Import of the watch repository from Pebble

src/libutil/includes/util/keyed_circular_cache.h

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+/*
+ * Copyright 2024 Google LLC
+ *
+ * Licensed 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.
+ */
+
+#pragma once
+
+#include "util/order.h"
+
+#include <stdbool.h>
+#include <stddef.h>
+#include <stdint.h>
+
+typedef uint32_t KeyedCircularCacheKey;
+
+//! Array-backed circular cache, optimized for data cache efficiency
+typedef struct {
+  KeyedCircularCacheKey *cache_keys;
+  uint8_t *cache_data; //<! Pointer to the array
+  size_t item_size; //<! Size of the array element in bytes
+  size_t next_item_to_erase_idx; //<! Next array element to be deleted
+  size_t total_items;
+} KeyedCircularCache;
+
+void keyed_circular_cache_init(KeyedCircularCache *c, KeyedCircularCacheKey *key_buffer,
+                               void *data_buffer, size_t item_size, size_t total_items);
+
+//! @return Pointer to buffer of entry in cache that contains the data
+//! @note Item must be of size item_size
+void *keyed_circular_cache_get(KeyedCircularCache *c, KeyedCircularCacheKey key);
+
+//! Push data of size item_size into the circular cache
+//! Overwrites the item at next_item_to_erase_idx
+void keyed_circular_cache_push(KeyedCircularCache *c, KeyedCircularCacheKey key,
+                               const void *item);