Simtel MSDOS 1992 June/SIMTEL_0692.cdr/msdos/modem/async.arc/HANDLER.ASM

Assembly Source File | 1986-10-18 | 3.6 KB | 198 lines

int14    equ    1    ; comment out to remove int14 routines
codeseg    segment para public 'CODE'
dataseg    segment para public 'DATA'
    extrn    _PSP_:word, $MEMRY:word
    old_com_int    dd 0
dataseg    ends
    public old_vector_,myds
old_vector_    label word
old_vector    dd    0
myds    dw    0

assume cs:codeseg,ds:dataseg
extrn    c_handler_:near
public    setup_int14_,restore_int14_,service
    ; service interrupts
service    proc    near
snoop:
    ; we've got a call we're worried about
    ; push registers in opposite of the order they'll appear as formal
    ; parameters to this program
    push    es    ; last
    push    ds    ;
    push    di    ;
    push    si    ;
    push    dx    ;
    push    cx    ;
    push    bx    ;
    push    ax    ;
    mov    ax,cs:myds
    mov    ds,ax
    mov    es,ax
    sti            ; enable interrupts
    call c_handler_
    pop    ax        ; restore registers
    pop    bx
    pop    cx
    pop    dx
    pop    si
    pop    di
    pop    ds
    pop    es
    iret        ; get outa here
service    endp


ifdef int14
    ; set up the interrupt service handler
setup_int14_    proc    near
    push    es
    mov    cs:myds,ds
    nop
    mov    ah,35H
    mov    al,14H                            ; offset of interrupt service
    int 21H
    mov    word    ptr cs:old_vector,bx
    mov    word    ptr cs:old_vector+2,es
    pop    es
    push    ds
    mov    ax,cs
    mov    ds,ax
    mov    dx,offset service
    mov    ah,25H
    mov    al,14H
    int    21H
    pop    ds
    ret                                        ; done
setup_int14_    endp

restore_int14_    proc    near
    push    ds
    mov    dx,word ptr cs:old_vector
    mov    ax,word ptr cs:old_vector+2
    mov    ds,ax
    mov    ah,25H
    mov    al,14H
    int 21H
    pop    ds
    ret
restore_int14_    endp

    public    call_rom_
call_rom_    proc    near
    push    bp
    mov    bp,sp
    mov    ax,[bp+4]    ; get ax parm
    mov    dx,[bp+6]
    mov    cx, word ptr cs:old_vector
    or    cx, word ptr cs:old_vector+2
    jnz chain_call
    int 14
    jmp outahere
chain_call:
    pushf
    call dword ptr cs:old_vector
outahere:
    pop    bp
    ret
call_rom_    endp

    public    terminate_
terminate_    proc    near
    ;calculate memory size in paragraphs
    mov        dx,$MEMRY
    add        dx,15        ;bump to next even paragraph
    mov        cx,4        ;move 4 places right
    shr        dx,cl        ;
    mov    ax,_PSP_        ; first paragraph of my program allocation
    mov    cx,ds            ; current data segment
    sub    cx,ax            ; subtract psp from ds to get size of psp
    add    dx,cx            ; add to number of paragraphs in data segment
    mov        al,0        ;exit code of 0
    mov        ah,31H        ;terminate and stay resident
    int        21H            ;go do it
    ret                    ;should never return!!!
terminate_    endp
endif

    ; core routines for communications

    extrn comserv_:near
comservice    proc    near
    push    es    ; last
    push    ds    ;
    push    di    ;
    push    si    ;
    push    dx    ;
    push    cx    ;
    push    bx    ;
    push    ax    ;
    mov    ax,cs:myds
    mov    ds,ax
    mov    es,ax
    sti            ; enable interrupts
    call comserv_
    pop    ax        ; restore registers
    pop    bx
    pop    cx
    pop    dx
    pop    si
    pop    di
    pop    ds
    pop    es
    iret        ; get outa here
comservice    endp

    public    setup_comint_
setup_comint_    proc    near
    push    bp
    mov    bp,sp
    push    es        ; es used in get vector call
    mov    al,4[bp]    ; pick up int num
    mov    ah,35H        ; get vector
    int 21H
    ; store it away
    mov    word ptr old_com_int,bx
    mov    word ptr old_com_int+2,es
    pop    es            ; restore es
    ; set up new vector
    mov    ah,25H
    mov    al,4[bp]    ; pick up int num again
    push    ds        ; ds used in set vector call
    mov    dx,cs        ; get segment
    mov    ds,dx        ;
    mov    dx,offset comservice    ; get offset
    int 21H            ; go do it
    pop    ds            ; restore ds
    pop    bp
    ret
setup_comint_    endp

    public    restore_comint_
restore_comint_    proc    near
    push    bp
    mov    bp,sp
    push    ds
    lds    dx,old_com_int
    mov    al,4[bp]    ; pick up int num
    mov    ah,25H        ; set vector
    int 21H
    pop    ds
    pop    bp
    ret
restore_comint_    endp

    public    cli_,sti_
cli_    proc    near
    cli
    ret
cli_    endp

sti_    proc    near
    sti
    ret
sti_    endp

codeseg    ends
    end