structure
; beginning of "Static" portion
Rlength db ? ; length of request header
Unit db ? ; unit number for this request
Command db ? ; request header's command code
Status dw ? ; driver's return status word
Reserve db 8 dup (?) ; reserved area
; end of "Static" portion
Media db ? ; media descriptor byte
Address dd ? ; memory address for transfer
Count dw ? ; byte/sector count value
Sector dw ? ; starting sector value
Request ends ; end of request header template
;
; Status word is interpreted as follows:
;
; Bit(s) Significance
; 15 Error
; 10-14 Reserved
; 9 Busy
; 8 Done
; 0-7 Error code if bit 15=1
; Predefined BDOS error codes are:
;
; 0 Write protect violation
; 1 Unknown unit
; 2 Drive not ready
; 3 Unknown command
; 4 CRC error
; 5 Bad drive request structure length
; 6 Seek error
; 7 Unknown media
; 8 Sector not found
; 9 Printer out of paper
; 10 Write fault
; 11 Read fault
; 12 General failure
; 13-14 Reserved
; 15 Invalid disk change (MS-DOS 3.x)
page
; Device Driver "Strategy Routine"
; Each time a request is made for this device, the BDOS
; first calls "Strategy routine", then immediately calls
; the "Interrupt routine".
; The Strategy routine is passed the address of the
; Request Header in ES:BX, which it saves in a local
; variable and then returns to the BDOS.
Strat proc far
; save address of Request Header
mov word ptr cs:[RH_Ptr],bx
mov word ptr cs:[RH_Ptr+2],es
ret ; back to BDOS
Strat endp
page
; Device Driver "Interrupt Routine"
; This entry point is called by the BDOS immediately after
; the call to the "Strategy Routine", which saved the long
; address of the Request Header in the local variable "RH_Ptr".
; The "Interrupt Routine" uses the Command Code passed in
; the Request Header to transfer to the appropriate device
; handling routine. Each command code routine is responsible
; for any necessary return information into the Request Header,
; then transfers to Error or Exit to set the Return Status code.
Intr proc far
push ax ; save general registers
push bx
push cx
push dx
push ds
push es
push di
push si
push bp
push cs ; make local data addressable
pop ds
les di,[RH_Ptr] ; ES:DI = Request Header
; get BX = Command Code
mov bl,es:[di.Command]
xor bh,bh
cmp bx,Max_Cmd ; make sure its legal
jg Unk_Command ; too big, exit with error code
shl bx,1 ; form index to Dispatch table
; and branch to driver routine
jmp word ptr [bx+Dispatch]
page
; General collection of exit points for the driver routines.
Unk_Command: ; Come here if Command Code too big.
mov al,3 ; Sets "Unknown Command" error
; code and "Done" bit.
Error: ; Transfer here with AL = error code.
mov ah,81h ; Sets "Error" and "Done" bits.
jmp Exit
Done: mov ah,1 ; Come here if I/O complete and
; no error, sets "Done" bit only.
Exit: ; General purpose exit point.
; Transfer here with AX =
; Return Status word to be
; placed into Request Header.
lds bx,cs:[RH_Ptr] ; set status
mov ds:[bx.Status],ax
pop bp ;restore general registers
pop si
pop di
pop es
pop ds
pop dx
pop cx
pop bx
pop ax
ret ; back to BDOS
page
; Function 1 Media Check
; Block devices only. Should be a NOP for character devices.
;
; This routine is called first by BDOS for a block device transfer,
; passing current media descriptor byte at Request Header +
;
; Media Check routine sets status word and in addition passes back
; return byte at Request Header + 14 as follows:
; -1 Media has been changed
; 0 Don't know if media changed
; 1 Media has not been changed
;
; If driver can return 1 or -1, performance is improved because
; MS-DOS does not need to reread the FAT for each directory access.
Media_Chk:
jmp Done
page
;
; Function 2 Build BIOS Parameter Block
;
; Block devices only. Should be a NOP for character devices.
;
; This routine is called by MS-DOS when Media-Changed code is
; returned by Media Check routine, or if Not Sure code is returned
; and there are no dirty buffers.
;
; Build BPB call receives pointer to one-sector buffer in Address
; Field of Request Header (offset 14). If "Non-IBM-Format" bit
; in attribute word is zero, the buffer contains the first sector
; of the FAT including the media identification byte and should not
; be altered by the driver. If the "Non-IBM-Format" bit is set,
; the buffer may be used as scratch space.
;
; The Build BPB routine sets status and returns a DWORD pointer to
; the new Bios Parameter Block at Request Header + 18.
;
Build_Bpb:
jmp Done
page
;
; Function 3 I/O Control Read
;
; Only called if IOCTL bit set in Device Header Attribute word.
;
; Called with:
;
; Request Header + 13 BYTE Media descriptor byte from DPB
; Request Header + 14 DWORD Transfer address
; Request Header + 18 WORD byte/sector count
; Request Header + 20 WORD starting sector no. (block dev.)
;
; Returns the Return Status word set appropriately, and
; Request Header + 18 WORD actual bytes or sectors transferred
;
; No error check is performed on IOCTL I/O calls.
Ioctl_Inp:
jmp Done
page
;
; Function 4 Read from Device
;
; Called with
;
; Request Header + 13 BYTE Media descriptor byte from DPB
; Request Header + 14 DWORD Transfer address
; Request Header + 18 WORD byte/sector count
; Request Header + 20 WORD starting sector no. (block dev.)
;
; Returns the Return Status word set appropriately, and
; Request Header + 18 WORD actual bytes or sectors transferred
Input:
jmp Done
page
;
; Function 5 Non-destructive Read from Device
;
; Character devices only.
;
; If Input Status request returns Busy bit=0 (characters
; waiting), ; the next character that would be read is returned
; at Request Header + 13. This character is not removed from
; the Input Buffer. This basically provides the capability to
; "look-ahead" by one character.
Nd_Input:
jmp Done
page
;
; Function 6 Input Status
;
; Character devices only.
;
; Sets the Returned Status word:
; Done bit = 1
; Busy bit = 1 read request would go to physical device
; = 0 characters already in device buffer, read request
; would return quickly.
;
; MS-DOS assumes all character devices have type-ahead buffer.
; If device does not have type-ahead buffer, should always
; return Busy bit=0 so MS-DOS will not hang.
Inp_Stat:
jmp Done
page
;
; Function 7 Flush Input Buffers
;
; Character devices only.
;
; Terminate all pending requests, i.e. the Input buffer is
; emptied.
Inp_Flush:
jmp Done
page
;
; Function 8 Write to Device
;
; Called with
;
; Request Header + 13 BYTE Media descriptor byte from DPB
; Request Header + 14 DWORD Transfer address
; Request Header + 18 WORD byte/sector count
; Request Header + 20 WORD starting sector no. (block dev.)
;
; Returns the Return Status word set appropriately, and
; Request Header + 18 WORD actual bytes or sectors transferred
Output:
jmp Done
page
;
; Function 9 Write with Verify to Device
;
; Called with
;
; Request Header + 13 BYTE Media descriptor byte from DPB
; Request Header + 14 DWORD Transfer address
; Request Header + 18 WORD byte/sector count
; Request Header + 20 WORD starting sector no. (block dev.)
;
; Returns the Return Status word set appropriately, and
; Request Header + 18 WORD actual bytes or sectors transferred
Outp_Vfy:
jmp Done
page
;
; Function 10 Output Status
;
; Character devices only.
;
; Sets the Returned Status word:
; Done bit = 1
; Busy bit = 1 write request would wait for completion of
; current request
; = 0 device idle, write request would start immediately.
;
Outp_Stat:
jmp Done
page
;
; Function 11 Flush Output Buffers
;
; Character devices only.
;
; Terminate pending requests. The output buffer, if any,
; is emptied.
Outp_Flush:
jmp Done
page
;
; Function 12 I/O Control Write
;
; Only called if IOCTL bit in Device Header Attribute word is set.
;
; Called with
;
; Request Header + 13 BYTE Media descriptor byte from DPB
; Request Header + 14 DWORD Transfer address
; Request Header + 18 WORD byte/sector count
; Request Header + 20 WORD starting sector no. (block dev.)
;
; Returns the Return Status word set appropriately, and
; Request Header + 18 WORD actual bytes or sectors transferred
;
; No error check is performed on IOCTL calls.
Ioctl_Outp:
jmp Done
page
;
; Function 13 Device Open
;
; MS-DOS version 3.0 and above only.
; Only called if OPEN/CLOSE/RM bit set in Attribute word.
; May be used to manage local buffering. Reference count
; is incremented keeping track of number of open files on
; the device. On character devices can be used to send
; device initialization string, which can be set by IOCTL
; Write. Note that CON AUX and PRN devices are always open.
;
; Returns the Return Status word set to "Done".
;
Dev_Open:
jmp Done
page
;
; Function 14 Device Close
;
; MS-DOS version 3.0 and above only.
; Only called if OPEN/CLOSE/RM bit set in Attribute word.
; May be used to manage local buffering. Reference count
; is decremented keeping track of number of open files on
; the device; when count reaches zero all files have been closed
; and the driver should flush buffers as user may change disks.
; On character devices can be used to send device post-I/O
; string such as a form feed, which can be set by IOCTL
; Write. Note that CON AUX and PRN devices are never closed.
;
; Returns the Return Status word set to "Done".
;
Dev_Close:
jmp Done
page
;
; Function 15 Removeable Media
;
; MS-DOS version 3.0 and above only.
; Only called if OPEN/CLOSE/RM bit set in Attribute word
; and device type is block.
;
; Returns the Return Status word set to "Done" and
; Busy bit = 1 if media is non-removable.
; = 0 if media is removable.
;
Rem_Media:
jmp Done
page
; This Initialization code for the driver is called only
; once when the driver is loaded. It is responsible for
; initializing the hardware, setting up any necessary
; interrupt vectors, and it must return the address
; of the first free memory after the driver to the BDOS.
; If it is a block device driver, Init must also return the
; address of the Bios Parameter Block pointer array; if all
; units are the same, all pointers can point to the same BPB.
; Only MS-DOS services 01-0CH and 30H can be called by the
; Initialization function.
;
; In this example, Init returns its own address to the DOS as
; the start of free memory after the driver, so that the memory
; occupied by INIT will be reclaimed after it is finished
; with its work.
;
; Called with:
;
; Request Header + 18 DWORD pointer to the character after the "="
; on the CONFIG.SYS line that loaded
; driver; this information is read only.
; 22 BYTE drive letter for first unit of a
; block driver (0=A 1=B etc)
; (MS-DOS 3.x only)
;
; Returns:
;
; Request Header + 13 BYTE Number of units (block devices only)
; + 14 DWORD address of first free memory above driver
; + 18 DWORD BPB pointer array (block devices only)
;
Init: ; Function 0
; initialize device driver
push es ; push Request Header addr
push di
mov ah,9 ; print sign-on message
mov dx,offset Ident
int 21h
pop di ; restore Request Header addr
pop es
; set first usable memory addr.
mov word ptr es:[di.Address],offset Init
mov word ptr es:[di.Address+2],cs
jmp Done
Intr endp
Driver endp
code ends
end