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/** @file assoccontain.H
* @brief Provides a memory pool container for allocating blocks of
* associations for the device driver framework.
*
* This class exists because storing the information in a normal map or
* vector would be exceptionally big for the expected sparseness of the
* device driver associations.
*/
#ifndef __DEVICEFW_ASSOCCONTAIN_H
#define __DEVICEFW_ASSOCCONTAIN_H
#include <stdint.h>
#include <builtins.h>
namespace DeviceFW
{
/** @struct AssociationData
* @brief Data about a particular association.
*
* Typically this is a offset (pointer) to another association and an
* optional flag for the associatior to use. This allows a user to
* construct a light-weight multi-dimensional sparse array.
*
* The purpose of the flag field is left to the user.
*/
struct AssociationData
{
bool flag:1;
size_t offset:15;
AssociationData() : flag(false), offset(0) { };
AssociationData(bool i_flag, size_t i_off)
: flag(i_flag), offset(i_off) { };
} PACKED;
/** @class AssociationContainer
* @brief The memory pool container of AssociationData blocks.
*
* The typical usage of this will be to create a multi-dimensional sparse
* associative array (map). The first block allocated will be the first
* dimension of the array. Each AssociationData entry in the block is the
* offset of the block containing the AssociationData for the next
* dimension. At the lowest level this offset might be used as an offset
* into another container, such as an std::vector.
*/
class AssociationContainer
{
public:
/**
* @brief Constructor for AssociationContainer.
*
* Initializes internal members to clean values.
*/
AssociationContainer();
/**
* @brief Destructor for AssociationContainer.
*
* Releases memory associated with container. After this call
* all pointers previously obtained through operator[] are invalid.
*/
~AssociationContainer();
/**
* @brief Look up a particular association entry by offset.
* @return A pointer to the requested association block.
*
* @note Will return a NULL pointer if an invalid offset is given.
*/
AssociationData* operator[](size_t) const;
/**
* @brief Allocate a new block into the pool.
* @return A offset to the newly allocated block.
*
* The blocks allocated will all be erased to 0's.
*
* @note This function can change the pointers previously
* returned by the operator[]. Treat this function
* as though all previous pointers are invalidated.
*/
size_t allocate(size_t);
private:
AssociationData* iv_data;
size_t iv_size;
};
};
#endif
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