如何在C中为通用内存池在指针之间自由转换?

我开始实现一个通用内存池。这是为了学习,所以,肯定有很多错误。但是,我在向前走。现在我被一个新的部分绊倒了。首先,代码

#include <stdlib.h>
#include <string.h>
#include <stddef.h>
#include <stdint.h>
#include <stdio.h>

typedef enum { FALSE, TRUE } BOOL;

typedef struct mem_block {
    uint8_t* data;
    size_t block_size;
    size_t pool_position;
    BOOL is_freed;
} mem_block;

typedef struct mem_pool {
    mem_block* blocks;
    size_t index;
    size_t pool_size;
} mem_pool;

mem_pool *pool_init() {
    mem_pool *pool = (mem_pool *) malloc(sizeof(mem_pool));
    pool->pool_size = (size_t) 128;
    mem_block* blk = (mem_block *) malloc(pool->pool_size * sizeof (mem_block));
    pool->index = 0;
    pool->blocks = blk;

    return pool;
}

void *pool_allocate(mem_pool **pool, size_t size) {
    mem_pool* _pool = *pool;
    size_t free_portion = _pool->pool_size - _pool->index;

    if(size < free_portion){
        mem_block* allocated_blk = _pool->blocks + _pool->index;
        uint8_t* data = (uint8_t*) malloc(size * sizeof(uint8_t));
        allocated_blk->data = data;
        allocated_blk->block_size = size;
        allocated_blk->is_freed = FALSE;
        allocated_blk->pool_position = _pool->index;
        _pool->index += size; 
        return (void *) allocated_blk->data;
    }
    else{
        printf("Pool is out of memory");
        return NULL;
    }
}

/*void pool_free(mem_pool **pool, void *block) {
    mem_block* cur = (mem_block*) block;
    mem_block* next = cur + 1;
    // override the unneeded memory
memmove(cur, next, (*pool)->pool_size - next->pool_position);
}*/

typedef struct complex {
    double i;
    double r;
} complex;

mem_pool *GLOBAL_POOL = pool_init();
int main() {
    complex *c1 = (complex *) pool_allocate(&GLOBAL_POOL, sizeof(complex));
    c1->r = 1.0;
    c1->i = 2.0;
    printf("Value is (%f + %fi)\n", c1->r, c1->i);
    printf("Remaining free size is %ld\n", GLOBAL_POOL->pool_size -   GLOBAL_POOL->index);

    complex *c2 = (complex *) pool_allocate(&GLOBAL_POOL, sizeof(complex));
    c2->r = 2.0;
    c2->i = 3.0;
    printf("Value is (%f + %fi)\n", c2->r, c2->i);
    printf("Remaining free size is %ld\n", GLOBAL_POOL->pool_size - GLOBAL_POOL->index);

    mem_block* cur = (mem_block *) &c2;
    printf("Position of c2 is %ld\n", cur->pool_position);
    printf("Adress of c2's block is %x\n", cur);
    printf("Address of c2 is %x\n", &c2);
    printf("c2 points to %x\n", c2);

    complex *c3 = (complex *) pool_allocate(&GLOBAL_POOL, sizeof(complex));
    c3->r = 3.0;
    c3->i = 4.0;
    printf("Value is (%f + %fi)\n", c3->r, c3->i);
    printf("Remaining free size is %ld\n", GLOBAL_POOL->pool_size - GLOBAL_POOL->index);

    cur = (mem_block *) &c3;
    printf("Position of c3 is %ld\n", cur->pool_position);
    printf("Adress of c3's block is %x\n", cur);
    printf("Address of c3 is %x\n", &c3);
    printf("c3 points to %x\n", c3);

    complex *c4 = (complex *) pool_allocate(&GLOBAL_POOL, sizeof(complex));
    c4->r = 4.0;
    c4->i = 5.0;
    printf("Value is (%f + %fi)\n", c4->r, c4->i);
    printf("Remaining free size is %ld\n", GLOBAL_POOL->pool_size - GLOBAL_POOL->index);

    complex *c5 = (complex *) pool_allocate(&GLOBAL_POOL, sizeof(complex));
    c5->r = 5.0;
    c5->i = 6.0;
    printf("Value is (%f + %fi)\n", c5->r, c5->i);
    printf("Remaining free size is %ld\n", GLOBAL_POOL->pool_size - GLOBAL_POOL->index);

    complex *c6 = (complex *) pool_allocate(&GLOBAL_POOL, sizeof(complex));
    c6->r = 6.0;
    c6->i = 7.0;
    printf("Value is (%f + %fi)\n", c6->r, c6->i);
    printf("Remaining free size is %ld\n", GLOBAL_POOL->pool_size - GLOBAL_POOL->index);

    complex *c7 = (complex *) pool_allocate(&GLOBAL_POOL, sizeof(complex));
    c7->r = 7.0;
    c7->i = 8.0;
    printf("Value is (%f + %fi)\n", c7->r, c7->i);
    printf("Remaining free size is %ld\n", GLOBAL_POOL->pool_size - GLOBAL_POOL->index);

    complex *c8 = (complex *) pool_allocate(&GLOBAL_POOL, sizeof(complex));
    if(c8 != NULL) {
        c8->r = 3.0;
        c8->i = 4.0;
        printf("Value is (%f + %fi)\n", c8->r, c8->i);
    }else {
        return -1;   
    }
    return 0;
}

目前,它的大小是128字节,但一旦我得到了基本的,我会使它的大小无限。分配可能工作正常,您可以看到输出,并看到我可以设置分配的指针和使用值。除此之外,我还想实现 free pool_free . 执行 memmove ,我需要知道 mem_block 我正在删除。

在 pool_allocate ,您可以看到我返回 data malloc 内存块 数据 .

mem_block* cur = (mem_block *) &c3;
printf("Position of c3 is %ld\n", cur->pool_position);
printf("Adress of c3's block is %x\n", cur);
printf("Address of c3 is %x\n", &c3);
printf("c3 points to %x\n", c3);

c3 这里是用 池分配 以及指向数据的指针, uint8_t* complex * 待使用。所以呢 c3级 指向 complex 对象。解引用应该给出实际的数据,我认为这是可行的。但它也有自己的地址。我想这个地址和 数据 其块的指针,因为它是 . 所以我把它随便丢给了一个 mem_block*

printf("Position of c3 is %ld\n", cur->pool_position);

说 Position of c3 is 0 或者其他胡言乱语。我希望看到像16,32等东西,因为每一个 是16字节。那么,为什么你认为演员们

mem_block* cur = (mem_block *) &c3;

不让我和你一起工作 好像是一个 内存块 ? 也许我没有通过引用正确地传递指针,所以指向的东西的更改在外面看不到?这似乎不太可能,因为我可以按预期处理分配的对象,但谁知道呢?我检查了每一部分,但仍然不能解决问题。