Category : Alternate Operating Systems - Quarterdeck DesqView, CP/M, etc
Archive   : MULTIDOS.ZIP
Filename : APPLCTX.ASM

;----------------------------------------------------------
;
; Sample TSR to demonstrate application specific task
; context save and restore routines.
;
; This TSR must be installed after MultiDos Plus is
; executed and before any other application task is
; started. Use the following MultiDos Plus commands
; to install this program:
;
; LC
; ND
; XQ
; APPLCTX
;
;
; One of the context choices is to save/restore the 10
; interrupt vectors used by Microsoft C's floating point
; emulator. If a task was written in Microsoft C and
; uses floating point, use the following sequence to
; load and execute the program.
;
; RM xxx
; MISCFLAG 2 indicates must save context
; other pre-load commands
; YOURPROG load your application program
;
; The MISCFLAG 2 command informs the context routines
; contained in this (APPLCTX) module that the interrupt
; vectors used by the Microsoft 8087 emulator are to be
; saved and restored for the task. Please note that this
; is only required if more than one task uses a floating
; point emulator. Only tasks which use the floating point
; emulator need to use the MISCFLAG 2 command.
;
;
;----------------------------------------------------------
;
; Copyright (c) 1990
; by
; Nanosoft Inc.
; 13 Westfield Road
; Natick, MA 01760
;
;-----------------------------------------------------------
.MODEL LARGE
.286
;
NAME APPLCTX

MISCFLG EQU 200 ;misc. flag word
TCBTSKNM EQU 220 ;task number


;------------------------------------------------------
;
; start of the code segment
;
;------------------------------------------------------

_TEXT SEGMENT BYTE PUBLIC 'CODE'
ASSUME CS:_TEXT

assume ds:NOTHING,ES:NOTHING,SS:NOTHING
;
db 'Copyright (c) 1990 Nanosoft Inc.'

MAXTASKS EQU 12 ; ALLOW ONLY FOR MULTIDOS PLUS DEFAULT

SVDATA87 DB 128 * MAXTASKS DUP(0)

SVINTMS DB 64 * MAXTASKS DUP(0)

;-----------------------------------------------------
;
; CONTEXT SAVE ENTRY POINT
; ENTRY:
; BX = OFFSET OF TCB
; ES = SEGMENT OF TCB
; EXIT:
; ALL REGISTERS MUST BE PRESERVED
;
;-----------------------------------------------------

CTXSAVE PROC FAR
PUSH AX
PUSH BX
PUSH CX
PUSH DX
PUSH DI
PUSH SI
PUSH DS
PUSH ES
;
TEST WORD PTR ES:[BX+MISCFLG],100H ; SAVE 8087?
JZ CTXSN100
;
; SAVE 8087 CONTEXT FOR THIS TASK
;
MOV SI,ES:[BX+TCBTSKNM] ;GET TASK NUMBER
SHL SI,7 ; * 128
ADD SI,OFFSET SVDATA87 ; ADD IN BASE OF CONTEXT SAVE TABLE
FNSAVE CS:[SI]
FWAIT
;
CTXSN100:
TEST WORD PTR ES:[BX+MISCFLG],200H ;SAVE EMULATOR INT?
JZ CTXSN200
;
; SAVE INT 34 - 3D INTERRUPT VECTORS FOR MICROSOFT FP EMULATOR
;
PUSH ES
MOV DI,ES:[BX+TCBTSKNM] ;GET TASK NUMBER
SHL DI,6 ; * 64
ADD DI,OFFSET SVINTMS ; ADD IN BASE OF CONTEXT SAVE TABLE
PUSH CS
POP ES ; DESTINATION IN CODE SEGMENT
MOV AX,0 ; SOURCE IN SEGMENT 0
MOV DS,AX
MOV SI,34H*4 ;
CLD
MOV CX,20 ; COPY 20 WORDS (10 VECTORS)
REP MOVSW
POP ES
;
CTXSN200:
;
CTXSNO:
POP ES
POP DS
POP SI
POP DI
POP DX
POP CX
POP BX
POP AX
RET
;
CTXSAVE ENDP

;----------------------------------------------------------
; Restore context routine
;----------------------------------------------------------

CTXRSTR PROC FAR
PUSH AX
PUSH BX
PUSH CX
PUSH DX
PUSH DI
PUSH SI
PUSH DS
PUSH ES

;
TEST WORD PTR ES:[BX+MISCFLG],100H ; SAVE 8087?
JZ CTXRN100
;
; SAVE 8087 CONTEXT FOR THIS TASK
;
MOV SI,ES:[BX+TCBTSKNM] ;GET TASK NUMBER
SHL SI,7 ; * 128
ADD SI,OFFSET SVDATA87 ; ADD IN BASE OF CONTEXT SAVE TABLE
FRSTOR CS:[SI]
FWAIT
;
CTXRN100:
TEST WORD PTR ES:[BX+MISCFLG],200H ;RESTORE EMULATOR INT?
JZ CTXRN200
;
; RESTORE INT 34 - 3D INTERRUPT VECTORS FOR MICROSOFT FP EMULATOR
;
PUSH ES
MOV SI,ES:[BX+TCBTSKNM] ;GET TASK NUMBER
SHL SI,6 ; * 64
ADD SI,OFFSET SVINTMS ; ADD IN BASE OF CONTEXT SAVE TABLE
PUSH CS
POP DS ; DESTINATION IN CODE SEGMENT
MOV AX,0 ; SOURCE IN SEGMENT 0
MOV ES,AX
MOV DI,34H*4 ;
CLD
MOV CX,20 ; COPY 20 WORDS (10 VECTORS)
REP MOVSW
POP ES
;
CTXRN200:
;
CTXRNO:
POP ES
POP DS
POP SI
POP DI
POP DX
POP CX
POP BX
POP AX
RET
CTXRSTR ENDP

lastlbl dw 0

;---------------------------------------------------------
;
; INITIALIZATION CODE TO INSTALL THIS PROGRAM AS A TSR
;
;---------------------------------------------------------
savds dw 0
saves dw 0
;
PUBLIC TSRINIT
TSRINIT PROC FAR
MOV CS:SAVDS,DS
MOV CS:SAVES,ES

MOV AX,1E08H ;FUNCTION AND SUBFUNCTION CODES
PUSH CS
POP DX
MOV BX,OFFSET CTXSAVE ;OFFSET OF CONTEXT SAVE ROUTINE
MOV CX,OFFSET CTXRSTR ;OFFSET OF CONTEXT RESTORE ROUTINE
INT 15H ;CALL MULTIDOS PLUS API
;
; COMPUTE THE END OF WHAT WE WANT TO STAY RESIDENT AND DO A DOS TSR
;
MOV AX,offset lastlbl
SAR AX,1
SAR AX,1
SAR AX,1
SAR AX,1
MOV DX,AX
MOV AX,seg lastlbl
ADD DX,AX
MOV AX,cs:savds ;get psp
SUB DX,AX
INC DX
MOV AX,3100H ;EXIT AND STAY RESIDENT
INT 21H
;
TSRINIT ENDP

;--------------------------------------------------------

_TEXT ENDS

_stack segment stack
db 500 dup(0)
_stack ends

END TSRINIT