Algorithm for processing data from accelerometers / gyroscope

I will commission a code fragment that would perform the function of eliminating the effect of gravity on the acceleration data of an object (vehicle).

The ideal would be such that the position of the accelerometer relative to the vehicle is arbitrary, and the result of the code would be pure acceleration in m / s2 for each axis.

The test environment is Arduino UNO + ADXL345.

Target device: STM processor + accelerometer or accelerometer / gyroscope.

I am considering commissioning the entire device design after checking the operation of this algorithm.