;    Virtual Ports for the BIOS Interaction
;
;    Copyright (C) 2010 Frank Zoll
;
;    This file is part of avrcpm.
;
;    avrcpm is free software: you can redistribute it and/or modify it
;    under the terms of the GNU General Public License as published by
;    the Free Software Foundation, either version 3 of the License, or
;    (at your option) any later version.
;
;    avrcpm is distributed in the hope that it will be useful,
;    but WITHOUT ANY WARRANTY; without even the implied warranty of
;    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
;    GNU General Public License for more details.
;
;    You should have received a copy of the GNU General Public License
;    along with avrcpm.  If not, see <http://www.gnu.org/licenses/>.
;
;    $Id$
;


; ---------------- Defines for the Virtual peripherial interface -------

;The hw is modelled to make writing a CPM BIOS easier.
;Ports:
;0 	- Con status. Returns 0xFF if the UART has a byte, 0 otherwise.
;1 	- Console input, aka UDR.
;2 	- Console output
;3	- "UART" status: bit 0=rx, bit 1 = tx
;4	- "UART" data register, no wait
;15	- Disk select
;16,17 	- Track select
;18 	- Sector select
;20 	- Write addr l
;21 	- Write addr h
;22 	- Trigger - write  to read, to write a sector using the above info;
;			, write to allocated/dirctory/unallocated

	.equ	READ_FUNC  = 7
	.equ	WRITE_FUNC = 6
	.equ	BOOT_FUNC  = 5
	.equ	HOME_FUNC  = 4

;----------------------------------------------- Start of Data Segment

	.dseg


; ---------------------------------------------- Start of Code Segment
	.cseg

uartstat:
	clr	temp
	lds	temp2,rxcount
	cpse	temp2,_0
	 sbr	temp,0x01		
	lds	temp2,txcount
	cpi	temp2,TXBUFSIZE
	breq	uartst_1
	 sbr	temp,0x02
uartst_1:
	ret

uartout:
	lds	temp2,txcount
	cpi	temp2,TXBUFSIZE
	breq	uartout_1
	rjmp uartputc
uartout_1:
	ret

uartin:
	clr	temp
	lds	temp2,rxcount
	cpse	temp2,_0
	 rjmp	uartgetc
	ret

conStatus:
	lds	temp,rxcount
	cpse	temp,_0
	 ldi	temp,0xff
	ret

conInp:
	rjmp uartgetc

dbgOut:
	printnewline
	printstring "Debug: "
	rcall printhex
	ret

conOut:
	rjmp uartputc

;Called with port in temp2. Should return value in temp.
portRead:
	cpi temp2,0
	breq conStatus
	cpi temp2,1
	breq conInp
	cpi	temp2,3
	breq	uartstat
	cpi	temp2,4
	breq	uartin

	cpi	temp2,15
	breq	dskDiskCheck
	cpi	temp2,22
	breq	dskErrorRet

	cpi	temp2,TIMER_MSECS
	brlo	pr_noclock
	cpi	temp2,TIMER_MSECS+6
	brsh	pr_noclock
	rjmp	clockget

pr_noclock:
	ldi	temp,0xFF
	ret

;Called with port in temp2 and value in temp.
portWrite:
	cpi temp2,0
	breq dbgOut
	cpi temp2,2
	breq conOut
	cpi temp2,4
	breq uartout

	cpi temp2,15
	breq dskDiskSel
	cpi temp2,16
	breq dskTrackSel_l
	cpi temp2,17
	breq dskTrackSel_h
	cpi temp2,18
	breq dskSecSel
	cpi temp2,20
	breq dskDmaL
	cpi temp2,21
	breq dskDmaH

	cpi temp2,22
	breq dskDoIt
	
	cpi	temp2,TIMERPORT
	brlo	pw_noclock
	cpi	temp2,TIMER_MSECS+6
	brsh	pw_noclock
	rjmp	clockput

pw_noclock:
	ret




;---------------------------------------------------------------------