[RTT例程练习] 3.2 动态内存管理之rt_realloc和free

realloc 用于重新分配内存的场景。如果原先通过 malloc分配的空间过小，则可通过realloc重新分配大小。当然具体实现的时候分两种情况，如果原内存块后有足够的空间，则之间将原内存块扩大，如果不够，则重新寻找一个地方，将原数据也拷贝至此。

代码：

#include <rtthread.h>

struct rt_thread thread1;
static rt_uint8_t thread1_stack[512];
void thread1_entry(void* parameter)
{
    int i,j = 1;
    char *ptr[10]; /* 用于放置10个分配内存块的指针*/
    /* 对指针清零*/
    for (i = 0; i <10; i ++)
    ptr[i] = RT_NULL;
    while(j--)
    {
        for (i = 0; i <10; i++)
        {
            /* 每次分配(1 <<i)大小字节数的内存空间*/
            ptr[i] = rt_malloc(10);
            /* 如果分配成功*/
            
            if (ptr[i] != RT_NULL)
            {
                rt_kprintf("get memory: 0x%x\n", ptr[i]);
                rt_realloc(ptr[i],16);
                /* 如果分配成功*/
                if (ptr[i] != RT_NULL)
                {
                    rt_kprintf("memory realloc success!\n");
                    /* 释放内存块*/
                    rt_free(ptr[i]);
                    rt_kprintf("memory free success!\n");
                    ptr[i] = RT_NULL;
                }
            }
        }
    }
}


int rt_application_init()
{
    rt_thread_init(&thread1,
        "thread1",
        thread1_entry, RT_NULL,
        &thread1_stack[0], sizeof(thread1_stack),
        10, 100);
    rt_thread_startup(&thread1);
    
    return 0;
}

结果：

get memory: 0x20000c58
memory realloc success!
memory free success!
get memory: 0x20000c58
memory realloc success!
memory free success!
get memory: 0x20000c58
memory realloc success!
memory free success!
get memory: 0x20000c58
memory realloc success!
memory free success!
get memory: 0x20000c58
memory realloc success!
memory free success!
get memory: 0x20000c58
memory realloc success!
memory free success!
get memory: 0x20000c58
memory realloc success!
memory free success!
get memory: 0x20000c58
memory realloc success!
memory free success!
get memory: 0x20000c58
memory realloc success!
memory free success!
get memory: 0x20000c58
memory realloc success!
memory free success!