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