storage.c

/*************************************************************************
	> File Name: storage.c
	> Author: weapon
	> Mail: hongweichen8888@sina.com
	> Created Time: 2016年07月16日 星期六 14时58分39秒
 ************************************************************************/

#include <stdio.h>
#include <stdlib.h>
#include <assert.h>
#include "memory.h"

typedef union {
    long        l_dummy;
    double      d_dummy;
    void        *p_dummy;
} Cell;

#define CELL_SIZE               (sizeof(Cell))
#define DEFAULT_PAGE_SIZE       (1024)  /* cell num */

typedef struct MemoryPage_tag MemoryPage;
typedef MemoryPage *MemoryPageList;

//内存页 每个页里有很多 cell
struct MemoryPage_tag {
    int                 cell_num;       //cell的数量
    int                 use_cell_num;   //被使用的cell的数量
    MemoryPageList      next;           //下一页
    Cell                cell[1];        //实际的提供外面使用的内存块
};

struct MEM_Storage_tag {
    MemoryPageList      page_list;      //storage的内存页列表
    int                 current_page_size;//每个页的页大小
};

#define larger(a, b) (((a) > (b)) ? (a) : (b))

MEM_Storage MEM_open_storage_func(MEM_Controller controller, char *filename, int line, int page_size) {
    MEM_Storage storage;

    storage = MEM_malloc_func(controller, filename, line,
                              sizeof(struct MEM_Storage_tag));
    storage->page_list = NULL;
    assert(page_size >= 0);
    if (page_size > 0) {
        storage->current_page_size = page_size;
    } else {
        storage->current_page_size = DEFAULT_PAGE_SIZE;
    }

    return storage;
}

void *MEM_storage_malloc_func(MEM_Controller controller, char *filename, int line, MEM_Storage storage, size_t size) {
    int                 cell_num;
    MemoryPage          *new_page;
    void                *p;

    cell_num = ((size - 1) / CELL_SIZE) + 1;

    if (storage->page_list != NULL
        && (storage->page_list->use_cell_num + cell_num < storage->page_list->cell_num)) {

        p = &(storage->page_list->cell[storage->page_list->use_cell_num]);
        storage->page_list->use_cell_num += cell_num;
    } else {
        int     alloc_cell_num;

        alloc_cell_num = larger(cell_num, storage->current_page_size);

        new_page = MEM_malloc_func(controller, filename, line, sizeof(MemoryPage) + CELL_SIZE * (alloc_cell_num - 1));
        new_page->next = storage->page_list;
        new_page->cell_num = alloc_cell_num;
        storage->page_list = new_page;

        p = &(new_page->cell[0]);
        new_page->use_cell_num = cell_num;
    }

    return p;
}

void MEM_dispose_storage_func(MEM_Controller controller, MEM_Storage storage) {
    MemoryPage  *temp;

    while (storage->page_list) {
        temp = storage->page_list->next;
        MEM_free_func(controller, storage->page_list);
        storage->page_list = temp;
    }
    MEM_free_func(controller, storage);
}