//headers for this device
#include "device.h"

#include "I2C.h"

//State of usi machine
uint16_t usi_state;

//pointer used internally by usi
uint8_t* usi_buf_ptr;

//command byte from master
uint16_t usi_command;

//super return flag
uint16_t super_flag;

void initialize_i2c( void )
{
	super_flag= 0;
	usi_buf_ptr= NULL;
	usi_state= USISTATE_NULL;

	//clear pin interrupts
	//P1IE&= ~( BIT6 | BIT7 );
	USICTL0= USIPE6 | USIPE7 | USISWRST;//Port, I2C slave, hold reset
	USICTL1= USII2C | USISTTIE;			//Enable I2C mode, disable counter
	USICKCTL= USICKPL;					//Setup clock polarity
	USICNT= 0x1f | USISCLREL;					//SCL released

	//Initialize State machine and sit idle until START condition
	usi_state= USISTATE_NULL;
	USICTL0&= ~USISWRST;				// Clear Reset of USI
}

#pragma vector=USI_VECTOR
__interrupt void usi_interrupt( )
{
	if( USICTL1 & USISTTIFG ) // START received....
	{
		USICTL1&= ~USISTTIFG;			// Clear START flag...
//		if( ! usi_state )
			usi_state= USISTATE_CONTROL | USISTATE_HAS_START;	// Next is receive control (address)
		//else
		USICNT= 0x08;					// 8 bits
	    USICTL1|= USIIE;				// Enable Counter Interrupt

		return;
	}
	//ack is a special case not for switch
	if( usi_state & USISTATE_ACK )
	{
		USICTL1&= ~USIIFG;			// Clear interrupt flag...
		if( usi_state & USISTATE_OUTPUT )
		{
			if( USISRL ) //master said no more
			{
				initialize_i2c( );//reset USI, Wait for next start
				return;
			}
			USISRL= *usi_buf_ptr++; //Load output byte
			USICTL0|= USIOE; //take SDA for output.
		}
		else //Input in progress, control, command or data
		{
			USICTL0&= ~USIOE;			//release SDA.
		}
		if( ! ( usi_state & USISTATE_ACKDONE ) )
		{
			USICNT= 0x08;				//next byte
			usi_state&= ~USISTATE_ACK;	//out of ack
		}
		else
		{
			while( P1IN & BIT6 ) //WAIT FOR LOW CLOCK
				;
			initialize_i2c( );//reset USI, Wait for next start
		}
		return;
	}

	switch( usi_state & USISTATE_MASK )
	{
	case USISTATE_CONTROL:
	{
		//Is it _not_ our address?
		if( USISRL >> 1 != USI_OURADDRESS )
		{
			initialize_i2c( );//reset USI, Wait for next start
			return;
		}
		//else our address, check the r/w bit next
		if( USISRL & 0x01 )
			usi_state= USISTATE_OUTPUT | USISTATE_OUTMODE | USISTATE_ACK;

		else
			usi_state= USISTATE_COMMAND | USISTATE_ACK;

		USISRL= 0;					//Zero to ack
		USICTL0|= USIOE;			//Take SDA to ack
		USICNT= 0x01 | USISCLREL;	//One bit to ack

		return;
	}
	case USISTATE_COMMAND:
	{
		usi_command= USISRL;
		super_flag= i2c_super_command( );
		if( ! super_flag  ) //super said don't awk
		{
			initialize_i2c( );
			return;
		}

		USISRL= 0;					//Zero to ack
		USICTL0|= USIOE;			//Take SDA to ack
		USICNT= 0x01 | USISCLREL;	//One bit to ack

		if( super_flag & SUPER_LPM_EXIT )
			LPM0_EXIT;

		//super should have set pointer
		//next is to read from master
		//second start condition will reset this
		usi_state= USISTATE_INPUT | USISTATE_ACK;

		if( !( super_flag & SUPER_CNT_MASK ) )
			usi_state|= USISTATE_ACKDONE;

		return;
	}

	case USISTATE_INPUT:
	{
		*usi_buf_ptr++= USISRL;

		//Do ack
		usi_state|= USISTATE_ACK;

		if( ! ( --super_flag & SUPER_CNT_MASK ) )//last byte?
			usi_state|= USISTATE_ACKDONE; //dec byte count

		USISRL= 0;					//Zero to ack
		USICTL0|= USIOE;			//Take SDA to ack
		USICNT= 0x01 | USISCLREL;	//One bit to ack
		return;
	}
	case USISTATE_OUTPUT:
	{
		//get master ack
		USICTL0&= ~USIOE; //Release SDA.
		usi_state|= USISTATE_ACK;

		USISRL= 0;
		USICNT= 0x01 | USISCLREL;	//clears USIIFLG
		return;
	}
	}//switch(...)!!!!!!

	//or assert, should never get here
	initialize_i2c( );
}