gfx/skia/trunk/src/core/SkChunkAlloc.cpp

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TOR_BUG_3246
changeset 7
129ffea94266
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-1:000000000000 0:60ed8cfd966c
1 /*
2 * Copyright 2006 The Android Open Source Project
3 *
4 * Use of this source code is governed by a BSD-style license that can be
5 * found in the LICENSE file.
6 */
7
8 #include "SkChunkAlloc.h"
9
10 // Don't malloc any chunks smaller than this
11 #define MIN_CHUNKALLOC_BLOCK_SIZE 1024
12
13 // Return the new min blocksize given the current value
14 static size_t increase_next_size(size_t size) {
15 return size + (size >> 1);
16 }
17
18 ///////////////////////////////////////////////////////////////////////////////
19
20 struct SkChunkAlloc::Block {
21 Block* fNext;
22 size_t fFreeSize;
23 char* fFreePtr;
24 // data[] follows
25
26 char* startOfData() {
27 return reinterpret_cast<char*>(this + 1);
28 }
29
30 static void FreeChain(Block* block) {
31 while (block) {
32 Block* next = block->fNext;
33 sk_free(block);
34 block = next;
35 }
36 };
37
38 bool contains(const void* addr) const {
39 const char* ptr = reinterpret_cast<const char*>(addr);
40 return ptr >= (const char*)(this + 1) && ptr < fFreePtr;
41 }
42 };
43
44 ///////////////////////////////////////////////////////////////////////////////
45
46 SkChunkAlloc::SkChunkAlloc(size_t minSize) {
47 if (minSize < MIN_CHUNKALLOC_BLOCK_SIZE) {
48 minSize = MIN_CHUNKALLOC_BLOCK_SIZE;
49 }
50
51 fBlock = NULL;
52 fMinSize = minSize;
53 fChunkSize = fMinSize;
54 fTotalCapacity = 0;
55 fTotalUsed = 0;
56 fBlockCount = 0;
57 }
58
59 SkChunkAlloc::~SkChunkAlloc() {
60 this->reset();
61 }
62
63 void SkChunkAlloc::reset() {
64 Block::FreeChain(fBlock);
65 fBlock = NULL;
66 fChunkSize = fMinSize; // reset to our initial minSize
67 fTotalCapacity = 0;
68 fTotalUsed = 0;
69 fBlockCount = 0;
70 }
71
72 SkChunkAlloc::Block* SkChunkAlloc::newBlock(size_t bytes, AllocFailType ftype) {
73 size_t size = bytes;
74 if (size < fChunkSize) {
75 size = fChunkSize;
76 }
77
78 Block* block = (Block*)sk_malloc_flags(sizeof(Block) + size,
79 ftype == kThrow_AllocFailType ? SK_MALLOC_THROW : 0);
80
81 if (block) {
82 // block->fNext = fBlock;
83 block->fFreeSize = size;
84 block->fFreePtr = block->startOfData();
85
86 fTotalCapacity += size;
87 fBlockCount += 1;
88
89 fChunkSize = increase_next_size(fChunkSize);
90 }
91 return block;
92 }
93
94 void* SkChunkAlloc::alloc(size_t bytes, AllocFailType ftype) {
95 fTotalUsed += bytes;
96
97 bytes = SkAlign4(bytes);
98
99 Block* block = fBlock;
100
101 if (block == NULL || bytes > block->fFreeSize) {
102 block = this->newBlock(bytes, ftype);
103 if (NULL == block) {
104 return NULL;
105 }
106 block->fNext = fBlock;
107 fBlock = block;
108 }
109
110 SkASSERT(block && bytes <= block->fFreeSize);
111 char* ptr = block->fFreePtr;
112
113 block->fFreeSize -= bytes;
114 block->fFreePtr = ptr + bytes;
115 return ptr;
116 }
117
118 size_t SkChunkAlloc::unalloc(void* ptr) {
119 size_t bytes = 0;
120 Block* block = fBlock;
121 if (block) {
122 char* cPtr = reinterpret_cast<char*>(ptr);
123 char* start = block->startOfData();
124 if (start <= cPtr && cPtr < block->fFreePtr) {
125 bytes = block->fFreePtr - cPtr;
126 block->fFreeSize += bytes;
127 block->fFreePtr = cPtr;
128 }
129 }
130 return bytes;
131 }
132
133 bool SkChunkAlloc::contains(const void* addr) const {
134 const Block* block = fBlock;
135 while (block) {
136 if (block->contains(addr)) {
137 return true;
138 }
139 block = block->fNext;
140 }
141 return false;
142 }

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