proc ::bpacket::encode::varint {value} {
  if {$value < 128} {  ; # 2**7
    append x [binary format c $value]
    return $x
  } elseif {$value < 16384} {  ; # 2**14
    append x [binary format c [expr {($value & 127) | 128}]]
    append x [binary format c [expr {$value >> 7}]]
    return $x
  } elseif {$value < 2097152} {  ;# 2**21
    append x [binary format c [expr {($value & 127) | 128}]]
    append x [binary format c [expr {(($value >> 7) & 127) | 128}]]
    append x [binary format c [expr {$value >> 14}]]
    return $x
  }
  set n 0; set sh 0
  while 1 {
    set b [expr {($value >> $sh) & 127}]
    incr sh 7
    incr n
    if {$value >> $sh} {
      append x [binary format c [expr {$b | 128}]]
    } else {
      append x [binary format c $b]
      return $x
    }
  }
  return $x
}