js/src/ds/BitArray.h@6474c204b198 (annotated)
js/src/ds/BitArray.h
Wed, 31 Dec 2014 06:09:35 +0100
- author
- Michael Schloh von Bennewitz <michael@schloh.com>
- date
- Wed, 31 Dec 2014 06:09:35 +0100
- changeset 0
- 6474c204b198
- permissions
- -rw-r--r--
Cloned upstream origin tor-browser at tor-browser-31.3.0esr-4.5-1-build1
revision ID fc1c9ff7c1b2defdbc039f12214767608f46423f for hacking purpose.
| michael@0 | 1 | /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*- |
| michael@0 | 2 | * vim: set ts=8 sts=4 et sw=4 tw=99: |
| michael@0 | 3 | * This Source Code Form is subject to the terms of the Mozilla Public |
| michael@0 | 4 | * License, v. 2.0. If a copy of the MPL was not distributed with this |
| michael@0 | 5 | * file, You can obtain one at http://mozilla.org/MPL/2.0/. */ |
| michael@0 | 6 | |
| michael@0 | 7 | #ifndef ds_BitArray_h |
| michael@0 | 8 | #define ds_BitArray_h |
| michael@0 | 9 | |
| michael@0 | 10 | #include "mozilla/TemplateLib.h" |
| michael@0 | 11 | |
| michael@0 | 12 | #include <limits.h> |
| michael@0 | 13 | |
| michael@0 | 14 | #include "jstypes.h" |
| michael@0 | 15 | |
| michael@0 | 16 | namespace js { |
| michael@0 | 17 | |
| michael@0 | 18 | template <size_t nbits> |
| michael@0 | 19 | class BitArray |
| michael@0 | 20 | { |
| michael@0 | 21 | private: |
| michael@0 | 22 | static const size_t bitsPerElement = sizeof(uintptr_t) * CHAR_BIT; |
| michael@0 | 23 | static const size_t numSlots = nbits / bitsPerElement + (nbits % bitsPerElement == 0 ? 0 : 1); |
| michael@0 | 24 | static const size_t paddingBits = (numSlots * bitsPerElement) - nbits; |
| michael@0 | 25 | static_assert(paddingBits < bitsPerElement, "More padding bits than expected."); |
| michael@0 | 26 | static const uintptr_t paddingMask = uintptr_t(-1) >> paddingBits; |
| michael@0 | 27 | |
| michael@0 | 28 | uintptr_t map[numSlots]; |
| michael@0 | 29 | |
| michael@0 | 30 | public: |
| michael@0 | 31 | void clear(bool value) { |
| michael@0 | 32 | memset(map, value ? 0xFF : 0, sizeof(map)); |
| michael@0 | 33 | if (value) |
| michael@0 | 34 | map[numSlots - 1] &= paddingMask; |
| michael@0 | 35 | } |
| michael@0 | 36 | |
| michael@0 | 37 | inline bool get(size_t offset) const { |
| michael@0 | 38 | uintptr_t index, mask; |
| michael@0 | 39 | getMarkWordAndMask(offset, &index, &mask); |
| michael@0 | 40 | return map[index] & mask; |
| michael@0 | 41 | } |
| michael@0 | 42 | |
| michael@0 | 43 | void set(size_t offset) { |
| michael@0 | 44 | uintptr_t index, mask; |
| michael@0 | 45 | getMarkWordAndMask(offset, &index, &mask); |
| michael@0 | 46 | map[index] |= mask; |
| michael@0 | 47 | } |
| michael@0 | 48 | |
| michael@0 | 49 | void unset(size_t offset) { |
| michael@0 | 50 | uintptr_t index, mask; |
| michael@0 | 51 | getMarkWordAndMask(offset, &index, &mask); |
| michael@0 | 52 | map[index] &= ~mask; |
| michael@0 | 53 | } |
| michael@0 | 54 | |
| michael@0 | 55 | bool isAllClear() const { |
| michael@0 | 56 | for (size_t i = 0; i < numSlots; i++) { |
| michael@0 | 57 | if (map[i]) |
| michael@0 | 58 | return false; |
| michael@0 | 59 | } |
| michael@0 | 60 | return true; |
| michael@0 | 61 | } |
| michael@0 | 62 | |
| michael@0 | 63 | private: |
| michael@0 | 64 | inline void getMarkWordAndMask(size_t offset, |
| michael@0 | 65 | uintptr_t *indexp, uintptr_t *maskp) const { |
| michael@0 | 66 | static_assert(bitsPerElement == 32 || bitsPerElement == 64, |
| michael@0 | 67 | "unexpected bitsPerElement value"); |
| michael@0 | 68 | *indexp = offset / bitsPerElement; |
| michael@0 | 69 | *maskp = uintptr_t(1) << (offset % bitsPerElement); |
| michael@0 | 70 | } |
| michael@0 | 71 | }; |
| michael@0 | 72 | |
| michael@0 | 73 | } /* namespace js */ |
| michael@0 | 74 | |
| michael@0 | 75 | #endif /* ds_BitArray_h */ |
