#include <wiringPi.h>
#include <wiringPiSPI.h>
#include <stdint.h>
#include <stdio.h>
#include <unistd.h>
#include <pthread.h>

const int CTRL_OUT = 16;
const int INTR_IN  = 19;
const int SPI_CHAN = 0;
const int SPI_SPEED = 1000000;

const uint8_t REG_MDR0 = 0b00001000;
const uint8_t REG_MDR1 = 0b00010000;
const uint8_t REG_DTR  = 0b00011000;
const uint8_t REG_CNTR = 0b00100000;
const uint8_t REG_OTR  = 0b00101000;
const uint8_t REG_STR  = 0b00110000;

const uint8_t CMD_CLR  = 0b00000000;
const uint8_t CMD_RD   = 0b01000000;
const uint8_t CMD_WR   = 0b10000000;
const uint8_t CMD_LOAD = 0b11000000;

const uint8_t STR_CY   = 0b10000000;
const uint8_t STR_BW   = 0b01000000;
const uint8_t STR_CMP  = 0b00100000;
const uint8_t STR_IDX  = 0b00010000;
const uint8_t STR_CEN  = 0b00001000;
const uint8_t STR_PLS  = 0b00000100;
const uint8_t STR_UD   = 0b00000010;
const uint8_t STR_S    = 0b00000001;

const uint8_t MDR0_NOQ = 0b00000000;
const uint8_t MDR0_Q1  = 0b00000001;
const uint8_t MDR0_Q2  = 0b00000010;
const uint8_t MDR0_Q4  = 0b00000011;
const uint8_t MDR0_FRC = 0b00000000;
const uint8_t MDR0_SCC = 0b00000100;
const uint8_t MDR0_RLC = 0b00001000;
const uint8_t MDR0_MNC = 0b00001100;
const uint8_t MDR0_DI  = 0b00000000;
const uint8_t MDR0_ILC = 0b00010000;
const uint8_t MDR0_IRC = 0b00100000;
const uint8_t MDR0_ILO = 0b00110000;
const uint8_t MDR0_AI  = 0b00000000;
const uint8_t MDR0_SI  = 0b01000000;
const uint8_t MDR0_FC1 = 0b00000000;
const uint8_t MDR0_FC2 = 0b10000000;

const uint8_t MDR1_4CM = 0b00000000;
const uint8_t MDR1_3CM = 0b00000001;
const uint8_t MDR1_2CM = 0b00000010;
const uint8_t MDR1_1CM = 0b00000011;
const uint8_t MDR1_EC  = 0b00000000;
const uint8_t MDR1_DC  = 0b00000100;
const uint8_t MDR1_F_IDX = 0b00010000;
const uint8_t MDR1_F_CMP = 0b00100000;
const uint8_t MDR1_F_BW  = 0b01000000;
const uint8_t MDR1_F_CY  = 0b10000000;


uint32_t ec = 0;
uint32_t counter = 0;
uint32_t diff = 0;


pthread_mutex_t counterMutex = PTHREAD_MUTEX_INITIALIZER;
pthread_mutex_t eventMutex = PTHREAD_MUTEX_INITIALIZER;
pthread_cond_t eventSignal = PTHREAD_COND_INITIALIZER;

void writeCmd(uint8_t c) {
  uint8_t buf[1];
  buf[0] = c;
  wiringPiSPIDataRW(SPI_CHAN, buf, 1);
}

void writeCmdData(uint8_t c, uint8_t d) {
  uint8_t buf[2];
  buf[0] = c;
  buf[1] = d;
  wiringPiSPIDataRW(SPI_CHAN, buf, 2);
}

uint8_t read8(uint8_t c) {
  uint8_t buf[2];
  buf[0] = c;
  wiringPiSPIDataRW(SPI_CHAN, buf, 2);
  return buf[1];
}

uint32_t read32(uint8_t c) {
  uint8_t buf[5];
  buf[0] = c;
  wiringPiSPIDataRW(SPI_CHAN, buf, 5);
  uint32_t r = ((uint32_t)buf[1] << 24) | ((uint32_t)buf[2] << 16) | ((uint32_t)buf[3] << 8) | ((uint32_t)buf[4]);
  return r;
}

void isr() {
  static uint32_t lastCounter = 0;

  uint32_t currentCounter = read32(CMD_RD | REG_OTR);

  pthread_mutex_lock(&counterMutex);
  diff = currentCounter - lastCounter;
  counter = currentCounter;
  ec++;
  pthread_mutex_unlock(&counterMutex);


  lastCounter = currentCounter;
  
  pthread_mutex_lock(&eventMutex);
  pthread_cond_signal(&eventSignal);
  pthread_mutex_unlock(&eventMutex);
}

void init() {
  wiringPiSetupGpio();

  wiringPiSPISetup(SPI_CHAN, SPI_SPEED);

  pinMode(CTRL_OUT, OUTPUT);
  digitalWrite(CTRL_OUT, 0);

  pinMode(INTR_IN, INPUT);
  wiringPiISR(INTR_IN, INT_EDGE_RISING, isr);
}

void initCounter() {
  writeCmd(CMD_CLR | REG_STR);
  writeCmd(CMD_CLR | REG_CNTR);
  writeCmdData(CMD_WR | REG_MDR0, MDR0_ILO);
}

int main (void) {
  static uint32_t lastDiff = 0;
  uint32_t my_ec = 0;
  uint32_t my_counter = 0;
  uint32_t my_diff = 0;

  init();
  initCounter();

  while (1) {
    pthread_mutex_lock(&eventMutex);
    pthread_cond_wait(&eventSignal, &eventMutex);
    pthread_mutex_unlock(&eventMutex);

    pthread_mutex_lock(&counterMutex);
    my_ec = ec;
    my_counter = counter;
    my_diff = diff;
    pthread_mutex_unlock(&counterMutex);

    if (my_diff != lastDiff || 1) {
      lastDiff = my_diff;
      double f = 1.0 / (((double) my_diff) / 1000000.0);
      printf("%d %d %d %f\n", my_ec, my_counter, my_diff, f);
    }
  }
}