1 /* $NetBSD: average.h,v 1.2 2021/12/19 10:38:38 riastradh Exp $ */ 2 3 /*- 4 * Copyright (c) 2020 The NetBSD Foundation, Inc. 5 * All rights reserved. 6 * 7 * Redistribution and use in source and binary forms, with or without 8 * modification, are permitted provided that the following conditions 9 * are met: 10 * 1. Redistributions of source code must retain the above copyright 11 * notice, this list of conditions and the following disclaimer. 12 * 2. Redistributions in binary form must reproduce the above copyright 13 * notice, this list of conditions and the following disclaimer in the 14 * documentation and/or other materials provided with the distribution. 15 * 16 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS 17 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 18 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 19 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS 20 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 21 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 22 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 23 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 24 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 25 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 26 * POSSIBILITY OF SUCH DAMAGE. 27 */ 28 29 #ifndef _LINUX_AVERAGE_H_ 30 #define _LINUX_AVERAGE_H_ 31 32 #define DECLARE_EWMA(NAME, PREC, RATE) \ 33 struct ewma_##NAME { \ 34 unsigned long ewma_state; \ 35 }; \ 36 \ 37 static inline void \ 38 ewma_##NAME##_init(struct ewma_##NAME *ewma) \ 39 { \ 40 ewma->ewma_state = 0; \ 41 } \ 42 \ 43 static inline unsigned long \ 44 ewma_##NAME##_read(struct ewma_##NAME *ewma) \ 45 { \ 46 return ewma->ewma_state >> (PREC); \ 47 } \ 48 \ 49 static inline void \ 50 ewma_##NAME##_add(struct ewma_##NAME *ewma, unsigned long sample) \ 51 { \ 52 const unsigned long shift = ilog2(RATE); \ 53 const unsigned long state = ewma->ewma_state; \ 54 \ 55 sample <<= (PREC); \ 56 if (state == 0) { \ 57 ewma->ewma_state = sample; \ 58 return; \ 59 } \ 60 ewma->ewma_state = (((state << shift) - state) + sample) >> shift; \ 61 } 62 63 #endif /* _LINUX_AVERAGE_H_ */ 64