tsrbones.asm

一个关于内存驻留的汇编源代码

;************************
PAGE 55,132             ;Format .LST listing at 55 lines by 132 columns.
TITLE TSRBONES Version 0.1 Jan 20 91 Robert Curtis Davis
SUBTTL Introduction
;**************************************************************************
;
;       TSRBONES.ASM     Version 0.1     Jan 20 91
;       A part of the TBONES software package.
;
;       Copyright (C) 1990, 1991 by Robert Curtis Davis,
;	All Rights Reserved.
;
;	DESCRIPTION:
;	ASM Program template for Terminate-and-Stay-Resident (TSR) programs
;		that are activated by a specified HotKey WHEN DOS IS NOT
;               BUSY (the InDOS Flag AND the DOS Critical Error Flag are zero)
;               flag), OR WHEN DOS IS AT "BUSY IDLE" (when INT28h is called),
;               AND WHEN NO HARDWARE INTERRUPT IRQ0-IRQ7 IS BEING HANDLED.
;               This avoids problems of interfering with hardware interrupt
;               handling and with DOS non-reentrancy; and allows DOS function
;               calls above 0Ch to be used in the TSR routine. The TSR's code
;               prevents multiple installations. Also checks DOS version and
;               requires DOS Version 2 or later before installation is
;               permitted.
;
;	PURPOSE:
;	Provides a skeletal framework program as a starting point in the 
;       design of your own HotKey TSRs which use DOS function calls, and
;       for which a single installation is desired.
;
;                   E-mail address:
;			  Internet: [e-mail]
;
;                  US Mail address:
;                                   430 Bahama Drive
;                                   Indialantic, FL 32903
;
;**************************************************************************
;
; Special thanks to Roy Silvernail, whose persistent hacking (in the best
; sense of that word) and E-mail exchanges over the holiday season in
; December 1990, rooted out TBONES incompatibilities with Borland's TASM v.1.0.
;
;**************************************************************************
;
; Special thanks to Anto Prijosoesilo and Richard Brittain for E-mail
; exchanges which helped solve detailed problems with the implementation of
; the "Pseudo-Environment" idea.
;
;**************************************************************************
;
; Special thanks to David Kirschbaum, whose Toad Hall Tweaks significantly
; improved an early version of the TBONES Assembly Language code:
;
;v0.01	Toad Hall Tweak, 25 Nov 90
;**************************************************************************
SUBTTL Code Segment
PAGE
;**************************************************************************
;
CodeSeg		segment
		assume cs:CodeSeg,ds:CodeSeg
BeginDump	EQU	$		;Roy Silvernail - Keep TASM 1.0 happy
					;when computing # resident paragraphs.
;
		org	2CH		;v0.01 ORG in PSP to pick up the
envseg		label	word		;v0.01 Environment Segment.
;
		org	100h		;ORG for all COM programs.
;
Entry		PROC	NEAR		;v0.01
		jmp	TSRinit		;Jump over resident portion and
					;initialize things and make code
					;between Entry: and TSRinit: resident.
;
; Old Interrupt Vectors are stored here during TSR initialization:
oldint09        dd      ?               ;Keyboard Hardware Interrupt.
oldint13        dd      ?               ;Disk BIOS Interrupt.
oldint16        dd      ?               ;Keyboard BIOS Interrupt.
oldint28        dd      ?               ;DOS Idle Interrupt.
;
; For this HotKey TSR Template, specify Keyboard Interrupt 09h as the Hook:
HOOK09		equ	09h			;Hooked Interrupt 09h.
; Int 13h is used to set a flag to prevent TSR trigger while disk active:
HOOK13          equ     13h                     ;Hooked Interrupt 13h.
; Int 16h is hooked solely to provide way to check for prior TSR installation.
HOOK16		equ	16h			;Hooked Interrupt 16h.
; We also have to hook Interrupt 28h to check for "DOS idle":
HOOK28		equ	28h			;Hooked Interrupt 28h.
;
bellgate	db	0	;Gate closed (=1) when in Bell routine.
				;Gate open (=0) when not in Bell routine.
; Below:
; EQUates related to the Intel 8259A Programmable Interrupt Controller (PIC)
;	chip. Hardware Interrupts IRQ0 through IRQ7 are controlled by the PIC.
;
;	To really understand the nitty-gritty details of this stuff, 
;	you have to study the Intel Specification data for the 8259A PIC chip.
;	These EQUates are used in this TSR to examine the PIC chip's In Service
;	Register (ISR) to be sure that the TSR is not interrupting one of
;	the hardware interrupt service routines. The reason for not wanting to 
;	interrupt these hardware interrupt service routines is that they are
;	often time-critical and can be compromised by intruding on them with
;	our TSR (for example, a hardware COM port interrupt-driven comm 
;	program might lose bytes on a modem transfer if we bull our way in and
;	steal the CPU away from the comm program's service routine):
PICPORT		EQU	20h		;I/O Port for the 8259A PIC chip.
ISRREQ		EQU	00001011B	;This is a byte defining the
					;Operation Control Word 3 (OCW3) to
					;output on port 20h to make the PIC
					;chip's In Service Register available 
					;for reading by the CPU on the
					;next IN 20h command.
;
; EQUs defining Key Flag weights in the Key Flag Byte:
RSHIFT		equ	00000001B		;Right Shift Key Flag weight.
LSHIFT		equ	00000010B		;Left Shift  Key Flag weight.
CTRL		equ	00000100B		;Ctrl        Key Flag weight.
ALT		equ	00001000B		;Alt         Key Flag weight.
;SCROLL          equ     00010000B               ;Scroll Lock Key Flag weight.
;NUM             equ     00100000B               ;Num Lock    Key Flag weight.
;CAPS            equ     01000000B               ;Caps Lock   Key Flag weight.
INSRT		equ	10000000B		;Ins         Key Flag weight.
;
LockKeyMask     equ     10001111B               ;For masking out Scroll, Caps,
                                                ;and Num Lock bits in KeyFlags.
;
; Pointer to "DOS busy" (InDOS) flag (loaded during TSR initialization):
indosptr	dd	?
;
; Pointer to "Critical Error" (CritErr) flag (loaded at TSR initialization):
criterrptr	dd	?
;
; Pointer to "Print Screen" busy (PrtScrn) flag
prtscrn         dd      00500000h
;
; hotkeyflag used to signal HotKey pressed to "DOS idle" Interrupt 28h:
hotkeyflag      db      0       ;hotkeyflag initially zero.
;
; diskflag used to prevent TSR trigger during time-critical Disk operations:
diskflag        db      0       ;diskflag initially zero.
;*************************************************************************
;	Your HotKey is specified here:
;       (This sample HotKey is set for Ctrl-Alt-B)
;
; Specify TSR's HotKey Shift Keys:
KEYFLAGBYTE     equ     CTRL+ALT                ;HotKey Flags
;
; Specify TSR's HotKey Scan Code:
HOTKEY          equ     30h                     ;'B' (for Bones) key
;
;*************************************************************************
; Specify TSR's signature words:
TSRsigA         equ     'TS'            ;'TSRBONES' Signature
TSRsigB         equ     'RB'
TSRsigC         equ     'ON'
TSRsigD         equ     'ES'
;*************************************************************************
Entry	ENDP		;v0.01
;
;*************************************************************************
SUBTTL User-supplied TSR Routine
PAGE
;*************************************************************************
ROUTINE         PROC    NEAR
;*************************************************************************
;	Code for your HotKey-triggered TSR routine  GOES HERE:
;	( Here, a dummy routine has been placed which simply rings the
;	  terminal Bell whenever the TSR is triggered. )
;
;	Announce this dummy TSR's trigger by a Bell signal:
;
Enter:
                mov     al,07h          ;al = ASCII Bell.
                mov     bh,0            ;Video page.
                mov     cx,1            ;No. of bytes to write.
                mov     ah,0Eh          ;BIOS Int10,OEh=TTY Screen.
                Int     10h             ;Write ASCII Bell to screen.
;
Exit:
                ret                     ;Return from TSR routine.
;
ROUTINE         endp
;
;	End of your HotKeyed TSR routine.
;***************************************************************************
SUBTTL Hooked Interrupts
PAGE
;***************************************************************************
;
NewInt09	PROC	FAR		;v0.01
;
; The following three instructions often are said to "simulate an interrupt"
; that calls the PRIOR interrupt handler routine and then the prior interrupt
; handler's IRET instruction pops the flags and returns here to the point
; after the following CALL instruction.
;    The reason for "simulating the interrupt" here is to give prior (and
; presumably more time-critical) handlers a shot at processing this interrupt
; before we process with this TSR's code.
;
		pushf			;Push flags as a true interrupt would.
                cli                     ;Be sure interrupts are disabled.
		call	CS:oldint09	;Call FAR PTR address of old interrupt
;					;     handler routine.
;
;
                push    ax      ;Prepare to check for Hotkey.
                push    bx      ;Save all registers (DS is already pushed).
                push    cx
                push    dx
                push    si
                push    di
                push    bp
                push    ds
                push    es
;
                push    CS              ;Set up data segment
                pop     DS              ;register to point to code segment.
;
                ASSUME  DS:CodeSeg      ;v0.01
;
;       Determine if the current Keyboard Interrupt (Int09h) occurred
;       because this TSR's HotKey was pressed:
                in      al,60h          ;Get current Key Scan Code.
                cmp     al,HOTKEY       ;Is it HotKey's Scan Code?
                jne     Exit09          ;Exit if not.
                mov     ah,02h          ;Int16h,Fcn02h:GetKEYFLAGBYTE.
                Int     16h             ;Return Key Flag Byte in al.
                and     al,LockKeyMask  ;Mask out Num, Caps, Scroll Lock bits.
                cmp     al,KEYFLAGBYTE  ;Are the HotKey Flags active ?
                jne     Exit09          ;Exit if not.
;
;       At this point, Hotkey is known to have been pressed. First, purge
;       the DOS Keyboard type-ahead buffer of the hot key(s) so they won't
;       be passed on to DOS:
;
ClrKbdBuf:      ;Clear Keyboard buffer:
                mov     ah,01h          ;Get Keyboard buffer status
                int     16h             ;via BIOS Interrupt 16h.
                jz      BufClr          ;Jump if buffer empty.
                mov     ah,00h          ;Get key from buffer (to purge it)
                int     16h             ;via BIOS Interrupt 16h.
                jmp     ClrKbdBuf       ;Loop back to purge another key.
BufClr:
;
; We shall allow other interrupts to occur during our TSR ROUTINE.
; If we didn't allow other interrupts (through the STI instruction),
; we could lock out time-critical interrupts from access to the CPU during
; our TSR routine. However, by allowing interrupts during our routine, we 
; have an increased responsibility to make sure critical portions of our
; own code is not re-entered. (The "bellgate" stuff below is an example
; of a measure necessary to keep us from re-entering our own TSR's code).
; What we really want to do by allowing interrupts is to make the CPU avail-
; able to OTHER critical interrupt service routines WITHOUT swarming all over 
; ourselves through multiple detections of our own HotKey.
;               This "gate" technique is a good one to keep in
;               mind whenever you have a code region in an interrupt handler
;               that needs to be protected from re-entry:
;
                cmp     bellgate,0      ;Is it clear to re-enter Hotkey code?
                jne     BusyExit09      ;Exit if not,
                mov     bellgate,1      ;Else, close gate and proceed.
;
                CLI                     ;DISABLE INTERRUPTS
;       Now we will check to be sure that no time-critical hardware interrupt