alexb/lib/lwip/contrib/src/core/mem.c File Reference

Dynamic memory manager. More...

#include "lwip/opt.h"
#include "lwip/def.h"
#include "lwip/mem.h"
#include "lwip/sys.h"
#include "lwip/stats.h"
#include "lwip/err.h"
#include <string.h>

Classes
struct	mem
	The heap is made up as a list of structs of this type. More...
Defines
#define	MIN_SIZE   12
	All allocated blocks will be MIN_SIZE bytes big, at least! MIN_SIZE can be overridden to suit your needs.
#define	MIN_SIZE_ALIGNED   LWIP_MEM_ALIGN_SIZE(MIN_SIZE)
#define	SIZEOF_STRUCT_MEM   LWIP_MEM_ALIGN_SIZE(sizeof(struct mem))
#define	MEM_SIZE_ALIGNED   LWIP_MEM_ALIGN_SIZE(MEM_SIZE)
#define	LWIP_RAM_HEAP_POINTER   ram_heap
#define	LWIP_MEM_FREE_DECL_PROTECT()
#define	LWIP_MEM_FREE_PROTECT()   sys_mutex_lock(&mem_mutex)
#define	LWIP_MEM_FREE_UNPROTECT()   sys_mutex_unlock(&mem_mutex)
#define	LWIP_MEM_ALLOC_DECL_PROTECT()
#define	LWIP_MEM_ALLOC_PROTECT()
#define	LWIP_MEM_ALLOC_UNPROTECT()
Functions
void	mem_init (void)
	Zero the heap and initialize start, end and lowest-free.
void	mem_free (void *rmem)
	Put a struct mem back on the heap.
void *	mem_trim (void *rmem, mem_size_t newsize)
	Shrink memory returned by mem_malloc().
void *	mem_malloc (mem_size_t size)
	Adam's mem_malloc() plus solution for bug #17922 Allocate a block of memory with a minimum of 'size' bytes.
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
u8_t	ram_heap [MEM_SIZE_ALIGNED+(2 *SIZEOF_STRUCT_MEM)+MEM_ALIGNMENT]
	If you want to relocate the heap to external memory, simply define LWIP_RAM_HEAP_POINTER as a void-pointer to that location.

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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 MEM_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

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Define Documentation

#define LWIP_MEM_ALLOC_DECL_PROTECT

(

)

#define LWIP_MEM_ALLOC_PROTECT

(

)

#define LWIP_MEM_ALLOC_UNPROTECT

(

)

#define LWIP_MEM_FREE_DECL_PROTECT

(

)

#define LWIP_MEM_FREE_PROTECT

(

)

sys_mutex_lock(&mem_mutex)

#define LWIP_MEM_FREE_UNPROTECT

(

)

sys_mutex_unlock(&mem_mutex)

#define LWIP_RAM_HEAP_POINTER   ram_heap

#define MEM_SIZE_ALIGNED   LWIP_MEM_ALIGN_SIZE(MEM_SIZE)

#define MIN_SIZE   12

All allocated blocks will be MIN_SIZE bytes big, at least! MIN_SIZE can be overridden to suit your needs.

Smaller values save space, larger values could prevent too small blocks to fragment the RAM too much.

#define MIN_SIZE_ALIGNED   LWIP_MEM_ALIGN_SIZE(MIN_SIZE)

#define SIZEOF_STRUCT_MEM   LWIP_MEM_ALIGN_SIZE(sizeof(struct mem))

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Function Documentation

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

void mem_free

(

void *

rmem

)

Put a struct mem back on the heap.

Parameters:

rmem

is the data portion of a struct mem as returned by a previous call to mem_malloc()

void mem_init

(

void

)

Zero the heap and initialize start, end and lowest-free.

void* mem_malloc

(

mem_size_t

size

)

Adam's mem_malloc() plus solution for bug #17922 Allocate a block of memory with a minimum of 'size' bytes.

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).

void* mem_trim	(	void *	rmem,
		mem_size_t	newsize
	)

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!

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Variable Documentation

u8_t ram_heap[MEM_SIZE_ALIGNED+(2 *SIZEOF_STRUCT_MEM)+MEM_ALIGNMENT]

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