#include "LPC17xx.h"

// PWM variables
unsigned long int duty_cycle = 0;
unsigned long int pwm_counter = 0;

// Pin definitions based on connectors
#define LED_SHIFT           4   // CNA: P0.4-P0.11 (8 LEDs)
#define LED_MASK            (0xFF << LED_SHIFT)

// Keypad on CND - Only ROW-0
#define COL0                (1<<0)   // P2.0
#define COL1                (1<<1)   // P2.1
#define COL2                (1<<23)  // P0.23
#define COL3                (1<<24)  // P0.24
#define ROW0                (1<<25)  // P0.25 (ROW-0 only)

#define COL_MASK_P0         (COL2 | COL3)
#define COL_MASK_P2         (COL0 | COL1)

static void short_delay(volatile unsigned int d) {
    while(d--) __NOP();
}

// Set a specific column low, others high
static void set_column(unsigned int col)
{
    // Set all columns high first
    LPC_GPIO2->FIOSET = COL_MASK_P2;
    LPC_GPIO0->FIOSET = COL_MASK_P0;

    // Pull specific column low
    switch(col) {
        case 0: LPC_GPIO2->FIOCLR = COL0; break;
        case 1: LPC_GPIO2->FIOCLR = COL1; break;
        case 2: LPC_GPIO0->FIOCLR = COL2; break;
        case 3: LPC_GPIO0->FIOCLR = COL3; break;
    }
}

// Check if ROW-0 is pressed
static unsigned int is_row0_pressed(void)
{
    return !(LPC_GPIO0->FIOPIN & ROW0);
}

// PWM Interrupt Handler
void PWM1_IRQHandler(void)
{
    if (LPC_PWM1->IR & (1 << 0))
    {
        // Software PWM for LEDs (CNA: P0.4-P0.11)
        pwm_counter++;
        if(pwm_counter >= 3000) pwm_counter = 0;

        if(pwm_counter < duty_cycle)
            LPC_GPIO0->FIOSET = LED_MASK;  // LEDs ON
        else
            LPC_GPIO0->FIOCLR = LED_MASK;  // LEDs OFF

        LPC_PWM1->IR = (1 << 0);  // Clear interrupt
    }
}

int main(void)
{
    unsigned int col_idx;
    unsigned int candidate_key = 0xFF;
    unsigned int stable = 0;
    unsigned int last_key = 0xFF;

    // === PIN CONFIGURATION ===
    LPC_PINCON->PINSEL0 = 0x00000000;  // All GPIO
    LPC_PINCON->PINSEL1 = 0x00000000;
    LPC_PINCON->PINSEL3 = (2 << 14);   // PWM1.4 on P1.23 (optional)
    LPC_PINCON->PINSEL4 = 0x00000000;

    // === GPIO DIRECTION SETUP ===
    // CNA: LEDs (P0.4-P0.11)
    LPC_GPIO0->FIODIR |= LED_MASK;

    // CND: Keypad - Columns output, Row-0 input
    LPC_GPIO0->FIODIR |= COL_MASK_P0;    // Columns (output)
    LPC_GPIO2->FIODIR |= COL_MASK_P2;    // Columns (output)
    LPC_GPIO0->FIODIR &= ~ROW0;          // Row-0 (input)

    // === INITIALIZE GPIO STATES ===
    LPC_GPIO0->FIOCLR = LED_MASK;        // LEDs off
    LPC_GPIO2->FIOSET = COL_MASK_P2;     // Columns high (idle)
    LPC_GPIO0->FIOSET = COL_MASK_P0;     // Columns high (idle)

    // === PWM CONFIGURATION ===
    LPC_PWM1->TCR = (1 << 1);            // Reset PWM
    LPC_PWM1->CTCR = 0;                  // Timer mode
    LPC_PWM1->PR = 0;                    // No prescaler

    LPC_PWM1->MR0 = 3000;                // PWM period = 3000
    LPC_PWM1->MR4 = duty_cycle;          // Initial duty cycle = 0

    LPC_PWM1->MCR = (1 << 1) | (1 << 0); // Reset and interrupt on MR0
    LPC_PWM1->PCR = (1 << 12);           // Enable PWM4 output
    LPC_PWM1->LER = (1 << 0) | (1 << 4); // Latch MR0 and MR4

    NVIC_EnableIRQ(PWM1_IRQn);           // Enable PWM interrupt

    LPC_PWM1->TCR = (1 << 0) | (1 << 3); // Enable counter and PWM

    // === MAIN LOOP ===
    while(1)
    {
        unsigned int read_key = 0xFF;

        // Scan ROW-0 only (columns 0-3 = keys 0, 1, 2, 3)
        for(col_idx = 0; col_idx < 4; col_idx++)
        {
            set_column(col_idx);
            short_delay(200);

            if(is_row0_pressed()) {
                read_key = col_idx;  // Key 0, 1, 2, or 3
                break;
            }
        }

        // Restore all columns high
        LPC_GPIO2->FIOSET = COL_MASK_P2;
        LPC_GPIO0->FIOSET = COL_MASK_P0;

        // Debounce logic
        if(read_key == candidate_key) {
            if(stable < 3) stable++;
        } else {
            candidate_key = read_key;
            stable = 1;
        }

        // Update intensity when key is stable and changed
        if(stable >= 3) {
            if(candidate_key != last_key && candidate_key != 0xFF) {
                last_key = candidate_key;

                // Set duty cycle based on key pressed
                switch(candidate_key) {
                    case 0: duty_cycle = 300;  break;  // 10% of 3000
                    case 1: duty_cycle = 750;  break;  // 25% of 3000
                    case 2: duty_cycle = 1500; break;  // 50% of 3000
                    case 3: duty_cycle = 2250; break;  // 75% of 3000
                }

                LPC_PWM1->MR4 = duty_cycle;
                LPC_PWM1->LER = (1 << 4);
            }
            stable = 3;
        }

        short_delay(2000);
    }
}