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helper.go
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/
helper.go
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// Copyright 2014, Shuhei Tanuma. All rights reserved.
// Use of this source code is governed by a MIT license
// that can be found in the LICENSE file.
package mqtt
import (
"encoding/binary"
"errors"
"io"
)
var overflow = errors.New("readvarint: varint overflows a 32-bit integer")
func ReadVarint(reader io.Reader) (int, error) {
var RemainingLength uint8
m := 1
v := 0
for i := 0; i < 4; i++ {
binary.Read(reader, binary.BigEndian, &RemainingLength)
v += (int(RemainingLength) & 0x7F) * m
m *= 0x80
if m > 0x200000 {
return 0, overflow
}
if (RemainingLength & 0x80) == 0 {
break
}
}
return v, nil
}
func WriteVarint(writer io.Writer, size int) (int, error) {
var encode_byte uint8
x := size
var i int
for i = 0; x > 0 && i < 4; i++ {
encode_byte = uint8(x % 0x80)
x = x / 0x80
if x > 0 {
encode_byte |= 0x80
}
binary.Write(writer, binary.BigEndian, encode_byte)
}
return i, nil
}