go-pulse/common/math/big.go
Felix Lange 30d706c35e cmd/geth: add --config file flag (#13875)
* p2p/discover, p2p/discv5: add marshaling methods to Node

* p2p/netutil: make Netlist decodable from TOML

* common/math: encode nil HexOrDecimal256 as 0x0

* cmd/geth: add --config file flag

* cmd/geth: add missing license header

* eth: prettify Config again, fix tests

* eth: use gasprice.Config instead of duplicating its fields

* eth/gasprice: hide nil default from dumpconfig output

* cmd/geth: hide genesis block in dumpconfig output

* node: make tests compile

* console: fix tests

* cmd/geth: make TOML keys look exactly like Go struct fields

* p2p: use discovery by default

This makes the zero Config slightly more useful. It also fixes package
node tests because Node detects reuse of the datadir through the
NodeDatabase.

* cmd/geth: make ethstats URL settable through config file

* cmd/faucet: fix configuration

* cmd/geth: dedup attach tests

* eth: add comment for DefaultConfig

* eth: pass downloader.SyncMode in Config

This removes the FastSync, LightSync flags in favour of a more
general SyncMode flag.

* cmd/utils: remove jitvm flags

* cmd/utils: make mutually exclusive flag error prettier

It now reads:

   Fatal: flags --dev, --testnet can't be used at the same time

* p2p: fix typo

* node: add DefaultConfig, use it for geth

* mobile: add missing NoDiscovery option

* cmd/utils: drop MakeNode

This exposed a couple of places that needed to be updated to use
node.DefaultConfig.

* node: fix typo

* eth: make fast sync the default mode

* cmd/utils: remove IPCApiFlag (unused)

* node: remove default IPC path

Set it in the frontends instead.

* cmd/geth: add --syncmode

* cmd/utils: make --ipcdisable and --ipcpath mutually exclusive

* cmd/utils: don't enable WS, HTTP when setting addr

* cmd/utils: fix --identity
2017-04-12 17:27:23 +03:00

183 lines
4.6 KiB
Go

// Copyright 2017 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 math provides integer math utilities.
package math
import (
"fmt"
"math/big"
)
var (
tt255 = BigPow(2, 255)
tt256 = BigPow(2, 256)
tt256m1 = new(big.Int).Sub(tt256, big.NewInt(1))
MaxBig256 = new(big.Int).Set(tt256m1)
)
const (
// number of bits in a big.Word
wordBits = 32 << (uint64(^big.Word(0)) >> 63)
// number of bytes in a big.Word
wordBytes = wordBits / 8
)
// HexOrDecimal256 marshals big.Int as hex or decimal.
type HexOrDecimal256 big.Int
// UnmarshalText implements encoding.TextUnmarshaler.
func (i *HexOrDecimal256) UnmarshalText(input []byte) error {
bigint, ok := ParseBig256(string(input))
if !ok {
return fmt.Errorf("invalid hex or decimal integer %q", input)
}
*i = HexOrDecimal256(*bigint)
return nil
}
// MarshalText implements encoding.TextMarshaler.
func (i *HexOrDecimal256) MarshalText() ([]byte, error) {
if i == nil {
return []byte("0x0"), nil
}
return []byte(fmt.Sprintf("%#x", (*big.Int)(i))), nil
}
// ParseBig256 parses s as a 256 bit integer in decimal or hexadecimal syntax.
// Leading zeros are accepted. The empty string parses as zero.
func ParseBig256(s string) (*big.Int, bool) {
if s == "" {
return new(big.Int), true
}
var bigint *big.Int
var ok bool
if len(s) >= 2 && (s[:2] == "0x" || s[:2] == "0X") {
bigint, ok = new(big.Int).SetString(s[2:], 16)
} else {
bigint, ok = new(big.Int).SetString(s, 10)
}
if ok && bigint.BitLen() > 256 {
bigint, ok = nil, false
}
return bigint, ok
}
// MustParseBig parses s as a 256 bit big integer and panics if the string is invalid.
func MustParseBig256(s string) *big.Int {
v, ok := ParseBig256(s)
if !ok {
panic("invalid 256 bit integer: " + s)
}
return v
}
// BigPow returns a ** b as a big integer.
func BigPow(a, b int64) *big.Int {
r := big.NewInt(a)
return r.Exp(r, big.NewInt(b), nil)
}
// BigMax returns the larger of x or y.
func BigMax(x, y *big.Int) *big.Int {
if x.Cmp(y) < 0 {
return y
}
return x
}
// BigMin returns the smaller of x or y.
func BigMin(x, y *big.Int) *big.Int {
if x.Cmp(y) > 0 {
return y
}
return x
}
// FirstBitSet returns the index of the first 1 bit in v, counting from LSB.
func FirstBitSet(v *big.Int) int {
for i := 0; i < v.BitLen(); i++ {
if v.Bit(i) > 0 {
return i
}
}
return v.BitLen()
}
// PaddedBigBytes encodes a big integer as a big-endian byte slice. The length
// of the slice is at least n bytes.
func PaddedBigBytes(bigint *big.Int, n int) []byte {
if bigint.BitLen()/8 >= n {
return bigint.Bytes()
}
ret := make([]byte, n)
ReadBits(bigint, ret)
return ret
}
// ReadBits encodes the absolute value of bigint as big-endian bytes. Callers must ensure
// that buf has enough space. If buf is too short the result will be incomplete.
func ReadBits(bigint *big.Int, buf []byte) {
i := len(buf)
for _, d := range bigint.Bits() {
for j := 0; j < wordBytes && i > 0; j++ {
i--
buf[i] = byte(d)
d >>= 8
}
}
}
// U256 encodes as a 256 bit two's complement number. This operation is destructive.
func U256(x *big.Int) *big.Int {
return x.And(x, tt256m1)
}
// S256 interprets x as a two's complement number.
// x must not exceed 256 bits (the result is undefined if it does) and is not modified.
//
// S256(0) = 0
// S256(1) = 1
// S256(2**255) = -2**255
// S256(2**256-1) = -1
func S256(x *big.Int) *big.Int {
if x.Cmp(tt255) < 0 {
return x
} else {
return new(big.Int).Sub(x, tt256)
}
}
// Exp implements exponentiation by squaring.
// Exp returns a newly-allocated big integer and does not change
// base or exponent. The result is truncated to 256 bits.
//
// Courtesy @karalabe and @chfast
func Exp(base, exponent *big.Int) *big.Int {
result := big.NewInt(1)
for _, word := range exponent.Bits() {
for i := 0; i < wordBits; i++ {
if word&1 == 1 {
U256(result.Mul(result, base))
}
U256(base.Mul(base, base))
word >>= 1
}
}
return result
}