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72 lines
1.5 KiB
72 lines
1.5 KiB
// Pool memory allocator
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#ifndef __POOL_INCLUDED__
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#define __POOL_INCLUDED__
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#pragma warning(disable:4200)
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struct BLK { // block in an allocation pool
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CB cbFree;
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BYTE* pFree;
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BLK* pNext;
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BYTE buf[];
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BLK(CB cb) : cbFree(cb), pFree(buf), pNext(0) { }
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void* alloc(CB cb) {
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cb = cbAlign(cb); // Round up for alignment
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if (cb <= cbFree) {
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cbFree -= cb;
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BYTE* p = pFree;
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pFree += cb;
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return p;
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}
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return 0;
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}
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void flush() { cbFree = 0; }
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CB cb() { return pFree - buf; }
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};
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const CB cbPage = 0x1000;
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inline CB cbRoundUp(CB cb, CB cbMult) { return (cb + cbMult-1) & ~(cbMult-1); }
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inline void* __cdecl operator new(size_t size, CB cb) { return new char[size + cb]; }
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struct POOL { // allocation pool
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BLK* pHead;
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BLK* pTail;
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CB cbTotal;
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POOL() : pHead(new (0) BLK(0)), pTail(pHead), cbTotal(0) { }
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~POOL() {
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BLK* pNext;
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for (BLK* pblk = pHead; pblk; pblk = pNext) {
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pNext = pblk->pNext;
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delete pblk;
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}
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}
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void* alloc(CB cb) {
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cb = cbAlign(cb); // Round up for alignment
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void* p = pTail->alloc(cb);
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if (!p) {
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CB cbAlloc = cbRoundUp(cb + cbPage, cbPage);
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if (pTail->pNext = new (cbAlloc) BLK(cbAlloc)) {
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pTail = pTail->pNext;
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p = pTail->alloc(cb);
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}
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}
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if (p)
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cbTotal += cb;
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return p;
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}
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void discard(CB cb) {
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cbTotal -= cb;
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}
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void blkFlush() { dassert(pTail); pTail->flush(); }
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CB cb() { return cbTotal; }
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private:
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POOL(const POOL&) { assert(0); } // error to copy a pool
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};
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inline void* __cdecl operator new(size_t size, POOL& pool) { return pool.alloc(size); }
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#endif // !__POOL_INCLUDED__
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