/*
 *  spreadspace avr utils
 *
 *
 *  Copyright (C) 2016 Bernhard Tittelbach <bernhard@tittelbach.org>
 *  appreciative nod to Adafruit for writing a great example, go buy their stuff
 *
 *  This file is part of spreadspace avr utils.
 *
 *  spreadspace avr utils is free software: you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation, either version 3 of the License, or
 *  any later version.
 *
 *  spreadspace avr utils is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with spreadspace avr utils. If not, see <http://www.gnu.org/licenses/>.
 */

#include <stdio.h>
#include <avr/pgmspace.h>
#include <LUFA/Drivers/Peripheral/SPI.h>
#include "bmp280.h"


int32_t bmp280_t_fine = 0;

void bmp280_cs(bmp280_sensor *sensor, uint8_t select)
{
  if (!select)
    *(sensor->cs_port) |= _BV(sensor->cs_pin);
  else
    *(sensor->cs_port) &= ~ _BV(sensor->cs_pin);
}

void bmp280_write8(uint8_t reg, uint8_t value)
{
  SPI_SendByte(reg & ~0x80); //bit 7 needs to be low for write mode
  SPI_SendByte(value);
}

uint8_t bmp280_read8(uint8_t reg)
{
  SPI_SendByte(reg | 0x80); //bit 7 high for read mode
  return SPI_ReceiveByte();
}

uint16_t bmp280_read16(uint8_t reg)
{
  uint16_t value = 0;
   SPI_SendByte(reg | 0x80); //bit 7 high for read mode
   value |= ((uint16_t) SPI_ReceiveByte() & 0xFF) << 8;
   value |= (uint16_t) SPI_ReceiveByte() & 0xFF;
   return value;
}

uint32_t bmp280_read24(uint8_t reg)
{
   uint32_t value = 0;
   SPI_SendByte(reg | 0x80); //bit 7 high for read mode
   value |= ((uint32_t) SPI_ReceiveByte() & 0xFF) << 16;
   value |= ((uint32_t) SPI_ReceiveByte() & 0xFF) << 8;
   value |= (uint32_t) SPI_ReceiveByte()  & 0xFF;
   return value;
}

int16_t bmp280_readS16(uint8_t reg)
{
  return (int16_t) bmp280_read16(reg);
}

uint16_t bmp280_read16_LE(uint8_t reg)
{
    uint16_t value = 0;
   SPI_SendByte(reg | 0x80); //bit 7 high for read mode
   value |= (uint16_t) SPI_ReceiveByte() & 0xFF;
   value |= ((uint16_t) SPI_ReceiveByte() & 0xFF) << 8;
   return value;
}

int16_t bmp280_readS16_LE(uint8_t reg)
{
  return (int16_t)bmp280_read16_LE(reg);
}

void bmp280_readCoefficients(bmp280_sensor *sensor)
{
  bmp280_cs(sensor, true);
  sensor->dig_T1 = bmp280_read16_LE(BMP280_REGISTER_DIG_T1);
  sensor->dig_T2 = bmp280_readS16_LE(BMP280_REGISTER_DIG_T2);
  sensor->dig_T3 = bmp280_readS16_LE(BMP280_REGISTER_DIG_T3);
  sensor->dig_P1 = bmp280_read16_LE(BMP280_REGISTER_DIG_P1);
  sensor->dig_P2 = bmp280_readS16_LE(BMP280_REGISTER_DIG_P2);
  sensor->dig_P3 = bmp280_readS16_LE(BMP280_REGISTER_DIG_P3);
  sensor->dig_P4 = bmp280_readS16_LE(BMP280_REGISTER_DIG_P4);
  sensor->dig_P5 = bmp280_readS16_LE(BMP280_REGISTER_DIG_P5);
  sensor->dig_P6 = bmp280_readS16_LE(BMP280_REGISTER_DIG_P6);
  sensor->dig_P7 = bmp280_readS16_LE(BMP280_REGISTER_DIG_P7);
  sensor->dig_P8 = bmp280_readS16_LE(BMP280_REGISTER_DIG_P8);
  sensor->dig_P9 = bmp280_readS16_LE(BMP280_REGISTER_DIG_P9);
  bmp280_cs(sensor, false);  
}

//need to init SPI beforehand
void bmp280_init(bmp280_sensor *sensor, volatile uint8_t *cs_port, uint8_t cs_pin)
{
  memset(sensor,0,sizeof(bmp280_sensor));
  sensor->cs_port = cs_port;
  sensor->cs_pin = cs_pin;
  bmp280_readCoefficients(sensor);
}

float bmp280_readTemp(bmp280_sensor *sensor)
{
  int32_t var1, var2;

  bmp280_cs(sensor, true);
  int32_t adc_T = bmp280_read24(BMP280_REGISTER_TEMPDATA);
  bmp280_cs(sensor, false);
  adc_T >>= 4;

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

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

  bmp280_t_fine = var1 + var2;

  float T  = (bmp280_t_fine * 5 + 128) >> 8;
  return T/100;
}

float bmp280_readPressure(bmp280_sensor *sensor)
{
  int64_t var1, var2, p;

  // Must be done first to get the bmp280_t_fine variable
  bmp280_readTemp(sensor);

  bmp280_cs(sensor, true);
  int32_t adc_P = bmp280_read24(BMP280_REGISTER_PRESSUREDATA);
  bmp280_cs(sensor, false);
  adc_P >>= 4;

  var1 = ((int64_t)bmp280_t_fine) - 128000;
  var2 = var1 * var1 * (int64_t)sensor->dig_P6;
  var2 = var2 + ((var1*(int64_t)sensor->dig_P5)<<17);
  var2 = var2 + (((int64_t)sensor->dig_P4)<<35);
  var1 = ((var1 * var1 * (int64_t)sensor->dig_P3)>>8) +
    ((var1 * (int64_t)sensor->dig_P2)<<12);
  var1 = (((((int64_t)1)<<47)+var1))*((int64_t)sensor->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)sensor->dig_P9) * (p>>13) * (p>>13)) >> 25;
  var2 = (((int64_t)sensor->dig_P8) * p) >> 19;

  p = ((p + var1 + var2) >> 8) + (((int64_t)sensor->dig_P7)<<4);
  return (float)p/256;
}

/*float bmp280_readAltitude(bmp280_sensor *sensor, float sealevelp)
{
  float altitude;

  float pressure = bmp280_readPressure(sensor); // in Si units for Pascal
  pressure /= 100;

  altitude = 44330 * (1.0 - pow(pressure / seaLevelhPa, 0.1903));

  return altitude;
}*/


/// Helper Functions