#include "LPC17xx.h"

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

// Pin definitions
#define LED_SHIFT           4   // CNA: P0.4-P0.11
#define LED_MASK            (0xFF << LED_SHIFT)

// Keypad on CND - 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

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

#define PWM_PERIOD          100      // Smaller for faster PWM

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

static void set_column(unsigned int col)
{
    LPC_GPIO2->FIOSET = COL_MASK_P2;
    LPC_GPIO0->FIOSET = COL_MASK_P0;

    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;
    }
}

static unsigned int is_row0_pressed(void)
{
    return !(LPC_GPIO0->FIOPIN & ROW0);
}

// PWM Interrupt Handler - Software PWM
void PWM1_IRQHandler(void)
{
    if (LPC_PWM1->IR & (1 << 0))
    {
        // Software PWM for all 8 LEDs
        if(pwm_counter < duty_cycle)
            LPC_GPIO0->FIOSET = LED_MASK;  // All LEDs ON
        else
            LPC_GPIO0->FIOCLR = LED_MASK;  // All LEDs OFF

        pwm_counter++;
        if(pwm_counter >= PWM_PERIOD)
            pwm_counter = 0;

        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;

    // === SYSTEM CLOCK SETUP (Optional but recommended) ===
    SystemInit();  // Use default clock setup

    // === PIN CONFIGURATION ===
    LPC_PINCON->PINSEL0 &= ~(0xFFFF << 8);   // Clear P0.4-P0.11 (GPIO)
    LPC_PINCON->PINSEL1 &= ~(0xFFFF << 14);  // Clear P0.23-P0.28
    LPC_PINCON->PINSEL3 &= ~(0x3 << 14);     // Clear P1.23
    LPC_PINCON->PINSEL4 &= ~(0xF << 0);      // Clear P2.0-P2.1

    // === GPIO DIRECTION SETUP ===
    LPC_GPIO0->FIODIR |= LED_MASK;       // P0.4-P0.11: LEDs (output)
    LPC_GPIO0->FIODIR |= COL_MASK_P0;    // Keypad columns (output)
    LPC_GPIO2->FIODIR |= COL_MASK_P2;    // Keypad columns (output)
    LPC_GPIO0->FIODIR &= ~ROW0;          // Row-0 (input)

    // === INITIALIZE GPIO ===
    LPC_GPIO0->FIOCLR = LED_MASK;        // All LEDs off initially
    LPC_GPIO2->FIOSET = COL_MASK_P2;     // Columns high
    LPC_GPIO0->FIOSET = COL_MASK_P0;     // Columns high

    // === PWM CONFIGURATION ===
    LPC_SC->PCONP |= (1 << 6);           // Power on PWM1

    LPC_PWM1->TCR = (1 << 1);            // Reset PWM
    LPC_PWM1->CTCR = 0;                  // Timer mode
    LPC_PWM1->PR = 99;                   // Prescaler: divide by 100
                                         // Creates ~10kHz interrupt rate

    LPC_PWM1->MR0 = PWM_PERIOD;          // PWM period = 100
    LPC_PWM1->MR4 = 0;                   // Duty cycle = 0

    LPC_PWM1->MCR = (1 << 1) | (1 << 0); // Reset on MR0, interrupt enabled
    LPC_PWM1->LER = (1 << 0);            // Latch MR0

    NVIC_EnableIRQ(PWM1_IRQn);           // Enable PWM interrupt
    NVIC_SetPriority(PWM1_IRQn, 0);      // Highest priority

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

    // Initial duty cycle: 10%
    duty_cycle = 10;

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

        // Scan ROW-0 (keys 0, 1, 2, 3)
        for(col_idx = 0; col_idx < 4; col_idx++)
        {
            set_column(col_idx);
            short_delay(500);

            if(is_row0_pressed()) {
                read_key = col_idx;
                break;
            }
        }

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

        // Debounce
        if(read_key == candidate_key) {
            if(stable < 5) stable++;
        } else {
            candidate_key = read_key;
            stable = 1;
        }

        // Update intensity when stable
        if(stable >= 5) {
            if(candidate_key != last_key && candidate_key != 0xFF) {
                last_key = candidate_key;

                // Set duty cycle (out of 100)
                switch(candidate_key) {
                    case 0: duty_cycle = 10;  break;  // 10%
                    case 1: duty_cycle = 25;  break;  // 25%
                    case 2: duty_cycle = 50;  break;  // 50%
                    case 3: duty_cycle = 75;  break;  // 75%
                }
            }
            stable = 5;
        }

        short_delay(5000);
    }
}