[src/trunk]: src/sys/external/bsd/drm2/include/linux Implement ewma API, expo...

[riastradh <riastradh%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/e02385b4405a
branches:  trunk
changeset: 1028326:e02385b4405a
user:      riastradh <riastradh%NetBSD.org@localhost>
date:      Sun Dec 19 10:38:38 2021 +0000

description:
Implement ewma API, exponentially weighted moving average.

diffstat:

 sys/external/bsd/drm2/include/linux/average.h |  63 +++++++++++++++++++++++++++
 1 files changed, 63 insertions(+), 0 deletions(-)

diffs (67 lines):

diff -r fbf667d71c31 -r e02385b4405a sys/external/bsd/drm2/include/linux/average.h
--- a/sys/external/bsd/drm2/include/linux/average.h     Sun Dec 19 10:38:31 2021 +0000
+++ b/sys/external/bsd/drm2/include/linux/average.h     Sun Dec 19 10:38:38 2021 +0000
@@ -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_ */