Aizu Advent Calendar 2013 - 2.c

enum memory_manager_constants {
    MAX_MEM_NODE_NUM = 4096,
    MEM_INFO_STATE_LOST = -1,
    MEM_INFO_STATE_FREE,
    MEM_INFO_STATE_ALLOC,
};


/* 管理対象のメモリ情報 */
struct memory_info {
    uint32_t base_addr, size;
    uint8_t state;
};
typedef struct memory_info Memory_info;


/* メモリ管理を行うオブジェクト */
struct memory_manager {
    uint32_t exist_info_num, lost_size, lost_times;
    Dlinked_list_node mem_lst;
};
typedef struct memory_manager Memory_manager;

/* grubから渡されるデータ */
struct multiboot_mmap {
    uint32_t size;
    uint64_t addr;
    uint64_t len;
    uint32_t type;
};
typedef struct multiboot_mmap Multiboot_memory_map;


static inline void init_memory_list(void) {
    dlst_nodes = (struct dlinked_list_node*)(get_kernel_end_addr() + sizeof(Memory_manager));
    mem_info = (Memory_info*)(dlst_nodes + sizeof(struct dlinked_list_node) * MAX_MEM_NODE_NUM);

    for (int i = 0; i < MAX_MEM_NODE_NUM; ++i) {
        // 各ノードにメモリ情報を付加
        // この時点でメモリの先頭と末尾は何も指していない
        init(&dlst_nodes[i], mem_info + i);
        memset(mem_info + i, 0, sizeof(Memory_info));
    }
}


static inline void set_meminfo(Multiboot_memory_map* mmap, Memory_info* mi) {
    mi->base_addr = mmap->addr;
    mi->size = mmap->len;
    mi->state = (mmap->type == MULTIBOOT_MEMORY_AVAILABLE) ? MEM_INFO_STATE_FREE : MEM_INFO_STATE_ALLOC;
}


void init_memory(Multiboot_memory_map* mmap, size_t mmap_len) {
    Multiboot_memory_map* limit = (Multiboot_memory_map*)((uint32_t)mmap + mmap_len);

    init_memory_list();

    // マネージャにカーネル領域末尾を使用
    mem_manager = (Memory_manager*)get_kernel_end_addr();
    mem_manager->mem_lst = &dlst_nodes[0];
    mem_manager->exist_info_num = 1;
    mem_manager->lost_times = 0;
    mem_manager->lost_size = 0;

    set_meminfo(mmap, mem_manager->mem_lst->data);

    Dlinked_list_node tdl = mem_manager->mem_lst;

    while (mmap < limit) {
        // 次の要素へ
        mmap = (Multiboot_memory_map*)((uint32_t)mmap + sizeof(mmap->size) + mmap->size);

        Dlinked_list_node dl = get_new_memory_list_node();
        Memory_info* mi = dl->data;

        set_meminfo(mmap, mi);

        tdl = insert_tail(tdl, dl);
    }

    // allocate kernel area
    Dlinked_list_node ka_node = mem_manager->mem_lst;
    Memory_info* ka_mi = ka_node->data;
    const uint32_t ka_start_addr = get_kernel_start_addr();
    const uint32_t ka_end_addr = get_kernel_end_addr() + (uint32_t)mem_info + sizeof(Memory_info) * MAX_MEM_NODE_NUM;
    const uint32_t ka_size = ka_end_addr - ka_start_addr;

    while (ka_node->tail != DUMMY) {
        if (ka_mi->base_addr <= ka_start_addr && ka_end_addr <= (ka_mi->base_addr + ka_mi->size)) {
            break;
        }

        ka_node = ka_node->tail;
        ka_mi = ka_node->data;
    }

    if (ka_mi->base_addr == ka_start_addr && (ka_mi->base_addr + ka_mi->size) == ka_end_addr) {
        ka_mi->state = MEM_INFO_STATE_ALLOC;
        return;
    }

    if (ka_mi->base_addr == ka_start_addr) {
        ka_mi->size = ka_size;
        ka_mi->state = MEM_INFO_STATE_ALLOC;

        Dlinked_list_node ka_new_node = get_new_memory_list_node();
        Memory_info* ka_new_mi = ka_new_node->data;

        ka_new_mi->base_addr = ka_mi->base_addr + ka_size;
        ka_new_mi->size = ka_mi->size - ka_size;
        ka_new_mi->state = MEM_INFO_STATE_FREE;

        insert_tail(ka_node, ka_new_node);
    } else {
        // TODO
    }
}