www.pudn.com > lwip-1.3.0.rar > mem.c
/**
* @file
* 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
*/
/*
* Copyright (c) 2001-2004 Swedish Institute of Computer Science.
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without modification,
* are permitted provided that the following conditions are met:
*
* 1. Redistributions of source code must retain the above copyright notice,
* this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright notice,
* this list of conditions and the following disclaimer in the documentation
* and/or other materials provided with the distribution.
* 3. The name of the author may not be used to endorse or promote products
* derived from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
* WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT
* SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
* OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
* IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY
* OF SUCH DAMAGE.
*
* This file is part of the lwIP TCP/IP stack.
*
* Author: Adam Dunkels
* Simon Goldschmidt
*
*/
#include "lwip/opt.h"
#if !MEM_LIBC_MALLOC /* don't build if not configured for use in lwipopts.h */
#include "lwip/def.h"
#include "lwip/mem.h"
#include "lwip/sys.h"
#include "lwip/stats.h"
#include
#if MEM_USE_POOLS
/* lwIP head implemented with different sized pools */
/**
* This structure is used to save the pool one element came from.
*/
struct mem_helper
{
memp_t poolnr;
};
/**
* Allocate memory: determine the smallest pool that is big enough
* to contain an element of 'size' and get an element from that pool.
*
* @param size the size in bytes of the memory needed
* @return a pointer to the allocated memory or NULL if the pool is empty
*/
void *
mem_malloc(mem_size_t size)
{
struct mem_helper *element;
memp_t poolnr;
for (poolnr = MEMP_POOL_FIRST; poolnr <= MEMP_POOL_LAST; poolnr++) {
/* is this pool big enough to hold an element of the required size
plus a struct mem_helper that saves the pool this element came from? */
if ((size + sizeof(struct mem_helper)) <= memp_sizes[poolnr]) {
break;
}
}
if (poolnr > MEMP_POOL_LAST) {
LWIP_ASSERT("mem_malloc(): no pool is that big!", 0);
return NULL;
}
element = (struct mem_helper*)memp_malloc(poolnr);
if (element == NULL) {
/* No need to DEBUGF or ASSERT: This error is already
taken care of in memp.c */
/** @todo: we could try a bigger pool if this one is empty! */
return NULL;
}
/* save the pool number this element came from */
element->poolnr = poolnr;
/* and return a pointer to the memory directly after the struct mem_helper */
element++;
return element;
}
/**
* Free memory previously allocated by mem_malloc. Loads the pool number
* and calls memp_free with that pool number to put the element back into
* its pool
*
* @param rmem the memory element to free
*/
void
mem_free(void *rmem)
{
struct mem_helper *hmem = (struct mem_helper*)rmem;
LWIP_ASSERT("rmem != NULL", (rmem != NULL));
LWIP_ASSERT("rmem == MEM_ALIGN(rmem)", (rmem == LWIP_MEM_ALIGN(rmem)));
/* get the original struct mem_helper */
hmem--;
LWIP_ASSERT("hmem != NULL", (hmem != NULL));
LWIP_ASSERT("hmem == MEM_ALIGN(hmem)", (hmem == LWIP_MEM_ALIGN(hmem)));
LWIP_ASSERT("hmem->poolnr < MEMP_MAX", (hmem->poolnr < MEMP_MAX));
/* and put it in the pool we saved earlier */
memp_free(hmem->poolnr, hmem);
}
#else /* MEM_USE_POOLS */
/* lwIP replacement for your libc malloc() */
/**
* The heap is made up as a list of structs of this type.
* This does not have to be aligned since for getting its size,
* we only use the macro SIZEOF_STRUCT_MEM, which automatically alignes.
*/
struct mem {
/** index (-> ram[next]) of the next struct */
mem_size_t next;
/** index (-> ram[next]) of the next struct */
mem_size_t prev;
/** 1: this area is used; 0: this area is unused */
u8_t used;
};
/** 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. */
#ifndef MIN_SIZE
#define MIN_SIZE 12
#endif /* MIN_SIZE */
/* some alignment macros: we define them here for better source code layout */
#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)
/** the heap. we need one struct mem at the end and some room for alignment */
static u8_t ram_heap[MEM_SIZE_ALIGNED + (2*SIZEOF_STRUCT_MEM) + MEM_ALIGNMENT];
/** pointer to the heap (ram_heap): for alignment, ram is now a pointer instead of an array */
static u8_t *ram;
/** the last entry, always unused! */
static struct mem *ram_end;
/** pointer to the lowest free block, this is used for faster search */
static struct mem *lfree;
/** concurrent access protection */
static sys_sem_t mem_sem;
/**
* "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.
*
* @param mem this points to a struct mem which just has been freed
* @internal this function is only called by mem_free() and mem_realloc()
*
* This assumes access to the heap is protected by the calling function
* already.
*/
static void
plug_holes(struct mem *mem)
{
struct mem *nmem;
struct mem *pmem;
LWIP_ASSERT("plug_holes: mem >= ram", (u8_t *)mem >= ram);
LWIP_ASSERT("plug_holes: mem < ram_end", (u8_t *)mem < (u8_t *)ram_end);
LWIP_ASSERT("plug_holes: mem->used == 0", mem->used == 0);
/* plug hole forward */
LWIP_ASSERT("plug_holes: mem->next <= MEM_SIZE_ALIGNED", mem->next <= MEM_SIZE_ALIGNED);
nmem = (struct mem *)&ram[mem->next];
if (mem != nmem && nmem->used == 0 && (u8_t *)nmem != (u8_t *)ram_end) {
/* if mem->next is unused and not end of ram, combine mem and mem->next */
if (lfree == nmem) {
lfree = mem;
}
mem->next = nmem->next;
((struct mem *)&ram[nmem->next])->prev = (u8_t *)mem - ram;
}
/* plug hole backward */
pmem = (struct mem *)&ram[mem->prev];
if (pmem != mem && pmem->used == 0) {
/* if mem->prev is unused, combine mem and mem->prev */
if (lfree == mem) {
lfree = pmem;
}
pmem->next = mem->next;
((struct mem *)&ram[mem->next])->prev = (u8_t *)pmem - ram;
}
}
/**
* Zero the heap and initialize start, end and lowest-free
*/
void
mem_init(void)
{
struct mem *mem;
LWIP_ASSERT("Sanity check alignment",
(SIZEOF_STRUCT_MEM & (MEM_ALIGNMENT-1)) == 0);
/* align the heap */
ram = LWIP_MEM_ALIGN(ram_heap);
/* initialize the start of the heap */
mem = (struct mem *)ram;
mem->next = MEM_SIZE_ALIGNED;
mem->prev = 0;
mem->used = 0;
/* initialize the end of the heap */
ram_end = (struct mem *)&ram[MEM_SIZE_ALIGNED];
ram_end->used = 1;
ram_end->next = MEM_SIZE_ALIGNED;
ram_end->prev = MEM_SIZE_ALIGNED;
mem_sem = sys_sem_new(1);
/* initialize the lowest-free pointer to the start of the heap */
lfree = (struct mem *)ram;
#if MEM_STATS
lwip_stats.mem.avail = MEM_SIZE_ALIGNED;
#endif /* MEM_STATS */
}
/**
* Put a struct mem back on the heap
*
* @param rmem is the data portion of a struct mem as returned by a previous
* call to mem_malloc()
*/
void
mem_free(void *rmem)
{
struct mem *mem;
if (rmem == NULL) {
LWIP_DEBUGF(MEM_DEBUG | LWIP_DBG_TRACE | 2, ("mem_free(p == NULL) was called.\n"));
return;
}
LWIP_ASSERT("mem_free: sanity check alignment", (((mem_ptr_t)rmem) & (MEM_ALIGNMENT-1)) == 0);
/* protect the heap from concurrent access */
sys_arch_sem_wait(mem_sem, 0);
LWIP_ASSERT("mem_free: legal memory", (u8_t *)rmem >= (u8_t *)ram &&
(u8_t *)rmem < (u8_t *)ram_end);
if ((u8_t *)rmem < (u8_t *)ram || (u8_t *)rmem >= (u8_t *)ram_end) {
LWIP_DEBUGF(MEM_DEBUG | 3, ("mem_free: illegal memory\n"));
#if MEM_STATS
++lwip_stats.mem.err;
#endif /* MEM_STATS */
sys_sem_signal(mem_sem);
return;
}
/* Get the corresponding struct mem ... */
mem = (struct mem *)((u8_t *)rmem - SIZEOF_STRUCT_MEM);
/* ... which has to be in a used state ... */
LWIP_ASSERT("mem_free: mem->used", mem->used);
/* ... and is now unused. */
mem->used = 0;
if (mem < lfree) {
/* the newly freed struct is now the lowest */
lfree = mem;
}
#if MEM_STATS
lwip_stats.mem.used -= mem->next - ((u8_t *)mem - ram);
#endif /* MEM_STATS */
/* finally, see if prev or next are free also */
plug_holes(mem);
sys_sem_signal(mem_sem);
}
/**
* In contrast to its name, mem_realloc can only shrink memory, not expand it.
* Since the only use (for now) is in pbuf_realloc (which also can only shrink),
* this shouldn't be a problem!
*
* @param rmem pointer to memory allocated by mem_malloc the is to be shrinked
* @param newsize required size after shrinking (needs to be smaller than or
* equal to the previous size)
* @return for compatibility reasons: is always == rmem, at the moment
*/
void *
mem_realloc(void *rmem, mem_size_t newsize)
{
mem_size_t size;
mem_size_t ptr, ptr2;
struct mem *mem, *mem2;
/* Expand the size of the allocated memory region so that we can
adjust for alignment. */
newsize = LWIP_MEM_ALIGN_SIZE(newsize);
if(newsize < MIN_SIZE_ALIGNED) {
/* every data block must be at least MIN_SIZE_ALIGNED long */
newsize = MIN_SIZE_ALIGNED;
}
if (newsize > MEM_SIZE_ALIGNED) {
return NULL;
}
LWIP_ASSERT("mem_realloc: legal memory", (u8_t *)rmem >= (u8_t *)ram &&
(u8_t *)rmem < (u8_t *)ram_end);
if ((u8_t *)rmem < (u8_t *)ram || (u8_t *)rmem >= (u8_t *)ram_end) {
LWIP_DEBUGF(MEM_DEBUG | 3, ("mem_realloc: illegal memory\n"));
return rmem;
}
/* Get the corresponding struct mem ... */
mem = (struct mem *)((u8_t *)rmem - SIZEOF_STRUCT_MEM);
/* ... and its offset pointer */
ptr = (u8_t *)mem - ram;
size = mem->next - ptr - SIZEOF_STRUCT_MEM;
LWIP_ASSERT("mem_realloc can only shrink memory", newsize <= size);
if (newsize > size) {
/* not supported */
return NULL;
}
if (newsize == size) {
/* No change in size, simply return */
return rmem;
}
/* protect the heap from concurrent access */
sys_arch_sem_wait(mem_sem, 0);
#if MEM_STATS
lwip_stats.mem.used -= (size - newsize);
#endif /* MEM_STATS */
mem2 = (struct mem *)&ram[mem->next];
if(mem2->used == 0) {
/* The next struct is unused, we can simply move it at little */
mem_size_t next;
/* remember the old next pointer */
next = mem2->next;
/* create new struct mem which is moved directly after the shrinked mem */
ptr2 = ptr + SIZEOF_STRUCT_MEM + newsize;
if (lfree == mem2) {
lfree = (struct mem *)&ram[ptr2];
}
mem2 = (struct mem *)&ram[ptr2];
mem2->used = 0;
/* restore the next pointer */
mem2->next = next;
/* link it back to mem */
mem2->prev = ptr;
/* link mem to it */
mem->next = ptr2;
/* last thing to restore linked list: as we have moved mem2,
* let 'mem2->next->prev' point to mem2 again. but only if mem2->next is not
* the end of the heap */
if (mem2->next != MEM_SIZE_ALIGNED) {
((struct mem *)&ram[mem2->next])->prev = ptr2;
}
/* no need to plug holes, we've already done that */
} else if (newsize + SIZEOF_STRUCT_MEM + MIN_SIZE_ALIGNED <= size) {
/* Next struct is used but there's room for another struct mem with
* at least MIN_SIZE_ALIGNED of data.
* Old size ('size') must be big enough to contain at least 'newsize' plus a struct mem
* ('SIZEOF_STRUCT_MEM') with some data ('MIN_SIZE_ALIGNED').
* @todo we could leave out MIN_SIZE_ALIGNED. We would create an empty
* region that couldn't hold data, but when mem->next gets freed,
* the 2 regions would be combined, resulting in more free memory */
ptr2 = ptr + SIZEOF_STRUCT_MEM + newsize;
mem2 = (struct mem *)&ram[ptr2];
if (mem2 < lfree) {
lfree = mem2;
}
mem2->used = 0;
mem2->next = mem->next;
mem2->prev = ptr;
mem->next = ptr2;
if (mem2->next != MEM_SIZE_ALIGNED) {
((struct mem *)&ram[mem2->next])->prev = ptr2;
}
/* the original mem->next is used, so no need to plug holes! */
}
/* else {
next struct mem is used but size between mem and mem2 is not big enough
to create another struct mem
-> don't do anyhting.
-> the remaining space stays unused since it is too small
} */
sys_sem_signal(mem_sem);
return rmem;
}
/**
* Adam's mem_malloc() plus solution for bug #17922
* Allocate a block of memory with a minimum of 'size' bytes.
*
* @param size is the minimum size of the requested block in bytes.
* @return 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_malloc(mem_size_t size)
{
mem_size_t ptr, ptr2;
struct mem *mem, *mem2;
if (size == 0) {
return NULL;
}
/* Expand the size of the allocated memory region so that we can
adjust for alignment. */
size = LWIP_MEM_ALIGN_SIZE(size);
if(size < MIN_SIZE_ALIGNED) {
/* every data block must be at least MIN_SIZE_ALIGNED long */
size = MIN_SIZE_ALIGNED;
}
if (size > MEM_SIZE_ALIGNED) {
return NULL;
}
/* protect the heap from concurrent access */
sys_arch_sem_wait(mem_sem, 0);
/* Scan through the heap searching for a free block that is big enough,
* beginning with the lowest free block.
*/
for (ptr = (u8_t *)lfree - ram; ptr < MEM_SIZE_ALIGNED - size;
ptr = ((struct mem *)&ram[ptr])->next) {
mem = (struct mem *)&ram[ptr];
if ((!mem->used) &&
(mem->next - (ptr + SIZEOF_STRUCT_MEM)) >= size) {
/* mem is not used and at least perfect fit is possible:
* mem->next - (ptr + SIZEOF_STRUCT_MEM) gives us the 'user data size' of mem */
if (mem->next - (ptr + SIZEOF_STRUCT_MEM) >= (size + SIZEOF_STRUCT_MEM + MIN_SIZE_ALIGNED)) {
/* (in addition to the above, we test if another struct mem (SIZEOF_STRUCT_MEM) containing
* at least MIN_SIZE_ALIGNED of data also fits in the 'user data space' of 'mem')
* -> split large block, create empty remainder,
* remainder must be large enough to contain MIN_SIZE_ALIGNED data: if
* mem->next - (ptr + (2*SIZEOF_STRUCT_MEM)) == size,
* struct mem would fit in but no data between mem2 and mem2->next
* @todo we could leave out MIN_SIZE_ALIGNED. We would create an empty
* region that couldn't hold data, but when mem->next gets freed,
* the 2 regions would be combined, resulting in more free memory
*/
ptr2 = ptr + SIZEOF_STRUCT_MEM + size;
/* create mem2 struct */
mem2 = (struct mem *)&ram[ptr2];
mem2->used = 0;
mem2->next = mem->next;
mem2->prev = ptr;
/* and insert it between mem and mem->next */
mem->next = ptr2;
mem->used = 1;
if (mem2->next != MEM_SIZE_ALIGNED) {
((struct mem *)&ram[mem2->next])->prev = ptr2;
}
#if MEM_STATS
lwip_stats.mem.used += (size + SIZEOF_STRUCT_MEM);
if (lwip_stats.mem.max < lwip_stats.mem.used) {
lwip_stats.mem.max = lwip_stats.mem.used;
}
#endif /* MEM_STATS */
} else {
/* (a mem2 struct does no fit into the user data space of mem and mem->next will always
* be used at this point: if not we have 2 unused structs in a row, plug_holes should have
* take care of this).
* -> near fit or excact fit: do not split, no mem2 creation
* also can't move mem->next directly behind mem, since mem->next
* will always be used at this point!
*/
mem->used = 1;
#if MEM_STATS
lwip_stats.mem.used += mem->next - ((u8_t *)mem - ram);
if (lwip_stats.mem.max < lwip_stats.mem.used) {
lwip_stats.mem.max = lwip_stats.mem.used;
}
#endif /* MEM_STATS */
}
if (mem == lfree) {
/* Find next free block after mem and update lowest free pointer */
while (lfree->used && lfree != ram_end) {
lfree = (struct mem *)&ram[lfree->next];
}
LWIP_ASSERT("mem_malloc: !lfree->used", ((lfree == ram_end) || (!lfree->used)));
}
sys_sem_signal(mem_sem);
LWIP_ASSERT("mem_malloc: allocated memory not above ram_end.",
(mem_ptr_t)mem + SIZEOF_STRUCT_MEM + size <= (mem_ptr_t)ram_end);
LWIP_ASSERT("mem_malloc: allocated memory properly aligned.",
(unsigned long)((u8_t *)mem + SIZEOF_STRUCT_MEM) % MEM_ALIGNMENT == 0);
LWIP_ASSERT("mem_malloc: sanity check alignment",
(((mem_ptr_t)mem) & (MEM_ALIGNMENT-1)) == 0);
return (u8_t *)mem + SIZEOF_STRUCT_MEM;
}
}
LWIP_DEBUGF(MEM_DEBUG | 2, ("mem_malloc: could not allocate %"S16_F" bytes\n", (s16_t)size));
#if MEM_STATS
++lwip_stats.mem.err;
#endif /* MEM_STATS */
sys_sem_signal(mem_sem);
return NULL;
}
#endif /* MEM_USE_POOLS */
/**
* 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.
*
* @param count number of objects to allocate
* @param size size of the objects to allocate
* @return pointer to allocated memory / NULL pointer if there is an error
*/
void *mem_calloc(mem_size_t count, mem_size_t size)
{
void *p;
/* allocate 'count' objects of size 'size' */
p = mem_malloc(count * size);
if (p) {
/* zero the memory */
memset(p, 0, count * size);
}
return p;
}
#endif /* !MEM_LIBC_MALLOC */