forked from ethereum/go-ethereum
-
Notifications
You must be signed in to change notification settings - Fork 5
/
big.go
153 lines (127 loc) · 3.26 KB
/
big.go
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
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
// Copyright 2014 The go-ethereum Authors
// This file is part of the go-ethereum library.
//
// The go-ethereum library is free software: you can redistribute it and/or modify
// it under the terms of the GNU Lesser General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// The go-ethereum library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public License
// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
package common
import "math/big"
// Common big integers often used
var (
Big1 = big.NewInt(1)
Big2 = big.NewInt(2)
Big3 = big.NewInt(3)
Big0 = big.NewInt(0)
BigTrue = Big1
BigFalse = Big0
Big32 = big.NewInt(32)
Big256 = big.NewInt(0xff)
Big257 = big.NewInt(257)
MaxBig = String2Big("0xffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff")
)
// Big pow
//
// Returns the power of two big integers
func BigPow(a, b int) *big.Int {
c := new(big.Int)
c.Exp(big.NewInt(int64(a)), big.NewInt(int64(b)), big.NewInt(0))
return c
}
// Big
//
// Shortcut for new(big.Int).SetString(..., 0)
func Big(num string) *big.Int {
n := new(big.Int)
n.SetString(num, 0)
return n
}
// Bytes2Big
//
func BytesToBig(data []byte) *big.Int {
n := new(big.Int)
n.SetBytes(data)
return n
}
func Bytes2Big(data []byte) *big.Int { return BytesToBig(data) }
func BigD(data []byte) *big.Int { return BytesToBig(data) }
func String2Big(num string) *big.Int {
n := new(big.Int)
n.SetString(num, 0)
return n
}
func BitTest(num *big.Int, i int) bool {
return num.Bit(i) > 0
}
// To256
//
// "cast" the big int to a 256 big int (i.e., limit to)
var tt256 = new(big.Int).Lsh(big.NewInt(1), 256)
var tt256m1 = new(big.Int).Sub(new(big.Int).Lsh(big.NewInt(1), 256), big.NewInt(1))
var tt255 = new(big.Int).Lsh(big.NewInt(1), 255)
func U256(x *big.Int) *big.Int {
//if x.Cmp(Big0) < 0 {
// return new(big.Int).Add(tt256, x)
// }
x.And(x, tt256m1)
return x
}
func S256(x *big.Int) *big.Int {
if x.Cmp(tt255) < 0 {
return x
} else {
// We don't want to modify x, ever
return new(big.Int).Sub(x, tt256)
}
}
func FirstBitSet(v *big.Int) int {
for i := 0; i < v.BitLen(); i++ {
if v.Bit(i) > 0 {
return i
}
}
return v.BitLen()
}
// Big to bytes
//
// Returns the bytes of a big integer with the size specified by **base**
// Attempts to pad the byte array with zeros.
func BigToBytes(num *big.Int, base int) []byte {
ret := make([]byte, base/8)
if len(num.Bytes()) > base/8 {
return num.Bytes()
}
return append(ret[:len(ret)-len(num.Bytes())], num.Bytes()...)
}
// Big copy
//
// Creates a copy of the given big integer
func BigCopy(src *big.Int) *big.Int {
return new(big.Int).Set(src)
}
// Big max
//
// Returns the maximum size big integer
func BigMax(x, y *big.Int) *big.Int {
if x.Cmp(y) < 0 {
return y
}
return x
}
// Big min
//
// Returns the minimum size big integer
func BigMin(x, y *big.Int) *big.Int {
if x.Cmp(y) > 0 {
return y
}
return x
}