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#pragma once
#include <stdlib.h>
class C4JMemoryPool
{
public:
unsigned int Align(unsigned int val, unsigned int align) { return int((val+(align-1))/align) * align; }
virtual void* Alloc(size_t size) = 0;
virtual void Free(void* ptr) = 0;
};
// Fast Efficient Fixed-Size Memory Pool : No Loops and No Overhead
// http://www.alogicalmind.com/memory_pools/index.htm
class C4JMemoryPoolFixed : public C4JMemoryPool
{
// Basic type define
typedef unsigned int uint;
typedef unsigned char uchar;
uint m_numOfBlocks; // Num of blocks
uint m_sizeOfEachBlock; // Size of each block
uint m_numFreeBlocks; // Num of remaining blocks
uint m_numInitialized; // Num of initialized blocks
uchar* m_memStart; // Beginning of memory pool
uchar* m_memEnd; // End of memory pool
uchar* m_next; // Num of next free block
// CRITICAL_SECTION m_CS;
public:
C4JMemoryPoolFixed()
{
m_numOfBlocks = 0;
m_sizeOfEachBlock = 0;
m_numFreeBlocks = 0;
m_numInitialized = 0;
m_memStart = NULL;
m_memEnd = NULL;
m_next = 0;
}
C4JMemoryPoolFixed(uint sizeOfEachBlock, uint numOfBlocks)
{
CreatePool(sizeOfEachBlock, numOfBlocks);
}
~C4JMemoryPoolFixed() { DestroyPool(); }
void CreatePool(uint sizeOfEachBlock, uint numOfBlocks)
{
assert(sizeOfEachBlock >= 4); // has to be at least the size of an int, for book keeping
m_numOfBlocks = numOfBlocks;
m_sizeOfEachBlock = sizeOfEachBlock;
m_numFreeBlocks = numOfBlocks;
m_numInitialized = 0;
m_memStart = new uchar[ m_sizeOfEachBlock *
m_numOfBlocks ];
m_memEnd = m_memStart + (m_sizeOfEachBlock * m_numOfBlocks);
m_next = m_memStart;
// InitializeCriticalSection(&m_CS);
}
void DestroyPool()
{
delete[] m_memStart;
m_memStart = NULL;
}
uchar* AddrFromIndex(uint i) const
{
return m_memStart + ( i * m_sizeOfEachBlock );
}
uint IndexFromAddr(const uchar* p) const
{
return (((uint)(p - m_memStart)) / m_sizeOfEachBlock);
}
virtual void* Alloc(size_t size)
{
if(size > m_sizeOfEachBlock)
return ::malloc(size);
// EnterCriticalSection(&m_CS);
if (m_numInitialized < m_numOfBlocks )
{
uint* p = (uint*)AddrFromIndex( m_numInitialized );
*p = m_numInitialized + 1;
m_numInitialized++;
}
void* ret = NULL;
if ( m_numFreeBlocks > 0 )
{
ret = (void*)m_next;
--m_numFreeBlocks;
if (m_numFreeBlocks!=0)
{
m_next = AddrFromIndex( *((uint*)m_next) );
}
else
{
m_next = NULL;
}
}
// LeaveCriticalSection(&m_CS);
return ret;
}
virtual void Free(void* ptr)
{
if(ptr < m_memStart || ptr > m_memEnd)
{
::free(ptr);
return;
}
// EnterCriticalSection(&m_CS);
if (m_next != NULL)
{
(*(uint*)ptr) = IndexFromAddr( m_next );
m_next = (uchar*)ptr;
}
else
{
*((uint*)ptr) = m_numOfBlocks;
m_next = (uchar*)ptr;
}
++m_numFreeBlocks;
// LeaveCriticalSection(&m_CS);
}
}; // End pool class
// this pool will constantly grow until it is reset (automatically when all allocs have been "freed")
class C4JMemoryPoolGrow : public C4JMemoryPool
{
uint32_t m_totalSize;
uint32_t m_memUsed;
uint32_t m_numAllocations;
uint8_t* m_pMemory;
uint32_t m_currentOffset;
public:
C4JMemoryPoolGrow(uint32_t size = 64*1024)
{
size = Align(size, 4);
m_totalSize = size;
m_pMemory = new uint8_t[size];
m_currentOffset = 0;
m_memUsed = 0;
m_numAllocations = 0;
}
virtual void* Alloc(size_t size)
{
size = Align(size, 4); // 4 byte align the memory
assert((m_currentOffset + size) < m_totalSize); // make sure we haven't ran out of space
void* returnMem = &m_pMemory[m_currentOffset]; // grab the return memory
m_currentOffset += size;
m_numAllocations++;
return returnMem;
}
virtual void Free(void* ptr)
{
m_numAllocations--;
if(m_numAllocations == 0)
m_currentOffset = 0; // reset the pool when we reach zero allocations
}
};
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