unsigned long int BMP280_Conver_Pressure (void)   
{
signed long int adc_P;
signed_64 var1, var2, p;  //64bit!!!
//
adc_P = BMP280_Read_3_Byte(0xF7);
//
var1 = ((signed_64)t_fine) - 128000;
var2 = var1 * var1 * (signed_64)dig_P6;
var2 = var2 + ((var1*(signed_64)dig_P5)<<17);
var2 = var2 + (((signed_64)dig_P4)<<35);
var1 = ((var1 * var1 * (signed_64)dig_P3)>>8) + ((var1 * (signed_64)dig_P2)<<12);
var1 = (((((signed_64)1)<<47)+var1))*((signed_64)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 = (((signed_64)dig_P9) * (p>>13) * (p>>13)) >> 25;
var2 = (((signed_64)dig_P8) * p) >> 19;
p = ((p + var1 + var2) >> 8) + (((signed_64)dig_P7)<<4);
return (unsigned long int)p;
}