/**
* @file
*
* @ingroup ScoreHeap
*
* @brief Heap Handler API.
*/
/*
* COPYRIGHT (c) 1989-2006.
* On-Line Applications Research Corporation (OAR).
*
* The license and distribution terms for this file may be
* found in the file LICENSE in this distribution or at
* http://www.rtems.com/license/LICENSE.
*
* $Id$
*/
#ifndef _RTEMS_SCORE_HEAP_H
#define _RTEMS_SCORE_HEAP_H
#ifdef __cplusplus
extern "C" {
#endif
/**
* @defgroup ScoreHeap Heap Handler
*
* @ingroup Score
*
* @brief The Heap Handler provides a heap.
*
* A heap is a doubly linked list of variable size blocks which are allocated
* using the first fit method. Garbage collection is performed each time a
* block is returned to the heap by coalescing neighbor blocks. Control
* information for both allocated and free blocks is contained in the heap
* area. A heap control structure contains control information for the heap.
*
* The alignment routines could be made faster should we require only powers of
* two to be supported for page size, alignment and boundary arguments. The
* minimum alignment requirement for pages is currently CPU_ALIGNMENT and this
* value is only required to be multiple of two and explicitly not required to
* be a power of two.
*
* There are two kinds of blocks. One sort describes a free block from which
* we can allocate memory. The other blocks are used and provide an allocated
* memory area. The free blocks are accessible via a list of free blocks.
*
* Blocks or areas cover a continuous set of memory addresses. They have a
* begin and end address. The end address is not part of the set. The size of
* a block or area equals the distance between the begin and end address in
* units of bytes.
*
* Free blocks look like:
* <table>
* <tr>
* <td rowspan=4>@ref Heap_Block</td><td>previous block size in case the
* previous block is free, <br> otherwise it may contain data used by
* the previous block</td>
* </tr>
* <tr>
* <td>block size and a flag which indicates if the previous block is free
* or used, <br> this field contains always valid data regardless of the
* block usage</td>
* </tr>
* <tr><td>pointer to next block (this field is page size aligned)</td></tr>
* <tr><td>pointer to previous block</td></tr>
* <tr><td colspan=2>free space</td></tr>
* </table>
*
* Used blocks look like:
* <table>
* <tr>
* <td rowspan=4>@ref Heap_Block</td><td>previous block size in case the
* previous block is free,<br>otherwise it may contain data used by
* the previous block</td>
* </tr>
* <tr>
* <td>block size and a flag which indicates if the previous block is free
* or used, <br> this field contains always valid data regardless of the
* block usage</td>
* </tr>
* <tr><td>begin of allocated area (this field is page size aligned)</td></tr>
* <tr><td>allocated space</td></tr>
* <tr><td colspan=2>allocated space</td></tr>
* </table>
*
* The heap area after initialization contains two blocks and looks like:
* <table>
* <tr><th>Label</th><th colspan=2>Content</th></tr>
* <tr><td>heap->area_begin</td><td colspan=2>heap area begin address</td></tr>
* <tr>
* <td>first_block->prev_size</td>
* <td colspan=2>page size (the value is arbitrary)</td>
* </tr>
* <tr>
* <td>first_block->size</td>
* <td colspan=2>size available for allocation
* | @c HEAP_PREV_BLOCK_USED</td>
* </tr>
* <tr>
* <td>first_block->next</td><td>_Heap_Free_list_tail(heap)</td>
* <td rowspan=3>memory area available for allocation</td>
* </tr>
* <tr><td>first_block->prev</td><td>_Heap_Free_list_head(heap)</td></tr>
* <tr><td>...</td></tr>
* <tr>
* <td>last_block->prev_size</td><td colspan=2>size of first block</td>
* </tr>
* <tr>
* <td>last_block->size</td>
* <td colspan=2>first block begin address - last block begin address</td>
* </tr>
* <tr><td>heap->area_end</td><td colspan=2>heap area end address</td></tr>
* </table>
* The next block of the last block is the first block. Since the first
* block indicates that the previous block is used, this ensures that the
* last block appears as used for the _Heap_Is_used() and _Heap_Is_free()
* functions.
*
* @{
*/
/**
* @brief See also @ref Heap_Block.size_and_flag.
*/
#define HEAP_PREV_BLOCK_USED ((uintptr_t) 1)
/**
* @brief Offset from the block begin up to the block size field
* (@ref Heap_Block.size_and_flag).
*/
#define HEAP_BLOCK_SIZE_OFFSET sizeof(uintptr_t)
/**
* @brief The block header consists of the two size fields
* (@ref Heap_Block.prev_size and @ref Heap_Block.size_and_flag).
*/
#define HEAP_BLOCK_HEADER_SIZE (sizeof(uintptr_t) * 2)
/**
* @brief Description for free or used blocks.
*/
typedef struct Heap_Block {
/**
* @brief Size of the previous block or part of the allocated area of the
* previous block.
*
* This field is only valid if the previous block is free. This case is
* indicated by a cleared @c HEAP_PREV_BLOCK_USED flag in the
* @a size_and_flag field of the current block.
*
* In a used block only the @a size_and_flag field needs to be valid. The
* @a prev_size field of the current block is maintained by the previous
* block. The current block can use the @a prev_size field in the next block
* for allocation.
*/
uintptr_t prev_size;
/**
* @brief Contains the size of the current block and a flag which indicates
* if the previous block is free or used.
*
* If the flag @c HEAP_PREV_BLOCK_USED is set, then the previous block is
* used, otherwise the previous block is free. A used previous block may
* claim the @a prev_size field for allocation. This trick allows to
* decrease the overhead in the used blocks by the size of the @a prev_size
* field. As sizes are required to be multiples of two, the least
* significant bits would be always zero. We use this bit to store the flag.
*
* This field is always valid.
*/
uintptr_t size_and_flag;
/**
* @brief Pointer to the next free block or part of the allocated area.
*
* This field is page size aligned and begins of the allocated area in case
* the block is used.
*
* This field is only valid if the block is free and thus part of the free
* block list.
*/
struct Heap_Block *next;
/**
* @brief Pointer to the previous free block or part of the allocated area.
*
* This field is only valid if the block is free and thus part of the free
* block list.
*/
struct Heap_Block *prev;
} Heap_Block;
/**
* @brief Run-time heap statistics.
*
* The value @a searches / @a allocs gives the mean number of searches per
* allocation, while @a max_search gives maximum number of searches ever
* performed on a single allocation call.
*/
typedef struct {
/**
* @brief Instance number of this heap.
*/
uint32_t instance;
/**
* @brief Size of the allocatable area in bytes.
*
* This value is an integral multiple of the page size.
*/
uintptr_t size;
/**
* @brief Current free size in bytes.
*
* This value is an integral multiple of the page size.
*/
uintptr_t free_size;
/**
* @brief Minimum free size ever in bytes.
*
* This value is an integral multiple of the page size.
*/
uintptr_t min_free_size;
/**
* @brief Current number of free blocks.
*/
uint32_t free_blocks;
/**
* @brief Maximum number of free blocks ever.
*/
uint32_t max_free_blocks;
/**
* @brief Current number of used blocks.
*/
uint32_t used_blocks;
/**
* @brief Maximum number of blocks searched ever.
*/
uint32_t max_search;
/**
* @brief Total number of successful allocations.
*/
uint32_t allocs;
/**
* @brief Total number of searches ever.
*/
uint32_t searches;
/**
* @brief Total number of suceessful calls to free.
*/
uint32_t frees;
/**
* @brief Total number of successful resizes.
*/
uint32_t resizes;
} Heap_Statistics;
/**
* @brief Control block used to manage a heap.
*/
typedef struct {
Heap_Block free_list;
uintptr_t page_size;
uintptr_t min_block_size;
uintptr_t area_begin;
uintptr_t area_end;
Heap_Block *first_block;
Heap_Block *last_block;
Heap_Statistics stats;
} Heap_Control;
/**
* @brief Information about blocks.
*/
typedef struct {
/**
* @brief Number of blocks of this type.
*/
uint32_t number;
/**
* @brief Largest block of this type.
*/
uint32_t largest;
/**
* @brief Total size of the blocks of this type.
*/
uint32_t total;
} Heap_Information;
/**
* @brief Information block returned by _Heap_Get_information().
*/
typedef struct {
Heap_Information Free;
Heap_Information Used;
} Heap_Information_block;
/**
* @brief See _Heap_Extend().
*/
typedef enum {
HEAP_EXTEND_SUCCESSFUL,
HEAP_EXTEND_ERROR,
HEAP_EXTEND_NOT_IMPLEMENTED
} Heap_Extend_status;
/**
* @brief See _Heap_Resize_block().
*/
typedef enum {
HEAP_RESIZE_SUCCESSFUL,
HEAP_RESIZE_UNSATISFIED,
HEAP_RESIZE_FATAL_ERROR
} Heap_Resize_status;
/**
* @brief Initializes the heap control block @a heap to manage the area
* starting at @a area_begin of size @a area_size bytes.
*
* Blocks of memory are allocated from the heap in multiples of @a page_size
* byte units. If the @a page_size is equal to zero or is not multiple of
* @c CPU_ALIGNMENT, it is aligned up to the nearest @c CPU_ALIGNMENT boundary.
*
* Returns the maximum memory available, or zero in case of failure.
*/
uintptr_t _Heap_Initialize(
Heap_Control *heap,
void *area_begin,
uintptr_t area_size,
uintptr_t page_size
);
/**
* @brief Extends the memory area of the heap @a heap using the memory area
* starting at @a area_begin of size @a area_size bytes.
*
* The extended space available for allocation will be returned in
* @a amount_extended.
*
* The memory area must start at the end of the currently used memory area.
*/
Heap_Extend_status _Heap_Extend(
Heap_Control *heap,
void *area_begin,
uintptr_t area_size,
uintptr_t *amount_extended
);
/**
* @brief Allocates a memory area of size @a size bytes from the heap @a heap.
*
* If the alignment parameter @a alignment is not equal to zero, the allocated
* memory area will begin at an address aligned by this value.
*
* If the boundary parameter @a boundary is not equal to zero, the allocated
* memory area will fulfill a boundary constraint. The boudnary value
* specifies the set of addresses which are aligned by the boundary value. The
* interior of the allocated memory area will not contain an element of this
* set. The begin or end address of the area may be a member of the set.
*
* A size value of zero will return a unique address which may be freed with
* _Heap_Free().
*
* Returns a pointer to the begin of the allocated memory area, or @c NULL if
* no memory is available or the parameters are inconsistent.
*/
void *_Heap_Allocate_aligned_with_boundary(
Heap_Control *heap,
uintptr_t size,
uintptr_t alignment,
uintptr_t boundary
);
/**
* @brief See _Heap_Allocate_aligned_with_boundary() with boundary equals zero.
*/
RTEMS_INLINE_ROUTINE void *_Heap_Allocate_aligned(
Heap_Control *heap,
uintptr_t size,
uintptr_t alignment
)
{
return _Heap_Allocate_aligned_with_boundary( heap, size, alignment, 0 );
}
/**
* @brief See _Heap_Allocate_aligned_with_boundary() with alignment and
* boundary equals zero.
*/
RTEMS_INLINE_ROUTINE void *_Heap_Allocate( Heap_Control *heap, uintptr_t size )
{
return _Heap_Allocate_aligned_with_boundary( heap, size, 0, 0 );
}
/**
* @brief Frees the allocated memory area starting at @a addr in the heap
* @a heap.
*
* Inappropriate values for @a addr may corrupt the heap.
*
* Returns @c true in case of success, and @c false otherwise.
*/
bool _Heap_Free( Heap_Control *heap, void *addr );
/**
* @brief Walks the heap @a heap to verify its integrity.
*
* If @a dump is @c true, then diagnostic messages will be printed to standard
* output. In this case @a source is used to mark the output lines.
*
* Returns @c true if no errors occured, and @c false if the heap is corrupt.
*/
bool _Heap_Walk(
Heap_Control *heap,
int source,
bool dump
);
/**
* @brief Returns information about used and free blocks for the heap @a heap
* in @a info.
*/
void _Heap_Get_information(
Heap_Control *heap,
Heap_Information_block *info
);
/**
* @brief Returns information about free blocks for the heap @a heap in
* @a info.
*/
void _Heap_Get_free_information(
Heap_Control *heap,
Heap_Information *info
);
/**
* @brief Returns the size of the allocatable memory area starting at @a addr
* in @a size.
*
* The size value may be greater than the initially requested size in
* _Heap_Allocate_aligned_with_boundary().
*
* Inappropriate values for @a addr will not corrupt the heap, but may yield
* invalid size values.
*
* Returns @a true if successful, and @c false otherwise.
*/
bool _Heap_Size_of_alloc_area(
Heap_Control *heap,
void *addr,
uintptr_t *size
);
/**
* @brief Resizes the block of the allocated memory area starting at @a addr.
*
* The new memory area will have a size of at least @a size bytes. A resize
* may be impossible and depends on the current heap usage.
*
* The size available for allocation in the current block before the resize
* will be returned in @a old_size. The size available for allocation in
* the resized block will be returned in @a new_size. If the resize was not
* successful, then a value of zero will be returned in @a new_size.
*
* Inappropriate values for @a addr may corrupt the heap.
*/
Heap_Resize_status _Heap_Resize_block(
Heap_Control *heap,
void *addr,
uintptr_t size,
uintptr_t *old_size,
uintptr_t *new_size
);
#if !defined(__RTEMS_APPLICATION__)
#include <rtems/score/heap.inl>
/**
* @brief Allocates the memory area starting at @a alloc_begin of size
* @a alloc_size bytes in the block @a block.
*
* The block may be split up into multiple blocks. The previous and next block
* may be used or free. Free block parts which form a vaild new block will be
* inserted into the free list or merged with an adjacent free block. If the
* block is used, they will be inserted after the free list head. If the block
* is free, they will be inserted after the previous block in the free list.
*
* Inappropriate values for @a alloc_begin or @a alloc_size may corrupt the
* heap.
*
* Returns the block containing the allocated memory area.
*/
Heap_Block *_Heap_Block_allocate(
Heap_Control *heap,
Heap_Block *block,
uintptr_t alloc_begin,
uintptr_t alloc_size
);
/** @} */
#ifdef RTEMS_DEBUG
#define RTEMS_HEAP_DEBUG
#define RTEMS_MALLOC_BOUNDARY_HELPERS
#endif
#ifdef RTEMS_HEAP_DEBUG
#include <assert.h>
#define _HAssert( cond ) \
do { \
if ( !(cond) ) { \
__assert( __FILE__, __LINE__, #cond ); \
} \
} while (0)
#else
#define _HAssert( cond ) ((void) 0)
#endif
#endif /* !defined(__RTEMS_APPLICATION__) */
#ifdef __cplusplus
}
#endif
#endif
/* end of include file */
