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| /* Copyright (c) 2018-2022 UT Longhorn Racing Solar */ | ||
| /* | ||
| * This file implements a EMA filter. | ||
| * This performs the operation y_t = α * x_t + (1 - α) * y_{t-1} | ||
| * | ||
| * In order to use it in another file, you must import it in | ||
| * a particular way. | ||
| * | ||
| * 1. Define your data type, like so | ||
| * #define EMA_FILTER_TYPE int | ||
| * 2. Define your filter cofficient, like so | ||
| * #define EMA_FILTER_ALPHA_NUMERATOR 1 | ||
| * #define EMA_FILTER_ALPHA_DEMONINATOR 8 | ||
| * 3. Define the number of channels in your filter, like so | ||
| * #define EMA_FILTER_CHANNELS (31) | ||
| * 3. Name your EMA filter | ||
| * #define EMA_FILTER_NAME my_filter | ||
| * 4. Import this file | ||
| * #include "EMAFilter.h" | ||
| * | ||
| * This file includes some defaults, but they might not work for | ||
| * your case! | ||
| * | ||
| * Also, this file undef's everything at the end, so you can import | ||
| * multiple times if you need. | ||
| * | ||
| * If EMA_FILTER_NAME == my_filter, then your new data structure will be | ||
| * called my_filter_t. | ||
| * | ||
| * NOTE: importantly, this does not currently support usage from | ||
| * header files. That is, all these types/functions are statically | ||
| * declared, so there cannot be a non-static fifo at the moment. | ||
| */ | ||
|
|
||
| // The header guard only guard the import, | ||
| // since this file can be imported multiple times | ||
| #ifndef EMA_FILTER_H | ||
| #define EMA_FILTER_H | ||
| #include <stdint.h> | ||
| #include <string.h> | ||
| #endif | ||
|
|
||
| // The type of the EMA filter | ||
| #ifndef EMA_FILTER_TYPE | ||
| #define EMA_FILTER_TYPE int32_t | ||
| #endif | ||
|
|
||
| // The alpha coefficient of the EMA filter, as a fraction | ||
| #ifndef EMA_FILTER_ALPHA_NUMERATOR | ||
| #define EMA_FILTER_ALPHA_NUMERATOR 1 | ||
| #endif | ||
|
|
||
| #ifndef EMA_FILTER_ALPHA_DEMONINATOR | ||
| #define EMA_FILTER_ALPHA_DEMONINATOR 8 | ||
| #endif | ||
|
|
||
| // The number of channels in the EMA filter | ||
| #ifndef EMA_FILTER_CHANNELS | ||
| #define EMA_FILTER_CHANNELS 1 | ||
| #endif | ||
|
|
||
| // The name of the EMA filter (minus the _t) | ||
| #ifndef EMA_FILTER_NAME | ||
| #define EMA_FILTER_NAME define_your_filter_type | ||
| #endif | ||
|
|
||
| // Utility definitions | ||
| #define _CONCAT(A, B) A ## B | ||
| #define CONCAT(A, B) _CONCAT(A, B) | ||
|
|
||
| // Type names | ||
| #define EMA_FILTER_STRUCT_NAME CONCAT(EMA_FILTER_NAME, _s) | ||
| #define EMA_FILTER_TYPE_NAME CONCAT(EMA_FILTER_NAME, _t) | ||
|
|
||
| // The actual structure | ||
| typedef struct EMA_FILTER_STRUCT_NAME { | ||
| EMA_FILTER_TYPE prev[EMA_FILTER_CHANNELS]; | ||
| } EMA_FILTER_TYPE_NAME; | ||
|
|
||
| // Define some names for our functions | ||
| #define INIT CONCAT(EMA_FILTER_NAME, _init) | ||
| #define GET CONCAT(EMA_FILTER_NAME, _get) | ||
| #define PUT CONCAT(EMA_FILTER_NAME, _put) | ||
|
|
||
| /** | ||
| * @brief Initialize a new EMA filter | ||
| * | ||
| * If the type of the filter is myfilter_t, then this function | ||
| * will be called myfilter_init(). | ||
| * | ||
| * @param filter a pointer to the EMA filter to initialize | ||
| * @param init initial value | ||
| */ | ||
| static inline void __attribute__((unused)) | ||
| INIT (EMA_FILTER_TYPE_NAME *filter, EMA_FILTER_TYPE init) { | ||
| for (uint32_t ch = 0; ch < EMA_FILTER_CHANNELS; ch++) { | ||
| filter->prev[ch] = init; | ||
| } | ||
| } | ||
|
|
||
| /** | ||
| * @brief update the EMA filter by giving it a new set of values for all channels | ||
| * | ||
| * @param filter a pointer to the EMA filter | ||
| * @param values a complete set of new values for all channels to add to the EMA filter | ||
| * | ||
| */ | ||
| static inline void __attribute__((unused)) | ||
| PUT (EMA_FILTER_TYPE_NAME *filter, EMA_FILTER_TYPE *values) { | ||
| for (uint32_t ch = 0; ch < EMA_FILTER_CHANNELS; ch++) { | ||
| filter->prev[ch] = | ||
| ( EMA_FILTER_ALPHA_NUMERATOR * values[ch] | ||
| + (EMA_FILTER_ALPHA_DEMONINATOR - EMA_FILTER_ALPHA_NUMERATOR) * filter->prev[ch] ) | ||
| / EMA_FILTER_ALPHA_DEMONINATOR; | ||
| } | ||
| } | ||
|
|
||
| /** | ||
| * @brief get a complete set of filtered values for all channels | ||
| * | ||
| * @param filter a pointer to the EMA filter | ||
| * @param dest a pointer to a buffer to store all of the filtered values | ||
| */ | ||
| static inline void __attribute__((unused)) | ||
| GET (EMA_FILTER_TYPE_NAME *filter, EMA_FILTER_TYPE *dest) { | ||
| memcpy(dest, filter->prev, sizeof(EMA_FILTER_TYPE) * EMA_FILTER_CHANNELS); | ||
| } | ||
|
|
||
|
|
||
| // undef everything, so this file can be included multiple times | ||
| #undef EMA_FILTER_TYPE | ||
| #undef EMA_FILTER_DEPTH | ||
| #undef EMA_FILTER_CHANNELS | ||
| #undef EMA_FILTER_NAME | ||
| #undef _CONCAT | ||
| #undef CONCAT | ||
| #undef EMA_FILTER_STRUCT_NAME | ||
| #undef EMA_FILTER_TYPE_NAME | ||
| #undef EMA | ||
| #undef INIT | ||
| #undef GET | ||
| #undef PUT | ||
|
|
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