汇编源码系列之driver

汇编源码系列之driver2008-04-30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