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bitset.cc
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bitset.cc
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// Copyright 2010-2022 Google LLC
// 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.
#include "ortools/util/bitset.h"
#include "ortools/base/commandlineflags.h"
#include "ortools/base/logging.h"
ABSL_FLAG(int, bitset_small_bitset_count, 8,
"threshold to count bits with buckets");
namespace operations_research {
// ---------- Bit Operations ----------
#define BIT_COUNT_RANGE(size, zero) \
uint##size##_t BitCountRange##size(const uint##size##_t* const bits, \
uint##size##_t start, \
uint##size##_t end) { \
if (static_cast<int##size##_t>(end - start) > \
absl::GetFlag(FLAGS_bitset_small_bitset_count)) { \
const int offset_start = BitOffset##size(start); \
const int pos_start = BitPos##size(start); \
const int offset_end = BitOffset##size(end); \
const int pos_end = BitPos##size(end); \
if (offset_end == offset_start) { \
return BitCount##size(bits[offset_start] & \
OneRange##size(pos_start, pos_end)); \
} else { \
uint##size##_t bit_count = zero; \
bit_count += \
BitCount##size(bits[offset_start] & IntervalUp##size(pos_start)); \
for (int offset = offset_start + 1; offset < offset_end; ++offset) { \
bit_count += BitCount##size(bits[offset]); \
} \
bit_count += \
BitCount##size(bits[offset_end] & IntervalDown##size(pos_end)); \
return bit_count; \
} \
} else { \
uint##size##_t bit_count = zero; \
for (uint##size##_t i = start; i <= end; ++i) { \
bit_count += IsBitSet##size(bits, i); \
} \
return bit_count; \
} \
}
BIT_COUNT_RANGE(64, uint64_t{0})
BIT_COUNT_RANGE(32, 0U)
#undef BIT_COUNT_RANGE
#define IS_EMPTY_RANGE(size) \
bool IsEmptyRange##size(const uint##size##_t* const bits, \
uint##size##_t start, uint##size##_t end) { \
const int offset_start = BitOffset##size(start); \
const int pos_start = BitPos##size(start); \
const int offset_end = BitOffset##size(end); \
const int pos_end = BitPos##size(end); \
if (offset_end == offset_start) { \
if (bits[offset_start] & OneRange##size(pos_start, pos_end)) { \
return false; \
} \
} else { \
if (bits[offset_start] & IntervalUp##size(pos_start)) { \
return false; \
} \
for (int offset = offset_start + 1; offset < offset_end; ++offset) { \
if (bits[offset]) { \
return false; \
} \
} \
if (bits[offset_end] & IntervalDown##size(pos_end)) { \
return false; \
} \
} \
return true; \
}
IS_EMPTY_RANGE(64)
IS_EMPTY_RANGE(32)
#undef IS_EMPTY_RANGE
#define LEAST_SIGNIFCANT_BIT_POSITION(size) \
int##size##_t LeastSignificantBitPosition##size( \
const uint##size##_t* const bits, uint##size##_t start, \
uint##size##_t end) { \
DCHECK_LE(start, end); \
if (IsBitSet##size(bits, start)) { \
return start; \
} \
const int offset_start = BitOffset##size(start); \
const int offset_end = BitOffset##size(end); \
const int pos_start = BitPos##size(start); \
if (offset_start == offset_end) { \
const int pos_end = BitPos##size(end); \
const uint##size##_t active_range = \
bits[offset_start] & OneRange##size(pos_start, pos_end); \
if (active_range) { \
return BitShift##size(offset_start) + \
LeastSignificantBitPosition##size(active_range); \
} \
return -1; \
} else { \
const uint##size##_t start_mask = \
bits[offset_start] & IntervalUp##size(pos_start); \
if (start_mask) { \
return BitShift##size(offset_start) + \
LeastSignificantBitPosition##size(start_mask); \
} else { \
for (int offset = offset_start + 1; offset < offset_end; ++offset) { \
if (bits[offset]) { \
return BitShift##size(offset) + \
LeastSignificantBitPosition##size(bits[offset]); \
} \
} \
const int pos_end = BitPos##size(end); \
const uint##size##_t active_range = \
bits[offset_end] & IntervalDown##size(pos_end); \
if (active_range) { \
return BitShift##size(offset_end) + \
LeastSignificantBitPosition##size(active_range); \
} else { \
return -1; \
} \
} \
} \
}
LEAST_SIGNIFCANT_BIT_POSITION(64)
LEAST_SIGNIFCANT_BIT_POSITION(32)
#undef LEAST_SIGNIFCANT_BIT_POSITION
#define MOST_SIGNIFICANT_BIT_POSITION(size) \
int##size##_t MostSignificantBitPosition##size( \
const uint##size##_t* const bits, uint##size##_t start, \
uint##size##_t end) { \
DCHECK_GE(end, start); \
if (IsBitSet##size(bits, end)) { \
return end; \
} \
const int offset_start = BitOffset##size(start); \
const int offset_end = BitOffset##size(end); \
const int pos_end = BitPos##size(end); \
if (offset_start == offset_end) { \
const int pos_start = BitPos##size(start); \
const uint##size##_t active_range = \
bits[offset_start] & OneRange##size(pos_start, pos_end); \
if (active_range) { \
return BitShift##size(offset_end) + \
MostSignificantBitPosition##size(active_range); \
} else { \
return -1; \
} \
} else { \
const uint##size##_t end_mask = \
bits[offset_end] & IntervalDown##size(pos_end); \
if (end_mask) { \
return BitShift##size(offset_end) + \
MostSignificantBitPosition##size(end_mask); \
} else { \
for (int offset = offset_end - 1; offset > offset_start; --offset) { \
if (bits[offset]) { \
return BitShift##size(offset) + \
MostSignificantBitPosition##size(bits[offset]); \
} \
} \
const int pos_start = BitPos##size(start); \
const uint##size##_t active_range = \
bits[offset_start] & IntervalUp##size(pos_start); \
if (active_range) { \
return BitShift##size(offset_start) + \
MostSignificantBitPosition##size(active_range); \
} else { \
return -1; \
} \
} \
} \
}
MOST_SIGNIFICANT_BIT_POSITION(64)
MOST_SIGNIFICANT_BIT_POSITION(32)
#undef MOST_SIGNIFICANT_BIT_POSITION
#define UNSAFE_LEAST_SIGNIFICANT_BIT_POSITION(size) \
int##size##_t UnsafeLeastSignificantBitPosition##size( \
const uint##size##_t* const bits, uint##size##_t start, \
uint##size##_t end) { \
DCHECK_LE(start, end); \
DCHECK(IsBitSet##size(bits, end)); \
if (IsBitSet##size(bits, start)) { \
return start; \
} \
const int offset_start = BitOffset##size(start); \
const int offset_end = BitOffset##size(end); \
const int pos_start = BitPos##size(start); \
const uint##size##_t start_mask = \
bits[offset_start] & IntervalUp##size(pos_start); \
if (start_mask) { \
return BitShift##size(offset_start) + \
LeastSignificantBitPosition##size(start_mask); \
} \
for (int offset = offset_start + 1; offset <= offset_end; ++offset) { \
if (bits[offset]) { \
return BitShift##size(offset) + \
LeastSignificantBitPosition##size(bits[offset]); \
} \
} \
return -1; \
}
UNSAFE_LEAST_SIGNIFICANT_BIT_POSITION(64)
UNSAFE_LEAST_SIGNIFICANT_BIT_POSITION(32)
#undef UNSAFE_LEAST_SIGNIFICANT_BIT_POSITION
#define UNSAFE_MOST_SIGNIFICANT_BIT_POSITION(size) \
int##size##_t UnsafeMostSignificantBitPosition##size( \
const uint##size##_t* const bits, uint##size##_t start, \
uint##size##_t end) { \
DCHECK_GE(end, start); \
DCHECK(IsBitSet##size(bits, start)); \
if (IsBitSet##size(bits, end)) { \
return end; \
} \
const int offset_start = BitOffset##size(start); \
const int offset_end = BitOffset##size(end); \
const int pos_end = BitPos##size(end); \
const uint##size##_t end_mask = \
bits[offset_end] & IntervalDown##size(pos_end); \
if (end_mask) { \
return BitShift##size(offset_end) + \
MostSignificantBitPosition##size(end_mask); \
} \
for (int offset = offset_end - 1; offset >= offset_start; --offset) { \
if (bits[offset]) { \
return BitShift##size(offset) + \
MostSignificantBitPosition##size(bits[offset]); \
} \
} \
return -1; \
}
UNSAFE_MOST_SIGNIFICANT_BIT_POSITION(64)
UNSAFE_MOST_SIGNIFICANT_BIT_POSITION(32)
#undef UNSAFE_MOST_SIGNIFICANT_BIT_POSITION
} // namespace operations_research