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69 lines
2.1 KiB
C
69 lines
2.1 KiB
C
/*
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* Copyright 2024 Google LLC
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#include "util/keyed_circular_cache.h"
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#include "util/assert.h"
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#include "util/math.h"
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#include <string.h>
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void keyed_circular_cache_init(KeyedCircularCache *c, KeyedCircularCacheKey *key_buffer,
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void *data_buffer, size_t item_size, size_t total_items) {
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UTIL_ASSERT(c);
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UTIL_ASSERT(key_buffer);
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UTIL_ASSERT(data_buffer);
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UTIL_ASSERT(item_size);
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*c = (KeyedCircularCache) {
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.cache_keys = key_buffer,
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.cache_data = (uint8_t *)data_buffer,
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.item_size = item_size,
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.total_items = total_items,
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};
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}
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static uint8_t *prv_get_item_at_index(KeyedCircularCache *c, int index) {
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return c->cache_data + (index * c->item_size);
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}
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void *keyed_circular_cache_get(KeyedCircularCache *c, KeyedCircularCacheKey key) {
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// Optimize for accessing most recently pushed elements.
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int idx = c->next_item_to_erase_idx;
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for (unsigned int i = 0; i < c->total_items; i++) {
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idx--;
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if (idx < 0) {
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idx += c->total_items;
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}
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if (c->cache_keys[idx] == key) {
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return prv_get_item_at_index(c, idx);
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}
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}
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return NULL;
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}
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void keyed_circular_cache_push(KeyedCircularCache *c, KeyedCircularCacheKey key,
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const void *new_item) {
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uint8_t *old_item = prv_get_item_at_index(c, c->next_item_to_erase_idx);
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memcpy(old_item, new_item, c->item_size);
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c->cache_keys[c->next_item_to_erase_idx] = key;
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c->next_item_to_erase_idx++;
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UTIL_ASSERT(c->next_item_to_erase_idx <= c->total_items);
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if (c->next_item_to_erase_idx == c->total_items) {
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c->next_item_to_erase_idx = 0;
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}
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}
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