tsrbones.asm

一个关于内存驻留的汇编源代码

                iret
;
NewInt28        ENDP            ;v0.01
;*************************************************************************
;	-END OF TSR's RESIDENT CODE-
;	Only the code above will remain locked in memory
;		after the initialization performed below.
;*************************************************************************
SUBTTL TSR BOOSTER (Initialization)
PAGE
;*************************************************************************
;       BEGINNING OF TSR's INITIALIZATION CODE (THE "BOOSTER"):
;	The following code is protected in RAM *ONLY* during initialization
;               of the TSR that occurs when the TSR name is first invoked
;		at the DOS command level. All the following code is abandonned
;               unprotected in RAM after the Terminate-and-Stay-Resident (TSR)
;		call to Function 31h of DOS Interrupt 21h below. This
;		is allowed to happen because the code's work is complete at
;		that point. The code will be overwritten as the memory which
;		it temporarily occupied is needed by DOS for other purposes.
;
;               I have seen this following section of code colorfully called
;               the TSR "Booster". This is quite appropriate since the code
;               sits here, strapped to the very end of the TSR, and it is of
;               use only during the "blastoff" (initialization) of the TSR, when
;               it is used to put the TSR into "orbit" (residency), and after
;               which it is "jettisoned" (abandonned unprotected in memory) by
;               the DOS TSR call, Int 21h, Fcn 31h.
;
TSRinit		PROC	NEAR				;v0.01
EndDump		EQU	$	;Roy Silvernail - Keep TASM 1.0 happy
				;when computing # resident paragraphs.
;
;       Get DOS Version Number:
                mov     ah,30h                  ;Fcn 30h = Get DOS Version
                int     21h                     ;DOS Version = al.ah
;
;       If this is DOS v.1.x, this TSR cannot work, so go print message
;       and exit without installing:
                cmp     al,1         ;Is this DOS Version 1.x?
                ja      DOSverOK     ;If not, DOS version is OK.
                push    bx           ;A "push" for the "pop" at DOSver1 label.
                jmp     DOSver1      ;If so, TSR won't work so exit.
;
DOSverOK:
;       If here, DOS version is 2.0 or later. TSR can work, so proceed.
;
;       Check for prior installation of this TSR:
;
                mov     ax,TSRsigA              ;Prime registers for our
                mov     bx,TSRsigB              ;Int16h handler's check
                mov     cx,TSRsigC              ;for prior installation
                mov     dx,TSRsigD              ;thru TSR signature words.
;
                Int     16h                     ;Check prior installation.
;
                cmp     ax,TSRsigD              ;Was TSR signature detected?
                jne     Install                 ;If not, Install it.
                cmp     bx,TSRsigC
                jne     Install         
                cmp     cx,TSRsigB
                jne     Install         
                cmp     dx,TSRsigA
                jne     Install
;
; If you are here, all four TSR signature words were detected and signalled,
; so the TSR is already installed.
;       Announce the TSR's PRIOR Installation and exit:
                mov     dx,Offset PriorInstMsg  ;DX points to message.
                mov     ah,09h                  ;DOS Fcn. 09h=Display String.
                Int     21h                     ;Display String via DOS.
;
                mov     ax,4C00h                ;Fcn 4C = DOS Terminate call
                Int     21h                     ;Do it.
;
Install:
;       If you are here, then DOS version is 2.+ and the TSR has not
;       previously been installed.
;
;       To conserve RAM usage, release from memory the copy of the DOS 
;	Environment passed to this TSR (this assumes, of course, that
;	your Interrupt handler routine will not need to reference this
;	de-allocated Environment) So, if you are going to write your
;	TSR routine to reference the Environment, DON'T DEALLOCATE IT
;	HERE.
;
                ;Get segment of Environment
		;from 02Ch in the Program
		;Segment Prefix (PSP).
;
                mov     ES,envseg       ;ES=PSP's environ seg   v0.01
                mov     ah,49h          ;DOS Fcn 49h = Release Memory
                int     21h             ;Release it via DOS interrupt.
;
; In order to make the TSR's command name show under the "owner" column in 
;	the "MAPMEM" command of Kim Kokkonen's excellent TSR Mark/Release 
;       package, allocate a tiny 1-paragraph "Pseudo-Environment" here which
;       contains nothing but the TSR name.
;
; Allocate the memory needed by the tiny 'Pseudo-Environment":
                mov     bx,1            ;Allocate one parag. (16bytes)
                mov     ah,48h          ;and return allocation
                int     21h             ;segment in ax via DOS call.
;
                mov     ES,ax           ;Pseudo-Env. Segment to ES.
		mov	si,OFFSET PseudoEnv	;si=source string OFFSET.
                mov     di,0            ;di=destination string OFFSET.
                mov     cx,ENVLNGTH     ;cx=Bytes in Pseudo-Env.string.
                cld                     ;Forward string move direction.
		rep	movsb	;Move Pseudo-Env. string @ DS:si to ES:di
;
; Set PSP's Environment segment pointer to point to tiny Pseudo-Environment.
		mov	envseg,ES	
;
;*****************************************************************************
; NOW, capture all the required Interrupts:
;
;       **** INT 09 ****
;       Get Old Interrupt 09h Vector:
                mov     ax,3500H+HOOK09 ;Get old Int 9 vector   v0.01
                int     21h             ;Int.Vector in ES:BX via DOS.
;
;	Save Old Interrupt 09h Vector:
		mov	Word Ptr oldint09,bx	;Save Offset of Old Interrupt.
		mov	word ptr oldint09+2,ES	;save seg		v0.01
;
;	Install New Interrupt Vector to this TSR's "NewInt09:" Label:
                mov     ax,2500H+HOOK09         ;Set new Int 9 vector   v0.01
		mov	dx,Offset NewInt09	;dx=Offset of New Int Handler.
                int     21h                     ;Set New Int via DOS.
;
;       **** INT 13 ****
;       Get Old Interrupt 13h Vector:
                mov     ax,3500H+HOOK13         ;Get old Int 13 vector
                int     21h                     ;Int.Vector in ES:BX via DOS.
;
;       Save Old Interrupt 13h Vector:
                mov     Word Ptr oldint13,bx    ;Save Offset of Old Interrupt.
                mov     word ptr oldint13+2,ES  ;save Segment.
;
;       Install New Interrupt Vector to this TSR's "NewInt13:" Label:
                mov     ax,2500H+HOOK13         ;Set new Int 13 vector.
                mov     dx,Offset NewInt13      ;dx=Offset of New Int Handler.
                int     21h                     ;Set New Int via DOS.
;
;       **** INT 16 ****
;       Get Old Interrupt 16h Vector:
                mov     ax,3500H+HOOK16         ;get old Int 16H vector v0.01
                int     21h                     ;Int.Vector in ES:BX via DOS.
;
;	Save Old Interrupt 16h Vector:
                mov     Word Ptr oldint16,bx    ;Save Offset of Old Interrupt.
                mov     word ptr oldint16+2,ES  ;save segment           v0.01
;
;	Install New Interrupt Vector to this TSR's "NewInt16:" Label:
                mov     ax,2500H+HOOK16         ;set new Int 16H vector v0.01
                mov     dx,Offset NewInt16      ;dx=Offset of New Int Handler.
                int     21h                     ;Set New Int via DOS.
;
;       **** INT 28 ****
;	Get Old Interrupt 28h Vector:
                mov     ax,3500H+HOOK28         ;Get old Int 28H vector v0.01
                int     21h                     ;Int.Vector in ES:BX via DOS.
;
;	Save Old Interrupt 28h Vector:
                mov     Word Ptr oldint28,bx    ;Save Offset of Old Interrupt.
                mov     word ptr oldint28+2,ES  ;save segment           v0.01
;
;	Install New Interrupt Vector to this TSR's "NewInt28:" Label:
                mov     ax,2500H+HOOK28         ;set new Int 28H vector v0.01
                mov     dx,Offset NewInt28      ;dx=Offset of New Int Handler.
                int     21h                     ;Set New Int via DOS.
;
;*****************************************************************************
;       Get Pointer to InDOS flag ("DOS Busy" flag) and save it:
                mov     ah,34h                  ;DOS FCN=34h:Get InDOS Pointer.
                int     21h                     ;Pointer in ES:BX
                mov     Word Ptr indosptr,bx    ;Save Offset of InDOS flag.
                mov     Word Ptr indosptr+2,ES  ;Save Segment of InDOS flag.
;
                mov     Word Ptr criterrptr+2,ES ;Also, Seg of CritErr flag.
                push    bx      ;Save indosptr on stack for use below.
;
;       Get DOS Version Number:
                mov     ah,30h          ;Fcn 30h = Get DOS Version
                int     21h             ;DOS Version = al.ah
;
;       If DOS version is 2.x, then DOS Critical Error flag is @ indosptr + 1.
;       If DOS version is 3.x+, then DOS Critical Error flag is @ indosptr - 1.
;	Determine DOS Version:
                cmp     al,2            ;Is it DOS Version 2.x?
                je      DOSver2         ;If yes, jump;
                ja      DOSver3         ;or, if later version, jump;
                                        ;else, it's DOS Version 1.x:
;
DOSver1:        ;If here, DOS Version 1.x is being run:
                mov     dx,OFFSET BailOutMsg    ;TBONES needs DOS 2.x or later.
                mov     ah,09h                  ;Say we're sorry, but NO GO
                int     21h                     ;via DOS.
                pop     bx                      ;Clear stack.
                int     20h                     ;Terminate without installing
                                                ;in only way DOS 1.x knows.
;
DOSver2:        ;If here, DOS Version 2.x is being run:
                pop     bx                      ;Get indosptr from stack.
                inc     bx                      ;CritErr flag is @ indosptr+1.
                mov     Word Ptr criterrptr,bx  ;Save CritErr Pointer.
                jmp     Announce                ;Go announce TSR installed.
;
DOSver3:        ;If here, DOS Version 3.+ is being run:
                pop     bx                      ;Get indosptr from stack.
                dec     bx                      ;CritErr flag is @ indosptr-1.
                mov     Word Ptr criterrptr,bx  ;Save CritErr Pointer.
;
;	Announce the TSR's Installation:
Announce:
                mov     dx,Offset InstallMsg    ;DX points to message.
                mov     ah,09h                  ;DOS Fcn. 09h=Display String.
                int     21h                     ;Display String via DOS.
;
; Lock resident code in memory via Terminate-and-Stay-Resident (TSR) DOS call:
;
;v0.11	DX requires size of resident code (in 16-byte paragraphs)
;	This awkward construct is required to keep
;	DOS Function 31h happy.  Notice how we first compute
;	the length of the TSR code in bytes [i.e., end of
;	the TSR code (EndDump) minus start of the TSR code
;	(0, our BeginDump)], round it up to the next whole paragraph ( + 0Fh),
;	and then divide by 16 (SHR 4) to get the number of resident paragraphs:
;
                mov     dx,(EndDump-BeginDump+0Fh)/16
;Roy Silvernail discovered that the BeginDump and EndDump symbols
;were necessary to keep TASM 1.0 happy when computing # resident paragraphs
;in the above statement.
;
                mov     ah,31h                  ;DOS FCN 31h=TSR Call.
                int     21h                     ;Go Resident via DOS TSR call.
;
PseudoEnv:      DB      ' ',0,0,1,0,'TSRBONES',0
ENVLNGTH	EQU	$-PseudoEnv
;
BailOutMsg:
                db      0Dh,0Ah
                db      'Sorry. TSRBONES needs DOS v.2+. You have v.1.x'
                db      0Dh,0Ah,'$'
PriorInstMsg:
                db      0Dh,0Ah
                db      'TSRBONES IS *ALREADY* INSTALLED.'
InstallMsg:
                db      0Dh,0Ah
                db      'HotKey => Ctrl-Alt-B'
                db      0Dh,0Ah
                db      0Dh,0Ah
                db      'TSRBONES Version 0.1'
                db      0Dh,0Ah
                db      'Copyright (C) 1990 by Robert Curtis Davis'
                db      0Dh,0Ah,'$'
;
TSRinit         ENDP    ;v0.01

CodeSeg         ends
                end     Entry
;***********************************************************************