#include <stdio.h>
#include <avr/pgmspace.h>
#include <avr/io.h>
#include <avr/interrupt.h>
#include "delay.h"

/* Definitions for pins */
#define PORTB_PLL_MUXOUT (1 << 0)
#define PORTB_PLL_LE (1 << 4)
#define PORTB_PLL_DATA (1 << 3)
#define PORTB_PLL_CLK (1 << 2)

void set_pin(int pin, int high)
{
    if (high) {
        PORTB |= pin;
    }
    else
    {
        PORTB &= ~pin;
    }
}

void shift_out(uint8_t value)
{
    for (uint8_t i = 0; i < 8; i++)  {
        set_pin(PORTB_PLL_DATA, !!(value & (1 << (7 - i))));

        set_pin(PORTB_PLL_CLK, 1);
        set_pin(PORTB_PLL_CLK, 0);
    }
}

void write_adf4002(uint32_t value)
{
    set_pin(PORTB_PLL_LE, 0);
    shift_out((value & 0x00FF0000) >> 16);
    shift_out((value & 0x0000FF00) >> 8);
    shift_out(value & 0x000000FF);
    set_pin(PORTB_PLL_LE, 1);
}

volatile uint8_t systick;        /* Timer (100Hz increment) */
volatile uint32_t seconds;

/* 200Hz timer interrupt */
ISR(TIM0_COMPA_vect)
{
    systick++;
    if (systick == 20) {
        systick = 0;
        seconds += 1;
    }
}

static int inittimer(void)
{
    /* Start 200Hz system timer */
    TCCR0B |= (1 << WGM01); // Configure timer for CTC mode
    TIMSK  |= (1 << OCIE0A); // enable compare match A interrupt
    OCR0A = (uint8_t)(F_CPU / 64 / 50); // Set CTC compare value to 50ms
    TCCR0B |= ((1 << CS00) | (1 << CS01)); // Start timer at Fcpu/64

    // Enable interrupts
    sei();

    return 0;
}


int main(void)
{
    systick = 0;
    seconds = 0;

    /* Configure GPIO */
    PORTB = PORTB_PLL_LE;
    DDRB  = PORTB_PLL_CLK | PORTB_PLL_LE | PORTB_PLL_DATA;

    /* initialise timer interrupt */
    inittimer();

    delay_ms(120);

    // See README.md
    const uint32_t r_counter = 400;
    const uint32_t n_counter = 1080;
    const uint32_t ldp = 1; // 5 consecutive cycles of phase delay less than 15ns before lock det
    const uint32_t cpi = 3; // I_CP = 2.5mA
    const uint32_t pd_polarity = 1; // positive
    const uint32_t muxout = 1; // lock detect, active high

    const uint32_t refernce_counter_latch = (ldp << 20) | (r_counter << 2) | 0;
    const uint32_t n_counter_latch = (n_counter << 8) | 1;
    const uint32_t function_latch = (cpi << 18) | (cpi << 15) | (pd_polarity << 7) | (muxout << 4) | 2;
    const uint32_t init_latch = (cpi << 18) | (cpi << 15) | (pd_polarity << 7) | (muxout << 4) | 3;

    // ADF4002 Datasheet Page 16
    // Device Programming After Initial Statup
    // Initialisation Latch Method
    write_adf4002(init_latch);
    write_adf4002(function_latch);
    write_adf4002(refernce_counter_latch);
    write_adf4002(n_counter_latch);

    while (1) {
        /*
        // We actually dont use the timer, but the code is kept around as a reference.
        const uint32_t second = seconds % 60uL;
        const uint32_t minute = seconds / 60uL;

        if ((PINB & PORTB_PLL_MUXOUT) == 0) {
            delay_ms(600);
        }
        */
        delay_ms(1000);
    }

    return 0;
}