home
***
CD-ROM
|
disk
|
FTP
|
other
***
search
/
ftp.wwiv.com
/
ftp.wwiv.com.zip
/
ftp.wwiv.com
/
pub
/
PPPBCKP
/
SRC
/
SRC15B94.ZIP
/
WATTSRC.ZIP
/
ELIB
/
BACKGRND.ASM
next >
Wrap
Assembly Source File
|
1994-11-28
|
3KB
|
207 lines
PAGE 66,132
;
;
;
;
;
;
;
;
; backgrnd.asm
;
; usage:
; extern init_bkg( int (*routine)(), char *stack, int stacklen)
; extern swap_bkg()
; extern kill_bkg()
;
; (c) 1990 University of Waterloo,
; Faculty of Engineering,
; Engineering Microcomputer Network Development Office
;
;
include masmdefs.hsm
include model.hsm
codedef BACKGRND
SETVEC equ 25h ; function to set interrupt vector
GETVEC equ 35h
TICKER equ 1ch
DOS equ 21h
datadef
cstart BACKGRND
oldint dq 0
inside db 0
stkbase dw 0 ; used to check stack depth
stkptr dw 0
stkseg dw 0
retstk dw 0,0
bkgptr dw 0, 0
swapstk macro
cli
mov AX, SS
xchg CS:stkseg, AX
mov SS, AX
xchg CS:stkptr, SP
sti
endm
; note, we do not push AX!!!!!!, assembly routine must
push_em macro
push BX
push CX
push DX
push BP
push SI
push DI
push DS
push ES
endm
pop_em macro
pop ES
pop DS
pop DI
pop SI
pop BP
pop DX
pop CX
pop BX
pop AX
endm
; bkg_int - the interrupt function called by the timer tick
bkg_int proc far
; first chain
pushf
call dword ptr CS:[oldint]
; establish if we are active
push AX
mov AL, 1
xchg CS:inside, AL
or AL, AL
jz @1 ; not busy, go ahead
; must be already active
pop AX
iret
@1: push_em
; switch over to the new stack
swapstk
pop_em
IF PTR_L
retf
ELSE
retn
ENDIF
bkg_int endp
; use cproc, does not use BP
cproc swap_bkg
push AX
push_em ; save them on
swapstk
pop_em
xor AL, AL ; clear flag
mov CS:inside, AL
iret
creturn swap_bkg
IF FUNC_L
OFSSTK equ 4
OFSLEN equ OFSSTK + 4
ELSE
OFSSTK equ 2
OFSLEN equ OFSSTK + 2
ENDIF
cpublic init_bkg ; int (*routine)(), char *stack, int stacklen
; get pointer to routine
mov DX, +@AB [BP]
mov CS:bkgptr, DX
IF FUNC_L
mov CX, +@AB + 2 [BP]
ELSE
mov CX, CS
ENDIF
mov CS:bkgptr+2, CX
; get stack area
mov AX, +@AB + OFSSTK [BP]
mov CS:stkbase, AX
IF PTR_L
mov BX, +@AB + OFSSTK + 2 [BP]
mov CS:stkseg, BX
ELSE
mov CS:stkseg, DS
ENDIF
; get length
add AX, +@AB + OFSLEN [BP]
sub AX, 2
mov CS:stkptr, AX
; get the stack area and set up the first call
swapstk
push CX
push DX
push AX
push_em
; done with that stack
swapstk
; set up the interrupt
push ES
push DS
mov AH, GETVEC
mov AL, TICKER
int DOS
mov word ptr CS:oldint, BX
mov word ptr CS:oldint+2, ES
push CS
pop DS
mov DX, offset bkg_int
mov AH, SETVEC
mov AL, TICKER
int DOS
mov DS, DX
pop DS
pop ES
xor AX, AX
creturn init_bkg
cpublic kill_bkg
push DS
xor AX, AX
mov DS, AX
mov BX, TICKER * 4
cli
mov CX, word ptr CS:oldint
mov DX, word ptr CS:oldint+2
mov DS:[BX], CX
mov DS:[BX+2], DX
sti
pop DS
creturn kill_bkg
cend BACKGRND
end