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479 lines
10 KiB
479 lines
10 KiB
title "Keyboard Detection"
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;++
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;
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; Copyright (c) 1989 Microsoft Corporation
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;
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; Module Name:
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;
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; cpu.asm
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;
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; Abstract:
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;
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; This module implements the assembley code necessary to determine
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; keyboard.
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;
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; Author:
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;
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; Shie-Lin Tzong (shielint) 16-Dec-1991. Most of the code is extracted
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; from Win31 Setup.
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;
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; Environment:
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;
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; 80x86 Real Mode.
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;
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; Revision History:
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;
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;
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;--
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extrn _READ_PORT_UCHAR:proc
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;
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; Now define the needed equates.
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;
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TRUE equ -1
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FALSE equ 0
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;
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; equates for ports -- these are used in the keyboard detection module.
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;
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ack_port equ 20h ; 8259 acknowledge port
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eoi equ 20h ; 8259 end of interrupt
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kb_data equ 60h
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kb_ctl equ 61h
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kb_command equ 64h ;
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kb_status equ 64h ; status port -- bit 1: ok to write
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ENABLE_KEYBOARD_COMMAND EQU 0AEH
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DISABLE_KEYBOARD_COMMAND EQU 0ADH
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.386
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_TEXT SEGMENT PARA USE16 PUBLIC 'CODE'
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ASSUME CS: _TEXT, DS:NOTHING, SS:NOTHING
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;++
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;
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; BOOLEAN
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; IsEnhancedKeyboard (
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; VOID
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; )
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;
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; Routine Description:
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;
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; Function looks at bios data area 40:96 to see if an enhanced keyboard
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; is present.
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;
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; Arguments:
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;
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; None.
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;
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; Return Value:
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;
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; TRUE if Enhanced keyboard is present. Else a value of FALSE is returned.
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;
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;--
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Public _IsEnhancedKeyboard
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_IsEnhancedKeyboard proc near
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push es
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mov ax,40h
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mov es,ax
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xor ax,ax
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mov al,byte ptr es:[96h]
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and al,00010000b
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pop es
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ret
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_IsEnhancedKeyboard endp
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;++
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;
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; SHORT
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; GetKeyboardIdBytes (
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; PCHAR IdBuffer,
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; SHORT Length
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; )
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;
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; Routine Description:
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;
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; This routine returns keyboard identification bytes.
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;
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; Note that this function accepts one argument. The arg is a pointer to a
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; character buffer allocated to hold five (five) bytes. Upon return from
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; this function the buffer will contain between 1 and 5 bytes of keyboard
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; ID information. The number of valid ID bytes in the buffer is returned
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; in AX as a C proc return value.
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;
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; Arguments:
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;
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; None.
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;
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; Return Value:
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;
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; Id bytes are stored in IdBuffer and the length of Id bytes is returned.
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;
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;--
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KeybID EQU [bp + 4] ; parameters
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ReqByte EQU [bp + 6]
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nKeyID EQU [bp - 2] ; Local variables
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AckByte EQU [bp - 3]
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public _GetKeyboardIdBytes
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_GetKeyboardIdBytes proc near
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push bp
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mov bp, sp
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sub sp, 4 ; space for local variables
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push bx
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push es
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;
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; First I initialize needed local vars. Next I find out if machine is AT
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; type or non AT type for the purpose of selecting proper acknowledgement
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; byte so I can talk to the interrupt controler.
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;
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mov bx, KeybID ; Initialize base pointer to buffer.
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mov word ptr nKeyID, 0 ; Initialize count to zero.
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mov byte ptr AckByte, 20h ; for all but AT-like. acknowledge for
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; interrupt controller. 61h for AT's.
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mov ax, 0fff0h ; look into 0FFF0:0FE location.
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mov es, ax ; this is where the model byte is.
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mov al, byte ptr es:[0feh]
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cmp al, 0fch ; is it AT-like?
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jne UnlikeAT
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mov byte ptr AckByte, 61h
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call _Empty8042
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if 0
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;
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; Disable keyboard is a right thing to do. But, it turned out
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; this causes some keyboards to fail GetId.
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;
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call DisableKeyboard
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endif
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UnlikeAT:
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;
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; Now, let's see if we can get some ID bytes from the keyboard controler.
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;
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mov ah, ReqByte ; AT: send second command.
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mov dx, 60h ; write to data port
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call Write8042 ; Output command byte to keyboard, bytes in AH
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call ReadKeyboard ; Get byte from keyboard, byte in AL if No CF
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jc gotNoByte
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mov [bx], al ; save a byte. remember bx is pointer.
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inc word ptr nKeyID
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call ReadKeyboard ; Get byte from keyboard, byte in AL if No CF
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jc gotNoByte
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mov [bx]+1, al ; save a byte. remember bx is pointer.
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inc word ptr nKeyID
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call ReadKeyboard ; check for extra bytes.
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jc gotNoByte
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mov [bx]+2, al ; save a byte. remember bx is pointer.
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inc word ptr nKeyID
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gotNoByte:
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mov al, AckByte
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out ack_port, al
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call EnableKeyboard
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call _Empty8042
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mov ax, nKeyID ; Return number of valid ID bytes obtained.
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pop es
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pop bx
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mov sp, bp
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pop bp
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ret
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_GetKeyboardIdBytes endp
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;++
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;
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; UCHAR
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; ReadKeyboard (
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; VOID
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; )
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;
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; Routine Description:
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;
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; This routine reads character from keyboard.
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;
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; It is assumed that a command (05H or 0F2H) has been set to request
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; that the keyboard send an identification byte.
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; It is also assumed that interrupts are disabled.
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;
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; Arguments:
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;
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; None.
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;
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; Return Value:
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;
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; If a character is returned, the carry bit is reset.
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; If no character is returned, the carry bit is set.
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;
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;--
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public ReadKeyboard
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ReadKeyboard proc near
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push cx
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push bx
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mov bx, 2 ; set outer timeout for double nested.
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cli
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inner_timeout:
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xor cx, cx ; set inner timeout for double nested.
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kbiwait:
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in al, kb_status ; wait for port ready
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test al, 1 ; ready?
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jnz kbiAvailable
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loop kbiwait
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dec bx ; decrement outer timeout loop.
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jnz inner_timeout ; zero out inner loop again.
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stc
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jmp short no_byte
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kbiAvailable: ; we received a byte.
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mov cx,100
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;
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; We need to let some time elapse before we try to read the data
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; because of a problem running this code in the DOS box under
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; OS/2.
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;
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wait_for_data:
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loop wait_for_data
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in al, kb_data ; get data byte.
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clc
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no_byte:
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sti
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pop bx
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pop cx
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ret
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ReadKeyboard endp
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;++
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;
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; UCHAR
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; Write8042 (
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; USHORT Port,
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; UCHAR Command
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; )
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;
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; Routine Description:
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;
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; This routine writes command byte to keyboard.
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;
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; It is assumed that a command (05H or 0F2H) has been set to request
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; that the keyboard send an identification byte.
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; It is also assumed that interrupts are disabled.
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;
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; Arguments:
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;
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; Port (dx) - Port to write data to
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; Command (ah) - to be written to keyboard.
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;
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; Return Value:
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;
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; None.
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;
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;--
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public Write8042
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Write8042 proc near
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push cx
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push bx
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mov bx, 4 ; set outer timeout for double nested.
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cli
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reset_inner:
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xor cx, cx ; set inner timeout for double dested.
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koutwait:
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in al, kb_status ; get 8042 status
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test al, 10b ; can we output a byte?
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jz ok_to_send
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loop koutwait
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dec bx ; decrement outer timeout loop.
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jnz reset_inner ; zero out inner loop again.
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jmp short nosiree ; timeout expired, don't try to send.
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ok_to_send:
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call _Empty8042
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mov al, ah ; ok, send the byte
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out dx, al
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nosiree:
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sti
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pop bx
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pop cx
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ret
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Write8042 endp
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;++
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;
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; UCHAR
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; GetKeyboardFlags (
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; VOID
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; )
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;
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; Routine Description:
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;
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; This routine returns the ROM BIOS flags byte that describes the state
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; of the various keyboard toggles and shift keys.
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;
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; Arguments:
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;
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; None.
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;
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; Return Value:
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;
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; Keyboard ROM BIOS Flags byte.
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;
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;--
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public _GetKeyboardFlags
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_GetKeyboardFlags proc near
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mov ah, 02
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int 16h
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ret
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_GetKeyboardFlags endp
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;++
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;
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; VOID
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; EnableKeyboard (
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; VOID
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; )
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;
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; Routine Description:
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;
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; This routine enables 8042 keyboard interface.
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;
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; Arguments:
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;
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; None.
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;
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; Return Value:
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;
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; None.
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;
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;--
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public EnableKeyboard
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EnableKeyboard proc near
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mov ah, ENABLE_KEYBOARD_COMMAND
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mov dx, kb_command
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call Write8042
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ret
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EnableKeyboard endp
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;++
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;
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; VOID
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; DisableKeyboard (
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; VOID
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; )
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;
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; Routine Description:
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;
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; This routine disables 8042 keyboard interface.
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;
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; Arguments:
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;
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; None.
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;
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; Return Value:
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;
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; None.
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;
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;--
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public DisableKeyboard
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DisableKeyboard proc near
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mov ah, DISABLE_KEYBOARD_COMMAND
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mov dx, kb_command
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call Write8042
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ret
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DisableKeyboard endp
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;++
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;
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; VOID
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; Empty8042 (
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; VOID
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; )
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;
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; Routine Description:
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;
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; This routine drains the i8042 controller's output buffer. This gets
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; rid of stale data that may have resulted from the user hitting a key
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; or moving the mouse, prior to the execution of keyboard initialization.
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;
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; Arguments:
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;
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; None.
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;
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; Return Value:
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;
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; None.
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;
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;--
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public _Empty8042
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_Empty8042 proc near
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push ax
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push dx
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pushf
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cli
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E8Check:
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in al, kb_status ; wait for port ready
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test al, 1 ; ready?
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jz E8Exit
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mov dx, kb_data
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push dx
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call _READ_PORT_UCHAR ; use this call to delay I/O
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add sp, 2
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jmp E8Check
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E8Exit:
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popf
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pop dx
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pop ax
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ret
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_Empty8042 endp
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_TEXT ends
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END
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