neoneo-go/pkg/util/io.go
Anthony De Meulemeester 628656483a
bug fixes (TCP + uint256) and started core part (#14)
* Fixed TCP read + Uint256 reversed array + started on some core pieces

* Disabled some debug output + muted test

* 0.5.0
2018-02-04 20:54:51 +01:00

65 lines
1.4 KiB
Go

package util
import (
"encoding/binary"
"errors"
"io"
)
// Variable length integer, can be encoded to save space according to the value typed.
// len 1 uint8
// len 3 0xfd + uint16
// len 5 0xfe = uint32
// len 9 0xff = uint64
// For more information about this:
// https://github.com/neo-project/neo/wiki/Network-Protocol
// ReadVarUint reads a variable unsigned integer and returns it as a uint64.
func ReadVarUint(r io.Reader) uint64 {
var b uint8
binary.Read(r, binary.LittleEndian, &b)
if b == 0xfd {
var v uint16
binary.Read(r, binary.LittleEndian, &v)
return uint64(v)
}
if b == 0xfe {
var v uint32
binary.Read(r, binary.LittleEndian, &v)
return uint64(v)
}
if b == 0xff {
var v uint64
binary.Read(r, binary.LittleEndian, &v)
return v
}
return uint64(b)
}
// WriteVarUint writes a variable unsigned integer.
func WriteVarUint(w io.Writer, val uint64) error {
if val < 0 {
return errors.New("value out of range")
}
if val < 0xfd {
binary.Write(w, binary.LittleEndian, uint8(val))
return nil
}
if val < 0xFFFF {
binary.Write(w, binary.LittleEndian, 0xfd)
binary.Write(w, binary.LittleEndian, uint16(val))
return nil
}
if val < 0xFFFFFFFF {
binary.Write(w, binary.LittleEndian, 0xfe)
binary.Write(w, binary.LittleEndian, uint32(val))
return nil
}
binary.Write(w, binary.LittleEndian, 0xff)
binary.Write(w, binary.LittleEndian, val)
return nil
}