#include <msp430g2231.h>

// inputs
#define PSWITCH BIT1
#define TRIGGER BIT3

// outputs
#define SVALVE BIT6
#define PUMP BIT0
#define FEED BIT7

// globals
enum weaponstate { NOCHARGE, CHARGED, CHARGING, FIRING };

int wstate; 

void fire (void)
{
	/* weapon firing subroutine */
	
	/* set the state */
	wstate = FIRING;
	
	/* NB: The pswitch should not trigger ther P1 INT routine while fire() is running since fire()
	   is only ever called from p1int. */
	
	/* activate FEED magnet (prevents non-chambered ammo from falling into chamber during firing) */
	
	P1OUT |= FEED;
	
	
	/* enabler timera */
	TACTL = TASSEL_2 + MC_3 + ID_2; // ACLK, up/down mode, factor 4 divider

	/* open solenoid valve / dump air */
	P1OUT |= SVALVE;
	
	/* done. the timer will close valve and then run the pump ( CHARGING state ) */
	
}

void __attribute__((interrupt (PORT1_VECTOR))) p1int (void)
{
	if (P1IFG & TRIGGER) {
		switch (wstate) {
			case FIRING:
			case CHARGING:
			case NOCHARGE:
				/* for now, do nothing. Maybe later I'll add a sound effect or something */
				break;
			case CHARGED:
				/* the gun is charged and the trigger was pulled. FIRE ZE WEAPON! */
				fire();
				break;
		}

		P1IFG &= ~ TRIGGER;
	}
	
	if (P1IFG & PSWITCH) {
		if (wstate == CHARGING) 
		{
			/* pressure switch tripped while charging, that means we're charged! */
			wstate = CHARGED;
			P1OUT &= ~PUMP; /* turn off pump */
		}
		
		P1IFG &= ~ PSWITCH;
	}
}

void __attribute__((interrupt (TIMERA0_VECTOR))) timera (void)
{
	static unsigned int i = 0;
	
	if ( i++ > 1 ) 
	{
		i = 0; 
		TACTL = MC_0; // stop timer
		
		P1OUT &= ~( FEED + SVALVE); // close svalve, turn off FEED magnet
		
		wstate = CHARGING; // change state to charging
		
		P1OUT |= PUMP; // and activate pump
	}
}

int main()
{
	WDTCTL = WDTPW + WDTHOLD; // disable watchdog 
	
	P1DIR |= SVALVE + PUMP + FEED; // set SVALVE PUMP FEED to output
	
	P1DIR &= ~( TRIGGER + PSWITCH ); // set TRIGGER and PSWITCH to input
	
	P1OUT &= ~( SVALVE + PUMP + FEED); // make sure SVALVE and PUMP and FEED are off


	// setup IRQ for GPIO 	
	P1IE = PSWITCH + TRIGGER;
	P1IES |= PSWITCH + TRIGGER; // set high-to-low transition interrupt trigger
	P1IFG = 0; // clear all interrupt flags
	
	P1REN &= ~ ( PSWITCH + TRIGGER ); // enable internal pull up/down internal resistor 
	P1OUT |= (PSWITCH + TRIGGER);  // set to pull up resistor


	// set up timera configuration ( but do not start timer)
	CCTL0 = CCIE; // enable timera's interrupt 
	CCR0 = 0xffff; // count up to this then down to zero
	
 	
	// check if the pswitch is active / figure out our state
	
	if ( (P1IN & PSWITCH) == 0)
	{
		wstate = CHARGING;
		P1OUT |= PUMP;
	} else {
		wstate = CHARGED;
	}	
	
	__eint(); // enable interrupts

	LPM0; // low power mode 0
}