[GitHub] ccollins476ad commented on a change in pull request #1268: util/debounce: Debouncing / hysteresis utility pkg

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ccollins476ad commented on a change in pull request #1268: util/debounce: Debouncing / hysteresis utility pkg
URL: https://github.com/apache/mynewt-core/pull/1268#discussion_r202192639
 
 

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 File path: util/debounce/include/debounce/debounce.h
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+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *  http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+#ifndef H_DEBOUNCE_
+#define H_DEBOUNCE_
+
+#include <inttypes.h>
+#include <stdbool.h>
+#include "os/mynewt.h"
+
+/**
+ * @brief Debouncer - toggles between two states with jitter control.
+ *
+ * A debouncer is always in one of two states: low or high.  The state is
+ * derived from changes to the debouncer's counter.  When the counter increases
+ * up to the debouncer's high threshold (>=), the debouncer enters the high state.
+ * The debouner remains in the high state until its counter drops down to its
+ * low threshold (<=).  The counter saturates at a configured maximum value
+ * (i.e., the counter will never exceed the max).
+ *
+ * Restrictions:
+ *     o thresh_low < thresh_high
+ *     o thresh_high <= max
+ * 
+ * All struct fields should be considered private.
+ */
+typedef struct debouncer_s {
+    uint16_t thresh_low;
+    uint16_t thresh_high;
+    uint16_t max;
+    uint16_t cur;
+    bool state;
+} debouncer_t;
+
+/**
+ * @brief Sets the provided debouncer's counter to the speified value.
+ *
+ * @param debouncer             The debouncer to set.
+ * @param val                   The value to set the deouncer's counter to.
+ *
+ * @return                      The debouncer's updated state.
+ */
+bool debouncer_set(debouncer_t *debouncer, uint16_t val);
+
+/**
+ * @brief Adjusts the provided debouncer's counter by the specified amonut.
+ *
+ * @param debouncer             The debouncer to adjust.
+ * @param delta                 The amount to change the debouncer's counter by
+ *                                  (positive for increase; negative for
+ *                                  decrease).
+ *
+ * @return                      0 on success;
+ *                              SYS_EINVAL if the specified delta is out of
+ *                                  range (less than -UINT16_MAX or greater
+ *                                  than UINT16_MAX)
+ */
+int debouncer_adjust(debouncer_t *debouncer, int32_t delta);
+
+/**
+ * @brief Initializes a debouncer with the specified configuration.
+ *
+ * @param debouncer             The debouncer to initialize.
+ * @param thresh_low            The low threshold.
+ * @param thresh_high           The high threshold.
+ * @param max                   The maximum value the debouncer's counter can
+ *                                  attain.
+ *
+ * @return                      0 on success; SYS_EINVAL on error
+ */
+int debouncer_init(debouncer_t *debouncer, uint16_t thresh_low,
+                   uint16_t thresh_high, uint16_t max);
+
+/**
+ * @brief Indicates which of the two states the provided debouncer is in.
+ *
+ * @param debouncer             The debouncer to query.
+ *
+ * @return                      true if the debouncer is in the high state;
+ *                              false if the debouncer is in the low state.
+ */
+static inline bool
+debouncer_high(const debouncer_t *debouncer)
 
 Review comment:
   Thanks, Andrzej.  I have changed `debouncer_high` to `debouncer_state`, and made it return 0 or 1 rather than a bool.

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