eis/inc/zlib/MemFix.hpp

/************************************************
 * Fixed element pointer position.
 * The current pointer points to the latest element
 *
 * create zoufuzhou 20201001
 *
 ************************************************/
#ifndef _MEM_FIX_ADDR_CACHE_HPP_
#define _MEM_FIX_ADDR_CACHE_HPP_

#include <glob/GlobMem.h>

template <typename T>
class CMemFix {
  typedef struct {
    unsigned int maxsize;
    unsigned int size;
    unsigned int next;
  } HEAD;

  // Local variable
 private:
  unsigned int m_getnext;

  // Memory variable
 private:
  HEAD* p_head;
  T* p_ptr;

 private:
  void init(const string& tableName) {
    char* ptr = (char*)GlobMem::GetInstancePtr()->GetTablePtr(tableName);
    if (ptr == nullptr) {
      p_ptr = nullptr;
      p_head = nullptr;

      assert(true);
      return;
    }
    p_head = (HEAD*)(ptr);
    p_ptr = (T*)(ptr + sizeof(HEAD));
  };

 public:
  // memfix get not need set cache maxsize
  CMemFix(const string& tableName) {
    this->init(tableName);
    // assert(p_head->maxsize>1);

    this->m_getnext = p_head->next;
  };

  // memfix push need set cache maxsize
  CMemFix(const string& tableName, unsigned int maxsize) {
    // assert(maxsize>1);
    this->init(tableName);

    p_head->maxsize = maxsize;
    if (p_head->size > p_head->maxsize) {
      p_head->size = p_head->maxsize;
    }

    if (p_head->next > p_head->maxsize) {
      p_head->next = p_head->maxsize;
    }
    p_head->next = p_head->next % p_head->maxsize;

    this->m_getnext = p_head->next;
  };

  ~CMemFix(){};

  T* operator()(void) { return p_ptr; };

  // Take the next value
  T* getNext() {
    if (this->m_getnext == p_head->next) {
      return nullptr;
    } else {
      unsigned int tmpnext = this->m_getnext;
      this->m_getnext = (this->m_getnext + 1) % this->p_head->maxsize;
      return this->operator[](tmpnext);
    }
  };



//   unsigned int get_next() { return this->m_getnext; }

  // Take the current latest value
  T* getCur(void) { return p_ptr + this->index_cur(); }

  unsigned int index_cur(void) {
    if (p_head->next <= 0) {
      return this->p_head->maxsize - 1;
    } else {
      return (p_head->next - 1) % this->p_head->maxsize;
    }
  }

  unsigned int max_size(void) { return this->p_head->maxsize; }

  T* operator[](unsigned int i) {
    if (p_ptr == nullptr) return nullptr;
    return p_ptr + i;
  };

  void push(T* t) {
    if (p_ptr == nullptr) return;
    if (p_head->size < this->p_head->maxsize) {
      p_head->size++;
    }

    memcpy(p_ptr + p_head->next, t, sizeof(T));
    //        cout<<"p_next:"<<p_head->next<<endl;
    p_head->next = (p_head->next + 1) % this->p_head->maxsize;
  };

  unsigned int size(void) {
    if (p_head == nullptr) return 0;
    return p_head->size;
  };

  void clear(void) {
    if (p_head == nullptr) return;
    p_head->size = 0;
    p_head->next = 0;
    this->m_getnext = p_head->next;
  };
};
#endif