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Heap Handler

The Heap Handler provides a heap. More...

Modules

 Protected Heap Handler
 Provides protected heap services.
 

Files

file  heap.h
 Heap Handler API.
 
file  heapimpl.h
 Heap Handler Implementation.
 
file  heapinfo.h
 Heap Handler Information API.
 
file  heap.c
 Heap Handler implementation.
 
file  heapallocate.c
 Heap Handler implementation.
 

Classes

struct  Heap_Error_context
 Context of a heap error. More...
 
struct  Heap_Block
 Description for free or used blocks. More...
 
struct  Heap_Control
 Control block used to manage a heap. More...
 
struct  Heap_Area
 Heap area structure for table based heap initialization and extension. More...
 
struct  Heap_Statistics
 Run-time heap statistics. More...
 
struct  Heap_Information
 Information about blocks. More...
 
struct  Heap_Information_block
 Information block returned by _Heap_Get_information(). More...
 

Macros

#define HEAP_PROTECTION_HEADER_SIZE   0
 
#define HEAP_BLOCK_HEADER_SIZE   (2 * sizeof(uintptr_t) + HEAP_PROTECTION_HEADER_SIZE)
 The block header consists of the two size fields (Heap_Block::prev_size and Heap_Block::size_and_flag).
 
#define HEAP_PREV_BLOCK_USED   ((uintptr_t) 1)
 See also Heap_Block::size_and_flag.
 
#define HEAP_ALLOC_BONUS   sizeof(uintptr_t)
 Size of the part at the block begin which may be used for allocation in charge of the previous block.
 
#define _Heap_Protection_block_initialize(heap, block)   ((void) 0)
 
#define _Heap_Protection_block_check(heap, block)   ((void) 0)
 
#define _Heap_Protection_block_error(heap, block, reason)   ((void) 0)
 
#define _Heap_Protection_free_all_delayed_blocks(heap)   ((void) 0)
 
#define _HAssert(cond)   ((void) 0)
 

Typedefs

typedef struct Heap_Control Heap_Control
 
typedef struct Heap_Block Heap_Block
 
typedef uintptr_t(* Heap_Initialization_or_extend_handler) (Heap_Control *heap, void *area_begin, uintptr_t area_size, uintptr_t page_size_or_unused)
 Heap initialization and extend handler type. More...
 
typedef bool(* Heap_Block_visitor) (const Heap_Block *block, uintptr_t block_size, bool block_is_used, void *visitor_arg)
 Heap block visitor. More...
 

Enumerations

enum  Heap_Error_reason {
  HEAP_ERROR_BROKEN_PROTECTOR, HEAP_ERROR_FREE_PATTERN, HEAP_ERROR_DOUBLE_FREE, HEAP_ERROR_BAD_USED_BLOCK,
  HEAP_ERROR_BAD_FREE_BLOCK
}
 The heap error reason. More...
 
enum  Heap_Resize_status { HEAP_RESIZE_SUCCESSFUL, HEAP_RESIZE_UNSATISFIED, HEAP_RESIZE_FATAL_ERROR }
 See _Heap_Resize_block().
 

Functions

uintptr_t _Heap_Extend (Heap_Control *heap, void *area_begin, uintptr_t area_size, uintptr_t unused)
 Extends the memory available for the heap. More...
 
uintptr_t _Heap_No_extend (Heap_Control *unused_0, void *unused_1, uintptr_t unused_2, uintptr_t unused_3)
 This function returns always zero. More...
 
RTEMS_INLINE_ROUTINE uintptr_t _Heap_Align_up (uintptr_t value, uintptr_t alignment)
 Aligns the value to a given alignment, rounding up. More...
 
RTEMS_INLINE_ROUTINE uintptr_t _Heap_Min_block_size (uintptr_t page_size)
 Returns the minimal Heap Block size for the given page_size. More...
 
RTEMS_INLINE_ROUTINE uintptr_t _Heap_Area_overhead (uintptr_t page_size)
 Returns the worst case overhead to manage a memory area. More...
 
RTEMS_INLINE_ROUTINE uintptr_t _Heap_Size_with_overhead (uintptr_t page_size, uintptr_t size, uintptr_t alignment)
 Returns the size with administration and alignment overhead for one allocation. More...
 
bool _Heap_Get_first_and_last_block (uintptr_t heap_area_begin, uintptr_t heap_area_size, uintptr_t page_size, uintptr_t min_block_size, Heap_Block **first_block_ptr, Heap_Block **last_block_ptr)
 Gets the first and last block for the heap area. More...
 
uintptr_t _Heap_Initialize (Heap_Control *heap, void *area_begin, uintptr_t area_size, uintptr_t page_size)
 Initializes the heap control block. More...
 
void * _Heap_Allocate_aligned_with_boundary (Heap_Control *heap, uintptr_t size, uintptr_t alignment, uintptr_t boundary)
 Allocates an aligned memory area with boundary constraint. More...
 
RTEMS_INLINE_ROUTINE void * _Heap_Allocate_aligned (Heap_Control *heap, uintptr_t size, uintptr_t alignment)
 Allocates an aligned memory area. More...
 
RTEMS_INLINE_ROUTINE void * _Heap_Allocate (Heap_Control *heap, uintptr_t size)
 Allocates a memory area. More...
 
bool _Heap_Free (Heap_Control *heap, void *addr)
 Frees the allocated memory area. More...
 
bool _Heap_Walk (Heap_Control *heap, int source, bool dump)
 Verifies the integrity of the heap. More...
 
void _Heap_Iterate (Heap_Control *heap, Heap_Block_visitor visitor, void *visitor_arg)
 Iterates over all blocks of the heap. More...
 
Heap_Block_Heap_Greedy_allocate (Heap_Control *heap, const uintptr_t *block_sizes, size_t block_count)
 Greedily allocates and empties the heap. More...
 
Heap_Block_Heap_Greedy_allocate_all_except_largest (Heap_Control *heap, uintptr_t *allocatable_size)
 Greedily allocates all blocks except the largest free block. More...
 
void _Heap_Greedy_free (Heap_Control *heap, Heap_Block *blocks)
 Frees blocks of a greedy allocation. More...
 
void _Heap_Get_information (Heap_Control *heap, Heap_Information_block *info)
 Returns information about used and free blocks for the heap. More...
 
void _Heap_Get_free_information (Heap_Control *heap, Heap_Information *info)
 Returns information about free blocks for the heap. More...
 
bool _Heap_Size_of_alloc_area (Heap_Control *heap, void *addr, uintptr_t *size)
 Returns the size of the allocatable memory area. More...
 
Heap_Resize_status _Heap_Resize_block (Heap_Control *heap, void *addr, uintptr_t size, uintptr_t *old_size, uintptr_t *new_size)
 Resizes the block of the allocated memory area. More...
 
Heap_Block_Heap_Block_allocate (Heap_Control *heap, Heap_Block *block, uintptr_t alloc_begin, uintptr_t alloc_size)
 Allocates the memory area. starting at alloc_begin of size alloc_size bytes in the block block. More...
 
RTEMS_INLINE_ROUTINE void _Heap_Protection_set_delayed_free_fraction (Heap_Control *heap, uintptr_t fraction)
 Sets the fraction of delayed free blocks that is actually freed during memory shortage. More...
 
RTEMS_INLINE_ROUTINE Heap_Block_Heap_Free_list_head (Heap_Control *heap)
 Returns the head of the free list of the heap. More...
 
RTEMS_INLINE_ROUTINE Heap_Block_Heap_Free_list_tail (Heap_Control *heap)
 Returns the tail of the free list of the heap. More...
 
RTEMS_INLINE_ROUTINE Heap_Block_Heap_Free_list_first (Heap_Control *heap)
 Returns the first block of the free list of the heap. More...
 
RTEMS_INLINE_ROUTINE Heap_Block_Heap_Free_list_last (Heap_Control *heap)
 Returns the last block of the free list of the heap. More...
 
RTEMS_INLINE_ROUTINE void _Heap_Free_list_remove (Heap_Block *block)
 Removes the block from the free list. More...
 
RTEMS_INLINE_ROUTINE void _Heap_Free_list_replace (Heap_Block *old_block, Heap_Block *new_block)
 Replaces one block in the free list by another. More...
 
RTEMS_INLINE_ROUTINE void _Heap_Free_list_insert_after (Heap_Block *block_before, Heap_Block *new_block)
 Inserts a block after an existing block in the free list. More...
 
RTEMS_INLINE_ROUTINE void _Heap_Free_list_insert_before (Heap_Block *block_next, Heap_Block *new_block)
 Inserts a block before an existing block in the free list. More...
 
RTEMS_INLINE_ROUTINE bool _Heap_Is_aligned (uintptr_t value, uintptr_t alignment)
 Checks if the value is aligned to the given alignment. More...
 
RTEMS_INLINE_ROUTINE uintptr_t _Heap_Align_down (uintptr_t value, uintptr_t alignment)
 Returns the aligned value, truncating. More...
 
RTEMS_INLINE_ROUTINE Heap_Block_Heap_Block_at (const Heap_Block *block, uintptr_t offset)
 Returns the block which is offset away from block. More...
 
RTEMS_INLINE_ROUTINE Heap_Block_Heap_Prev_block (const Heap_Block *block)
 Returns the address of the previous block. More...
 
RTEMS_INLINE_ROUTINE uintptr_t _Heap_Alloc_area_of_block (const Heap_Block *block)
 Returns the first address in the block without the heap header. More...
 
RTEMS_INLINE_ROUTINE Heap_Block_Heap_Block_of_alloc_area (uintptr_t alloc_begin, uintptr_t page_size)
 Returns the starting address of the block corresponding to the allocatable area. More...
 
RTEMS_INLINE_ROUTINE uintptr_t _Heap_Block_size (const Heap_Block *block)
 Returns the block size. More...
 
RTEMS_INLINE_ROUTINE void _Heap_Block_set_size (Heap_Block *block, uintptr_t size)
 Sets the block size. More...
 
RTEMS_INLINE_ROUTINE bool _Heap_Is_prev_used (const Heap_Block *block)
 Returns if the previous heap block is used. More...
 
RTEMS_INLINE_ROUTINE bool _Heap_Is_used (const Heap_Block *block)
 Returns if the heap block is used. More...
 
RTEMS_INLINE_ROUTINE bool _Heap_Is_free (const Heap_Block *block)
 Returns if the heap block is free. More...
 
RTEMS_INLINE_ROUTINE bool _Heap_Is_block_in_heap (const Heap_Control *heap, const Heap_Block *block)
 Returns if the block is part of the heap. More...
 
RTEMS_INLINE_ROUTINE void _Heap_Set_last_block_size (Heap_Control *heap)
 Sets the size of the last block for the heap. More...
 
RTEMS_INLINE_ROUTINE uintptr_t _Heap_Get_size (const Heap_Control *heap)
 Returns the size of the allocatable area in bytes. More...
 
RTEMS_INLINE_ROUTINE uintptr_t _Heap_Max (uintptr_t a, uintptr_t b)
 Returns the bigger one of the two arguments. More...
 
RTEMS_INLINE_ROUTINE uintptr_t _Heap_Min (uintptr_t a, uintptr_t b)
 Returns the smaller one of the two arguments. More...
 

Detailed Description

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:

Heap_Blockprevious block size in case the previous block is free,
otherwise it may contain data used by the previous block
block size and a flag which indicates if the previous block is free or used,
this field contains always valid data regardless of the block usage
pointer to next block (this field is page size aligned)
pointer to previous block
free space

Used blocks look like:

Heap_Blockprevious block size in case the previous block is free,
otherwise it may contain data used by the previous block
block size and a flag which indicates if the previous block is free or used,
this field contains always valid data regardless of the block usage
begin of allocated area (this field is page size aligned)
allocated space
allocated space

The heap area after initialization contains two blocks and looks like:

LabelContent
heap->area_beginheap area begin address
first_block->prev_size subordinate heap area end address (this will be used to maintain a linked list of scattered heap areas)
first_block->size size available for allocation | HEAP_PREV_BLOCK_USED
first_block->next_Heap_Free_list_tail(heap) memory area available for allocation
first_block->prev_Heap_Free_list_head(heap)
...
last_block->prev_sizesize of first block
last_block->size first block begin address - last block begin address
heap->area_endheap area end address

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 Documentation

◆ Heap_Block_visitor

typedef bool(* Heap_Block_visitor) (const Heap_Block *block, uintptr_t block_size, bool block_is_used, void *visitor_arg)

Heap block visitor.

See also
_Heap_Iterate().
Return values
trueStop the iteration.
falseContinue the iteration.

Definition at line 204 of file heapimpl.h.

◆ Heap_Initialization_or_extend_handler

typedef uintptr_t(* Heap_Initialization_or_extend_handler) (Heap_Control *heap, void *area_begin, uintptr_t area_size, uintptr_t page_size_or_unused)

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 also
Heap_Area, _Heap_Initialize(), _Heap_Extend(), or _Heap_No_extend().

Definition at line 352 of file heap.h.

Enumeration Type Documentation

◆ Heap_Error_reason

The heap error reason.

See also
_Heap_Protection_block_error().
Enumerator
HEAP_ERROR_BROKEN_PROTECTOR 

There is an unexpected value in the heap block protector area.

HEAP_ERROR_FREE_PATTERN 

There is an unexpected value in the free pattern of a free heap block.

HEAP_ERROR_DOUBLE_FREE 

There is was an attempt to free the same block twice.

HEAP_ERROR_BAD_USED_BLOCK 

The next block of a supposed to be used block does not indicate that the block is used.

HEAP_ERROR_BAD_FREE_BLOCK 

A supposed to be free block is not inside the heap memory area.

Definition at line 142 of file heap.h.

Function Documentation

◆ _Heap_Align_down()

RTEMS_INLINE_ROUTINE uintptr_t _Heap_Align_down ( uintptr_t  value,
uintptr_t  alignment 
)

Returns the aligned value, truncating.

Parameters
valueThe value to be aligned
alignmentThe alignment for the operation.
Returns
The aligned value, truncated.

Definition at line 590 of file heapimpl.h.

◆ _Heap_Align_up()

RTEMS_INLINE_ROUTINE uintptr_t _Heap_Align_up ( uintptr_t  value,
uintptr_t  alignment 
)

Aligns the value to a given alignment, rounding up.

Parameters
valueThe value to be aligned.
alignmentThe alignment for the value.
Returns
The value aligned to the given alignment, rounded up.

Definition at line 413 of file heap.h.

◆ _Heap_Alloc_area_of_block()

RTEMS_INLINE_ROUTINE uintptr_t _Heap_Alloc_area_of_block ( const Heap_Block block)

Returns the first address in the block without the heap header.

Parameters
blockThe block for the operation.
Returns
The first address after the heap header.

Definition at line 635 of file heapimpl.h.

◆ _Heap_Allocate()

RTEMS_INLINE_ROUTINE void* _Heap_Allocate ( Heap_Control heap,
uintptr_t  size 
)

Allocates a memory area.

A size value of zero will return a unique address which may be freed with _Heap_Free().

Parameters
[in,out]heapThe heap to allocate a memory are from.
sizeThe size of the desired memory are in bytes.
Return values
pointerThe starting address of the allocated memory area.
NULLNo memory is available of the parameters are inconsistent.

Definition at line 160 of file heapimpl.h.

◆ _Heap_Allocate_aligned()

RTEMS_INLINE_ROUTINE void* _Heap_Allocate_aligned ( Heap_Control heap,
uintptr_t  size,
uintptr_t  alignment 
)

Allocates an aligned memory area.

A size value of zero will return a unique address which may be freed with _Heap_Free().

Parameters
[in,out]heapThe heap to allocate a memory are from.
sizeThe size of the desired memory are in bytes.
alignmentThe allocated memory area will begin at an address aligned by this value.
Return values
pointerThe starting address of the allocated memory area.
NULLNo memory is available of the parameters are inconsistent.

Definition at line 139 of file heapimpl.h.

◆ _Heap_Allocate_aligned_with_boundary()

void* _Heap_Allocate_aligned_with_boundary ( Heap_Control heap,
uintptr_t  size,
uintptr_t  alignment,
uintptr_t  boundary 
)

Allocates an aligned memory area with boundary constraint.

A size value of zero will return a unique address which may be freed with _Heap_Free().

Parameters
[in,out]heapThe heap to allocate a memory are from.
sizeThe size of the desired memory are in bytes.
alignmentThe allocated memory area will begin at an address aligned by this value.
boundaryThe allocated memory area will fulfill a boundary constraint, if this value is not equal to zero. The boundary 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.
Return values
pointerThe starting address of the allocated memory area.
NULLNo memory is available of the parameters are inconsistent.

Definition at line 192 of file heapallocate.c.

◆ _Heap_Area_overhead()

RTEMS_INLINE_ROUTINE uintptr_t _Heap_Area_overhead ( uintptr_t  page_size)

Returns the worst case overhead to manage a memory area.

Parameters
page_sizeThe page size to calculate the worst case memory manage overhead.
Returns
The worst case overhead to manage a memory area.

Definition at line 446 of file heap.h.

◆ _Heap_Block_allocate()

Heap_Block* _Heap_Block_allocate ( Heap_Control heap,
Heap_Block block,
uintptr_t  alloc_begin,
uintptr_t  alloc_size 
)

Allocates the memory area. starting at alloc_begin of size alloc_size bytes in the block 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 alloc_begin or alloc_size may corrupt the heap.

Parameters
[in,out]heapThe heap to operate upon.
blockThe block in which the memory area should be allocated
alloc_beginThe starting address of the memory area that shall be allocated.
alloc_sizeThe size of the desired allocated area in bytes.
Returns
The block containing the allocated memory area.

Definition at line 431 of file heap.c.

◆ _Heap_Block_at()

RTEMS_INLINE_ROUTINE Heap_Block* _Heap_Block_at ( const Heap_Block block,
uintptr_t  offset 
)

Returns the block which is offset away from block.

Parameters
blockThe block for the relative calculation.
offsetThe offset for the calculation.
Returns
The address of the block which is offset away from block.

Definition at line 606 of file heapimpl.h.

◆ _Heap_Block_of_alloc_area()

RTEMS_INLINE_ROUTINE Heap_Block* _Heap_Block_of_alloc_area ( uintptr_t  alloc_begin,
uintptr_t  page_size 
)

Returns the starting address of the block corresponding to the allocatable area.

Parameters
alloc_beginThe starting address of the allocatable area.
page_sizeThe page size for the calculation.
Returns
The Starting address of the corresponding block of the allocatable area.

Definition at line 650 of file heapimpl.h.

◆ _Heap_Block_set_size()

RTEMS_INLINE_ROUTINE void _Heap_Block_set_size ( Heap_Block block,
uintptr_t  size 
)

Sets the block size.

Parameters
[in,out]blockThe block of which the size shall be set.
sizeThe new size of the block.

Definition at line 677 of file heapimpl.h.

◆ _Heap_Block_size()

RTEMS_INLINE_ROUTINE uintptr_t _Heap_Block_size ( const Heap_Block block)

Returns the block size.

Parameters
blockThe block of which the size is requested.
Returns
The block size.

Definition at line 666 of file heapimpl.h.

◆ _Heap_Extend()

uintptr_t _Heap_Extend ( Heap_Control heap,
void *  area_begin,
uintptr_t  area_size,
uintptr_t  unused 
)

Extends the memory available for the heap.

There are no alignment requirements for the memory area. The memory area must be big enough to contain some maintenance blocks. It must not overlap parts of the current heap memory areas. Disconnected memory areas added to the heap will lead to used blocks which cover the gaps. Extending with an inappropriate memory area will corrupt the heap resulting in undefined behaviour.

Parameters
[in,out]heapThe heap to extend.
[out]area_beginThe start address of the area to extend the heap with.
area_sizeThe size of the area in bytes.
unusedIs not used, only provided to have the same signature as _Heap_Initialize().
Return values
some_valueThe extended space available for allocation after successful extension.
0The heap extension failed.
See also
Heap_Initialization_or_extend_handler.

◆ _Heap_Free()

bool _Heap_Free ( Heap_Control heap,
void *  addr 
)

Frees the allocated memory area.

Inappropriate values for addr may corrupt the heap.

Parameters
[in,out]heapThe heap of the allocated memory area.
addrThe starting address of the memory area to be freed.
Return values
trueThe allocated memory area was successfully freed.
falseThe method failed.

◆ _Heap_Free_list_first()

RTEMS_INLINE_ROUTINE Heap_Block* _Heap_Free_list_first ( Heap_Control heap)

Returns the first block of the free list of the heap.

Parameters
heapThe heap to operate upon.
Returns
The first block of the free list.

Definition at line 475 of file heapimpl.h.

◆ _Heap_Free_list_head()

RTEMS_INLINE_ROUTINE Heap_Block* _Heap_Free_list_head ( Heap_Control heap)

Returns the head of the free list of the heap.

Parameters
heapThe heap to operate upon.
Returns
The head of the free list.

Definition at line 451 of file heapimpl.h.

◆ _Heap_Free_list_insert_after()

RTEMS_INLINE_ROUTINE void _Heap_Free_list_insert_after ( Heap_Block block_before,
Heap_Block new_block 
)

Inserts a block after an existing block in the free list.

Parameters
block_beforeThe block that is already in the free list.
new_blockThe block to be inserted after block_before.

Definition at line 533 of file heapimpl.h.

◆ _Heap_Free_list_insert_before()

RTEMS_INLINE_ROUTINE void _Heap_Free_list_insert_before ( Heap_Block block_next,
Heap_Block new_block 
)

Inserts a block before an existing block in the free list.

Parameters
block_beforeThe block that is already in the free list.
new_blockThe block to be inserted before block_before.

Definition at line 552 of file heapimpl.h.

◆ _Heap_Free_list_last()

RTEMS_INLINE_ROUTINE Heap_Block* _Heap_Free_list_last ( Heap_Control heap)

Returns the last block of the free list of the heap.

Parameters
heapThe heap to operate upon.
Returns
The last block of the free list.

Definition at line 487 of file heapimpl.h.

◆ _Heap_Free_list_remove()

RTEMS_INLINE_ROUTINE void _Heap_Free_list_remove ( Heap_Block block)

Removes the block from the free list.

Parameters
blockThe block to be removed.

Definition at line 497 of file heapimpl.h.

◆ _Heap_Free_list_replace()

RTEMS_INLINE_ROUTINE void _Heap_Free_list_replace ( Heap_Block old_block,
Heap_Block new_block 
)

Replaces one block in the free list by another.

Parameters
old_blockThe block in the free list to replace.
new_blockThe block that should replace old_block.

Definition at line 512 of file heapimpl.h.

◆ _Heap_Free_list_tail()

RTEMS_INLINE_ROUTINE Heap_Block* _Heap_Free_list_tail ( Heap_Control heap)

Returns the tail of the free list of the heap.

Parameters
heapThe heap to operate upon.
Returns
The tail of the free list.

Definition at line 463 of file heapimpl.h.

◆ _Heap_Get_first_and_last_block()

bool _Heap_Get_first_and_last_block ( uintptr_t  heap_area_begin,
uintptr_t  heap_area_size,
uintptr_t  page_size,
uintptr_t  min_block_size,
Heap_Block **  first_block_ptr,
Heap_Block **  last_block_ptr 
)

Gets the first and last block for the heap area.

Nothing will be written to this area.

Parameters
heap_area_beginThe starting address of the heap area.
heap_area_sizeThe size of the heap area.
page_sizeThe page size for the calculation.
min_block_sizeThe minimal block size for the calculation.
[out]first_block_ptrThe pointer to the first block in the case of success
[out]last_block_ptrThe pointer to the last block in the case of success
Return values
trueThe area is big enough.
falseThe area is not big enough.

Definition at line 170 of file heap.c.

◆ _Heap_Get_free_information()

void _Heap_Get_free_information ( Heap_Control heap,
Heap_Information info 
)

Returns information about free blocks for the heap.

Parameters
heapThe heap to get the information from.
[out]infoStores the information about free blocks of heap after the method call.

◆ _Heap_Get_information()

void _Heap_Get_information ( Heap_Control heap,
Heap_Information_block info 
)

Returns information about used and free blocks for the heap.

Parameters
heapThe heap to get the information from.
[out]infoStores the information of the heap after the method call.

◆ _Heap_Get_size()

RTEMS_INLINE_ROUTINE uintptr_t _Heap_Get_size ( const Heap_Control heap)

Returns the size of the allocatable area in bytes.

This value is an integral multiple of the page size.

Parameters
heapThe heap to get the allocatable area from.
Returns
The size of the allocatable area in heap in bytes.

Definition at line 782 of file heapimpl.h.

◆ _Heap_Greedy_allocate()

Heap_Block* _Heap_Greedy_allocate ( Heap_Control heap,
const uintptr_t *  block_sizes,
size_t  block_count 
)

Greedily allocates and empties the heap.

Afterwards, the heap has at most block_count allocatable blocks of sizes specified by block_sizes. All other blocks are used.

Parameters
[in,out]heapThe heap to operate upon
block_sizesThe sizes of the allocatable blocks. Must point to an array with block_count members.
block_countThe maximum number of allocatable blocks of sizes specified by .
Returns
Pointer to the first allocated block.
See also
_Heap_Greedy_free().

◆ _Heap_Greedy_allocate_all_except_largest()

Heap_Block* _Heap_Greedy_allocate_all_except_largest ( Heap_Control heap,
uintptr_t *  allocatable_size 
)

Greedily allocates all blocks except the largest free block.

Afterwards the heap has at most one allocatable block. This block is the largest free block if it exists. All other blocks are used.

Parameters
[in,out]heapThe heap to operate upon.
[out]allocatable_sizeStores the size of the largest free block of the heap after the method call.
Returns
Pointer to the first allocated block.
See also
_Heap_Greedy_free().

◆ _Heap_Greedy_free()

void _Heap_Greedy_free ( Heap_Control heap,
Heap_Block blocks 
)

Frees blocks of a greedy allocation.

Parameters
[in,out]heapThe heap to operate upon.
blocksMust be the return value of _Heap_Greedy_allocate().

◆ _Heap_Initialize()

uintptr_t _Heap_Initialize ( Heap_Control heap,
void *  area_begin,
uintptr_t  area_size,
uintptr_t  page_size 
)

Initializes the heap control block.

Blocks of memory are allocated from the heap in multiples of page_size byte units. If the page_size is equal to zero or is not multiple of CPU_ALIGNMENT, it is aligned up to the nearest CPU_ALIGNMENT boundary.

Parameters
[out]heapThe heap control block to manage the area.
area_beginThe starting address of the area.
area_sizeThe size of the area in bytes.
page_sizeThe page size for the calculation
Return values
some_valueThe maximum memory available.
0The initialization failed.
See also
Heap_Initialization_or_extend_handler.

Definition at line 207 of file heap.c.

◆ _Heap_Is_aligned()

RTEMS_INLINE_ROUTINE bool _Heap_Is_aligned ( uintptr_t  value,
uintptr_t  alignment 
)

Checks if the value is aligned to the given alignment.

Parameters
valueThe value to check the alignment of.
alignmentThe alignment for the operation.
Return values
trueThe value is aligned to the given alignment.
falseThe value is not aligned to the given alignment.

Definition at line 574 of file heapimpl.h.

◆ _Heap_Is_block_in_heap()

RTEMS_INLINE_ROUTINE bool _Heap_Is_block_in_heap ( const Heap_Control heap,
const Heap_Block block 
)

Returns if the block is part of the heap.

Parameters
heapThe heap to test if the block is part of it.
blockThe block of which the information is requested.
Return values
trueThe block is part of the heap.
falseThe block is not part of the heap.

Definition at line 743 of file heapimpl.h.

◆ _Heap_Is_free()

RTEMS_INLINE_ROUTINE bool _Heap_Is_free ( const Heap_Block block)

Returns if the heap block is free.

Parameters
blockThe block of which the information is requested.
Return values
trueThe block is free.
falseThe block is not free.

Definition at line 727 of file heapimpl.h.

◆ _Heap_Is_prev_used()

RTEMS_INLINE_ROUTINE bool _Heap_Is_prev_used ( const Heap_Block block)

Returns if the previous heap block is used.

Parameters
blockThe block of which the information about the previous block is requested.
Return values
trueThe previous block is used.
falseThe previous block is not used.

Definition at line 696 of file heapimpl.h.

◆ _Heap_Is_used()

RTEMS_INLINE_ROUTINE bool _Heap_Is_used ( const Heap_Block block)

Returns if the heap block is used.

Parameters
blockThe block of which the information is requested.
Return values
trueThe block is used.
falseThe block is not used.

Definition at line 709 of file heapimpl.h.

◆ _Heap_Iterate()

void _Heap_Iterate ( Heap_Control heap,
Heap_Block_visitor  visitor,
void *  visitor_arg 
)

Iterates over all blocks of the heap.

Parameters
[in,out]heapThe heap to iterate over.
visitorThis will be called for each heap block with the argument visitor_arg.
[in,out]visitor_argThe argument for all calls of visitor.

◆ _Heap_Max()

RTEMS_INLINE_ROUTINE uintptr_t _Heap_Max ( uintptr_t  a,
uintptr_t  b 
)

Returns the bigger one of the two arguments.

Parameters
aThe parameter on the left hand side of the comparison.
bThe parameter on the right hand side of the comparison.
Return values
aIf a > b.
bIf b >= a

Definition at line 796 of file heapimpl.h.

◆ _Heap_Min()

RTEMS_INLINE_ROUTINE uintptr_t _Heap_Min ( uintptr_t  a,
uintptr_t  b 
)

Returns the smaller one of the two arguments.

Parameters
aThe parameter on the left hand side of the comparison.
bThe parameter on the right hand side of the comparison.
Return values
aIf a < b.
bIf b <= a

Definition at line 810 of file heapimpl.h.

◆ _Heap_Min_block_size()

RTEMS_INLINE_ROUTINE uintptr_t _Heap_Min_block_size ( uintptr_t  page_size)

Returns the minimal Heap Block size for the given page_size.

Parameters
page_sizeThe page size for the heap.
Returns
The minimal Heap Block size for the given page_size.

Definition at line 434 of file heap.h.

◆ _Heap_No_extend()

uintptr_t _Heap_No_extend ( Heap_Control unused_0,
void *  unused_1,
uintptr_t  unused_2,
uintptr_t  unused_3 
)

This function returns always zero.

This function only returns zero and does nothing else.

Parameters
unused_0This parameter does nothing.
unused_1This parameter does nothing.
unused_2This parameter does nothing.
unused_3This parameter does nothing.
See also
Heap_Initialization_or_extend_handler.

◆ _Heap_Prev_block()

RTEMS_INLINE_ROUTINE Heap_Block* _Heap_Prev_block ( const Heap_Block block)

Returns the address of the previous block.

Parameters
blockThe block of which the address of the previous block is requested.
Returns
The address of the previous block.

Definition at line 621 of file heapimpl.h.

◆ _Heap_Protection_set_delayed_free_fraction()

RTEMS_INLINE_ROUTINE void _Heap_Protection_set_delayed_free_fraction ( Heap_Control heap,
uintptr_t  fraction 
)

Sets the fraction of delayed free blocks that is actually freed during memory shortage.

The default is to free half the delayed free blocks. This is equal to a fraction value of two.

Parameters
[in,out]heapThe heap control.
fractionThe fraction is one divided by this fraction value.

Definition at line 431 of file heapimpl.h.

◆ _Heap_Resize_block()

Heap_Resize_status _Heap_Resize_block ( Heap_Control heap,
void *  addr,
uintptr_t  size,
uintptr_t *  old_size,
uintptr_t *  new_size 
)

Resizes the block of the allocated memory area.

Inappropriate values for addr may corrupt the heap.

Parameters
[in,out]heapThe heap to operate upon.
addrThe starting address of the allocated memory area to be resized.
sizeThe least possible size for the new memory area. Resize may be impossible and depends on the current heap usage.
[out]old_sizeStores the size available for allocation in the current block before the resize after the method call.
[out]new_sizeStores the size available for allocation in the resized block after the method call. In the case of an unsuccessful resize, zero is returned in this parameter
Return values
HEAP_RESIZE_SUCCESSFULThe resize was successful.
HEAP_RESIZE_UNSATISFIEDThe least possible size size was too big. Resize not possible.
HEAP_RESIZE_FATAL_ERRORThe block starting at addr is not part of the heap.

◆ _Heap_Set_last_block_size()

RTEMS_INLINE_ROUTINE void _Heap_Set_last_block_size ( Heap_Control heap)

Sets the size of the last block for the heap.

The next block of the last block will be 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.

This feature will be used to terminate the scattered heap area list. See also _Heap_Extend().

Parameters
[in,out]heapThe heap to set the last block size of.

Definition at line 765 of file heapimpl.h.

◆ _Heap_Size_of_alloc_area()

bool _Heap_Size_of_alloc_area ( Heap_Control heap,
void *  addr,
uintptr_t *  size 
)

Returns the size of the allocatable memory area.

The size value may be greater than the initially requested size in _Heap_Allocate_aligned_with_boundary().

Inappropriate values for addr will not corrupt the heap, but may yield invalid size values.

Parameters
heapThe heap to operate upon.
addrThe starting address of the allocatable memory area.
[out]sizeStores the size of the allocatable memory area after the method call.
Return values
trueThe operation was successful.
falseThe operation was not successful.

◆ _Heap_Size_with_overhead()

RTEMS_INLINE_ROUTINE uintptr_t _Heap_Size_with_overhead ( uintptr_t  page_size,
uintptr_t  size,
uintptr_t  alignment 
)

Returns the size with administration and alignment overhead for one allocation.

Parameters
page_sizeThe page size for the allocation.
sizeThe size to allocate.
alignmentThe alignment that needs to be considered.
Returns
The size with administration and alignment overhead for one allocation.

Definition at line 469 of file heap.h.

◆ _Heap_Walk()

bool _Heap_Walk ( Heap_Control heap,
int  source,
bool  dump 
)

Verifies the integrity of the heap.

Walks the heap to verify its integrity.

Parameters
heapThe heap whose integrity is to be verified.
sourceIf dump is true, this is used to mark the output lines.
dumpIndicates whether diagnostic messages will be printed to standard output.
Return values
trueNo errors occured, the heapĀ“s integrity is not violated.
falseThe heap is corrupt.