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authorMatt A. Tobin <mattatobin@localhost.localdomain>2018-02-02 04:16:08 -0500
committerMatt A. Tobin <mattatobin@localhost.localdomain>2018-02-02 04:16:08 -0500
commit5f8de423f190bbb79a62f804151bc24824fa32d8 (patch)
tree10027f336435511475e392454359edea8e25895d /js/src/ds/BitArray.h
parent49ee0794b5d912db1f95dce6eb52d781dc210db5 (diff)
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Add m-esr52 at 52.6.0
Diffstat (limited to 'js/src/ds/BitArray.h')
-rw-r--r--js/src/ds/BitArray.h82
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diff --git a/js/src/ds/BitArray.h b/js/src/ds/BitArray.h
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+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
+ * vim: set ts=8 sts=4 et sw=4 tw=99:
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef ds_BitArray_h
+#define ds_BitArray_h
+
+#include "mozilla/TemplateLib.h"
+
+#include <limits.h>
+
+#include "jstypes.h"
+
+namespace js {
+
+template <size_t nbits>
+class BitArray
+{
+ private:
+ // Use a 32 bit word to make it easier to access a BitArray from JIT code.
+ using WordT = uint32_t;
+
+ static const size_t bitsPerElement = sizeof(WordT) * CHAR_BIT;
+ static const size_t numSlots = nbits / bitsPerElement + (nbits % bitsPerElement == 0 ? 0 : 1);
+ static const size_t paddingBits = (numSlots * bitsPerElement) - nbits;
+ static_assert(paddingBits < bitsPerElement, "More padding bits than expected.");
+ static const WordT paddingMask = WordT(-1) >> paddingBits;
+
+ WordT map[numSlots];
+
+ public:
+ void clear(bool value) {
+ memset(map, value ? 0xFF : 0, sizeof(map));
+ if (value)
+ map[numSlots - 1] &= paddingMask;
+ }
+
+ inline bool get(size_t offset) const {
+ size_t index;
+ WordT mask;
+ getIndexAndMask(offset, &index, &mask);
+ return map[index] & mask;
+ }
+
+ void set(size_t offset) {
+ size_t index;
+ WordT mask;
+ getIndexAndMask(offset, &index, &mask);
+ map[index] |= mask;
+ }
+
+ void unset(size_t offset) {
+ size_t index;
+ WordT mask;
+ getIndexAndMask(offset, &index, &mask);
+ map[index] &= ~mask;
+ }
+
+ bool isAllClear() const {
+ for (size_t i = 0; i < numSlots; i++) {
+ if (map[i])
+ return false;
+ }
+ return true;
+ }
+
+ static void getIndexAndMask(size_t offset, size_t* indexp, WordT* maskp) {
+ static_assert(bitsPerElement == 32, "unexpected bitsPerElement value");
+ *indexp = offset / bitsPerElement;
+ *maskp = WordT(1) << (offset % bitsPerElement);
+ }
+
+ static size_t offsetOfMap() {
+ return offsetof(BitArray<nbits>, map);
+ }
+};
+
+} /* namespace js */
+
+#endif /* ds_BitArray_h */