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Diffstat (limited to 'include/rtems/score/heap.h')
-rw-r--r-- | include/rtems/score/heap.h | 517 |
1 files changed, 517 insertions, 0 deletions
diff --git a/include/rtems/score/heap.h b/include/rtems/score/heap.h new file mode 100644 index 0000000000..5db22cf2ed --- /dev/null +++ b/include/rtems/score/heap.h @@ -0,0 +1,517 @@ +/** + * @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.org/license/LICENSE. + */ + +#ifndef _RTEMS_SCORE_HEAP_H +#define _RTEMS_SCORE_HEAP_H + +#include <rtems/score/cpu.h> +#include <rtems/score/thread.h> + +#ifdef __cplusplus +extern "C" { +#endif + +#ifdef RTEMS_DEBUG + #define HEAP_PROTECTION +#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> + * subordinate heap area end address (this will be used to maintain a + * linked list of scattered heap areas) + * </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. + */ +/**@{**/ + +typedef struct Heap_Control Heap_Control; + +typedef struct Heap_Block Heap_Block; + +#ifndef HEAP_PROTECTION + #define HEAP_PROTECTION_HEADER_SIZE 0 +#else + #define HEAP_PROTECTOR_COUNT 2 + + #define HEAP_BEGIN_PROTECTOR_0 ((uintptr_t) 0xfd75a98f) + #define HEAP_BEGIN_PROTECTOR_1 ((uintptr_t) 0xbfa1f177) + #define HEAP_END_PROTECTOR_0 ((uintptr_t) 0xd6b8855e) + #define HEAP_END_PROTECTOR_1 ((uintptr_t) 0x13a44a5b) + + #define HEAP_FREE_PATTERN ((uintptr_t) 0xe7093cdf) + + #define HEAP_PROTECTION_OBOLUS ((Heap_Block *) 1) + + typedef void (*_Heap_Protection_handler)( + Heap_Control *heap, + Heap_Block *block + ); + + typedef struct { + _Heap_Protection_handler block_initialize; + _Heap_Protection_handler block_check; + _Heap_Protection_handler block_error; + void *handler_data; + Heap_Block *first_delayed_free_block; + Heap_Block *last_delayed_free_block; + uintptr_t delayed_free_block_count; + uintptr_t delayed_free_fraction; + } Heap_Protection; + + typedef struct { + uintptr_t protector [HEAP_PROTECTOR_COUNT]; + Heap_Block *next_delayed_free_block; + Thread_Control *task; + void *tag; + } Heap_Protection_block_begin; + + typedef struct { + uintptr_t protector [HEAP_PROTECTOR_COUNT]; + } Heap_Protection_block_end; + + #define HEAP_PROTECTION_HEADER_SIZE \ + (sizeof(Heap_Protection_block_begin) + sizeof(Heap_Protection_block_end)) +#endif + +/** + * @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 \ + (2 * sizeof(uintptr_t) + HEAP_PROTECTION_HEADER_SIZE) + +/** + * @brief Description for free or used blocks. + */ +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; + + #ifdef HEAP_PROTECTION + Heap_Protection_block_begin Protection_begin; + #endif + + /** + * @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; + + #ifdef HEAP_PROTECTION + Heap_Protection_block_end Protection_end; + #endif + + /** + * @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. + */ + 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. + */ + Heap_Block *prev; +}; + +/** + * @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 Lifetime number of bytes allocated from this heap. + * + * This value is an integral multiple of the page size. + */ + uint64_t lifetime_allocated; + + /** + * @brief Lifetime number of bytes freed to this heap. + * + * This value is an integral multiple of the page size. + */ + uint64_t lifetime_freed; + + /** + * @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 searches. + */ + uint32_t searches; + + /** + * @brief Total number of successful allocations. + */ + uint32_t allocs; + + /** + * @brief Total number of failed allocations. + */ + uint32_t failed_allocs; + + /** + * @brief Total number of successful frees. + */ + uint32_t frees; + + /** + * @brief Total number of successful resizes. + */ + uint32_t resizes; +} Heap_Statistics; + +/** + * @brief Control block used to manage a heap. + */ +struct Heap_Control { + 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; + #ifdef HEAP_PROTECTION + Heap_Protection Protection; + #endif +}; + +/** + * @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_Statistics Stats; +} Heap_Information_block; + +/** + * @brief Heap area structure for table based heap initialization and + * extension. + * + * @see Heap_Initialization_or_extend_handler. + */ +typedef struct { + void *begin; + uintptr_t size; +} Heap_Area; + +/** + * @brief Heap initialization and extend handler type. + * + * This helps to do a table based heap initialization and extension. Create a + * table of Heap_Area elements and iterate through it. Set the handler to + * _Heap_Initialize() in the first iteration and then to _Heap_Extend(). + * + * @see Heap_Area, _Heap_Initialize(), _Heap_Extend(), or _Heap_No_extend(). + */ +typedef uintptr_t (*Heap_Initialization_or_extend_handler)( + Heap_Control *heap, + void *area_begin, + uintptr_t area_size, + uintptr_t page_size_or_unused +); + +/** + * @brief Extends the memory available for the heap @a heap using the memory + * area starting at @a area_begin of size @a area_size bytes. + * + * There are no alignment requirements. The memory area must be big enough to + * contain some maintainance blocks. It must not overlap parts of the current + * heap areas. Disconnected subordinate heap areas will lead to used blocks + * which cover the gaps. Extending with an inappropriate memory area will + * corrupt the heap. + * + * The unused fourth parameter is provided to have the same signature as + * _Heap_Initialize(). + * + * Returns the extended space available for allocation, or zero in case of failure. + * + * @see Heap_Initialization_or_extend_handler. + */ +uintptr_t _Heap_Extend( + Heap_Control *heap, + void *area_begin, + uintptr_t area_size, + uintptr_t unused +); + +/** + * @brief This function returns always zero. + * + * This function only returns zero and does nothing else. + * + * Returns always zero. + * + * @see Heap_Initialization_or_extend_handler. + */ +uintptr_t _Heap_No_extend( + Heap_Control *unused_0, + void *unused_1, + uintptr_t unused_2, + uintptr_t unused_3 +); + +RTEMS_INLINE_ROUTINE uintptr_t _Heap_Align_up( + uintptr_t value, + uintptr_t alignment +) +{ + uintptr_t remainder = value % alignment; + + if ( remainder != 0 ) { + return value - remainder + alignment; + } else { + return value; + } +} + +RTEMS_INLINE_ROUTINE uintptr_t _Heap_Min_block_size( uintptr_t page_size ) +{ + return _Heap_Align_up( sizeof( Heap_Block ), page_size ); +} + +/** + * @brief Returns the worst case overhead to manage a memory area. + */ +RTEMS_INLINE_ROUTINE uintptr_t _Heap_Area_overhead( + uintptr_t page_size +) +{ + if ( page_size != 0 ) { + page_size = _Heap_Align_up( page_size, CPU_ALIGNMENT ); + } else { + page_size = CPU_ALIGNMENT; + } + + return 2 * (page_size - 1) + HEAP_BLOCK_HEADER_SIZE; +} + +/** + * @brief Returns the size with administration and alignment overhead for one + * allocation. + */ +RTEMS_INLINE_ROUTINE uintptr_t _Heap_Size_with_overhead( + uintptr_t page_size, + uintptr_t size, + uintptr_t alignment +) +{ + if ( page_size != 0 ) { + page_size = _Heap_Align_up( page_size, CPU_ALIGNMENT ); + } else { + page_size = CPU_ALIGNMENT; + } + + if ( page_size < alignment ) { + page_size = alignment; + } + + return HEAP_BLOCK_HEADER_SIZE + page_size - 1 + size; +} + +/** @} */ + +#ifdef __cplusplus +} +#endif + +#endif +/* end of include file */ |