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|
_TEXT SEGMENT BYTE PUBLIC 'CODE'
ASSUME CS:_TEXT,CS:_TEXT
public _indos
public _inexec
_stackp dw _stack
_indos dw 0
_inexec dw 0
public _odos
public _oi20
public _oi27
public _oi25
public _oi26
_stack dw 128 dup (?)
_odos dd (?)
_oi20 dd (?)
_oi27 dd (?)
_oi25 dd (?)
_oi26 dd (?)
public _i20chain
_i20chain: inc _indos
jmp cs:[_oi20]
public _i27chain
_i27chain: inc _indos
jmp cs:[_oi27]
public _i25chain
_i25chain:
pushf ; Save regs
push ax
push bp
push si
push ds
push cs
pop ds
mov bp,sp ; Point to stack
inc _indos
cli
mov ax,10[bp] ; Save return address
mov si,_stackp
mov [si],ax
inc si
inc si
mov ax,12[bp]
mov [si],ax
inc si
inc si
mov _stackp,si
mov ax,offset _cntd1
mov 10[bp],ax
mov 12[bp],cs
pop ds
pop si
pop bp
pop ax
popf
jmp cs:[_oi25]
public _i26chain
_i26chain:
pushf ; Save regs
push ax
push bp
push si
push ds
push cs
pop ds
mov bp,sp ; Point to stack
inc _indos
cli
mov ax,10[bp] ; Save return address
mov si,_stackp
mov [si],ax
inc si
inc si
mov ax,12[bp]
mov [si],ax
inc si
inc si
mov _stackp,si
mov ax,offset _cntd1
mov 10[bp],ax
mov 12[bp],cs
pop ds
pop si
pop bp
pop ax
popf
jmp cs:[_oi26]
_cntd1: pushf ; Flags
pushf ; Space for return address
pushf
push ax
push bp
push si
push ds
mov bp,sp
push cs
pop ds
dec _indos
cli
mov si,_stackp
dec si
dec si
mov ax,[si]
mov 10[bp],ax
dec si
dec si
mov ax,[si]
mov 8[bp],ax
mov _stackp,si
pop ds
pop si
pop bp
pop ax
iret
public _doschain
vrx: inc _indos
jmp over
_doschain:
pushf ; Save regs
push ax
push bp
push si
push ds
push cs
pop ds
mov bp,sp ; Point to stack
mov _inexec,0
cmp ah,1
jnz vv1
; character input with echo
jmp vr1
vv1: cmp ah,2
jnz vv2
; character output
jmp vr1
vv2: cmp ah,6
jnz vv3
; Direct console I/O
jmp vr1
vv3: cmp ah,7
jnz vv4
; Unfiltered character input without echo
jmp vr1
vv4: cmp ah,8
jnz vv5
; Character input without echo
jmp vr1
vv5: cmp ah,9
jnz vv6
; Output string
jmp vr1
vv6: cmp ah,10
jnz vv7
; Buffered keyboard input
jmp vr1
vv7: cmp ah,11
jnz vv8
; Get input status
jmp vr1
vv8: cmp ah,12
jnz vv9
; Dump input
jmp vr1
vv9: cmp ah,63
jnz vv10
; Read file or device
jmp vr1
vv10: cmp ah,64
jnz vv11
; Write to file or device
jmp vr1
vv11: cmp ah,0
jz vrx
cmp ah,49
jz vrx
cmp ah,76
jz vrx
cmp ah,75
jnz vr1
mov _inexec,50
jmp vr
vr1: inc _indos
vr: cli
mov ax,10[bp] ; Save return address
mov si,_stackp
mov [si],ax
inc si
inc si
mov ax,12[bp]
mov [si],ax
inc si
inc si
mov _stackp,si
mov ax,offset _cntd
mov 10[bp],ax
mov 12[bp],cs
over:
pop ds
pop si
pop bp
pop ax
popf
jmp cs:[_odos]
_cntd: pushf ; Flags
pushf ; Space for return address
pushf
push ax
push bp
push si
push ds
mov bp,sp
push cs
pop ds
cmp _inexec,0
jnz ooo
dec _indos
ooo: mov _inexec,0
cli
mov si,_stackp
dec si
dec si
mov ax,[si]
mov 10[bp],ax
dec si
dec si
mov ax,[si]
mov 8[bp],ax
mov _stackp,si
extrn _dos:near
pop ds
pop si
pop bp
pop ax
jmp cs:_dos
_TEXT ENDS
END
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