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/*
* Copyright 2010 Google Inc.
*
* Use of this source code is governed by a BSD-style license that can be
* found in the LICENSE file.
*/
#ifndef GrAllocator_DEFINED
#define GrAllocator_DEFINED
#include "GrConfig.h"
#include "GrTArray.h"
class GrAllocator {
public:
virtual ~GrAllocator() {
reset();
}
/**
* Create an allocator
*
* @param itemSize the size of each item to allocate
* @param itemsPerBlock the number of items to allocate at once
* @param initialBlock optional memory to use for the first block.
* Must be at least itemSize*itemsPerBlock sized.
* Caller is responsible for freeing this memory.
*/
GrAllocator(size_t itemSize, int itemsPerBlock, void* initialBlock) :
fBlocks(fBlockInitialStorage, NUM_INIT_BLOCK_PTRS),
fItemSize(itemSize),
fItemsPerBlock(itemsPerBlock),
fOwnFirstBlock(NULL == initialBlock),
fCount(0) {
GrAssert(itemsPerBlock > 0);
fBlockSize = fItemSize * fItemsPerBlock;
fBlocks.push_back() = initialBlock;
GR_DEBUGCODE(if (!fOwnFirstBlock) {*((char*)initialBlock+fBlockSize-1)='a';} );
}
/**
* Adds an item and returns pointer to it.
*
* @return pointer to the added item.
*/
void* push_back() {
int indexInBlock = fCount % fItemsPerBlock;
// we always have at least one block
if (0 == indexInBlock) {
if (0 != fCount) {
fBlocks.push_back() = GrMalloc(fBlockSize);
} else if (fOwnFirstBlock) {
fBlocks[0] = GrMalloc(fBlockSize);
}
}
void* ret = (char*)fBlocks[fCount/fItemsPerBlock] +
fItemSize * indexInBlock;
++fCount;
return ret;
}
/**
* removes all added items
*/
void reset() {
int blockCount = GrMax((unsigned)1,
GrUIDivRoundUp(fCount, fItemsPerBlock));
for (int i = 1; i < blockCount; ++i) {
GrFree(fBlocks[i]);
}
if (fOwnFirstBlock) {
GrFree(fBlocks[0]);
fBlocks[0] = NULL;
}
fBlocks.pop_back_n(blockCount-1);
fCount = 0;
}
/**
* count of items
*/
int count() const {
return fCount;
}
/**
* is the count 0
*/
bool empty() const { return fCount == 0; }
/**
* access last item, only call if count() != 0
*/
void* back() {
GrAssert(fCount);
return (*this)[fCount-1];
}
/**
* access last item, only call if count() != 0
*/
const void* back() const {
GrAssert(fCount);
return (*this)[fCount-1];
}
/**
* access item by index.
*/
void* operator[] (int i) {
GrAssert(i >= 0 && i < fCount);
return (char*)fBlocks[i / fItemsPerBlock] +
fItemSize * (i % fItemsPerBlock);
}
/**
* access item by index.
*/
const void* operator[] (int i) const {
GrAssert(i >= 0 && i < fCount);
return (const char*)fBlocks[i / fItemsPerBlock] +
fItemSize * (i % fItemsPerBlock);
}
private:
static const int NUM_INIT_BLOCK_PTRS = 8;
GrTArray<void*> fBlocks;
size_t fBlockSize;
char fBlockInitialStorage[NUM_INIT_BLOCK_PTRS*sizeof(void*)];
size_t fItemSize;
int fItemsPerBlock;
bool fOwnFirstBlock;
int fCount;
};
template <typename T>
class GrTAllocator {
private:
GrAllocator fAllocator;
public:
virtual ~GrTAllocator() {};
/**
* Create an allocator
*
* @param itemsPerBlock the number of items to allocate at once
* @param initialBlock optional memory to use for the first block.
* Must be at least size(T)*itemsPerBlock sized.
* Caller is responsible for freeing this memory.
*/
GrTAllocator(int itemsPerBlock, void* initialBlock)
: fAllocator(sizeof(T), itemsPerBlock, initialBlock) {}
/**
* Create an allocator using a GrAlignedTAlloc as the initial block.
*
* @param initialBlock specifies the storage for the initial block
* and the size of subsequent blocks.
*/
template <int N>
GrTAllocator(GrAlignedSTStorage<N,T>* initialBlock)
: fAllocator(sizeof(T), N, initialBlock->get()) {}
/**
* Adds an item and returns it.
*
* @return the added item.
*/
T& push_back() {
void* item = fAllocator.push_back();
GrAssert(NULL != item);
new (item) T;
return *(T*)item;
}
/**
* removes all added items
*/
void reset() {
int c = fAllocator.count();
for (int i = 0; i < c; ++i) {
((T*)fAllocator[i])->~T();
}
fAllocator.reset();
}
/**
* count of items
*/
int count() const {
return fAllocator.count();
}
/**
* is the count 0
*/
bool empty() const { return fAllocator.empty(); }
/**
* access last item, only call if count() != 0
*/
T& back() {
return *(T*)fAllocator.back();
}
/**
* access last item, only call if count() != 0
*/
const T& back() const {
return *(const T*)fAllocator.back();
}
/**
* access item by index.
*/
T& operator[] (int i) {
return *(T*)(fAllocator[i]);
}
/**
* access item by index.
*/
const T& operator[] (int i) const {
return *(const T*)(fAllocator[i]);
}
};
#endif
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