blob: 745ccde795cc8da879bfe3b5b7033baca4486728 (
plain) (
blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
|
// Copyright Vespa.ai. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
#pragma once
#include <cstdint>
#include <cstddef>
#include <limits>
namespace search {
class BitWord {
public:
using Word = uint64_t;
using Index = uint32_t;
static Word checkTab(Index index) noexcept { return _checkTab[bitNum(index)]; }
static constexpr Word startBits(Index index) noexcept { return (std::numeric_limits<Word>::max() >> 1) >> (WordLen - 1 - bitNum(index)); }
static constexpr size_t WordLen = sizeof(Word)*8;
static constexpr uint8_t bitNum(Index idx) noexcept { return (idx % WordLen); }
static constexpr Word endBits(Index index) noexcept { return (std::numeric_limits<Word>::max() - 1) << bitNum(index); }
static constexpr Word allBits() noexcept { return std::numeric_limits<Word>::max(); }
static constexpr Index wordNum(Index idx) noexcept { return idx >> numWordBits(); }
static constexpr Word mask(Index idx) noexcept { return Word(1) << bitNum(idx); }
static constexpr uint8_t size_bits(uint8_t n) noexcept { return (n > 1) ? (1 + size_bits(n >> 1)) : 0; }
static constexpr uint8_t numWordBits() noexcept { return size_bits(WordLen); }
private:
static Word _checkTab[WordLen];
struct Init {
Init();
};
static Init _initializer;
};
}
|
