Documentation
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Overview ¶
Package math provides convenience functions to use big.Int and to parse a string into an integer.
`big.go` provides Max, Min, Pow, and Parse functions for big.Int type and it also implements encoding.TextMarshaler and encoding.TextUnmarshaler.
`integer.go` provides functions to parse string into unsigned int and to calculate safely by detecting overflow. It also provides implementation of encoding.TextMarshaler and encoding.TextUnmarshaler.
encoding.TextMarshaler is the interface implemented by an object that can marshal itself into a textual form. Its MarshalText encodes the receiver into UTF-8-encoded text and returns the result.
encoding.TextUnmarshaler is the interface implemented by an object that can unmarshal a textual representation of itself. Its UnmarshalText must be able to decode the form generated by MarshalText.
Index ¶
- Constants
- Variables
- func BigMax(x, y *big.Int) *big.Int
- func BigMin(x, y *big.Int) *big.Int
- func BigPow(a, b int64) *big.Int
- func Byte(bigint *big.Int, padlength, n int) byte
- func Exp(base, exponent *big.Int) *big.Int
- func FirstBitSet(v *big.Int) int
- func MustParseBig256(s string) *big.Int
- func MustParseUint64(s string) uint64
- func PaddedBigBytes(bigint *big.Int, n int) []byte
- func ParseBig256(s string) (*big.Int, bool)
- func ParseUint64(s string) (uint64, bool)
- func ReadBits(bigint *big.Int, buf []byte)
- func S256(x *big.Int) *big.Int
- func SafeAdd(x, y uint64) (uint64, bool)
- func SafeMul(x, y uint64) (uint64, bool)
- func SafeSub(x, y uint64) (uint64, bool)
- func U256(x *big.Int) *big.Int
- func U256Bytes(n *big.Int) []byte
- type HexOrDecimal256
- type HexOrDecimal64
Constants ¶
const ( // Integer limit values. MaxInt8 = 1<<7 - 1 MinInt8 = -1 << 7 MaxInt16 = 1<<15 - 1 MinInt16 = -1 << 15 MaxInt32 = 1<<31 - 1 MinInt32 = -1 << 31 MaxInt64 = 1<<63 - 1 MinInt64 = -1 << 63 MaxUint8 = 1<<8 - 1 MaxUint16 = 1<<16 - 1 MaxUint32 = 1<<32 - 1 MaxUint64 = 1<<64 - 1 )
Variables ¶
Functions ¶
func Byte ¶
Byte returns the byte at position n, with the supplied padlength in Little-Endian encoding. n==0 returns the MSB Example: bigint '5', padlength 32, n=31 => 5
func Exp ¶
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 FirstBitSet ¶
FirstBitSet returns the index of the first 1 bit in v, counting from LSB.
func MustParseBig256 ¶
MustParseBig256 parses s as a 256 bit big integer and panics if the string is invalid.
func MustParseUint64 ¶
MustParseUint64 parses s as an integer and panics if the string is invalid.
func PaddedBigBytes ¶
PaddedBigBytes encodes a big integer as a big-endian byte slice. The length of the slice is at least n bytes.
func ParseBig256 ¶
ParseBig256 parses s as a 256 bit integer in decimal or hexadecimal syntax. Leading zeros are accepted. The empty string parses as zero.
func ParseUint64 ¶
ParseUint64 parses s as an integer in decimal or hexadecimal syntax. Leading zeros are accepted. The empty string parses as zero.
func ReadBits ¶
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 S256 ¶
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
Types ¶
type HexOrDecimal256 ¶
HexOrDecimal256 marshals big.Int as hex or decimal.
func (*HexOrDecimal256) MarshalText ¶
func (i *HexOrDecimal256) MarshalText() ([]byte, error)
MarshalText implements encoding.TextMarshaler.
func (*HexOrDecimal256) UnmarshalText ¶
func (i *HexOrDecimal256) UnmarshalText(input []byte) error
UnmarshalText implements encoding.TextUnmarshaler.
type HexOrDecimal64 ¶
type HexOrDecimal64 uint64
HexOrDecimal64 marshals uint64 as hex or decimal.
func (HexOrDecimal64) MarshalText ¶
func (i HexOrDecimal64) MarshalText() ([]byte, error)
MarshalText implements encoding.TextMarshaler.
func (*HexOrDecimal64) UnmarshalText ¶
func (i *HexOrDecimal64) UnmarshalText(input []byte) error
UnmarshalText implements encoding.TextUnmarshaler.
Source Files