Function rt_smem_realloc

src/mem.c:403–488

* @brief This function will change the size of previously allocated memory block. * * @param m the small memory management object. * * @param rmem is the pointer to memory allocated by rt_mem_alloc. * * @param newsize is the required new size. * * @return the changed memory block address. */

 * @return the changed memory block address.
 */
void *rt_smem_realloc(rt_smem_t m, void *rmem, rt_size_t newsize)
{
    rt_size_t size;
    rt_size_t ptr, ptr2;
    struct rt_small_mem_item *mem, *mem2;
    struct rt_small_mem *small_mem;
    void *nmem;

    RT_ASSERT(m != RT_NULL);
    RT_ASSERT(rt_object_get_type(&m->parent) == RT_Object_Class_Memory);
    RT_ASSERT(rt_object_is_systemobject(&m->parent));

    small_mem = (struct rt_small_mem *)m;
    /* alignment size */
    newsize = RT_ALIGN(newsize, RT_ALIGN_SIZE);
    if (newsize > small_mem->mem_size_aligned)
    {
        LOG_D("realloc: out of memory");

        return RT_NULL;
    }
    else if (newsize == 0)
    {
        rt_smem_free(rmem);
        return RT_NULL;
    }

    /* allocate a new memory block */
    if (rmem == RT_NULL)
        return rt_smem_alloc(&small_mem->parent, newsize);

    RT_ASSERT((((rt_uintptr_t)rmem) & (RT_ALIGN_SIZE - 1)) == 0);
    RT_ASSERT((rt_uint8_t *)rmem >= (rt_uint8_t *)small_mem->heap_ptr);
    RT_ASSERT((rt_uint8_t *)rmem < (rt_uint8_t *)small_mem->heap_end);

    mem = (struct rt_small_mem_item *)((rt_uint8_t *)rmem - SIZEOF_STRUCT_MEM);

    /* current memory block size */
    ptr = (rt_uint8_t *)mem - small_mem->heap_ptr;
    size = mem->next - ptr - SIZEOF_STRUCT_MEM;
    if (size == newsize)
    {
        /* the size is the same as */
        return rmem;
    }

    if (newsize + SIZEOF_STRUCT_MEM + MIN_SIZE < size)
    {
        /* split memory block */
        small_mem->parent.used -= (size - newsize);

        ptr2 = ptr + SIZEOF_STRUCT_MEM + newsize;
        mem2 = (struct rt_small_mem_item *)&small_mem->heap_ptr[ptr2];
        mem2->pool_ptr = MEM_FREED(small_mem);
        mem2->next = mem->next;
        mem2->prev = ptr;
#ifdef RT_USING_MEMTRACE
        rt_smem_setname(mem2, "    ");