github.com/arieschain/arieschain@v0.0.0-20191023063405-37c074544356/common/math/integer.go (about) 1 package math 2 3 import ( 4 "fmt" 5 "strconv" 6 ) 7 8 const ( 9 // Integer limit values. 10 MaxInt8 = 1<<7 - 1 11 MinInt8 = -1 << 7 12 MaxInt16 = 1<<15 - 1 13 MinInt16 = -1 << 15 14 MaxInt32 = 1<<31 - 1 15 MinInt32 = -1 << 31 16 MaxInt64 = 1<<63 - 1 17 MinInt64 = -1 << 63 18 MaxUint8 = 1<<8 - 1 19 MaxUint16 = 1<<16 - 1 20 MaxUint32 = 1<<32 - 1 21 MaxUint64 = 1<<64 - 1 22 ) 23 24 // HexOrDecimal64 marshals uint64 as hex or decimal. 25 type HexOrDecimal64 uint64 26 27 // UnmarshalText implements encoding.TextUnmarshaler. 28 func (i *HexOrDecimal64) UnmarshalText(input []byte) error { 29 int, ok := ParseUint64(string(input)) 30 if !ok { 31 return fmt.Errorf("invalid hex or decimal integer %q", input) 32 } 33 *i = HexOrDecimal64(int) 34 return nil 35 } 36 37 // MarshalText implements encoding.TextMarshaler. 38 func (i HexOrDecimal64) MarshalText() ([]byte, error) { 39 return []byte(fmt.Sprintf("%#x", uint64(i))), nil 40 } 41 42 // ParseUint64 parses s as an integer in decimal or hexadecimal syntax. 43 // Leading zeros are accepted. The empty string parses as zero. 44 func ParseUint64(s string) (uint64, bool) { 45 if s == "" { 46 return 0, true 47 } 48 if len(s) >= 2 && (s[:2] == "0x" || s[:2] == "0X") { 49 v, err := strconv.ParseUint(s[2:], 16, 64) 50 return v, err == nil 51 } 52 v, err := strconv.ParseUint(s, 10, 64) 53 return v, err == nil 54 } 55 56 // MustParseUint64 parses s as an integer and panics if the string is invalid. 57 func MustParseUint64(s string) uint64 { 58 v, ok := ParseUint64(s) 59 if !ok { 60 panic("invalid unsigned 64 bit integer: " + s) 61 } 62 return v 63 } 64 65 // NOTE: The following methods need to be optimised using either bit checking or asm 66 67 // SafeSub returns subtraction result and whether overflow occurred. 68 func SafeSub(x, y uint64) (uint64, bool) { 69 return x - y, x < y 70 } 71 72 // SafeAdd returns the result and whether overflow occurred. 73 func SafeAdd(x, y uint64) (uint64, bool) { 74 return x + y, y > MaxUint64-x 75 } 76 77 // SafeMul returns multiplication result and whether overflow occurred. 78 func SafeMul(x, y uint64) (uint64, bool) { 79 if x == 0 || y == 0 { 80 return 0, false 81 } 82 return x * y, y > MaxUint64/x 83 }