1 /*
2  * Copyright 2011 Google Inc.
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 #ifndef SkBitSet_DEFINED
9 #define SkBitSet_DEFINED
10 
11 #include "SkTemplates.h"
12 
13 class SkBitSet {
14 public:
SkBitSet(int numberOfBits)15     explicit SkBitSet(int numberOfBits) {
16         SkASSERT(numberOfBits >= 0);
17         fDwordCount = (numberOfBits + 31) / 32;  // Round up size to 32-bit boundary.
18         if (fDwordCount > 0) {
19             fBitData.reset((uint32_t*)sk_calloc_throw(fDwordCount * sizeof(uint32_t)));
20         }
21     }
22 
23     /** Set the value of the index-th bit to true.  */
set(int index)24     void set(int index) {
25         uint32_t mask = 1 << (index & 31);
26         uint32_t* chunk = this->internalGet(index);
27         SkASSERT(chunk);
28         *chunk |= mask;
29     }
30 
has(int index)31     bool has(int index) const {
32         const uint32_t* chunk = this->internalGet(index);
33         uint32_t mask = 1 << (index & 31);
34         return chunk && SkToBool(*chunk & mask);
35     }
36 
37     // Calls f(unsigned) for each set value.
38     template<typename FN>
getSetValues(FN f)39     void getSetValues(FN f) const {
40         const uint32_t* data = fBitData.get();
41         for (unsigned i = 0; i < fDwordCount; ++i) {
42             if (uint32_t value = data[i]) {  // There are set bits
43                 unsigned index = i * 32;
44                 for (unsigned j = 0; j < 32; ++j) {
45                     if (0x1 & (value >> j)) {
46                         f(index | j);
47                     }
48                 }
49             }
50         }
51     }
52 
53 private:
54     std::unique_ptr<uint32_t, SkFunctionWrapper<void, void, sk_free>> fBitData;
55     size_t fDwordCount;  // Dword (32-bit) count of the bitset.
56 
internalGet(int index)57     uint32_t* internalGet(int index) const {
58         size_t internalIndex = index / 32;
59         if (internalIndex >= fDwordCount) {
60             return nullptr;
61         }
62         return fBitData.get() + internalIndex;
63     }
64 };
65 
66 
67 #endif
68