Convert Raw 14 bit Two's Complement to Signed 16 bit Integer

Question

I am doing some work in embedded C with an accelerometer that returns data as a 14 bit 2\'s complement number. I am storing this result directly into a uint16_t

Answer 1

Assuming when code reaches return ((int32_t)raw_signed ..., it has a value in the [-8192 ... +8191] range:

If RAW_SCALE_FACTOR is a multiple of 4 then a little savings can be had.

So rather than

int16_t raw_signed = raw << 2; 
raw_signed >>= 2;

instead

int16_t fxls8471qr1_convert_raw_accel_to_mag(uint16_t raw,enum fxls8471qr1_fs_range range){
  int16_t raw_signed = raw << 2;
  uint16_t divisor;
  ...
  // return ((int32_t)raw_signed * RAW_SCALE_FACTOR) / divisor;
  return ((int32_t)raw_signed * (RAW_SCALE_FACTOR/4)) / divisor;
}