--- /dev/null
+/*
+ * Copyright 2017 Facebook, Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+/**
+ * BitIterator
+ * Wrapper around an iterator over an integral type that iterates
+ * over its underlying bits in MSb to LSb order
+ *
+ * findFirstSet(BitIterator begin, BitIterator end)
+ * return a BitIterator pointing to the first 1 bit in [begin, end), or
+ * end if all bits in [begin, end) are 0
+ *
+ * @author Tudor Bosman (tudorb@fb.com)
+ */
+
+#pragma once
+
+#include <cassert>
+#include <cinttypes>
+#include <cstdint>
+#include <cstring>
+#include <iterator>
+#include <limits>
+#include <type_traits>
+
+#include <boost/iterator/iterator_adaptor.hpp>
+
+#include <folly/Bits.h>
+#include <folly/Portability.h>
+#include <folly/detail/BitIteratorDetail.h>
+
+namespace folly {
+
+/**
+ * Fast bit iteration facility.
+ */
+
+template <class BaseIter>
+class BitIterator;
+template <class BaseIter>
+BitIterator<BaseIter> findFirstSet(
+ BitIterator<BaseIter>,
+ BitIterator<BaseIter>);
+/**
+ * Wrapper around an iterator over an integer type that iterates
+ * over its underlying bits in LSb to MSb order.
+ *
+ * BitIterator models the same iterator concepts as the base iterator.
+ */
+template <class BaseIter>
+class BitIterator : public bititerator_detail::BitIteratorBase<BaseIter>::type {
+ public:
+ /**
+ * Return the number of bits in an element of the underlying iterator.
+ */
+ static unsigned int bitsPerBlock() {
+ return std::numeric_limits<typename std::make_unsigned<
+ typename std::iterator_traits<BaseIter>::value_type>::type>::digits;
+ }
+
+ /**
+ * Construct a BitIterator that points at a given bit offset (default 0)
+ * in iter.
+ */
+ explicit BitIterator(const BaseIter& iter, size_t bitOff = 0)
+ : bititerator_detail::BitIteratorBase<BaseIter>::type(iter),
+ bitOffset_(bitOff) {
+ assert(bitOffset_ < bitsPerBlock());
+ }
+
+ size_t bitOffset() const {
+ return bitOffset_;
+ }
+
+ void advanceToNextBlock() {
+ bitOffset_ = 0;
+ ++this->base_reference();
+ }
+
+ BitIterator& operator=(const BaseIter& other) {
+ this->~BitIterator();
+ new (this) BitIterator(other);
+ return *this;
+ }
+
+ private:
+ friend class boost::iterator_core_access;
+ friend BitIterator findFirstSet<>(BitIterator, BitIterator);
+
+ typedef bititerator_detail::BitReference<
+ typename std::iterator_traits<BaseIter>::reference,
+ typename std::iterator_traits<BaseIter>::value_type>
+ BitRef;
+
+ void advanceInBlock(size_t n) {
+ bitOffset_ += n;
+ assert(bitOffset_ < bitsPerBlock());
+ }
+
+ BitRef dereference() const {
+ return BitRef(*this->base_reference(), bitOffset_);
+ }
+
+ void advance(ssize_t n) {
+ size_t bpb = bitsPerBlock();
+ ssize_t blocks = n / ssize_t(bpb);
+ bitOffset_ += n % bpb;
+ if (bitOffset_ >= bpb) {
+ bitOffset_ -= bpb;
+ ++blocks;
+ }
+ this->base_reference() += blocks;
+ }
+
+ void increment() {
+ if (++bitOffset_ == bitsPerBlock()) {
+ advanceToNextBlock();
+ }
+ }
+
+ void decrement() {
+ if (bitOffset_-- == 0) {
+ bitOffset_ = bitsPerBlock() - 1;
+ --this->base_reference();
+ }
+ }
+
+ bool equal(const BitIterator& other) const {
+ return (
+ bitOffset_ == other.bitOffset_ &&
+ this->base_reference() == other.base_reference());
+ }
+
+ ssize_t distance_to(const BitIterator& other) const {
+ return ssize_t(
+ (other.base_reference() - this->base_reference()) * bitsPerBlock() +
+ other.bitOffset_ - bitOffset_);
+ }
+
+ size_t bitOffset_;
+};
+
+/**
+ * Helper function, so you can write
+ * auto bi = makeBitIterator(container.begin());
+ */
+template <class BaseIter>
+BitIterator<BaseIter> makeBitIterator(const BaseIter& iter) {
+ return BitIterator<BaseIter>(iter);
+}
+
+/**
+ * Find first bit set in a range of bit iterators.
+ * 4.5x faster than the obvious std::find(begin, end, true);
+ */
+template <class BaseIter>
+BitIterator<BaseIter> findFirstSet(
+ BitIterator<BaseIter> begin,
+ BitIterator<BaseIter> end) {
+ // shortcut to avoid ugly static_cast<>
+ static const typename BaseIter::value_type one = 1;
+
+ while (begin.base() != end.base()) {
+ typename BaseIter::value_type v = *begin.base();
+ // mask out the bits that don't matter (< begin.bitOffset)
+ v &= ~((one << begin.bitOffset()) - 1);
+ size_t firstSet = findFirstSet(v);
+ if (firstSet) {
+ --firstSet; // now it's 0-based
+ assert(firstSet >= begin.bitOffset());
+ begin.advanceInBlock(firstSet - begin.bitOffset());
+ return begin;
+ }
+ begin.advanceToNextBlock();
+ }
+
+ // now begin points to the same block as end
+ if (end.bitOffset() != 0) { // assume end is dereferenceable
+ typename BaseIter::value_type v = *begin.base();
+ // mask out the bits that don't matter (< begin.bitOffset)
+ v &= ~((one << begin.bitOffset()) - 1);
+ // mask out the bits that don't matter (>= end.bitOffset)
+ v &= (one << end.bitOffset()) - 1;
+ size_t firstSet = findFirstSet(v);
+ if (firstSet) {
+ --firstSet; // now it's 0-based
+ assert(firstSet >= begin.bitOffset());
+ begin.advanceInBlock(firstSet - begin.bitOffset());
+ return begin;
+ }
+ }
+
+ return end;
+}
+
+} // namespace folly
* Endian::little(x) little <-> native
* Endian::swap(x) big <-> little
*
- * BitIterator
- * Wrapper around an iterator over an integral type that iterates
- * over its underlying bits in MSb to LSb order
- *
- * findFirstSet(BitIterator begin, BitIterator end)
- * return a BitIterator pointing to the first 1 bit in [begin, end), or
- * end if all bits in [begin, end) are 0
- *
* @author Tudor Bosman (tudorb@fb.com)
*/
#include <cinttypes>
#include <cstdint>
#include <cstring>
-#include <iterator>
#include <limits>
#include <type_traits>
-#include <boost/iterator/iterator_adaptor.hpp>
-
#include <folly/Assume.h>
-#include <folly/Likely.h>
#include <folly/Portability.h>
-#include <folly/detail/BitIteratorDetail.h>
#include <folly/portability/Builtins.h>
namespace folly {
#undef FB_GEN2
#undef FB_GEN1
-/**
- * Fast bit iteration facility.
- */
-
-
-template <class BaseIter> class BitIterator;
-template <class BaseIter>
-BitIterator<BaseIter> findFirstSet(BitIterator<BaseIter>,
- BitIterator<BaseIter>);
-/**
- * Wrapper around an iterator over an integer type that iterates
- * over its underlying bits in LSb to MSb order.
- *
- * BitIterator models the same iterator concepts as the base iterator.
- */
-template <class BaseIter>
-class BitIterator
- : public bititerator_detail::BitIteratorBase<BaseIter>::type {
- public:
- /**
- * Return the number of bits in an element of the underlying iterator.
- */
- static unsigned int bitsPerBlock() {
- return std::numeric_limits<
- typename std::make_unsigned<
- typename std::iterator_traits<BaseIter>::value_type
- >::type
- >::digits;
- }
-
- /**
- * Construct a BitIterator that points at a given bit offset (default 0)
- * in iter.
- */
- explicit BitIterator(const BaseIter& iter, size_t bitOff=0)
- : bititerator_detail::BitIteratorBase<BaseIter>::type(iter),
- bitOffset_(bitOff) {
- assert(bitOffset_ < bitsPerBlock());
- }
-
- size_t bitOffset() const {
- return bitOffset_;
- }
-
- void advanceToNextBlock() {
- bitOffset_ = 0;
- ++this->base_reference();
- }
-
- BitIterator& operator=(const BaseIter& other) {
- this->~BitIterator();
- new (this) BitIterator(other);
- return *this;
- }
-
- private:
- friend class boost::iterator_core_access;
- friend BitIterator findFirstSet<>(BitIterator, BitIterator);
-
- typedef bititerator_detail::BitReference<
- typename std::iterator_traits<BaseIter>::reference,
- typename std::iterator_traits<BaseIter>::value_type
- > BitRef;
-
- void advanceInBlock(size_t n) {
- bitOffset_ += n;
- assert(bitOffset_ < bitsPerBlock());
- }
-
- BitRef dereference() const {
- return BitRef(*this->base_reference(), bitOffset_);
- }
-
- void advance(ssize_t n) {
- size_t bpb = bitsPerBlock();
- ssize_t blocks = n / ssize_t(bpb);
- bitOffset_ += n % bpb;
- if (bitOffset_ >= bpb) {
- bitOffset_ -= bpb;
- ++blocks;
- }
- this->base_reference() += blocks;
- }
-
- void increment() {
- if (++bitOffset_ == bitsPerBlock()) {
- advanceToNextBlock();
- }
- }
-
- void decrement() {
- if (bitOffset_-- == 0) {
- bitOffset_ = bitsPerBlock() - 1;
- --this->base_reference();
- }
- }
-
- bool equal(const BitIterator& other) const {
- return (bitOffset_ == other.bitOffset_ &&
- this->base_reference() == other.base_reference());
- }
-
- ssize_t distance_to(const BitIterator& other) const {
- return ssize_t(
- (other.base_reference() - this->base_reference()) * bitsPerBlock() +
- other.bitOffset_ - bitOffset_);
- }
-
- size_t bitOffset_;
-};
-
-/**
- * Helper function, so you can write
- * auto bi = makeBitIterator(container.begin());
- */
-template <class BaseIter>
-BitIterator<BaseIter> makeBitIterator(const BaseIter& iter) {
- return BitIterator<BaseIter>(iter);
-}
-
-
-/**
- * Find first bit set in a range of bit iterators.
- * 4.5x faster than the obvious std::find(begin, end, true);
- */
-template <class BaseIter>
-BitIterator<BaseIter> findFirstSet(BitIterator<BaseIter> begin,
- BitIterator<BaseIter> end) {
- // shortcut to avoid ugly static_cast<>
- static const typename BaseIter::value_type one = 1;
-
- while (begin.base() != end.base()) {
- typename BaseIter::value_type v = *begin.base();
- // mask out the bits that don't matter (< begin.bitOffset)
- v &= ~((one << begin.bitOffset()) - 1);
- size_t firstSet = findFirstSet(v);
- if (firstSet) {
- --firstSet; // now it's 0-based
- assert(firstSet >= begin.bitOffset());
- begin.advanceInBlock(firstSet - begin.bitOffset());
- return begin;
- }
- begin.advanceToNextBlock();
- }
-
- // now begin points to the same block as end
- if (end.bitOffset() != 0) { // assume end is dereferenceable
- typename BaseIter::value_type v = *begin.base();
- // mask out the bits that don't matter (< begin.bitOffset)
- v &= ~((one << begin.bitOffset()) - 1);
- // mask out the bits that don't matter (>= end.bitOffset)
- v &= (one << end.bitOffset()) - 1;
- size_t firstSet = findFirstSet(v);
- if (firstSet) {
- --firstSet; // now it's 0-based
- assert(firstSet >= begin.bitOffset());
- begin.advanceInBlock(firstSet - begin.bitOffset());
- return begin;
- }
- }
-
- return end;
-}
-
template <class T, class Enable=void> struct Unaligned;
#include <folly/io/async/HHWheelTimer.h>
#include <folly/io/async/Request.h>
+#include <folly/BitIterator.h>
#include <folly/Memory.h>
#include <folly/Optional.h>
#include <folly/ScopeGuard.h>
* limitations under the License.
*/
-#include <folly/Bits.h>
+#include <folly/BitIterator.h>
#include <algorithm>
#include <limits>
#include <string>
+#include <folly/BitIterator.h>
#include <folly/Bits.h>
#include <folly/Format.h>
#include <folly/IPAddress.h>
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