/usr/local/lib64/python3.6/site-packages/pyarrow/include/arrow/util
Edit: /usr/local/lib64/python3.6/site-packages/pyarrow/include/arrow/util/bit_util.h (11568B)
// Licensed to the Apache Software Foundation (ASF) under one
// or more contributor license agreements. See the NOTICE file
// distributed with this work for additional information
// regarding copyright ownership. The ASF licenses this file
// to you 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.
#pragma once
#if defined(_MSC_VER)
#include
// IWYU pragma: keep
#include
#pragma intrinsic(_BitScanReverse)
#pragma intrinsic(_BitScanForward)
#define ARROW_POPCOUNT64 __popcnt64
#define ARROW_POPCOUNT32 __popcnt
#else
#define ARROW_POPCOUNT64 __builtin_popcountll
#define ARROW_POPCOUNT32 __builtin_popcount
#endif
#include
#include
#include "arrow/util/macros.h"
#include "arrow/util/visibility.h"
namespace arrow {
namespace detail {
template
typename std::make_unsigned::type as_unsigned(Integer x) {
return static_cast::type>(x);
}
} // namespace detail
namespace BitUtil {
// The number of set bits in a given unsigned byte value, pre-computed
//
// Generated with the following Python code
// output = 'static constexpr uint8_t kBytePopcount[] = {{{0}}};'
// popcounts = [str(bin(i).count('1')) for i in range(0, 256)]
// print(output.format(', '.join(popcounts)))
static constexpr uint8_t kBytePopcount[] = {
0, 1, 1, 2, 1, 2, 2, 3, 1, 2, 2, 3, 2, 3, 3, 4, 1, 2, 2, 3, 2, 3, 3, 4, 2, 3, 3, 4, 3,
4, 4, 5, 1, 2, 2, 3, 2, 3, 3, 4, 2, 3, 3, 4, 3, 4, 4, 5, 2, 3, 3, 4, 3, 4, 4, 5, 3, 4,
4, 5, 4, 5, 5, 6, 1, 2, 2, 3, 2, 3, 3, 4, 2, 3, 3, 4, 3, 4, 4, 5, 2, 3, 3, 4, 3, 4, 4,
5, 3, 4, 4, 5, 4, 5, 5, 6, 2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6, 3, 4, 4, 5,
4, 5, 5, 6, 4, 5, 5, 6, 5, 6, 6, 7, 1, 2, 2, 3, 2, 3, 3, 4, 2, 3, 3, 4, 3, 4, 4, 5, 2,
3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6, 2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5,
5, 6, 3, 4, 4, 5, 4, 5, 5, 6, 4, 5, 5, 6, 5, 6, 6, 7, 2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4,
5, 4, 5, 5, 6, 3, 4, 4, 5, 4, 5, 5, 6, 4, 5, 5, 6, 5, 6, 6, 7, 3, 4, 4, 5, 4, 5, 5, 6,
4, 5, 5, 6, 5, 6, 6, 7, 4, 5, 5, 6, 5, 6, 6, 7, 5, 6, 6, 7, 6, 7, 7, 8};
static inline uint64_t PopCount(uint64_t bitmap) { return ARROW_POPCOUNT64(bitmap); }
static inline uint32_t PopCount(uint32_t bitmap) { return ARROW_POPCOUNT32(bitmap); }
//
// Bit-related computations on integer values
//
// Returns the ceil of value/divisor
constexpr int64_t CeilDiv(int64_t value, int64_t divisor) {
return (value == 0) ? 0 : 1 + (value - 1) / divisor;
}
// Return the number of bytes needed to fit the given number of bits
constexpr int64_t BytesForBits(int64_t bits) {
// This formula avoids integer overflow on very large `bits`
return (bits >> 3) + ((bits & 7) != 0);
}
constexpr bool IsPowerOf2(int64_t value) {
return value > 0 && (value & (value - 1)) == 0;
}
constexpr bool IsPowerOf2(uint64_t value) {
return value > 0 && (value & (value - 1)) == 0;
}
// Returns the smallest power of two that contains v. If v is already a
// power of two, it is returned as is.
static inline int64_t NextPower2(int64_t n) {
// Taken from
// http://graphics.stanford.edu/~seander/bithacks.html#RoundUpPowerOf2
n--;
n |= n >> 1;
n |= n >> 2;
n |= n >> 4;
n |= n >> 8;
n |= n >> 16;
n |= n >> 32;
n++;
return n;
}
constexpr bool IsMultipleOf64(int64_t n) { return (n & 63) == 0; }
constexpr bool IsMultipleOf8(int64_t n) { return (n & 7) == 0; }
// Returns a mask for the bit_index lower order bits.
// Only valid for bit_index in the range [0, 64).
constexpr uint64_t LeastSignificantBitMask(int64_t bit_index) {
return (static_cast(1) << bit_index) - 1;
}
// Returns 'value' rounded up to the nearest multiple of 'factor'
constexpr int64_t RoundUp(int64_t value, int64_t factor) {
return CeilDiv(value, factor) * factor;
}
// Returns 'value' rounded down to the nearest multiple of 'factor'
constexpr int64_t RoundDown(int64_t value, int64_t factor) {
return (value / factor) * factor;
}
// Returns 'value' rounded up to the nearest multiple of 'factor' when factor
// is a power of two.
// The result is undefined on overflow, i.e. if `value > 2**64 - factor`,
// since we cannot return the correct result which would be 2**64.
constexpr int64_t RoundUpToPowerOf2(int64_t value, int64_t factor) {
// DCHECK(value >= 0);
// DCHECK(IsPowerOf2(factor));
return (value + (factor - 1)) & ~(factor - 1);
}
constexpr uint64_t RoundUpToPowerOf2(uint64_t value, uint64_t factor) {
// DCHECK(IsPowerOf2(factor));
return (value + (factor - 1)) & ~(factor - 1);
}
constexpr int64_t RoundUpToMultipleOf8(int64_t num) { return RoundUpToPowerOf2(num, 8); }
constexpr int64_t RoundUpToMultipleOf64(int64_t num) {
return RoundUpToPowerOf2(num, 64);
}
// Returns the number of bytes covering a sliced bitmap. Find the length
// rounded to cover full bytes on both extremities.
//
// The following example represents a slice (offset=10, length=9)
//
// 0 8 16 24
// |-------|-------|------|
// [ ] (slice)
// [ ] (same slice aligned to bytes bounds, length=16)
//
// The covering bytes is the length (in bytes) of this new aligned slice.
constexpr int64_t CoveringBytes(int64_t offset, int64_t length) {
return (BitUtil::RoundUp(length + offset, 8) - BitUtil::RoundDown(offset, 8)) / 8;
}
// Returns the 'num_bits' least-significant bits of 'v'.
static inline uint64_t TrailingBits(uint64_t v, int num_bits) {
if (ARROW_PREDICT_FALSE(num_bits == 0)) return 0;
if (ARROW_PREDICT_FALSE(num_bits >= 64)) return v;
int n = 64 - num_bits;
return (v << n) >> n;
}
/// \brief Count the number of leading zeros in an unsigned integer.
static inline int CountLeadingZeros(uint32_t value) {
#if defined(__clang__) || defined(__GNUC__)
if (value == 0) return 32;
return static_cast(__builtin_clz(value));
#elif defined(_MSC_VER)
unsigned long index; // NOLINT
if (_BitScanReverse(&index, static_cast(value))) { // NOLINT
return 31 - static_cast(index);
} else {
return 32;
}
#else
int bitpos = 0;
while (value != 0) {
value >>= 1;
++bitpos;
}
return 32 - bitpos;
#endif
}
static inline int CountLeadingZeros(uint64_t value) {
#if defined(__clang__) || defined(__GNUC__)
if (value == 0) return 64;
return static_cast(__builtin_clzll(value));
#elif defined(_MSC_VER)
unsigned long index; // NOLINT
if (_BitScanReverse64(&index, value)) { // NOLINT
return 63 - static_cast(index);
} else {
return 64;
}
#else
int bitpos = 0;
while (value != 0) {
value >>= 1;
++bitpos;
}
return 64 - bitpos;
#endif
}
static inline int CountTrailingZeros(uint32_t value) {
#if defined(__clang__) || defined(__GNUC__)
if (value == 0) return 32;
return static_cast(__builtin_ctzl(value));
#elif defined(_MSC_VER)
unsigned long index; // NOLINT
if (_BitScanForward(&index, value)) {
return static_cast(index);
} else {
return 32;
}
#else
int bitpos = 0;
if (value) {
while (value & 1 == 0) {
value >>= 1;
++bitpos;
}
} else {
bitpos = 32;
}
return bitpos;
#endif
}
static inline int CountTrailingZeros(uint64_t value) {
#if defined(__clang__) || defined(__GNUC__)
if (value == 0) return 64;
return static_cast(__builtin_ctzll(value));
#elif defined(_MSC_VER)
unsigned long index; // NOLINT
if (_BitScanForward64(&index, value)) {
return static_cast(index);
} else {
return 64;
}
#else
int bitpos = 0;
if (value) {
while (value & 1 == 0) {
value >>= 1;
++bitpos;
}
} else {
bitpos = 64;
}
return bitpos;
#endif
}
// Returns the minimum number of bits needed to represent an unsigned value
static inline int NumRequiredBits(uint64_t x) { return 64 - CountLeadingZeros(x); }
// Returns ceil(log2(x)).
static inline int Log2(uint64_t x) {
// DCHECK_GT(x, 0);
return NumRequiredBits(x - 1);
}
//
// Utilities for reading and writing individual bits by their index
// in a memory area.
//
// Bitmask selecting the k-th bit in a byte
static constexpr uint8_t kBitmask[] = {1, 2, 4, 8, 16, 32, 64, 128};
// the bitwise complement version of kBitmask
static constexpr uint8_t kFlippedBitmask[] = {254, 253, 251, 247, 239, 223, 191, 127};
// Bitmask selecting the (k - 1) preceding bits in a byte
static constexpr uint8_t kPrecedingBitmask[] = {0, 1, 3, 7, 15, 31, 63, 127};
static constexpr uint8_t kPrecedingWrappingBitmask[] = {255, 1, 3, 7, 15, 31, 63, 127};
// the bitwise complement version of kPrecedingBitmask
static constexpr uint8_t kTrailingBitmask[] = {255, 254, 252, 248, 240, 224, 192, 128};
static constexpr bool GetBit(const uint8_t* bits, uint64_t i) {
return (bits[i >> 3] >> (i & 0x07)) & 1;
}
// Gets the i-th bit from a byte. Should only be used with i <= 7.
static constexpr bool GetBitFromByte(uint8_t byte, uint8_t i) {
return byte & kBitmask[i];
}
static inline void ClearBit(uint8_t* bits, int64_t i) {
bits[i / 8] &= kFlippedBitmask[i % 8];
}
static inline void SetBit(uint8_t* bits, int64_t i) { bits[i / 8] |= kBitmask[i % 8]; }
static inline void SetBitTo(uint8_t* bits, int64_t i, bool bit_is_set) {
// https://graphics.stanford.edu/~seander/bithacks.html
// "Conditionally set or clear bits without branching"
// NOTE: this seems to confuse Valgrind as it reads from potentially
// uninitialized memory
bits[i / 8] ^= static_cast(-static_cast(bit_is_set) ^ bits[i / 8]) &
kBitmask[i % 8];
}
/// \brief set or clear a range of bits quickly
ARROW_EXPORT
void SetBitsTo(uint8_t* bits, int64_t start_offset, int64_t length, bool bits_are_set);
/// \brief Sets all bits in the bitmap to true
ARROW_EXPORT
void SetBitmap(uint8_t* data, int64_t offset, int64_t length);
/// \brief Clears all bits in the bitmap (set to false)
ARROW_EXPORT
void ClearBitmap(uint8_t* data, int64_t offset, int64_t length);
/// Returns a mask with lower i bits set to 1. If i >= sizeof(Word)*8, all-ones will be
/// returned
/// ex:
/// ref: https://stackoverflow.com/a/59523400
template
constexpr Word PrecedingWordBitmask(unsigned int const i) {
return (static_cast(i < sizeof(Word) * 8) << (i & (sizeof(Word) * 8 - 1))) - 1;
}
static_assert(PrecedingWordBitmask(0) == 0x00, "");
static_assert(PrecedingWordBitmask(4) == 0x0f, "");
static_assert(PrecedingWordBitmask(8) == 0xff, "");
static_assert(PrecedingWordBitmask(8) == 0x00ff, "");
/// \brief Create a word with low `n` bits from `low` and high `sizeof(Word)-n` bits
/// from `high`.
/// Word ret
/// for (i = 0; i < sizeof(Word)*8; i++){
/// ret[i]= i < n ? low[i]: high[i];
/// }
template
constexpr Word SpliceWord(int n, Word low, Word high) {
return (high & ~PrecedingWordBitmask(n)) | (low & PrecedingWordBitmask(n));
}
} // namespace BitUtil
} // namespace arrow