/**
* @file
*
* @brief Red-Black Tree Heap API
*/
/*
* Copyright (c) 2012 embedded brains GmbH. All rights reserved.
*
* embedded brains GmbH
* Obere Lagerstr. 30
* 82178 Puchheim
* Germany
* <rtems@embedded-brains.de>
*
* The license and distribution terms for this file may be
* found in the file LICENSE in this distribution or at
* http://www.rtems.org/license/LICENSE.
*/
#ifndef _RTEMS_RBHEAP_H
#define _RTEMS_RBHEAP_H
#include <rtems.h>
#include <rtems/chain.h>
#include <rtems/rbtree.h>
#ifdef __cplusplus
extern "C" {
#endif
/**
* @defgroup RBHeap Red-Black Tree Heap
*
* @ingroup ClassicRTEMS
*
* @brief Red-Black Tree Heap API.
*
* The red-black tree heap provides a memory allocator suitable to implement
* the malloc() and free() interface. It uses a first-fit allocation strategy.
* In the red-black tree heap the administration data structures are not
* contained in the managed memory area. Thus writing beyond the boundaries of
* a chunk does not damage the data to maintain the heap. This can be used for
* example in a task stack allocator which protects the task stacks from access
* by other tasks. The allocated and free memory parts of the managed area are
* called chunks. Each chunk needs a descriptor which is stored outside of the
* managed area.
*/
/**@{*/
/**
* @brief Red-black heap chunk descriptor.
*/
typedef struct {
/**
* This chain node can be used in two chains
* - the chain of spare chunk descriptors and
* - the chain of free chunks in the managed memory area.
*
* In case this chain node is not part of a chain, the chunk represents a
* used chunk in the managed memory area.
*/
rtems_chain_node chain_node;
/**
* Tree node for chunks that represent a part of the managed memory area.
* These chunks are either free or used.
*/
rtems_rbtree_node tree_node;
/**
* Begin address of the chunk. The address alignment it specified in the
* @ref rtems_rbheap_control.
*/
uintptr_t begin;
/**
* Size of the chunk in bytes.
*/
uintptr_t size;
} rtems_rbheap_chunk;
typedef struct rtems_rbheap_control rtems_rbheap_control;
/**
* @brief Handler to extend the available chunk descriptors.
*
* This handler is called when no more chunk descriptors are available. An
* example implementation is this:
*
* @code
* void extend_descriptors_with_malloc(rtems_rbheap_control *control)
* {
* rtems_rbheap_chunk *chunk = malloc(sizeof(*chunk));
*
* if (chunk != NULL) {
* rtems_rbheap_add_to_spare_descriptor_chain(control, chunk);
* }
* }
* @endcode
*
* @see rtems_rbheap_extend_descriptors_never() and
* rtems_rbheap_extend_descriptors_with_malloc().
*/
typedef void (*rtems_rbheap_extend_descriptors)(rtems_rbheap_control *control);
/**
* @brief Red-black heap control.
*/
struct rtems_rbheap_control {
/**
* Chain of free chunks in the managed memory area.
*/
rtems_chain_control free_chunk_chain;
/**
* Chain of free chunk descriptors. Descriptors are consumed during
* allocation and may be produced during free if contiguous chunks can be
* coalesced. In case of descriptor starvation the @ref extend_descriptors
* handler will be called.
*/
rtems_chain_control spare_descriptor_chain;
/**
* Tree of chunks representing the state of the managed memory area.
*/
rtems_rbtree_control chunk_tree;
/**
* Minimum chunk begin alignment in bytes.
*/
uintptr_t alignment;
/**
* Handler to extend the available chunk descriptors.
*/
rtems_rbheap_extend_descriptors extend_descriptors;
/**
* User specified argument handler for private handler data.
*/
void *handler_arg;
};
/**
* @brief Initializes the red-black tree heap @a control.
*
* @param[in, out] control The red-black tree heap.
* @param[in] area_begin The managed memory area begin.
* @param[in] area_size The managed memory area size.
* @param[in] alignment The minimum chunk alignment.
* @param[in] extend_descriptors The handler to extend the available chunk
* descriptors.
* @param[in] handler_arg The handler argument.
*
* @retval RTEMS_SUCCESSFUL Successful operation.
* @retval RTEMS_INVALID_ADDRESS The memory area is invalid.
* @retval RTEMS_NO_MEMORY Not enough chunk descriptors.
*/
rtems_status_code rtems_rbheap_initialize(
rtems_rbheap_control *control,
void *area_begin,
uintptr_t area_size,
uintptr_t alignment,
rtems_rbheap_extend_descriptors extend_descriptors,
void *handler_arg
);
/**
* @brief Allocates a chunk of memory of at least @a size bytes from the
* red-black tree heap @a control.
*
* The chunk begin is aligned by the value specified in
* rtems_rbheap_initialize().
*
* @param[in, out] control The red-black tree heap.
* @param[in] size The requested chunk size in bytes.
*
* @retval NULL Not enough free space in the heap.
* @retval otherwise Pointer to allocated chunk of memory.
*/
void *rtems_rbheap_allocate(rtems_rbheap_control *control, size_t size);
/**
* @brief Frees a chunk of memory @a ptr allocated from the red-black tree heap
* @a control.
*
* @param[in, out] control The red-black tree heap.
* @param[in] ptr The pointer to the chunk of memory.
*
* @retval RTEMS_SUCCESSFUL Successful operation.
* @retval RTEMS_INVALID_ID The chunk of memory is not a valid chunk in the
* red-black tree heap.
* @retval RTEMS_INCORRECT_STATE The chunk of memory is not in the right state.
*/
rtems_status_code rtems_rbheap_free(rtems_rbheap_control *control, void *ptr);
static inline rtems_chain_control *rtems_rbheap_get_spare_descriptor_chain(
rtems_rbheap_control *control
)
{
return &control->spare_descriptor_chain;
}
static inline void rtems_rbheap_add_to_spare_descriptor_chain(
rtems_rbheap_control *control,
rtems_rbheap_chunk *chunk
)
{
rtems_chain_control *chain =
rtems_rbheap_get_spare_descriptor_chain(control);
rtems_chain_initialize_node(&chunk->chain_node);
rtems_chain_prepend_unprotected(chain, &chunk->chain_node);
}
static inline void rtems_rbheap_set_extend_descriptors(
rtems_rbheap_control *control,
rtems_rbheap_extend_descriptors extend_descriptors
)
{
control->extend_descriptors = extend_descriptors;
}
static inline void *rtems_rbheap_get_handler_arg(
const rtems_rbheap_control *control
)
{
return control->handler_arg;
}
static inline void rtems_rbheap_set_handler_arg(
rtems_rbheap_control *control,
void *handler_arg
)
{
control->handler_arg = handler_arg;
}
/**
* @brief Chunk descriptor extend handler that does nothing.
*/
void rtems_rbheap_extend_descriptors_never(rtems_rbheap_control *control);
/**
* @brief Chunk descriptor extend handler that uses malloc().
*/
void rtems_rbheap_extend_descriptors_with_malloc(
rtems_rbheap_control *control
);
/** @} */
/* Private API */
#define rtems_rbheap_chunk_of_node(node) \
RTEMS_CONTAINER_OF(node, rtems_rbheap_chunk, tree_node)
static inline bool rtems_rbheap_is_chunk_free(const rtems_rbheap_chunk *chunk)
{
return !rtems_chain_is_node_off_chain(&chunk->chain_node);
}
#ifdef __cplusplus
}
#endif
#endif /* _RTEMS_RBHEAP_H */
