reed@android.com | 8a1c16f | 2008-12-17 15:59:43 +0000 | [diff] [blame^] | 1 | /* libs/corecg/SkChunkAlloc.cpp |
| 2 | ** |
| 3 | ** Copyright 2006, The Android Open Source Project |
| 4 | ** |
| 5 | ** Licensed under the Apache License, Version 2.0 (the "License"); |
| 6 | ** you may not use this file except in compliance with the License. |
| 7 | ** You may obtain a copy of the License at |
| 8 | ** |
| 9 | ** http://www.apache.org/licenses/LICENSE-2.0 |
| 10 | ** |
| 11 | ** Unless required by applicable law or agreed to in writing, software |
| 12 | ** distributed under the License is distributed on an "AS IS" BASIS, |
| 13 | ** WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| 14 | ** See the License for the specific language governing permissions and |
| 15 | ** limitations under the License. |
| 16 | */ |
| 17 | |
| 18 | #include "SkChunkAlloc.h" |
| 19 | |
| 20 | struct SkChunkAlloc::Block { |
| 21 | Block* fNext; |
| 22 | size_t fFreeSize; |
| 23 | char* fFreePtr; |
| 24 | // data[] follows |
| 25 | |
| 26 | void freeChain() { // this can be null |
| 27 | Block* block = this; |
| 28 | while (block) { |
| 29 | Block* next = block->fNext; |
| 30 | sk_free(block); |
| 31 | block = next; |
| 32 | } |
| 33 | }; |
| 34 | |
| 35 | Block* tail() { |
| 36 | Block* block = this; |
| 37 | if (block) { |
| 38 | for (;;) { |
| 39 | Block* next = block->fNext; |
| 40 | if (NULL == next) { |
| 41 | break; |
| 42 | } |
| 43 | block = next; |
| 44 | } |
| 45 | } |
| 46 | return block; |
| 47 | } |
| 48 | }; |
| 49 | |
| 50 | SkChunkAlloc::SkChunkAlloc(size_t minSize) |
| 51 | : fBlock(NULL), fMinSize(SkAlign4(minSize)), fPool(NULL), fTotalCapacity(0) |
| 52 | { |
| 53 | } |
| 54 | |
| 55 | SkChunkAlloc::~SkChunkAlloc() { |
| 56 | this->reset(); |
| 57 | } |
| 58 | |
| 59 | void SkChunkAlloc::reset() { |
| 60 | fBlock->freeChain(); |
| 61 | fBlock = NULL; |
| 62 | fPool->freeChain(); |
| 63 | fPool = NULL; |
| 64 | fTotalCapacity = 0; |
| 65 | } |
| 66 | |
| 67 | void SkChunkAlloc::reuse() { |
| 68 | if (fPool && fBlock) { |
| 69 | fPool->tail()->fNext = fBlock; |
| 70 | } |
| 71 | fPool = fBlock; |
| 72 | fBlock = NULL; |
| 73 | fTotalCapacity = 0; |
| 74 | } |
| 75 | |
| 76 | SkChunkAlloc::Block* SkChunkAlloc::newBlock(size_t bytes, AllocFailType ftype) { |
| 77 | Block* block = fPool; |
| 78 | |
| 79 | if (block && bytes <= block->fFreeSize) { |
| 80 | fPool = block->fNext; |
| 81 | return block; |
| 82 | } |
| 83 | |
| 84 | size_t size = SkMax32((int32_t)bytes, (int32_t)fMinSize); |
| 85 | |
| 86 | block = (Block*)sk_malloc_flags(sizeof(Block) + size, |
| 87 | ftype == kThrow_AllocFailType ? SK_MALLOC_THROW : 0); |
| 88 | |
| 89 | if (block) { |
| 90 | // block->fNext = fBlock; |
| 91 | block->fFreeSize = size; |
| 92 | block->fFreePtr = (char*)block + sizeof(Block); |
| 93 | |
| 94 | fTotalCapacity += size; |
| 95 | } |
| 96 | return block; |
| 97 | } |
| 98 | |
| 99 | void* SkChunkAlloc::alloc(size_t bytes, AllocFailType ftype) { |
| 100 | bytes = SkAlign4(bytes); |
| 101 | |
| 102 | Block* block = fBlock; |
| 103 | |
| 104 | if (block == NULL || bytes > block->fFreeSize) { |
| 105 | block = this->newBlock(bytes, ftype); |
| 106 | if (NULL == block) { |
| 107 | return NULL; |
| 108 | } |
| 109 | block->fNext = fBlock; |
| 110 | fBlock = block; |
| 111 | } |
| 112 | |
| 113 | SkASSERT(block && bytes <= block->fFreeSize); |
| 114 | void* ptr = block->fFreePtr; |
| 115 | |
| 116 | block->fFreeSize -= bytes; |
| 117 | block->fFreePtr += bytes; |
| 118 | return ptr; |
| 119 | } |
| 120 | |