Rtos API example
Dynamic memory manager. More...
Go to the source code of this file.
Functions | |
void | mem_init (void) |
mem_init is not used when using pools instead of a heap or using C library malloc(). | |
void * | mem_trim (void *mem, mem_size_t size) |
mem_trim is not used when using pools instead of a heap or using C library malloc(): we can't free part of a pool element and the stack support mem_trim() to return a different pointer | |
void * | mem_malloc (mem_size_t size) |
Allocate a block of memory with a minimum of 'size' bytes. | |
void | mem_free (void *rmem) |
Put memory back on the heap. | |
LWIP_DECLARE_MEMORY_ALIGNED (ram_heap, MEM_SIZE_ALIGNED+(2U *SIZEOF_STRUCT_MEM)) | |
If you want to relocate the heap to external memory, simply define LWIP_RAM_HEAP_POINTER as a void-pointer to that location. | |
static void | plug_holes (struct mem *mem) |
"Plug holes" by combining adjacent empty struct mems. | |
void * | mem_calloc (mem_size_t count, mem_size_t size) |
Contiguously allocates enough space for count objects that are size bytes of memory each and returns a pointer to the allocated memory. | |
Variables | |
static u8_t * | ram |
pointer to the heap (ram_heap): for alignment, ram is now a pointer instead of an array | |
static struct mem * | ram_end |
the last entry, always unused! | |
static struct mem * | lfree |
pointer to the lowest free block, this is used for faster search | |
static sys_mutex_t | mem_mutex |
concurrent access protection |
Detailed Description
Dynamic memory manager.
This is a lightweight replacement for the standard C library malloc().
If you want to use the standard C library malloc() instead, define MEM_LIBC_MALLOC to 1 in your lwipopts.h
To let mem_malloc() use pools (prevents fragmentation and is much faster than a heap but might waste some memory), define MEM_USE_POOLS to 1, define MEMP_USE_CUSTOM_POOLS to 1 and create a file "lwippools.h" that includes a list of pools like this (more pools can be added between _START and _END):
Define three pools with sizes 256, 512, and 1512 bytes LWIP_MALLOC_MEMPOOL_START LWIP_MALLOC_MEMPOOL(20, 256) LWIP_MALLOC_MEMPOOL(10, 512) LWIP_MALLOC_MEMPOOL(5, 1512) LWIP_MALLOC_MEMPOOL_END
Definition in file lwip_mem.c.
Function Documentation
LWIP_DECLARE_MEMORY_ALIGNED | ( | ram_heap | , |
MEM_SIZE_ALIGNED+ | 2U *SIZEOF_STRUCT_MEM | ||
) |
If you want to relocate the heap to external memory, simply define LWIP_RAM_HEAP_POINTER as a void-pointer to that location.
If so, make sure the memory at that location is big enough (see below on how that space is calculated). the heap. we need one struct mem at the end and some room for alignment
void * mem_calloc | ( | mem_size_t | count, |
mem_size_t | size | ||
) |
Contiguously allocates enough space for count objects that are size bytes of memory each and returns a pointer to the allocated memory.
The allocated memory is filled with bytes of value zero.
- Parameters:
-
count number of objects to allocate size size of the objects to allocate
- Returns:
- pointer to allocated memory / NULL pointer if there is an error
Definition at line 748 of file lwip_mem.c.
void mem_free | ( | void * | rmem ) |
Put memory back on the heap.
Put a struct mem back on the heap.
Free memory previously allocated by mem_malloc.
- Parameters:
-
rmem is the pointer as returned by a previous call to mem_malloc()
Loads the pool number and calls memp_free with that pool number to put the element back into its pool
- Parameters:
-
rmem the memory element to free rmem is the data portion of a struct mem as returned by a previous call to mem_malloc()
Definition at line 143 of file lwip_mem.c.
void mem_init | ( | void | ) |
mem_init is not used when using pools instead of a heap or using C library malloc().
Zero the heap and initialize start, end and lowest-free.
Definition at line 75 of file lwip_mem.c.
void * mem_malloc | ( | mem_size_t | size ) |
Allocate a block of memory with a minimum of 'size' bytes.
Allocate memory: determine the smallest pool that is big enough to contain an element of 'size' and get an element from that pool.
- Parameters:
-
size is the minimum size of the requested block in bytes.
- Returns:
- pointer to allocated memory or NULL if no free memory was found.
Note that the returned value must always be aligned (as defined by MEM_ALIGNMENT).
- Parameters:
-
size the size in bytes of the memory needed
- Returns:
- a pointer to the allocated memory or NULL if the pool is empty
- Parameters:
-
size is the minimum size of the requested block in bytes.
- Returns:
- pointer to allocated memory or NULL if no free memory was found.
Note that the returned value will always be aligned (as defined by MEM_ALIGNMENT).
Try a bigger pool if this one is empty!
Definition at line 122 of file lwip_mem.c.
void * mem_trim | ( | void * | rmem, |
mem_size_t | newsize | ||
) |
mem_trim is not used when using pools instead of a heap or using C library malloc(): we can't free part of a pool element and the stack support mem_trim() to return a different pointer
Shrink memory returned by mem_malloc().
- Parameters:
-
rmem pointer to memory allocated by mem_malloc the is to be shrinked newsize required size after shrinking (needs to be smaller than or equal to the previous size)
- Returns:
- for compatibility reasons: is always == rmem, at the moment or NULL if newsize is > old size, in which case rmem is NOT touched or freed!
Definition at line 84 of file lwip_mem.c.
static void plug_holes | ( | struct mem * | mem ) | [static] |
"Plug holes" by combining adjacent empty struct mems.
After this function is through, there should not exist one empty struct mem pointing to another empty struct mem.
- Parameters:
-
mem this points to a struct mem which just has been freed
Definition at line 344 of file lwip_mem.c.
Variable Documentation
struct mem* lfree [static] |
pointer to the lowest free block, this is used for faster search
Definition at line 299 of file lwip_mem.c.
sys_mutex_t mem_mutex [static] |
concurrent access protection
Definition at line 303 of file lwip_mem.c.
u8_t* ram [static] |
pointer to the heap (ram_heap): for alignment, ram is now a pointer instead of an array
Definition at line 295 of file lwip_mem.c.
struct mem* ram_end [static] |
the last entry, always unused!
Definition at line 297 of file lwip_mem.c.
Generated on Sun Jul 17 2022 08:25:35 by 1.7.2