michael@0: /*
michael@0:  * Copyright 2010 Google Inc.
michael@0:  *
michael@0:  * Use of this source code is governed by a BSD-style license that can be
michael@0:  * found in the LICENSE file.
michael@0:  */
michael@0: 
michael@0: #include "GrAllocPool.h"
michael@0: 
michael@0: #include "GrTypes.h"
michael@0: 
michael@0: #define GrAllocPool_MIN_BLOCK_SIZE      ((size_t)128)
michael@0: 
michael@0: struct GrAllocPool::Block {
michael@0:     Block*  fNext;
michael@0:     char*   fPtr;
michael@0:     size_t  fBytesFree;
michael@0:     size_t  fBytesTotal;
michael@0: 
michael@0:     static Block* Create(size_t size, Block* next) {
michael@0:         SkASSERT(size >= GrAllocPool_MIN_BLOCK_SIZE);
michael@0: 
michael@0:         Block* block = (Block*)sk_malloc_throw(sizeof(Block) + size);
michael@0:         block->fNext = next;
michael@0:         block->fPtr = (char*)block + sizeof(Block);
michael@0:         block->fBytesFree = size;
michael@0:         block->fBytesTotal = size;
michael@0:         return block;
michael@0:     }
michael@0: 
michael@0:     bool canAlloc(size_t bytes) const {
michael@0:         return bytes <= fBytesFree;
michael@0:     }
michael@0: 
michael@0:     void* alloc(size_t bytes) {
michael@0:         SkASSERT(bytes <= fBytesFree);
michael@0:         fBytesFree -= bytes;
michael@0:         void* ptr = fPtr;
michael@0:         fPtr += bytes;
michael@0:         return ptr;
michael@0:     }
michael@0: 
michael@0:     size_t release(size_t bytes) {
michael@0:         SkASSERT(bytes > 0);
michael@0:         size_t free = GrMin(bytes, fBytesTotal - fBytesFree);
michael@0:         fBytesFree += free;
michael@0:         fPtr -= free;
michael@0:         return bytes - free;
michael@0:     }
michael@0: 
michael@0:     bool empty() const { return fBytesTotal == fBytesFree; }
michael@0: };
michael@0: 
michael@0: ///////////////////////////////////////////////////////////////////////////////
michael@0: 
michael@0: GrAllocPool::GrAllocPool(size_t blockSize) {
michael@0:     fBlock = NULL;
michael@0:     fMinBlockSize = GrMax(blockSize, GrAllocPool_MIN_BLOCK_SIZE);
michael@0:     SkDEBUGCODE(fBlocksAllocated = 0;)
michael@0: }
michael@0: 
michael@0: GrAllocPool::~GrAllocPool() {
michael@0:     this->reset();
michael@0: }
michael@0: 
michael@0: void GrAllocPool::reset() {
michael@0:     this->validate();
michael@0: 
michael@0:     Block* block = fBlock;
michael@0:     while (block) {
michael@0:         Block* next = block->fNext;
michael@0:         sk_free(block);
michael@0:         block = next;
michael@0:     }
michael@0:     fBlock = NULL;
michael@0:     SkDEBUGCODE(fBlocksAllocated = 0;)
michael@0: }
michael@0: 
michael@0: void* GrAllocPool::alloc(size_t size) {
michael@0:     this->validate();
michael@0: 
michael@0:     if (!fBlock || !fBlock->canAlloc(size)) {
michael@0:         size_t blockSize = GrMax(fMinBlockSize, size);
michael@0:         fBlock = Block::Create(blockSize, fBlock);
michael@0:         SkDEBUGCODE(fBlocksAllocated += 1;)
michael@0:     }
michael@0:     return fBlock->alloc(size);
michael@0: }
michael@0: 
michael@0: void GrAllocPool::release(size_t bytes) {
michael@0:     this->validate();
michael@0: 
michael@0:     while (bytes && NULL != fBlock) {
michael@0:         bytes = fBlock->release(bytes);
michael@0:         if (fBlock->empty()) {
michael@0:             Block* next = fBlock->fNext;
michael@0:             sk_free(fBlock);
michael@0:             fBlock = next;
michael@0:             SkDEBUGCODE(fBlocksAllocated -= 1;)
michael@0:         }
michael@0:     }
michael@0: }
michael@0: 
michael@0: #ifdef SK_DEBUG
michael@0: 
michael@0: void GrAllocPool::validate() const {
michael@0:     Block* block = fBlock;
michael@0:     int count = 0;
michael@0:     while (block) {
michael@0:         count += 1;
michael@0:         block = block->fNext;
michael@0:     }
michael@0:     SkASSERT(fBlocksAllocated == count);
michael@0: }
michael@0: 
michael@0: #endif