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    /*
     * Copyright 2011-2015 Formal Methods and Tools, University of Twente
     *
     * 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.
     */
    
    #include <sylvan_config.h>
    #include <stdint.h> // for uint32_t etc
    
    #ifndef REFS_INLINE_H
    #define REFS_INLINE_H
    
    #ifdef __cplusplus
    extern "C" {
    #endif /* __cplusplus */
    
    /**
     * Implementation of external references
     * Based on a hash table for 40-bit non-null values, linear probing
     * Use tombstones for deleting, higher bits for reference count
     */
    typedef struct
    {
        uint64_t *refs_table;           // table itself
        size_t refs_size;               // number of buckets
    
        /* helpers during resize operation */
        volatile uint32_t refs_control; // control field
        uint64_t *refs_resize_table;    // previous table
        size_t refs_resize_size;        // size of previous table
        size_t refs_resize_part;        // which part is next
        size_t refs_resize_done;        // how many parts are done
    } refs_table_t;
    
    // Count number of unique entries (not number of references)
    size_t refs_count(refs_table_t *tbl);
    
    // Increase or decrease reference to 40-bit value a
    // Will fail (assertion) if more down than up are called for a
    void refs_up(refs_table_t *tbl, uint64_t a);
    void refs_down(refs_table_t *tbl, uint64_t a);
    
    // Return a bucket or NULL to start iterating
    uint64_t *refs_iter(refs_table_t *tbl, size_t first, size_t end);
    
    // Continue iterating, set bucket to next bucket or NULL
    uint64_t refs_next(refs_table_t *tbl, uint64_t **bucket, size_t end);
    
    // User must supply a pointer, refs_create and refs_free handle initialization/destruction
    void refs_create(refs_table_t *tbl, size_t _refs_size);
    void refs_free(refs_table_t *tbl);
    
    // The same, but now for 64-bit values ("protect pointers")
    size_t protect_count(refs_table_t *tbl);
    void protect_up(refs_table_t *tbl, uint64_t a);
    void protect_down(refs_table_t *tbl, uint64_t a);
    uint64_t *protect_iter(refs_table_t *tbl, size_t first, size_t end);
    uint64_t protect_next(refs_table_t *tbl, uint64_t **bucket, size_t end);
    void protect_create(refs_table_t *tbl, size_t _refs_size);
    void protect_free(refs_table_t *tbl);
    
    #ifdef __cplusplus
    }
    #endif /* __cplusplus */
    
    
    #endif