/* p6_1: PORTA interrupt from a switch */
/* Upon pressing a switch connecting either PTA1 or PTA2 to ground, the green LED will toggle for three times. */
 /* Main program toggles red LED while waiting for interrupt from switches. */
 
#include "MKL25Z4.h"

void delayMs(int n);

int main(void) {
    __disable_irq();            /* disable all IRQs */
    SIM->SCGC5 |= 0x400;        /* enable clock to Port B */
    PORTB->PCR[18] = 0x100;     /* make PTB18 pin as GPIO */
    PORTB->PCR[19] = 0x100;     /* make PTB19 pin as GPIO */
    PTB->PDDR |= 0xC0000;       /* make PTB18, 19 as output pin */
    PTB->PDOR |= 0xC0000;       /* turn off LEDs */
    
    SIM->SCGC5 |= 0x200;        /* enable clock to Port A */
    /* configure PTA1 for interrupt */
    PORTA->PCR[1] |=  0x00100;  /* make it GPIO  */
    PORTA->PCR[1] |=  0x00003;  /* enable pull-up */
    PTA->PDDR &= ~0x0002;       /* make pin input */
    PORTA->PCR[1] &= ~0xF0000;  /* clear interrupt selection */
    PORTA->PCR[1] |=  0xA0000;  /* enable falling edge interrupt */
    // configure PTA2 for interrupt
    PORTA->PCR[2] |=  0x00100;  /* make it GPIO  */
    PORTA->PCR[2] |=  0x00003;  /* enable pull-up */
    PTA->PDDR &= ~0x0004;       /* make pin input */
    PORTA->PCR[2] &= ~0xF0000;  /* clear interrupt selection */
    PORTA->PCR[2] |=  0xA0000;  /* enable falling edge interrupt */
    
    NVIC->ISER[0] |= 0x40000000;    /* enable INT30 (bit 30 of ISER[0]) */
    __enable_irq();             /* global enable IRQs */

    /* toggle the red LED continuously */
    while(1) {
        PTB->PTOR |= 0x40000;   /* toggle red LED */
        delayMs(500);
    }
}

/* A pushbutton switch is connecting either PTA1 or PTA2 to ground to trigger PORTA interrupt */
void PORTA_IRQHandler(void) {
    int i;

    /* toggle green LED (PTB19) three times */
    for (i = 0; i < 3; i++) {
        PTB->PDOR &= ~0x80000;  /* turn on green LED */
        delayMs(500);
        PTB->PDOR |= 0x80000;   /* turn off green LED */
        delayMs(500);
    }
    PORTA->ISFR = 0x00000006;  /* clear interrupt flag */
}

/* Delay n milliseconds
 * The CPU core clock is set to MCGFLLCLK at 41.94 MHz in SystemInit().
 */
void delayMs(int n) {
    int i;
    int j;
    for(i = 0 ; i < n; i++)
        for (j = 0; j < 7000; j++) {}
}