Assembly Source series of driver

This is the past DOS era of the compilation of source code, although has passed, but for the study of the assembly is still helpful, assembly language is just a basic programmer language, most people can grasp, not necessarily in-depth research.

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 the "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 for MS-DOS 3.x
; And 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;d evice "strategy" entry point
DW Intr;d evice "Interrupt" entry point
DB ' DRIVER '; char device name, 8 char, or
; If block device, No. of units
; In the followed by
; 7 don ' t care bytes
; Interpretation of attributes Word:
;
; Bit significance
;
; =1 for character drivers
; =1 If driver can handle IOCTL
; =1 if block device & NON-IBM format
; 12 0
; One 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-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; Ten = return current output status
DW Outp_flush; one = Flush output buffers
DW IOCTL_OUTP; = I/O control output
DW Dev_open; Device open (MS-DOS 3.x)
DW Dev_close; = Device Close (MS-DOS 3.x)
DW Rem_media; MB = removeable Media (MS-DOS 3.x)
Page
;
; MS-DOS REQUEST Header structure definition
;
; The 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
; 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
; Ten Write fault
; One Read fault
; General failure
; 13-14 Reserved
; Invalid Disk Change (MS-DOS 3.x)
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; Device Driver "strategy routine"
; Each time a request is made to this device, the BDOs
; The 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 the 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's called by the BDOs immediately
; The call to the "strategy routine", which saved the long
; Address to 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.
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 IS
; Placed into the 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 is a NOP for character devices.
;
; This routine is called the 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 + 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 is a NOP for character devices.
;
; This routine was called by MS-DOS when media-changed the code is
; Returned by Media Check routine, or if not sure the code is returned
; And there are no dirty buffers.
;
; Build BPB call receives pointer to One-sector buffer in
;　Field of Request Header (offset 14). If "Non-ibm-format" bit
; In attribute word is zero, the buffer contains the 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 is 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 the set in Device Header is word.
;
; Called with:
;
; Request Header + byte Media descriptor BYTE from DPB
; Request Header + DWORD Transfer Address
; Request Header + WORD byte/sector count
; Request Header + WORD starting Sector No. (Block Dev.)
;
; Returns The return Status Word set appropriately, and
; Request Header + 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 + byte Media descriptor BYTE from DPB
; Request Header + DWORD Transfer Address
; Request Header + WORD byte/sector count
; Request Header + WORD starting Sector No. (Block Dev.)
;
; Returns The return Status Word set appropriately, and
; Request Header + 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 was read is returned
;　At Request Header + 13. This character isn't removed from
;　The Input Buffer. This is 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 would 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 + byte Media descriptor BYTE from DPB
; Request Header + DWORD Transfer Address
; Request Header + WORD byte/sector count
; Request Header + WORD starting Sector No. (Block Dev.)
;
; Returns The return Status Word set appropriately, and
; Request Header + WORD actual bytes or sectors transferred
Output:
JMP Done
Page
;
; Function 9 Write with Verify to Device
;
; Called with
;
; Request Header + byte Media descriptor BYTE from DPB
; Request Header + DWORD Transfer Address
; Request Header + WORD byte/sector count
; Request Header + WORD starting Sector No. (Block Dev.)
;
; Returns The return Status Word set appropriately, and
; Request Header + WORD actual bytes or sectors transferred
Outp_vfy:
JMP Done
Page
;
; Function Ten 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 One Flush Output buffers
;
; Character devices only.
;
;　Terminate pending requests. The output buffer, if any,
; is emptied.
Outp_flush:
JMP Done
Page
;
; Function I/O control Write
;
; Only called if IOCTL the bit in Device Header is the word is set.
;
; Called with
;
; Request Header + byte Media descriptor BYTE from DPB
; Request Header + DWORD Transfer Address
; Request Header + WORD byte/sector count
; Request Header + WORD starting Sector No. (Block Dev.)
;
; Returns The return Status Word set appropriately, and
; Request Header + WORD actual bytes or sectors transferred
;
; No error check is performed on IOCTL calls.
IOCTL_OUTP:
JMP Done
Page
;
; Function Device Open
;
; MS-DOS version 3.0 and above only.
; Only called if OPEN/CLOSE/RM bit sets in Attribute word.
;　May is used to manage the local buffering. Reference Count
; Are incremented keeping track of number of open files on
;　The device. On character devices can is used to send
; Device initialization string, which can is set by IOCTL
;　Write. Note that CON AUX and PRN devices are always open.
;
; Returns The return Status of Word set to ' done '.
;
Dev_open:
JMP Done
Page
;
; Function Device Close
;
; MS-DOS version 3.0 and above only.
; Only called if OPEN/CLOSE/RM bit sets in Attribute word.
;　May is used to manage the local buffering. Reference Count
; are 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 is used to send device post-i/o
; String such as a form feed, which can is set by IOCTL
;　Write. Note that CON AUX and PRN devices are never closed.
;
; Returns The return Status of Word set to ' done '.
;
Dev_close:
JMP Done
Page
;
; Function 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 of 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 the driver is loaded. It is responsible for
; Initializing the hardware, setting up any necessary
; Interrupt vectors, and it must return to the address
; Of the the memory after the driver to the BDOs.
; If It is a blocks device driver, Init must also return the
; Address to 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 is called by the
; initialization function.
;
; In this example, INIT returns it own address to the DOS as
; The start of free memory after the driver and so this memory
; occupied by INIT would be reclaimed after the it is finished
; With its work.
;
; Called with:
;
; Request Header + DWORD Pointer to the character after the "="
; On the CONFIG. SYS line that loaded
; Driver This information are read only.
; BYTE Drive letter for a
; Block Driver (0=a 1=b etc)
; (MS-DOS 3.x only)
;
; Returns:
;
; Request Header + BYTE number of units (block devices only)
; + DWORD Address of the memory above driver
; + 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 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