Module Name:    src
Committed By:   riastradh
Date:           Sun Dec 19 10:38:39 UTC 2021

Modified Files:
        src/sys/external/bsd/drm2/include/linux: average.h

Log Message:
Implement ewma API, exponentially weighted moving average.


To generate a diff of this commit:
cvs rdiff -u -r1.1 -r1.2 src/sys/external/bsd/drm2/include/linux/average.h

Please note that diffs are not public domain; they are subject to the
copyright notices on the relevant files.

Modified files:

Index: src/sys/external/bsd/drm2/include/linux/average.h
diff -u src/sys/external/bsd/drm2/include/linux/average.h:1.1 src/sys/external/bsd/drm2/include/linux/average.h:1.2
--- src/sys/external/bsd/drm2/include/linux/average.h:1.1	Sun Dec 19 01:53:29 2021
+++ src/sys/external/bsd/drm2/include/linux/average.h	Sun Dec 19 10:38:38 2021
@@ -0,0 +1,63 @@
+/*	$NetBSD: average.h,v 1.2 2021/12/19 10:38:38 riastradh Exp $	*/
+
+/*-
+ * Copyright (c) 2020 The NetBSD Foundation, Inc.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
+ * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
+ * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
+ * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
+ * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#ifndef	_LINUX_AVERAGE_H_
+#define	_LINUX_AVERAGE_H_
+
+#define	DECLARE_EWMA(NAME, PREC, RATE)					      \
+struct ewma_##NAME {							      \
+	unsigned long ewma_state;					      \
+};									      \
+									      \
+static inline void							      \
+ewma_##NAME##_init(struct ewma_##NAME *ewma)				      \
+{									      \
+	ewma->ewma_state = 0;						      \
+}									      \
+									      \
+static inline unsigned long						      \
+ewma_##NAME##_read(struct ewma_##NAME *ewma)				      \
+{									      \
+	return ewma->ewma_state >> (PREC);				      \
+}									      \
+									      \
+static inline void							      \
+ewma_##NAME##_add(struct ewma_##NAME *ewma, unsigned long sample)	      \
+{									      \
+	const unsigned long shift = ilog2(RATE);			      \
+	const unsigned long state = ewma->ewma_state;			      \
+									      \
+	sample <<= (PREC);						      \
+	if (state == 0) {						      \
+		ewma->ewma_state = sample;				      \
+		return;							      \
+	}								      \
+	ewma->ewma_state = (((state << shift) - state) + sample) >> shift;    \
+}
+
+#endif	/* _LINUX_AVERAGE_H_ */

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