#include "rtl_433.h"

// ** WH2 Temperature and Humidity Outdoor Sensor **

uint8_t crc8( uint8_t *addr, uint8_t len)
{
  uint8_t crc = 0;
  
  // Indicated changes are from reference CRC-8 function in OneWire library
  while (len--) {
    uint8_t inbyte = *addr++;
    int i;
    for (i = 8; i; i--) {
      uint8_t mix = (crc ^ inbyte) & 0x80; // changed from & 0x01
      crc <<= 1; // changed from right shift
      if (mix) crc ^= 0x31;// changed from 0x8C;
        inbyte <<= 1; // changed from right shift
    }
  }
  return crc;
}
                                                      
static int wh2_callback(uint8_t bb[BITBUF_ROWS][BITBUF_COLS],int16_t bits_per_row[BITBUF_ROWS]) {
    int i,j,k;

    uint8_t payload[4];
    int received_crc8,payload_crc8;

    int wh2_id;
    float wh2_temp;
    float wh2_humidity;

    if (bb[0][0] != 0xFE) return 0;

    payload[0] = bb[0][1]>>1;
    payload[1] = bb[0][2]>>1 | ((bb[0][1]&1) << 7 );
    payload[2] = bb[0][3]>>1 | ((bb[0][2]&1) << 7 );
    payload[3] = bb[0][4]>>1 | ((bb[0][3]&1) << 7 );
    
    received_crc8 = (bb[0][5]>>1) | ((bb[0][4]&1) << 7 );

    payload_crc8 = crc8(payload,4);
    
    if (payload_crc8 != received_crc8) {
        fprintf(stderr,"Bad WH2 payload CRC, skipping...\n");
        return 0;
    }
    
    wh2_id = (payload[0] << 4) + (payload[1] >> 4);
    wh2_temp = ((payload[1] & 0x7) << 8) + payload[2];
    if (payload[1] & 0x8) {
        wh2_temp = -wh2_temp;
    }
    wh2_temp = wh2_temp/10;
    
    wh2_humidity = payload[3];
    
    fprintf(stdout, "SENSOR:TYPE=WH2,ID=%X,HUMIDITY=%g,TEMPERATURE=%g\n",wh2_id,wh2_humidity,wh2_temp);
    fprintf(stderr, "SENSOR:TYPE=WH2,ID=%X,HUMIDITY=%g,TEMPERATURE=%g\n",wh2_id,wh2_humidity,wh2_temp);

    return 1;
        
}

r_device wh2 = {
    /* .id             = */ 19,
    /* .name           = */ "WH2 Weather Station",
    /* .modulation     = */ OOK_PWM_P,
    /* .short_limit    = */ 150,
    /* .long_limit     = */ 400, 
    /* .reset_limit    = */ 20000,
    /* .json_callback  = */ &wh2_callback,
};