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/* PipeWire */
/* SPDX-FileCopyrightText: Copyright © 2018 Wim Taymans */
/* SPDX-License-Identifier: MIT */
#ifndef PIPEWIRE_MAP_H
#define PIPEWIRE_MAP_H
#ifdef __cplusplus
extern "C" {
#endif
#include <string.h>
#include <errno.h>
#include <spa/utils/defs.h>
#include <pipewire/array.h>
/** \defgroup pw_map Map
*
* \brief A map that holds pointers to objects indexed by id
*
* The map is a sparse version of the \ref pw_array "pw_array" that manages the
* indices of elements for the caller. Adding items with
* pw_map_insert_new() returns the assigned index for that item; if items
* are removed the map re-uses indices to keep the array at the minimum
* required size.
*
* \code{.c}
* struct pw_map map = PW_MAP_INIT(4);
*
* idx1 = pw_map_insert_new(&map, ptr1);
* idx2 = pw_map_insert_new(&map, ptr2);
* // the map is now [ptr1, ptr2], size 2
* pw_map_remove(&map, idx1);
* // the map is now [<unused>, ptr2], size 2
* pw_map_insert_new(&map, ptr3);
* // the map is now [ptr3, ptr2], size 2
* \endcode
*/
/**
* \addtogroup pw_map
* \{
*/
/** \private
* An entry in the map. This is used internally only. Each element in the
* backing pw_array is a union pw_map_item. For real items, the data pointer
* points to the item. If an element has been removed, pw_map->free_list
* is the index of the most recently removed item. That item contains
* the index of the next removed item until item->next is SPA_ID_INVALID.
*
* The free list is prepended only, the last item to be removed will be the
* first item to get re-used on the next insert.
*/
union pw_map_item {
uintptr_t next; /* next free index */
void *data; /* data of this item, must be an even address */
};
/** A map. This struct should be treated as opaque by the caller. */
struct pw_map {
struct pw_array items; /* an array with the map items */
uint32_t free_list; /* first free index */
};
/** \param extend the amount of bytes to grow the map with when needed */
#define PW_MAP_INIT(extend) ((struct pw_map) { PW_ARRAY_INIT(extend), SPA_ID_INVALID })
/**
* Get the number of currently allocated elements in the map.
* \note pw_map_get_size() returns the currently allocated number of
* elements in the map, not the number of actually set elements.
* \return the number of available elements before the map needs to grow
*/
#define pw_map_get_size(m) pw_array_get_len(&(m)->items, union pw_map_item)
#define pw_map_get_item(m,id) pw_array_get_unchecked(&(m)->items,id,union pw_map_item)
#define pw_map_item_is_free(item) ((item)->next & 0x1)
#define pw_map_id_is_free(m,id) (pw_map_item_is_free(pw_map_get_item(m,id)))
/** \return true if the id fits within the current map size */
#define pw_map_check_id(m,id) ((id) < pw_map_get_size(m))
/** \return true if there is a valid item at \a id */
#define pw_map_has_item(m,id) (pw_map_check_id(m,id) && !pw_map_id_is_free(m, id))
#define pw_map_lookup_unchecked(m,id) pw_map_get_item(m,id)->data
/** Convert an id to a pointer that can be inserted into the map */
#define PW_MAP_ID_TO_PTR(id) (SPA_UINT32_TO_PTR((id)<<1))
/** Convert a pointer to an id that can be retrieved from the map */
#define PW_MAP_PTR_TO_ID(p) (SPA_PTR_TO_UINT32(p)>>1)
/** Initialize a map
* \param map the map to initialize
* \param size the initial size of the map
* \param extend the amount to bytes to grow the map with when needed
*/
static inline void pw_map_init(struct pw_map *map, size_t size, size_t extend)
{
pw_array_init(&map->items, extend * sizeof(union pw_map_item));
pw_array_ensure_size(&map->items, size * sizeof(union pw_map_item));
map->free_list = SPA_ID_INVALID;
}
/** Clear a map and free the data storage. All previously returned ids
* must be treated as invalid.
*/
static inline void pw_map_clear(struct pw_map *map)
{
pw_array_clear(&map->items);
}
/** Reset a map but keep previously allocated storage. All previously
* returned ids must be treated as invalid.
*/
static inline void pw_map_reset(struct pw_map *map)
{
pw_array_reset(&map->items);
map->free_list = SPA_ID_INVALID;
}
/** Insert data in the map. This function causes the map to grow if required.
* \param map the map to insert into
* \param data the item to add
* \return the id where the item was inserted or SPA_ID_INVALID when the
* item can not be inserted.
*/
static inline uint32_t pw_map_insert_new(struct pw_map *map, void *data)
{
union pw_map_item *start, *item;
uint32_t id;
if (map->free_list != SPA_ID_INVALID) {
start = (union pw_map_item *) map->items.data;
item = &start[map->free_list >> 1]; /* lsb always 1, see pw_map_remove */
map->free_list = item->next;
} else {
item = (union pw_map_item *) pw_array_add(&map->items, sizeof(union pw_map_item));
if (item == NULL)
return SPA_ID_INVALID;
start = (union pw_map_item *) map->items.data;
}
item->data = data;
id = (item - start);
return id;
}
/** Replace the data in the map at an index.
*
* \param map the map to insert into
* \param id the index to insert at, must be less or equal to pw_map_get_size()
* \param data the data to insert
* \return 0 on success, -ENOSPC value when the index is invalid or a negative errno
*/
static inline int pw_map_insert_at(struct pw_map *map, uint32_t id, void *data)
{
size_t size = pw_map_get_size(map);
union pw_map_item *item;
if (id > size)
return -ENOSPC;
else if (id == size) {
item = (union pw_map_item *) pw_array_add(&map->items, sizeof(union pw_map_item));
if (item == NULL)
return -errno;
} else {
item = pw_map_get_item(map, id);
if (pw_map_item_is_free(item))
return -EINVAL;
}
item->data = data;
return 0;
}
/** Remove an item at index. The id may get re-used in the future.
*
* \param map the map to remove from
* \param id the index to remove
*/
static inline void pw_map_remove(struct pw_map *map, uint32_t id)
{
if (pw_map_id_is_free(map, id))
return;
pw_map_get_item(map, id)->next = map->free_list;
map->free_list = (id << 1) | 1;
}
/** Find an item in the map
* \param map the map to use
* \param id the index to look at
* \return the item at \a id or NULL when no such item exists
*/
static inline void *pw_map_lookup(const struct pw_map *map, uint32_t id)
{
if (SPA_LIKELY(pw_map_check_id(map, id))) {
union pw_map_item *item = pw_map_get_item(map, id);
if (!pw_map_item_is_free(item))
return item->data;
}
return NULL;
}
/** Iterate all map items
* \param map the map to iterate
* \param func the function to call for each item, the item data and \a data is
* passed to the function. When \a func returns a non-zero result,
* iteration ends and the result is returned.
* \param data data to pass to \a func
* \return the result of the last call to \a func or 0 when all callbacks returned 0.
*/
static inline int pw_map_for_each(const struct pw_map *map,
int (*func) (void *item_data, void *data), void *data)
{
union pw_map_item *item;
int res = 0;
pw_array_for_each(item, &map->items) {
if (!pw_map_item_is_free(item))
if ((res = func(item->data, data)) != 0)
break;
}
return res;
}
/**
* \}
*/
#ifdef __cplusplus
} /* extern "C" */
#endif
#endif /* PIPEWIRE_MAP_H */