mem.c File Reference

#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
Defines
#define	MIN_SIZE   12
Functions
void	mem_init (void)
void	mem_free (void *rmem)
void *	mem_trim (void *rmem, mem_size_t newsize)
void *	mem_malloc (mem_size_t size)
void *	mem_calloc (mem_size_t count, mem_size_t size)
Variables
u8_t	ram_heap [MEM_SIZE_ALIGNED+(2 *SIZEOF_STRUCT_MEM)+MEM_ALIGNMENT]

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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 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.

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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]

the heap. we need one struct mem at the end and some room for alignment

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