firmware/os/algos/calibration/common/calibration_data.c

#include "calibration/common/calibration_data.h"

#include <string.h>

#include "common/math/vec.h"

// FUNCTION IMPLEMENTATIONS
//////////////////////////////////////////////////////////////////////////////

// Set calibration data to identity scale factors, zero skew and
// zero bias.
void calDataReset(struct ThreeAxisCalData *calstruct) {
  memset(calstruct, 0, sizeof(struct ThreeAxisCalData));
  calstruct->scale_factor_x = 1.0f;
  calstruct->scale_factor_y = 1.0f;
  calstruct->scale_factor_z = 1.0f;
}

void calDataCorrectData(const struct ThreeAxisCalData* calstruct,
                        const float x_impaired[THREE_AXIS_DIM],
                        float* x_corrected) {
  // x_temp = (x_impaired - bias).
  float x_temp[THREE_AXIS_DIM];
  vecSub(x_temp, x_impaired, calstruct->bias, THREE_AXIS_DIM);

  // x_corrected = scale_skew_mat * x_temp, where:
  // scale_skew_mat = [scale_factor_x    0         0
  //                   skew_yx    scale_factor_y   0
  //                   skew_zx       skew_zy   scale_factor_z].
  x_corrected[0] = calstruct->scale_factor_x * x_temp[0];
  x_corrected[1] = calstruct->skew_yx * x_temp[0] +
      calstruct->scale_factor_y * x_temp[1];
  x_corrected[2] = calstruct->skew_zx * x_temp[0] +
      calstruct->skew_zy * x_temp[1] +
      calstruct->scale_factor_z * x_temp[2];
}