_event.asm

BIOS emulator and interface to Realmode X86 Emulator Library Can emulate a PCI Graphic Controller V

;****************************************************************************
;*
;*					SciTech Multi-platform Graphics Library
;*
;*  ========================================================================
;*
;*    The contents of this file are subject to the SciTech MGL Public
;*    License Version 1.0 (the "License"); you may not use this file
;*    except in compliance with the License. You may obtain a copy of
;*    the License at http://www.scitechsoft.com/mgl-license.txt
;*
;*    Software distributed under the License is distributed on an
;*    "AS IS" basis, WITHOUT WARRANTY OF ANY KIND, either express or
;*    implied. See the License for the specific language governing
;*    rights and limitations under the License.
;*
;*    The Original Code is Copyright (C) 1991-1998 SciTech Software, Inc.
;*
;*    The Initial Developer of the Original Code is SciTech Software, Inc.
;*    All Rights Reserved.
;*
;*  ========================================================================
;*
;* Language:	80386 Assembler
;* Environment:	IBM PC (MS DOS)
;*
;* Description:	Assembly language support routines for the event module.
;*
;****************************************************************************

		ideal

include	"scitech.mac"			; Memory model macros

ifdef flatmodel

header	_event					; Set up memory model

begdataseg	_event

	cextern  _EVT_biosPtr,DPTR

	cpublic	_EVT_dataStart

ifdef	USE_NASM
%define KB_HEAD		WORD esi+01Ah	; Keyboard buffer head in BIOS data area
%define KB_TAIL		WORD esi+01Ch	; Keyboard buffer tail in BIOS data area
%define KB_START	WORD esi+080h	; Start of keyboard buffer in BIOS data area
%define KB_END		WORD esi+082h	; End of keyboard buffer in BIOS data area
else
KB_HEAD		EQU WORD esi+01Ah		; Keyboard buffer head in BIOS data area
KB_TAIL		EQU	WORD esi+01Ch		; Keyboard buffer tail in BIOS data area
KB_START	EQU	WORD esi+080h		; Start of keyboard buffer in BIOS data area
KB_END		EQU	WORD esi+082h		; End of keyboard buffer in BIOS data area
endif

	cpublic _EVT_dataEnd

enddataseg	_event

begcodeseg	_event				; Start of code segment

	cpublic _EVT_codeStart

;----------------------------------------------------------------------------
; int _EVT_getKeyCode(void)
;----------------------------------------------------------------------------
; Returns the key code for the next available key by extracting it from
; the BIOS keyboard buffer.
;----------------------------------------------------------------------------
cprocstart	_EVT_getKeyCode

		enter_c

		mov		esi,[_EVT_biosPtr]
		xor		ebx,ebx
		xor		eax,eax
		mov		bx,[KB_HEAD]
		cmp		bx,[KB_TAIL]
		jz		@@Done
		xor		eax,eax
		mov     ax,[esi+ebx]	; EAX := character from keyboard buffer
		inc		_bx
		inc		_bx
		cmp		bx,[KB_END]		; Hit the end of the keyboard buffer?
		jl		@@1
		mov		bx,[KB_START]
@@1:	mov     [KB_HEAD],bx	; Update keyboard buffer head pointer

@@Done:	leave_c
		ret

cprocend

;----------------------------------------------------------------------------
; int _EVT_disableInt(void);
;----------------------------------------------------------------------------
; Return processor interrupt status and disable interrupts.
;----------------------------------------------------------------------------
cprocstart	_EVT_disableInt

        pushf                   ; Put flag word on stack
        cli                     ; Disable interrupts!
		pop     eax             ; deposit flag word in return register
		ret

cprocend

;----------------------------------------------------------------------------
; void _EVT_restoreInt(int ps);
;----------------------------------------------------------------------------
; Restore processor interrupt status.
;----------------------------------------------------------------------------
cprocstart	_EVT_restoreInt

		ARG		ps:UINT

		push    ebp
		mov     ebp,esp         ; Set up stack frame
        push    [DWORD ps]
        popf                    ; Restore processor status (and interrupts)
		pop     ebp
		ret

cprocend

;----------------------------------------------------------------------------
; int EVT_rdinx(int port,int index)
;----------------------------------------------------------------------------
; Reads an indexed register value from an I/O port.
;----------------------------------------------------------------------------
cprocstart	EVT_rdinx

		ARG		port:UINT, index:UINT

		push	ebp
		mov		ebp,esp
		mov		edx,[port]
		mov		al,[BYTE index]
		out		dx,al
		inc		dx
		in		al,dx
		movzx	eax,al
		pop		ebp
		ret

cprocend

;----------------------------------------------------------------------------
; void EVT_wrinx(int port,int index,int value)
;----------------------------------------------------------------------------
; Writes an indexed register value to an I/O port.
;----------------------------------------------------------------------------
cprocstart	EVT_wrinx

		ARG		port:UINT, index:UINT, value:UINT

		push	ebp
		mov		ebp,esp
		mov		edx,[port]
		mov		al,[BYTE index]
		mov		ah,[BYTE value]
		out		dx,ax
		pop		ebp
		ret

cprocend

	cpublic _EVT_codeEnd

endcodeseg	_event

endif

		END							; End of module