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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>
36 lines
605 B
C
36 lines
605 B
C
/* Copyright (c) 2012 The Chromium OS Authors. All rights reserved.
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* Use of this source code is governed by a BSD-style license that can be
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* found in the LICENSE file.
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*/
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/* Math utility functions for ARMv7 */
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#ifndef __CROS_EC_MATH_H
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#define __CROS_EC_MATH_H
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#ifdef CONFIG_FPU
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static inline float sqrtf(float v)
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{
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float root;
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asm volatile(
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"fsqrts %0, %1"
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: "=w" (root)
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: "w" (v)
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);
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return root;
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}
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static inline float fabsf(float v)
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{
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float root;
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asm volatile(
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"fabss %0, %1"
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: "=w" (root)
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: "w" (v)
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);
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return root;
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}
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#endif /* CONFIG_FPU */
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#endif /* __CROS_EC_MATH_H */
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