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rt-thread/src/memheap.c

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/*
* File : memheap.c
* This file is part of RT-Thread RTOS
* COPYRIGHT (C) 2012, RT-Thread Development Team
*
* The license and distribution terms for this file may be
* found in the file LICENSE in this distribution or at
* http://www.rt-thread.org/license/LICENSE
*
* Change Logs:
* Date Author Notes
* 2012-04-10 Bernard first implementation
* 2012-10-16 Bernard add the mutex lock for heap object.
*/
#include <rtthread.h>
#ifdef RT_USING_MEMHEAP
/* dynamic pool magic and mask */
#define RT_MEMHEAP_MAGIC 0x1ea01ea0
#define RT_MEMHEAP_MASK 0xfffffffe
#define RT_MEMHEAP_USED 0x01
#define RT_MEMHEAP_FREED 0x00
#define RT_MEMHEAP_IS_USED(i) ((i)->magic & RT_MEMHEAP_USED)
#define RT_MEMHEAP_MINIALLOC 12
#define RT_MEMHEAP_SIZE RT_ALIGN(sizeof(struct rt_memheap_item), RT_ALIGN_SIZE)
/*
* The initialized memory pool will be:
* +-----------------------------------+--------------------------+
* | whole freed memory block | Used Memory Block Tailer |
* +-----------------------------------+--------------------------+
*
* block_list --> whole freed memory block
*
* The length of Used Memory Block Tailer is 0, which is prevents block merging across list
*/
rt_err_t rt_memheap_init(struct rt_memheap *memheap, const char *name,
void *start_addr,
rt_uint32_t size)
{
struct rt_memheap_item *item;
RT_ASSERT(memheap != RT_NULL);
/* initialize pool object */
rt_object_init(&(memheap->parent), RT_Object_Class_MemHeap, name);
memheap->start_addr = start_addr;
memheap->pool_size = RT_ALIGN_DOWN(size, RT_ALIGN_SIZE);
memheap->available_size = memheap->pool_size - (2 * RT_MEMHEAP_SIZE);
/* initialize the free list header */
item = &(memheap->free_header);
item->magic = RT_MEMHEAP_MAGIC;
item->pool_ptr = memheap;
item->next = RT_NULL;
item->prev = RT_NULL;
item->next_free = item;
item->prev_free = item;
/* set the free list to free list header */
memheap->free_list = item;
/* initialize the first big memory block */
item = (struct rt_memheap_item *)start_addr;
item->magic = RT_MEMHEAP_MAGIC;
item->pool_ptr = memheap;
item->next = RT_NULL;
item->prev = RT_NULL;
item->next_free = item;
item->prev_free = item;
item->next = (struct rt_memheap_item *)
((rt_uint8_t *)item + memheap->available_size + RT_MEMHEAP_SIZE);
item->prev = item->next;
/* block list header */
memheap->block_list = item;
/* place the big memory block to free list */
item->next_free = memheap->free_list->next_free;
item->prev_free = memheap->free_list;
memheap->free_list->next_free->prev_free = item;
memheap->free_list->next_free = item;
/* move to the end of memory pool to build a small tailer block, which prevents block merging */
item = item->next;
/* it's a used memory block */
item->magic = RT_MEMHEAP_MAGIC | RT_MEMHEAP_USED;
item->pool_ptr = memheap;
item->next = (struct rt_memheap_item *)start_addr;
item->prev = (struct rt_memheap_item *)start_addr;
/* not in free list */
item->next_free = item->prev_free = RT_NULL;
/* initialize mutex lock */
rt_mutex_init(&(memheap->lock), name, RT_IPC_FLAG_FIFO);
RT_DEBUG_LOG(RT_DEBUG_MEMHEAP,
("memory heap: start addr 0x%08x, size %d, free list header 0x%08x",
start_addr, size, &(memheap->free_header)));
return RT_EOK;
}
RTM_EXPORT(rt_memheap_init);
rt_err_t rt_memheap_detach(struct rt_memheap *heap)
{
RT_ASSERT(heap);
rt_object_detach(&(heap->lock.parent.parent));
rt_object_detach(&(heap->parent));
/* Return a successful completion. */
return RT_EOK;
}
RTM_EXPORT(rt_memheap_detach);
void *rt_memheap_alloc(struct rt_memheap *heap, rt_uint32_t size)
{
rt_err_t result;
rt_uint32_t free_size;
struct rt_memheap_item *header_ptr;
RT_ASSERT(heap != RT_NULL);
/* align allocated size */
size = RT_ALIGN(size, RT_ALIGN_SIZE);
if (size < RT_MEMHEAP_MINIALLOC)
size = RT_MEMHEAP_MINIALLOC;
RT_DEBUG_LOG(RT_DEBUG_MEMHEAP, ("allocate %d", size));
if (size < heap->available_size)
{
/* search on free list */
free_size = 0;
/* lock memheap */
result = rt_mutex_take(&(heap->lock), RT_WAITING_FOREVER);
if (result != RT_EOK)
{
rt_set_errno(result);
return RT_NULL;
}
/* get the first free memory block */
header_ptr = heap->free_list->next_free;
while (header_ptr != heap->free_list && free_size < size)
{
/* get current freed memory block size */
free_size = (rt_uint32_t)(header_ptr->next) - (rt_uint32_t)header_ptr - RT_MEMHEAP_SIZE;
if (free_size < size)
{
/* move to next free memory block */
header_ptr = header_ptr->next_free;
}
}
/* determine if the memory is available. */
if (free_size >= size)
{
/* a block that satisfies the request has been found. */
/* determine if the block needs to be split. */
if (free_size >= (size + RT_MEMHEAP_SIZE + RT_MEMHEAP_MINIALLOC))
{
struct rt_memheap_item *new_ptr;
/* split the block. */
new_ptr = (struct rt_memheap_item *)(((rt_uint8_t *)header_ptr) + size + RT_MEMHEAP_SIZE);
RT_DEBUG_LOG(RT_DEBUG_MEMHEAP,
("split: h[0x%08x] nm[0x%08x] pm[0x%08x] to n[0x%08x]",
header_ptr,
header_ptr->next,
header_ptr->prev,
new_ptr));
/* mark the new block as a memory block and freed. */
new_ptr->magic = RT_MEMHEAP_MAGIC;
/* put the pool pointer into the new block. */
new_ptr->pool_ptr = heap;
/* break down the block list */
new_ptr->prev = header_ptr;
new_ptr->next = header_ptr->next;
header_ptr->next->prev = new_ptr;
header_ptr->next = new_ptr;
/* remove header ptr from free list */
header_ptr->next_free->prev_free = header_ptr->prev_free;
header_ptr->prev_free->next_free = header_ptr->next_free;
header_ptr->next_free = RT_NULL;
header_ptr->prev_free = RT_NULL;
/* insert new_ptr to free list */
new_ptr->next_free = heap->free_list->next_free;
new_ptr->prev_free = heap->free_list;
heap->free_list->next_free->prev_free = new_ptr;
heap->free_list->next_free = new_ptr;
RT_DEBUG_LOG(RT_DEBUG_MEMHEAP, ("new ptr: nf 0x%08x, pf 0x%08x",
new_ptr->next_free,
new_ptr->prev_free));
/* decrement the available byte count. */
heap->available_size = heap->available_size - size - RT_MEMHEAP_SIZE;
}
else
{
/* decrement the entire free size from the available bytes count. */
heap->available_size = heap->available_size - free_size;
/* remove header_ptr from free list */
RT_DEBUG_LOG(RT_DEBUG_MEMHEAP,
("one block: h[0x%08x], nf 0x%08x, pf 0x%08x",
header_ptr,
header_ptr->next_free,
header_ptr->prev_free));
header_ptr->next_free->prev_free = header_ptr->prev_free;
header_ptr->prev_free->next_free = header_ptr->next_free;
header_ptr->next_free = RT_NULL;
header_ptr->prev_free = RT_NULL;
}
/* release lock */
rt_mutex_release(&(heap->lock));
/* Mark the allocated block as not available. */
header_ptr->magic |= RT_MEMHEAP_USED;
/* Return a memory address to the caller. */
RT_DEBUG_LOG(RT_DEBUG_MEMHEAP,
("am: m[0x%08x], h[0x%08x], size: %d",
(void *)((rt_uint8_t *)header_ptr + RT_MEMHEAP_SIZE),
header_ptr,
size);
return (void *)((rt_uint8_t *)header_ptr + RT_MEMHEAP_SIZE));
}
/* release lock */
rt_mutex_release(&(heap->lock));
}
RT_DEBUG_LOG(RT_DEBUG_MEMHEAP, ("allocate memory: failed\n"));
/* Return the completion status. */
return RT_NULL;
}
RTM_EXPORT(rt_memheap_alloc);
void rt_memheap_free(void *ptr)
{
rt_err_t result;
struct rt_memheap *heap;
struct rt_memheap_item *header_ptr, *new_ptr;
rt_uint32_t insert_header;
/* set initial status as OK */
insert_header = 1;
new_ptr = RT_NULL;
header_ptr = (struct rt_memheap_item *)((rt_uint8_t *)ptr - RT_MEMHEAP_SIZE);
RT_DEBUG_LOG(RT_DEBUG_MEMHEAP, ("free memory: m[0x%08x], h[0x%08x]",
ptr, header_ptr));
/* check magic */
RT_ASSERT((header_ptr->magic & RT_MEMHEAP_MASK) == RT_MEMHEAP_MAGIC);
/* get pool ptr */
heap = header_ptr->pool_ptr;
/* lock memheap */
result = rt_mutex_take(&(heap->lock), RT_WAITING_FOREVER);
if (result != RT_EOK)
{
rt_set_errno(result);
return ;
}
/* Mark the memory as available. */
header_ptr->magic &= ~RT_MEMHEAP_USED;
/* Adjust the available number of bytes. */
heap->available_size = heap->available_size +
((rt_uint32_t)(header_ptr->next) -
(rt_uint32_t)header_ptr) - RT_MEMHEAP_SIZE;
/* Determine if the block can be merged with the previous neighbor. */
if (!RT_MEMHEAP_IS_USED(header_ptr->prev))
{
RT_DEBUG_LOG(RT_DEBUG_MEMHEAP, ("merge: left node 0x%08x",
header_ptr->prev));
/* adjust the available number of bytes. */
heap->available_size = heap->available_size + RT_MEMHEAP_SIZE;
/* yes, merge block with previous neighbor. */
(header_ptr->prev)->next = header_ptr->next;
(header_ptr->next)->prev = header_ptr->prev;
/* move header pointer to previous. */
header_ptr = header_ptr->prev;
/* don't insert header to free list */
insert_header = 0;
}
/* determine if the block can be merged with the next neighbor. */
if (!RT_MEMHEAP_IS_USED(header_ptr->next))
{
/* adjust the available number of bytes. */
heap->available_size = heap->available_size + RT_MEMHEAP_SIZE;
/* merge block with next neighbor. */
new_ptr = header_ptr->next;
RT_DEBUG_LOG(RT_DEBUG_MEMHEAP,
("merge: right node 0x%08x, nf 0x%08x, pf 0x%08x",
new_ptr, new_ptr->next_free, new_ptr->prev_free));
new_ptr->next->prev = header_ptr;
header_ptr->next = new_ptr->next;
/* remove new ptr from free list */
new_ptr->next_free->prev_free = new_ptr->prev_free;
new_ptr->prev_free->next_free = new_ptr->next_free;
}
if (insert_header)
{
/* no left merge, insert to free list */
header_ptr->next_free = heap->free_list->next_free;
header_ptr->prev_free = heap->free_list;
heap->free_list->next_free->prev_free = header_ptr;
heap->free_list->next_free = header_ptr;
RT_DEBUG_LOG(RT_DEBUG_MEMHEAP,
("insert to free list: nf 0x%08x, pf 0x%08x",
header_ptr->next_free, header_ptr->prev_free));
}
/* release lock */
rt_mutex_release(&(heap->lock));
}
RTM_EXPORT(rt_memheap_free);
#endif
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