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/*
* Copyright 2006 The Android Open Source Project
*
* Use of this source code is governed by a BSD-style license that can be
* found in the LICENSE file.
*/
#include "SkChunkAlloc.h"
// Don't malloc any chunks smaller than this
#define MIN_CHUNKALLOC_BLOCK_SIZE 1024
// Return the new min blocksize given the current value
static size_t increase_next_size(size_t size) {
return size + (size >> 1);
}
///////////////////////////////////////////////////////////////////////////////
struct SkChunkAlloc::Block {
Block* fNext;
size_t fFreeSize;
char* fFreePtr;
// data[] follows
char* startOfData() {
return reinterpret_cast<char*>(this + 1);
}
static void FreeChain(Block* block) {
while (block) {
Block* next = block->fNext;
sk_free(block);
block = next;
}
};
bool contains(const void* addr) const {
const char* ptr = reinterpret_cast<const char*>(addr);
return ptr >= (const char*)(this + 1) && ptr < fFreePtr;
}
};
///////////////////////////////////////////////////////////////////////////////
SkChunkAlloc::SkChunkAlloc(size_t minSize) {
if (minSize < MIN_CHUNKALLOC_BLOCK_SIZE) {
minSize = MIN_CHUNKALLOC_BLOCK_SIZE;
}
fBlock = NULL;
fMinSize = minSize;
fChunkSize = fMinSize;
fTotalCapacity = 0;
fTotalUsed = 0;
fBlockCount = 0;
}
SkChunkAlloc::~SkChunkAlloc() {
this->reset();
}
void SkChunkAlloc::reset() {
Block::FreeChain(fBlock);
fBlock = NULL;
fChunkSize = fMinSize; // reset to our initial minSize
fTotalCapacity = 0;
fTotalUsed = 0;
fBlockCount = 0;
}
SkChunkAlloc::Block* SkChunkAlloc::newBlock(size_t bytes, AllocFailType ftype) {
size_t size = bytes;
if (size < fChunkSize) {
size = fChunkSize;
}
Block* block = (Block*)sk_malloc_flags(sizeof(Block) + size,
ftype == kThrow_AllocFailType ? SK_MALLOC_THROW : 0);
if (block) {
// block->fNext = fBlock;
block->fFreeSize = size;
block->fFreePtr = block->startOfData();
fTotalCapacity += size;
fBlockCount += 1;
fChunkSize = increase_next_size(fChunkSize);
}
return block;
}
void* SkChunkAlloc::alloc(size_t bytes, AllocFailType ftype) {
fTotalUsed += bytes;
bytes = SkAlign4(bytes);
Block* block = fBlock;
if (block == NULL || bytes > block->fFreeSize) {
block = this->newBlock(bytes, ftype);
if (NULL == block) {
return NULL;
}
block->fNext = fBlock;
fBlock = block;
}
SkASSERT(block && bytes <= block->fFreeSize);
char* ptr = block->fFreePtr;
block->fFreeSize -= bytes;
block->fFreePtr = ptr + bytes;
return ptr;
}
size_t SkChunkAlloc::unalloc(void* ptr) {
size_t bytes = 0;
Block* block = fBlock;
if (block) {
char* cPtr = reinterpret_cast<char*>(ptr);
char* start = block->startOfData();
if (start <= cPtr && cPtr < block->fFreePtr) {
bytes = block->fFreePtr - cPtr;
block->fFreeSize += bytes;
block->fFreePtr = cPtr;
}
}
return bytes;
}
bool SkChunkAlloc::contains(const void* addr) const {
const Block* block = fBlock;
while (block) {
if (block->contains(addr)) {
return true;
}
block = block->fNext;
}
return false;
}
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