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
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
|
// Copyright 2020 The Inet.Af AUTHORS. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package netipx
import (
"encoding/binary"
"math/bits"
"net/netip"
)
// uint128 represents a uint128 using two uint64s.
//
// When the methods below mention a bit number, bit 0 is the most
// significant bit (in hi) and bit 127 is the lowest (lo&1).
type uint128 struct {
hi uint64
lo uint64
}
func u128From16(a [16]byte) uint128 {
return uint128{
binary.BigEndian.Uint64(a[:8]),
binary.BigEndian.Uint64(a[8:]),
}
}
func (u uint128) IP6() netip.Addr {
var a [16]byte
binary.BigEndian.PutUint64(a[:8], u.hi)
binary.BigEndian.PutUint64(a[8:], u.lo)
return netip.AddrFrom16(a)
}
func (u uint128) IP4() netip.Addr {
var a [8]byte
binary.BigEndian.PutUint64(a[:], u.lo)
return netip.AddrFrom4([4]byte{a[4], a[5], a[6], a[7]})
}
// isZero reports whether u == 0.
//
// It's faster than u == (uint128{}) because the compiler (as of Go
// 1.15/1.16b1) doesn't do this trick and instead inserts a branch in
// its eq alg's generated code.
func (u uint128) isZero() bool { return u.hi|u.lo == 0 }
// and returns the bitwise AND of u and m (u&m).
func (u uint128) and(m uint128) uint128 {
return uint128{u.hi & m.hi, u.lo & m.lo}
}
// xor returns the bitwise XOR of u and m (u^m).
func (u uint128) xor(m uint128) uint128 {
return uint128{u.hi ^ m.hi, u.lo ^ m.lo}
}
// or returns the bitwise OR of u and m (u|m).
func (u uint128) or(m uint128) uint128 {
return uint128{u.hi | m.hi, u.lo | m.lo}
}
// not returns the bitwise NOT of u.
func (u uint128) not() uint128 {
return uint128{^u.hi, ^u.lo}
}
// subOne returns u - 1.
func (u uint128) subOne() uint128 {
lo, borrow := bits.Sub64(u.lo, 1, 0)
return uint128{u.hi - borrow, lo}
}
// addOne returns u + 1.
func (u uint128) addOne() uint128 {
lo, carry := bits.Add64(u.lo, 1, 0)
return uint128{u.hi + carry, lo}
}
func u64CommonPrefixLen(a, b uint64) uint8 {
return uint8(bits.LeadingZeros64(a ^ b))
}
func (u uint128) commonPrefixLen(v uint128) (n uint8) {
if n = u64CommonPrefixLen(u.hi, v.hi); n == 64 {
n += u64CommonPrefixLen(u.lo, v.lo)
}
return
}
// func (u *uint128) halves() [2]*uint64 {
// return [2]*uint64{&u.hi, &u.lo}
// }
// bitsSetFrom returns a copy of u with the given bit
// and all subsequent ones set.
func (u uint128) bitsSetFrom(bit uint8) uint128 {
return u.or(mask6[bit].not())
}
// bitsClearedFrom returns a copy of u with the given bit
// and all subsequent ones cleared.
func (u uint128) bitsClearedFrom(bit uint8) uint128 {
return u.and(mask6[bit])
}
|
