ddnet/src/engine/shared/memheap.cpp

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/* (c) Magnus Auvinen. See licence.txt in the root of the distribution for more information. */
/* If you are missing that file, acquire a complete release at teeworlds.com. */
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#include "memheap.h"
#include <base/system.h>
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#include <cstdint>
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// allocates a new chunk to be used
void CHeap::NewChunk()
{
CChunk *pChunk;
char *pMem;
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// allocate memory
pMem = (char *)malloc(sizeof(CChunk) + CHUNK_SIZE);
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if(!pMem)
return;
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// the chunk structure is located in the beginning of the chunk
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// init it and return the chunk
pChunk = (CChunk *)pMem;
pChunk->m_pMemory = (char *)(pChunk + 1);
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pChunk->m_pCurrent = pChunk->m_pMemory;
pChunk->m_pEnd = pChunk->m_pMemory + CHUNK_SIZE;
pChunk->m_pNext = (CChunk *)0x0;
pChunk->m_pNext = m_pCurrent;
m_pCurrent = pChunk;
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}
//****************
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void *CHeap::AllocateFromChunk(unsigned int Size, unsigned Alignment)
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{
char *pMem;
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size_t Offset = reinterpret_cast<uintptr_t>(m_pCurrent->m_pCurrent) % Alignment;
if(Offset)
Offset = Alignment - Offset;
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// check if we need can fit the allocation
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if(m_pCurrent->m_pCurrent + Offset + Size > m_pCurrent->m_pEnd)
return (void *)0x0;
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// get memory and move the pointer forward
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pMem = m_pCurrent->m_pCurrent + Offset;
m_pCurrent->m_pCurrent += Offset + Size;
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return pMem;
}
// creates a heap
CHeap::CHeap()
{
m_pCurrent = 0x0;
Reset();
}
CHeap::~CHeap()
{
Clear();
}
void CHeap::Reset()
{
Clear();
NewChunk();
}
// destroys the heap
void CHeap::Clear()
{
CChunk *pChunk = m_pCurrent;
CChunk *pNext;
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while(pChunk)
{
pNext = pChunk->m_pNext;
free(pChunk);
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pChunk = pNext;
}
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m_pCurrent = 0x0;
}
//
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void *CHeap::Allocate(unsigned Size, unsigned Alignment)
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{
char *pMem;
// try to allocate from current chunk
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pMem = (char *)AllocateFromChunk(Size, Alignment);
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if(!pMem)
{
// allocate new chunk and add it to the heap
NewChunk();
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// try to allocate again
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pMem = (char *)AllocateFromChunk(Size, Alignment);
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}
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return pMem;
}