common: Add magnetometer online calibration.

Code for hard iron calibration: Every seconds (or faster if enough
samples), find a sphere that fit the compass data.

Based on Android code.

BRANCH=smaug
BUG=chrome-os-partner:39900
TEST=Check hard-iron bias is removed. Works better outside.

Change-Id: Iab479d5113b6560b4f01b0fd87373d2eecdb9b54
Signed-off-by: Gwendal Grignou <gwendal@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/299583
Reviewed-by: Anton Staaf <robotboy@chromium.org>

1 files changed, 30 insertions, 0 deletions

diff --git a/include/mat33.h b/include/mat33.h
new file mode 100644
index 0000000000..de7debbbc1
--- /dev/null
+++ b/include/mat33.h
@@ -0,0 +1,30 @@
+/* Copyright 2015 The Chromium OS Authors. All rights reserved.
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#ifndef __CROS_EC_MAT_33_H
+
+#define __CROS_EC_MAT_33_H
+
+#include "vec3.h"
+#include "util.h"
+
+typedef float mat33_t[3][3];
+typedef size_t size3_t[3];
+
+void init_zero_matrix(mat33_t A);
+void init_diagonal_matrix(mat33_t A, float x);
+
+void mat33_scalar_mul(mat33_t A, float c);
+
+void mat33_swap_rows(mat33_t A, const size_t i, const size_t j);
+
+void mat33_get_eigenbasis(mat33_t S, vec3_t eigenvals, mat33_t eigenvecs);
+
+size_t mat33_maxind(mat33_t A, size_t k);
+
+void mat33_rotate(mat33_t A, float c, float s,
+		  size_t k, size_t l, size_t i, size_t j);
+
+#endif  /* __CROS_EC_MAT_33_H */