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#ifndef APOS_NODES_H
#define APOS_NODES_H
/**
* @file nodes.h
* Node subsystem. Used by a number of subsystems for allocating specific sizes
* of memory nodes smaller than memory pages.
*/
#include <apos/types.h>
/** Node slot status. */
enum node_status {
/** Free. */
FREE = 0,
/** Used. */
USED = 1
};
/** Header for a region in memory with node slots. */
struct node_region {
/** Number of used slots in this region.
* \note Total number of slots is calculated on an instance basis. */
size_t used_nodes;
/** Next node region in free list. */
struct node_region *av_next;
/** Previous node region in free list. */
struct node_region *av_prev;
/** Next node slot region. */
struct node_region *next;
/** Previous slot node region. */
struct node_region *prev;
};
/** Node subsystem instance. */
struct node_root {
/** Size of each node. */
size_t node_size;
/** Maximum number of node slots in one region. */
size_t max_nodes;
/** Offset of node slot state bitmap from start of region. */
ptrdiff_t bitmap;
/** Offset of first node from start of region. */
ptrdiff_t first_node;
/** List of all node regions. */
struct node_region *head;
/** List of node regions with free slots. */
struct node_region *av_head;
};
/**
* Initialize node subsystem instance.
*
* @param r Node region root.
* @param node_size Size of one node.
*/
void init_nodes(struct node_root *r, size_t node_size);
/**
* Destroy node subsystem instance.
*
* @param r Node region root.
*/
void destroy_nodes(struct node_root *r);
/**
* Allocate a new node.
*
* @param r Node region root.
* @return Pointer to allocated node when succesful, \c 0 otherwise.
*/
void *get_node(struct node_root *r);
/**
* Free a node.
*
* @param r Node region root.
* @param p Pointer to node to free.
*/
void free_node(struct node_root *r, void *p);
#endif /* APOS_NODES_H */
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