哥们内存分配 - 主要功能

进出口新的C++，我发现哥们系统内存分配的这个代码，但没有主函数，所有成员函数是正确的，我希望你们帮我主要的功能，我想分配一些内存，然后显示了存储空间的状态之前和分配之后，再解除分配内存以验证哥们正在合并，并显示空闲块列表哥们内存分配 - 主要功能

--BuddyPool.h--

#ifndef BUDDYPOOL_INC 
#define BUDDYPOOL_INC 

class BuddyPool{ 
public: 
    enum Status { free, reserved }; 
    struct Header 
    { 
     Status status: 1; 
     //unsigned int k : bitsizeof(unsigned int) - 1U; 
     unsigned int k : 31; 
    }; 
    struct Block : public Header 
    { 
     //enum { size = 16 }; 

     enum { size = 64 }; 
     struct Links 
     { 
      Block *next; 
      Block *prev; 
     }; 
     union 
     { 
      Links link; 
      char userPart [size - sizeof(Header)]; 
     }; 
    }; 

private: 
    unsigned int m; 
    unsigned int numberOfBlocks; 
    Block *pool; 
    Block *sentinel; 

    static void Unlink(Block &); 
    static void InsertAfter(Block &, Block &); 
    Block &Buddy(Block &) const; 

public: 
    BuddyPool(size_t); 
    ~BuddyPool(); 

    void *Acquire(size_t); 
    void Release(void *); 
}; 

#endif /* ----- #ifndef BUDDYPOOL_INC ----- */

--BuddyPool.cpp--

#include <WinDef.h> 
#include "BuddyPool.h" 

unsigned int Log2Ceil(unsigned int val){ 
    unsigned int L; 
    for (L = 0; (1ul<<L) < val; L++); 
    return L; 
} 

BuddyPool::BuddyPool(size_t bytes) 
    : m(Log2Ceil(bytes)) 
    , numberOfBlocks((1 << m)/sizeof(Block)) 
    , pool (new Block[numberOfBlocks + m +1]) 
    , sentinel(pool + numberOfBlocks) 
{ 
    for (unsigned int i = 0; i <= m; ++i) { 
     sentinel[i].link.next = &sentinel[i]; 
     sentinel[i].link.prev = &sentinel[i]; 
    } 

    Block &head = pool[0]; 
    head.status = free; 
    head.k = m; 
    InsertAfter(sentinel[m], head); 
} 

BuddyPool::~BuddyPool(){ 
    delete [] pool; 
} 

void *BuddyPool::Acquire(size_t bytes){ 
    unsigned int kPrime = Log2Ceil(bytes + sizeof(Header)); 

    unsigned int i = kPrime; 
    while (i <= m && sentinel[i].link.next == &sentinel[i]) { 
     ++i; 
    } 
    if (i > m) { 
     return NULL; // throw bad_alloc("out of memory"); 
    } 

    Block &block = *sentinel[i].link.next; 
    Unlink(block); 
    while (block.k > kPrime) { 
     block.k -= 1; 
     Block &buddy = Buddy(block); 
     buddy.status = free; 
     buddy.k = block.k; 
     InsertAfter(sentinel[buddy.k], buddy); 
    } 
    block.status = reserved; 
    return block.userPart; 
} 

void BuddyPool::Release(void *arg){ 
    Block &block = *reinterpret_cast<Block *>(
               reinterpret_cast<Header *>(arg) - 1U); 

    if (&block < pool || &block >= pool + numberOfBlocks) { 
     return; // throw invalid_argument("invalid pointer"); 
    } 

    block.status = free; 
    Block *ptr; 
    for (ptr = &block; ptr->k < m; ptr->k += 1) { 
     Block &buddy = Buddy(*ptr); 
     if (buddy.status == reserved || buddy.k != ptr->k) { 
      break; 
     } 
     Unlink(buddy); 
     if (&buddy < ptr) { 
      ptr = &buddy; 
     } 
    } 

    InsertAfter(sentinel[ptr->k], *ptr); 
} 

BuddyPool::Block &BuddyPool::Buddy(Block &block) const{ 
    unsigned int addr = reinterpret_cast<unsigned int>(&block) + (1 << block.k); 
    return *(reinterpret_cast<Block *>(addr)); 
} 

void BuddyPool::Unlink(Block &block){ 
    if (block.link.next) { 
     block.link.next->link.prev = block.link.prev; 
    } 
    if (block.link.prev) { 
     block.link.prev->link.next = block.link.next; 
    } 
    block.link.next = block.link.prev = &block; 
} 

void BuddyPool::InsertAfter(Block &src, Block &block){ 
    block.link.next = src.link.next; 
    block.link.prev = &src; 

    if (src.link.next) { 
     src.link.next->link.prev = &block; 
    } 
    src.link.next = &block; 
}

来源

2013-02-22 user2098877

你可以从调用公共函数开始。

可视化的内部活动还是比较有点困难。对此没有简短的回答。对于一些语言，比如python，有可视化器，甚至是在线可视化器，但是对于C++来说，这就像是要求SO读者为你开发你的应用程序一样... l

更高级的用法：分配器类（请参见std::allocator），然后您可以使用它分配和释放例如一个std::vector。

和/或可以定义operator new和operator delete对于某些类

（分别为单一对象分配和dellocation功能）

来源

2013-02-22 10:48:09

哥们内存分配 - 主要功能

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