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93 lines
2.7 KiB
C
93 lines
2.7 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/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 circular_cache_init(CircularCache* c, uint8_t* buffer, size_t item_size,
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int total_items, Comparator compare_cb) {
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UTIL_ASSERT(c);
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UTIL_ASSERT(buffer);
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UTIL_ASSERT(item_size);
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UTIL_ASSERT(compare_cb);
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*c = (CircularCache) {
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.cache = buffer,
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.next_erased_item_idx = 0,
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.item_size = item_size,
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.total_items = total_items,
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.compare_cb = compare_cb
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};
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}
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void circular_cache_set_item_destructor(CircularCache *c, CircularCacheItemDestructor destructor) {
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c->item_destructor = destructor;
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}
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static uint8_t* prv_get_item_at_index(CircularCache* c, int index) {
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return c->cache + index * c->item_size;
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}
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bool circular_cache_contains(CircularCache* c, void* theirs) {
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return (circular_cache_get(c, theirs) != NULL);
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}
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void *circular_cache_get(CircularCache* c, void* theirs) {
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for (int i = 0; i < c->total_items; ++i) {
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uint8_t* ours = prv_get_item_at_index(c, i);
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if (c->compare_cb(ours, theirs) == 0) {
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return ours;
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}
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}
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return NULL;
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}
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void circular_cache_push(CircularCache* c, void* new_item) {
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uint8_t* old_item = prv_get_item_at_index(c, c->next_erased_item_idx);
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if (c->item_destructor) {
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c->item_destructor(old_item);
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}
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memcpy(old_item, new_item, c->item_size);
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++c->next_erased_item_idx;
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UTIL_ASSERT(c->next_erased_item_idx <= c->total_items);
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if (c->next_erased_item_idx == c->total_items) {
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c->next_erased_item_idx = 0;
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}
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}
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void circular_cache_fill(CircularCache *c, uint8_t *item) {
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// If you need item_destructor and fill, add an index pointing to the oldest item for destruction
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UTIL_ASSERT(c->item_destructor == NULL);
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for (int i = 0; i < c->total_items; ++i) {
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memcpy(c->cache + i * c->item_size, item, c->item_size);
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}
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}
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void circular_cache_flush(CircularCache *c) {
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// This assumes that the user of this library can differentiate empty entries in the cache from
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// valid ones.
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for (int i = 0; i < c->total_items; i++) {
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uint8_t* item = prv_get_item_at_index(c, i);
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if (c->item_destructor) {
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c->item_destructor(item);
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}
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}
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c->next_erased_item_idx = 0;
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}
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