283 lines
9.8 KiB
C
283 lines
9.8 KiB
C
#ifdef HAVE_CONFIG_H
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# include <config.h>
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#endif
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#include "eo_ptr_indirection.h"
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/* Start of pointer indirection:
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*
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* This feature is responsible of hiding from the developer the real pointer of
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* the Eo object to supply a better memory management by preventing bad usage
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* of the pointers.
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*
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* Eo * is no more a pointer but an index to an entry into a ids table.
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* For a better memory usage, we don't allocate all the tables at the beginning,
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* but only when needed (i.e no more empty entries in allocated tables.
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* In addition, tables are composed of intermediate tables, this for memory
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* optimizations. Finding the different table, intermediate table and relative
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* entry is done by bits manipulation of the id:
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*
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* id = Table | Inter_table | Entry | Generation
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*
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* Generation helps finding abuse of ids. When an entry is assigned to an
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* object, a generation is inserted into the id. If the developer uses this id
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* although the object is freed and another one has replaced it into the same
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* entry of the table, the generation will be different and an error will
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* occur when accessing with the old id.
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*
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* Each table is composed of:
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* - pointers to the objects
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* - generations assigned to the objects
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* - a boolean table indicating if an entry is active
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* - an index 'start' indicating which entry is the next one to use.
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* - a queue that will help us to store the unused entries. It stores only the
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* entries that have been used at least one time. The entries that have
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* never been used are "pointed" by the start parameter.
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* When an entry is searched into a table, we first try to pop from the
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* queue. If a NULL value is returned, we have to use one of the entries that
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* have never been used. If a such entry doesn't exist, we pass to the next
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* table. Otherwise, we reserve this entry to the object pointer and create
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* the id with the table id, the intermediate table id, the entry and a
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* generation.
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* When an object is freed, the entry into the table is released by pushing
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* it into the queue.
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*/
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#if SIZEOF_UINTPTR_T == 4
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/* 32 bits */
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# define BITS_FOR_IDS_TABLE 8
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# define BITS_FOR_IDS_INTER_TABLE 4
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# define BITS_FOR_ID_IN_TABLE 10
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# define BITS_FOR_GENERATION_COUNTER 10
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#else
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/* 64 bits */
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# define BITS_FOR_IDS_TABLE 8
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# define BITS_FOR_IDS_INTER_TABLE 20
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# define BITS_FOR_ID_IN_TABLE 16
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# define BITS_FOR_GENERATION_COUNTER 20
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#endif
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typedef uintptr_t Table_Index;
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/* Shifts macros to manipulate the Eo id */
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#define SHIFT_FOR_IDS_TABLE \
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(BITS_FOR_IDS_INTER_TABLE + BITS_FOR_ID_IN_TABLE + BITS_FOR_GENERATION_COUNTER)
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#define SHIFT_FOR_IDS_INTER_TABLE \
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(BITS_FOR_ID_IN_TABLE + BITS_FOR_GENERATION_COUNTER)
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#define SHIFT_FOR_ID_IN_TABLE (BITS_FOR_GENERATION_COUNTER)
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/* Maximum ranges */
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#define MAX_IDS_TABLES (1 << BITS_FOR_IDS_TABLE)
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#define MAX_IDS_INTER_TABLES (1 << BITS_FOR_IDS_INTER_TABLE)
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#define MAX_IDS_PER_TABLE (1 << BITS_FOR_ID_IN_TABLE)
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#define MAX_GENERATIONS (1 << BITS_FOR_GENERATION_COUNTER)
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/* Table */
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typedef struct
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{
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/* Pointers of objects stored in table */
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_Eo *ptrs[MAX_IDS_PER_TABLE];
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/* Generations */
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Table_Index generation[MAX_IDS_PER_TABLE];
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/* Active flags */
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char active[MAX_IDS_PER_TABLE >> 3];
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/* Queue to handle free entries */
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Eina_Trash *queue;
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/* Indicates where start the "never used" entries */
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Table_Index start;
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} _Eo_Ids_Table;
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/* Tables handling pointers indirection */
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_Eo_Ids_Table **_eo_ids_tables[MAX_IDS_TABLES] = { NULL };
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/* Next generation to use when assigning a new entry to a Eo pointer */
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Table_Index _eo_generation_counter;
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/* Internal macro for active flag manipulation */
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#define _ENTRY_ACTIVE_DO_OP(table, id_in_table, op) \
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(table)->active[(id_in_table) >> 3] op (1 << ((id_in_table) % 8))
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/* Macro that indicates if an entry is active */
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#define IS_ENTRY_ACTIVE(table, id_in_table) \
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(_ENTRY_ACTIVE_DO_OP(table, id_in_table, &))
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/* Macro that activates an entry */
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#define ACTIVATE_ENTRY(table, id_in_table) \
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_ENTRY_ACTIVE_DO_OP(table, id_in_table, |=)
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/* Macro that de-activates an entry */
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#define DEACTIVATE_ENTRY(table, id_in_table) \
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_ENTRY_ACTIVE_DO_OP(table, id_in_table, &=~)
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/* Macro used to compose an Eo id */
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#define EO_COMPOSE_ID(TABLE, INTER_TABLE, ENTRY, GENERATION) \
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(Eo_Id)(((TABLE & (MAX_IDS_TABLES - 1)) << SHIFT_FOR_IDS_TABLE) | \
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((INTER_TABLE & (MAX_IDS_INTER_TABLES - 1)) << SHIFT_FOR_IDS_INTER_TABLE) |\
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((ENTRY & (MAX_IDS_PER_TABLE - 1)) << SHIFT_FOR_ID_IN_TABLE) | \
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(GENERATION & (MAX_GENERATIONS - 1) ))
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/* Macro to extract from an Eo id the indexes of the tables */
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#define EO_DECOMPOSE_ID(ID, TABLE, INTER_TABLE, ENTRY, GENERATION) \
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TABLE = (ID >> SHIFT_FOR_IDS_TABLE) & (MAX_IDS_TABLES - 1); \
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INTER_TABLE = (ID >> SHIFT_FOR_IDS_INTER_TABLE) & (MAX_IDS_INTER_TABLES - 1); \
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ENTRY = (ID >> SHIFT_FOR_ID_IN_TABLE) & (MAX_IDS_PER_TABLE - 1); \
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GENERATION = ID & (MAX_GENERATIONS - 1); \
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/* Macro used for readability */
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#define ID_TABLE _eo_ids_tables[table_id][int_table_id]
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_Eo *
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_eo_obj_pointer_get(const Eo_Id obj_id)
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{
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#ifdef HAVE_EO_ID
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Table_Index table_id, int_table_id, entry_id, generation;
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EO_DECOMPOSE_ID((Table_Index) obj_id, table_id, int_table_id, entry_id, generation);
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/* Checking the validity of the entry */
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if (_eo_ids_tables[table_id] && ID_TABLE && IS_ENTRY_ACTIVE(ID_TABLE, entry_id) &&
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ID_TABLE->generation[entry_id] == generation)
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return ID_TABLE->ptrs[entry_id];
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ERR("obj_id %p is not pointing to a valid object. Maybe it has already been freed.",
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(void *)obj_id);
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return NULL;
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#else
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return (_Eo *)obj_id;
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#endif
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}
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Eo_Id
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_eo_id_allocate(const _Eo *obj)
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{
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#ifdef HAVE_EO_ID
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Eo_Id ret = 0;
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for (Table_Index table_id = 1; table_id < MAX_IDS_TABLES; table_id++)
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{
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if (!_eo_ids_tables[table_id])
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{
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/* We allocate a new table */
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_eo_ids_tables[table_id] = calloc(MAX_IDS_INTER_TABLES, sizeof(_Eo_Ids_Table*));
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}
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for (Table_Index int_table_id = 0; int_table_id < MAX_IDS_INTER_TABLES; int_table_id++)
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{
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_Eo **ptr;
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if (!ID_TABLE)
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{
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/* We allocate a new intermediate table */
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ID_TABLE = calloc(1, sizeof(_Eo_Ids_Table));
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eina_trash_init(&(ID_TABLE->queue));
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/* We select directly the first entry of the new table */
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ptr = &(ID_TABLE->ptrs[0]);
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ID_TABLE->start = 1;
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}
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else
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{
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/* We try to pop from the queue an unused entry */
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ptr = (_Eo **)eina_trash_pop(&(ID_TABLE->queue));
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}
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if (!ptr && ID_TABLE->start < MAX_IDS_PER_TABLE)
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{
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/* No more unused entries in the trash but still empty entries in the table */
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ptr = &(ID_TABLE->ptrs[ID_TABLE->start]);
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ID_TABLE->start++;
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}
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if (ptr)
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{
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/* An entry was found - need to find the entry id and fill it */
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Table_Index id = ptr - ID_TABLE->ptrs;
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ID_TABLE->generation[id] = _eo_generation_counter;
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ACTIVATE_ENTRY(ID_TABLE, id);
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*ptr = (_Eo *)obj;
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ret = EO_COMPOSE_ID(table_id, int_table_id, id, _eo_generation_counter);
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_eo_generation_counter++;
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_eo_generation_counter %= MAX_GENERATIONS;
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return ret;
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}
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}
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}
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return ret;
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#else
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return (Eo_Id)obj;
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#endif
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}
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void
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_eo_id_release(const Eo_Id obj_id)
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{
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#ifdef HAVE_EO_ID
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Table_Index table_id, int_table_id, entry_id, generation;
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EO_DECOMPOSE_ID((Table_Index) obj_id, table_id, int_table_id, entry_id, generation);
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/* Checking the validity of the entry */
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if (!_eo_ids_tables[table_id]) goto error;
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if (!ID_TABLE) goto error;
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if (ID_TABLE->generation[entry_id] != generation) goto error;
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/* Disable the entry */
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DEACTIVATE_ENTRY(ID_TABLE, entry_id);
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/* Push the entry into the queue */
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eina_trash_push(&(ID_TABLE->queue), &(ID_TABLE->ptrs[entry_id]));
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return;
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error:
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ERR("obj_id %p is not pointing to a valid object. Maybe it has already been freed.", (void *)obj_id);
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#else
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(void) obj_id;
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#endif
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}
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void
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_eo_free_ids_tables()
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{
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for (Table_Index table_id = 0; table_id < MAX_IDS_TABLES; table_id++)
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{
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if (_eo_ids_tables[table_id])
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{
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for (Table_Index int_table_id = 0; int_table_id < MAX_IDS_INTER_TABLES; int_table_id++)
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{
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if (ID_TABLE)
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{
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free(ID_TABLE);
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}
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}
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free(_eo_ids_tables[table_id]);
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}
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_eo_ids_tables[table_id] = NULL;
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}
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}
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#ifdef EFL_DEBUG
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void
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_eo_print()
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{
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unsigned long obj_number = 0;
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for (Table_Index table_id = 0; table_id < MAX_IDS_TABLES; table_id++)
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{
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if (_eo_ids_tables[table_id])
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{
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for (Table_Index int_table_id = 0; int_table_id < MAX_IDS_INTER_TABLES; int_table_id++)
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{
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if (ID_TABLE)
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{
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for (Table_Index entry_id = 0; entry_id < MAX_IDS_PER_TABLE; entry_id++)
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{
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if (IS_ENTRY_ACTIVE(ID_TABLE, entry_id))
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{
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printf("%ld: %p -> (%p, %p, %p, %p)\n", obj_number++,
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ID_TABLE->ptrs[entry_id],
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(void *)table_id, (void *)int_table_id, (void *)entry_id,
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(void *)ID_TABLE->generation[entry_id]);
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}
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}
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}
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}
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}
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}
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}
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#endif
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