87 lines
1.0 KiB
NASM
87 lines
1.0 KiB
NASM
; Register a interrupt handler (21h AH=25h)
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; in: AL interrupt number
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; DS:DX far ptr
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isr_intr_register:
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; backup previous stos ptr
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push es
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push di
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; DI = AL * 4
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mov ah, 4
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mul ah
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mov di, ax
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; ES = 0
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xor ax, ax
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mov es, ax
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; store offset
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mov ax, dx
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stosw
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; store segment
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mov ax, ds
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stosw
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; restore previous stos ptr
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pop di
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pop es
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iret
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; Register a interrupt handler
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; in: AL interrupt number
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; ES:DI far ptr to routine/data
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intr_register:
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; backup original values
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push ax
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push es
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push di
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; pop as ax later
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push es
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push di
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; DI = AL * 4
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mov ah, 4
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mul ah
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mov di, ax
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; ES = 0
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xor ax, ax
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mov es, ax
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; store offset
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pop ax
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stosw
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; store segment
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pop ax
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stosw
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pop di
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pop es
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pop ax
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ret
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; Get address for a interrupt vector
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; in AL interrupt number
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; out DS:SI far ptr to routine/data
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intr_load:
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push ax
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; SI = AL * 4
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mov ah, 4
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mul ah
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mov si, ax
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; DS = 0
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xor ax, ax
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mov ds, ax
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; load segment and offset in one go
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lds si, [si]
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pop ax
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ret
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