#include "Arduino.h"
#include <Wire.h> 

#include "myI2c.h" 
#include "BME280.h" 


bme280_calib_data _bme280_calib;
int32_t t_fine;



//-------------------------------------------------
void bme280_readCoefficients(void)
{
    _bme280_calib.dig_T1 = I2C_read16_LE(BME280_REGISTER_DIG_T1);
    _bme280_calib.dig_T2 = I2C_readS16_LE(BME280_REGISTER_DIG_T2);
    _bme280_calib.dig_T3 = I2C_readS16_LE(BME280_REGISTER_DIG_T3);

    _bme280_calib.dig_P1 = I2C_read16_LE(BME280_REGISTER_DIG_P1);
    _bme280_calib.dig_P2 = I2C_readS16_LE(BME280_REGISTER_DIG_P2);
    _bme280_calib.dig_P3 = I2C_readS16_LE(BME280_REGISTER_DIG_P3);
    _bme280_calib.dig_P4 = I2C_readS16_LE(BME280_REGISTER_DIG_P4);
    _bme280_calib.dig_P5 = I2C_readS16_LE(BME280_REGISTER_DIG_P5);
    _bme280_calib.dig_P6 = I2C_readS16_LE(BME280_REGISTER_DIG_P6);
    _bme280_calib.dig_P7 = I2C_readS16_LE(BME280_REGISTER_DIG_P7);
    _bme280_calib.dig_P8 = I2C_readS16_LE(BME280_REGISTER_DIG_P8);
    _bme280_calib.dig_P9 = I2C_readS16_LE(BME280_REGISTER_DIG_P9);

    _bme280_calib.dig_H1 = I2C_read8(BME280_REGISTER_DIG_H1);
    _bme280_calib.dig_H2 = I2C_readS16_LE(BME280_REGISTER_DIG_H2);
    _bme280_calib.dig_H3 = I2C_read8(BME280_REGISTER_DIG_H3);
    _bme280_calib.dig_H4 = (I2C_read8(BME280_REGISTER_DIG_H4) << 4) | (I2C_read8(BME280_REGISTER_DIG_H4+1) & 0xF);
    _bme280_calib.dig_H5 = (I2C_read8(BME280_REGISTER_DIG_H5+1) << 4) | (I2C_read8(BME280_REGISTER_DIG_H5) >> 4);
    _bme280_calib.dig_H6 = (int8_t)I2C_read8(BME280_REGISTER_DIG_H6); 
    
} 
//-------------------------------------------------------------
float bme280_readTemperature(void)
{
  int32_t var1, var2;
  
  int32_t adc_T = I2C_Read24(BME280_REGISTER_TEMPDATA);
  adc_T >>= 4;

  var1  = ((((adc_T>>3) - ((int32_t)_bme280_calib.dig_T1 <<1))) *
     ((int32_t)_bme280_calib.dig_T2)) >> 11;

  var2  = (((((adc_T>>4) - ((int32_t)_bme280_calib.dig_T1)) *
       ((adc_T>>4) - ((int32_t)_bme280_calib.dig_T1))) >> 12) *
     ((int32_t)_bme280_calib.dig_T3)) >> 14;

  t_fine = var1 + var2;

  float T  = (t_fine * 5 + 128) >> 8;
  return T/100;
} 
//---------------------------------------------------
float bme280_readPressure(void)
{
  int64_t var1, var2, p;
  

  // Must be done first to get the t_fine variable set up
  bme280_readTemperature();

  int32_t adc_P = I2C_Read24(BME280_REGISTER_PRESSUREDATA);
  adc_P >>= 4;

  var1 = ((int64_t)t_fine) - 128000;
  var2 = var1 * var1 * (int64_t)_bme280_calib.dig_P6;
  var2 = var2 + ((var1*(int64_t)_bme280_calib.dig_P5)<<17);
  var2 = var2 + (((int64_t)_bme280_calib.dig_P4)<<35);
  var1 = ((var1 * var1 * (int64_t)_bme280_calib.dig_P3)>>8) +
    ((var1 * (int64_t)_bme280_calib.dig_P2)<<12);
  var1 = (((((int64_t)1)<<47)+var1))*((int64_t)_bme280_calib.dig_P1)>>33;

  if (var1 == 0) {
    return 0;  // avoid exception caused by division by zero
  }
  p = 1048576 - adc_P;
  p = (((p<<31) - var2)*3125) / var1;
  var1 = (((int64_t)_bme280_calib.dig_P9) * (p>>13) * (p>>13)) >> 25;
  var2 = (((int64_t)_bme280_calib.dig_P8) * p) >> 19;

  p = ((p + var1 + var2) >> 8) + (((int64_t)_bme280_calib.dig_P7)<<4);
  return (float)p/256;
}
//----------------------------------------------------------
float bme280_readHumidity(void) 
{
  bme280_readTemperature(); // must be done first to get t_fine

  int32_t adc_H = I2C_read16(BME280_REGISTER_HUMIDDATA);

  int32_t v_x1_u32r;

  v_x1_u32r = (t_fine - ((int32_t)76800));

  v_x1_u32r = (((((adc_H << 14) - (((int32_t)_bme280_calib.dig_H4) << 20) -
      (((int32_t)_bme280_calib.dig_H5) * v_x1_u32r)) + ((int32_t)16384)) >> 15) *
         (((((((v_x1_u32r * ((int32_t)_bme280_calib.dig_H6)) >> 10) *
        (((v_x1_u32r * ((int32_t)_bme280_calib.dig_H3)) >> 11) + ((int32_t)32768))) >> 10) +
      ((int32_t)2097152)) * ((int32_t)_bme280_calib.dig_H2) + 8192) >> 14));

  v_x1_u32r = (v_x1_u32r - (((((v_x1_u32r >> 15) * (v_x1_u32r >> 15)) >> 7) *
           ((int32_t)_bme280_calib.dig_H1)) >> 4));

  v_x1_u32r = (v_x1_u32r < 0) ? 0 : v_x1_u32r;
  v_x1_u32r = (v_x1_u32r > 419430400) ? 419430400 : v_x1_u32r;
  float h = (v_x1_u32r>>12);
  return  h / 1024.0;
}