/*******************************************************************************
*hostutils.c	Robert Buels, rmb32@cornell.edu
*ps/2 host emulator, useful in debuggings ps2.c
*April, 2002
*
*    This program 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 2 of the License, or
*    (at your option) any later version.
*
*    This program 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 this program; if not, write to the Free Software
*    Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
*
*
******************************************************************************/
#include <90s8515.h>
#include <delay.h> 


#asm
  .equ PORTA=0x1b 
  .equ PORTB=0x18
  .equ PINA=0x19
  .equ DDRA=0x1a
  .def temp=r17
  .def delay=r18
  .def output=r19
  .def input=r19
  .def temp2=r20
  .def parity=r21
  .def ptemp=r22
  .equ CLOCK=PORTA,1

        .MACRO __SETDATA
        cbi DDRA,0  ;DDRA.0 = 0
        sbi PORTA,0 ;PORTA.0 = 1
        .ENDM      
        
        .MACRO __CLEARDATA
        sbi DDRA,0   ;DDRA.0 = 1
        cbi PORTA,0  ;PORTA.0 = 0
        .ENDM

        .MACRO __SETCLOCK
        cbi DDRA,1
        sbi PORTA,1
        .ENDM      
        
        .MACRO __CLEARCLOCK
        sbi DDRA,1
        cbi PORTA,1
        .ENDM      
        

#endasm
#pragma regalloc-   
#define TIMER0RELOAD 131
unsigned char buttonState;
unsigned char deltaX, deltaY, deltaZ;

unsigned char hostCommand,mouseResponse;

unsigned char sendResult;
char transmitMode;

unsigned char sampleTime,sampleReload;
                   
#pragma regalloc+

void receiveByte();
void sendData();
void sendByte();
void processCommand();
void readN64();

void init() {
   PORTA = 0xff;
   DDRA = 0x00;  //port A: PS2 in-out
   DDRB = 0xff;  //port B: control to 1200
   DDRC = 0x00;
   DDRD = 0x00;  //port D: input from 1200
   
   
   sampleTime = 10;
   sampleReload = 10;
   
  // buttonState = deltaX = deltaY = 0b01001011;
}

void main() {
	init();         

	while(1) {            
 /*
		#asm("__CLEARCLOCK")
		while(!(~PIND)) PORTB=~0x01;
		#asm("__CLEARDATA")
		delay_us(84);
		#asm("__SETCLOCK")
		delay_us(5);
		while(PINA.1) {
			PORTB=~0x0A;
		}
		#asm("__SETDATA")
   */   
		PORTB=~0x01;   
		while(!(~PIND)) {}
		PORTB=~0xFF;
		switch (~PIND) {
			case 0x01:  hostCommand = 0xFF; break;  //reset
			case 0x02:  hostCommand = 0xF4; break;  //enable data reporting
			case 0x04:  hostCommand = 0xF5; break;  //disable data reporting
			case 0x08:  hostCommand = 0xF3; break;  //set sample rate
			case 0x10:  hostCommand = 0xE8; break;  //get device ID
			case 0x20:  hostCommand = 0x00; break;	//200
			case 0x40:  hostCommand = 0x01; break;  //100
			case 0x80:  hostCommand = 0x02; break;  //80
			default: hostCommand = 0xFF; break;		
		
		}
		sendByte();
		
  					
	    	delay_ms(500);		
	}
}


void sendByte() {
	#asm("__CLEARCLOCK")
	delay_ms(200);
	#asm
	lds output,_hostCommand
	__CLEARDATA
	__DELAY_USB 112   ; delay 84 us like the Dell computers in the lab
	__SETCLOCK

	ldi delay,0xFF
	out PORTB,delay

	mov temp,output
            
	ldi temp2,8
ByteOutLoop:
	rcall __WaitForClockLow
	rcall __OutBit
	lsr temp
	rcall __WaitForClockHigh
	dec temp2
	brne ByteOutLoop
 
    	;; calculate parity
	    mov temp,output
        mov parity,output
        swap parity
        eor temp,parity
        mov parity,temp
        lsr temp
        lsr temp
        eor temp,parity
        mov parity,temp
        lsr temp
        eor temp,parity			; now lsb of parity is even parity
        com temp                ; invert it to get odd parity
  rcall __WaitForClockLow       
  rcall __OutBit				; send our parity
  rcall __WaitForClockHigh
  rcall __WaitForClockLow
  rjmp ByteOutEnd

;;outputs a single bit to the ps2 line as a host would
__OutBit:               
	sbrs temp,0
	rjmp OutBitClear
	rjmp OutBitSet
OutBitClear:
	__CLEARDATA
	rjmp OutBit2:
OutBitSet:
	__SETDATA
OutBit2:	
        ret

ByteOutEnd:
	__SETDATA
	#endasm
}
    

#asm

    __WaitForClockLow:
    	__DELAY_USB 7	; 5 us
	WaitForClockLowLoop:
		sbic PINA,1		
		rjmp WaitForClockLowLoop
		ret	
	
    __WaitForClockHigh:
    	__DELAY_USB 7	; 5 us
	WaitForClockHighLoop:
		sbis PINA,1
		rjmp WaitForClockHighLoop
		ret
		
#endasm