path: root/ethutil/bytes.go

package ethutil

import (
    "bytes"
    "encoding/binary"
    "fmt"
)

// Number to bytes
//
// Returns the number in bytes with the specified base
func NumberToBytes(num interface{}, bits int) []byte {
    buf := new(bytes.Buffer)
    err := binary.Write(buf, binary.BigEndian, num)
    if err != nil {
        fmt.Println("NumberToBytes failed:", err)
    }

    return buf.Bytes()[buf.Len()-(bits/8):]
}

// Bytes to number
//
// Attempts to cast a byte slice to a unsigned integer
func BytesToNumber(b []byte) uint64 {
    var number uint64

    // Make sure the buffer is 64bits
    data := make([]byte, 8)
    data = append(data[:len(b)], b...)

    buf := bytes.NewReader(data)
    err := binary.Read(buf, binary.BigEndian, &number)
    if err != nil {
        fmt.Println("BytesToNumber failed:", err)
    }

    return number
}

// Read variable int
//
// Read a variable length number in big endian byte order
func ReadVarint(reader *bytes.Reader) (ret uint64) {
    if reader.Len() == 8 {
        var num uint64
        binary.Read(reader, binary.BigEndian, &num)
        ret = uint64(num)
    } else if reader.Len() == 4 {
        var num uint32
        binary.Read(reader, binary.BigEndian, &num)
        ret = uint64(num)
    } else if reader.Len() == 2 {
        var num uint16
        binary.Read(reader, binary.BigEndian, &num)
        ret = uint64(num)
    } else {
        var num uint8
        binary.Read(reader, binary.BigEndian, &num)
        ret = uint64(num)
    }

    return ret
}

// Binary length
//
// Returns the true binary length of the given number
func BinaryLength(num int) int {
    if num == 0 {
        return 0
    }

    return 1 + BinaryLength(num>>8)
}

// Copy bytes
//
// Returns an exact copy of the provided bytes
func CopyBytes(b []byte) (copiedBytes []byte) {
    copiedBytes = make([]byte, len(b))
    copy(copiedBytes, b)

    return
}

func IsHex(str string) bool {
    l := len(str)
    return l >= 4 && l%2 == 0 && str[0:2] == "0x"
}