The Tor Browser / file comparison
comparison: js/src/ds/BitArray.h
js/src/ds/BitArray.h
- branch
- TOR_BUG_9701
- changeset 15
- b8a032363ba2
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| -1:000000000000 | 0:7752025426ea |
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| 1 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*- | |
| 2 * vim: set ts=8 sts=4 et sw=4 tw=99: | |
| 3 * This Source Code Form is subject to the terms of the Mozilla Public | |
| 4 * License, v. 2.0. If a copy of the MPL was not distributed with this | |
| 5 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */ | |
| 6 | |
| 7 #ifndef ds_BitArray_h | |
| 8 #define ds_BitArray_h | |
| 9 | |
| 10 #include "mozilla/TemplateLib.h" | |
| 11 | |
| 12 #include <limits.h> | |
| 13 | |
| 14 #include "jstypes.h" | |
| 15 | |
| 16 namespace js { | |
| 17 | |
| 18 template <size_t nbits> | |
| 19 class BitArray | |
| 20 { | |
| 21 private: | |
| 22 static const size_t bitsPerElement = sizeof(uintptr_t) * CHAR_BIT; | |
| 23 static const size_t numSlots = nbits / bitsPerElement + (nbits % bitsPerElement == 0 ? 0 : 1); | |
| 24 static const size_t paddingBits = (numSlots * bitsPerElement) - nbits; | |
| 25 static_assert(paddingBits < bitsPerElement, "More padding bits than expected."); | |
| 26 static const uintptr_t paddingMask = uintptr_t(-1) >> paddingBits; | |
| 27 | |
| 28 uintptr_t map[numSlots]; | |
| 29 | |
| 30 public: | |
| 31 void clear(bool value) { | |
| 32 memset(map, value ? 0xFF : 0, sizeof(map)); | |
| 33 if (value) | |
| 34 map[numSlots - 1] &= paddingMask; | |
| 35 } | |
| 36 | |
| 37 inline bool get(size_t offset) const { | |
| 38 uintptr_t index, mask; | |
| 39 getMarkWordAndMask(offset, &index, &mask); | |
| 40 return map[index] & mask; | |
| 41 } | |
| 42 | |
| 43 void set(size_t offset) { | |
| 44 uintptr_t index, mask; | |
| 45 getMarkWordAndMask(offset, &index, &mask); | |
| 46 map[index] |= mask; | |
| 47 } | |
| 48 | |
| 49 void unset(size_t offset) { | |
| 50 uintptr_t index, mask; | |
| 51 getMarkWordAndMask(offset, &index, &mask); | |
| 52 map[index] &= ~mask; | |
| 53 } | |
| 54 | |
| 55 bool isAllClear() const { | |
| 56 for (size_t i = 0; i < numSlots; i++) { | |
| 57 if (map[i]) | |
| 58 return false; | |
| 59 } | |
| 60 return true; | |
| 61 } | |
| 62 | |
| 63 private: | |
| 64 inline void getMarkWordAndMask(size_t offset, | |
| 65 uintptr_t *indexp, uintptr_t *maskp) const { | |
| 66 static_assert(bitsPerElement == 32 || bitsPerElement == 64, | |
| 67 "unexpected bitsPerElement value"); | |
| 68 *indexp = offset / bitsPerElement; | |
| 69 *maskp = uintptr_t(1) << (offset % bitsPerElement); | |
| 70 } | |
| 71 }; | |
| 72 | |
| 73 } /* namespace js */ | |
| 74 | |
| 75 #endif /* ds_BitArray_h */ |
