1// Copyright 2017 The go-ethereum Authors 2// This file is part of the go-ethereum library. 3// 4// The go-ethereum library is free software: you can redistribute it and/or modify 5// it under the terms of the GNU Lesser General Public License as published by 6// the Free Software Foundation, either version 3 of the License, or 7// (at your option) any later version. 8// 9// The go-ethereum library is distributed in the hope that it will be useful, 10// but WITHOUT ANY WARRANTY; without even the implied warranty of 11// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 12// GNU Lesser General Public License for more details. 13// 14// You should have received a copy of the GNU Lesser General Public License 15// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>. 16 17package math 18 19import ( 20 "fmt" 21 "math/bits" 22 "strconv" 23) 24 25// Integer limit values. 26const ( 27 MaxInt8 = 1<<7 - 1 28 MinInt8 = -1 << 7 29 MaxInt16 = 1<<15 - 1 30 MinInt16 = -1 << 15 31 MaxInt32 = 1<<31 - 1 32 MinInt32 = -1 << 31 33 MaxInt64 = 1<<63 - 1 34 MinInt64 = -1 << 63 35 MaxUint8 = 1<<8 - 1 36 MaxUint16 = 1<<16 - 1 37 MaxUint32 = 1<<32 - 1 38 MaxUint64 = 1<<64 - 1 39) 40 41// HexOrDecimal64 marshals uint64 as hex or decimal. 42type HexOrDecimal64 uint64 43 44// UnmarshalText implements encoding.TextUnmarshaler. 45func (i *HexOrDecimal64) UnmarshalText(input []byte) error { 46 int, ok := ParseUint64(string(input)) 47 if !ok { 48 return fmt.Errorf("invalid hex or decimal integer %q", input) 49 } 50 *i = HexOrDecimal64(int) 51 return nil 52} 53 54// MarshalText implements encoding.TextMarshaler. 55func (i HexOrDecimal64) MarshalText() ([]byte, error) { 56 return []byte(fmt.Sprintf("%#x", uint64(i))), nil 57} 58 59// ParseUint64 parses s as an integer in decimal or hexadecimal syntax. 60// Leading zeros are accepted. The empty string parses as zero. 61func ParseUint64(s string) (uint64, bool) { 62 if s == "" { 63 return 0, true 64 } 65 if len(s) >= 2 && (s[:2] == "0x" || s[:2] == "0X") { 66 v, err := strconv.ParseUint(s[2:], 16, 64) 67 return v, err == nil 68 } 69 v, err := strconv.ParseUint(s, 10, 64) 70 return v, err == nil 71} 72 73// MustParseUint64 parses s as an integer and panics if the string is invalid. 74func MustParseUint64(s string) uint64 { 75 v, ok := ParseUint64(s) 76 if !ok { 77 panic("invalid unsigned 64 bit integer: " + s) 78 } 79 return v 80} 81 82// SafeSub returns x-y and checks for overflow. 83func SafeSub(x, y uint64) (uint64, bool) { 84 diff, borrowOut := bits.Sub64(x, y, 0) 85 return diff, borrowOut != 0 86} 87 88// SafeAdd returns x+y and checks for overflow. 89func SafeAdd(x, y uint64) (uint64, bool) { 90 sum, carryOut := bits.Add64(x, y, 0) 91 return sum, carryOut != 0 92} 93 94// SafeMul returns x*y and checks for overflow. 95func SafeMul(x, y uint64) (uint64, bool) { 96 hi, lo := bits.Mul64(x, y) 97 return lo, hi != 0 98} 99