Module: KRPC::ProtobufUtils::Decoder

Defined in:
lib/krpc/protobuf_utils.rb

Class Method Summary collapse

Class Method Details

.decode(bytes, type) ⇒ Object

Raises:

  • (RuntimeError) 


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# File 'lib/krpc/protobuf_utils.rb', line 8

def decode(bytes, type)
  meth_name = "decode_" + type
  raise RuntimeError.new("Unsupported type #{type}") unless respond_to?(meth_name)
  send(meth_name, bytes)
end

.decode_bool(bytes) ⇒ Object 



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# File 'lib/krpc/protobuf_utils.rb', line 49

def decode_bool(bytes)
  decode_varint(bytes) != 0
end

.decode_bytes(bytes) ⇒ Object 



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# File 'lib/krpc/protobuf_utils.rb', line 56

def decode_bytes(bytes)
  size, pos = decode_varint_pos(bytes)
  bytes[pos..(pos+size)].bytes
end

.decode_double(bytes) ⇒ Object 



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# File 'lib/krpc/protobuf_utils.rb', line 46

def decode_double(bytes)
  bytes.unpack('E').first
end

.decode_float(bytes) ⇒ Object

based on: github.com/ruby-protobuf/protobuf/search?q=pack



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# File 'lib/krpc/protobuf_utils.rb', line 43

def decode_float(bytes)
  bytes.unpack('e').first
end

.decode_string(bytes) ⇒ Object 



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# File 'lib/krpc/protobuf_utils.rb', line 52

def decode_string(bytes)
  size, pos = decode_varint_pos(bytes)
  bytes[pos..(pos+size)].force_encoding(Encoding::UTF_8)
end

.decode_varint(bytes) ⇒ Object Also known as: decode_uint32, decode_uint64

based on: developers.google.com/protocol-buffers/docs/encoding#varints & www.rubydoc.info/gems/ruby-protocol-buffers/1.0.1/ProtocolBuffers/Varint#decode-class_method & github.com/google/protobuf/blob/master/python/google/protobuf/internal/decoder.py#L136



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# File 'lib/krpc/protobuf_utils.rb', line 15

def decode_varint(bytes)
  decode_varint_pos(bytes)[0]
end

.decode_varint_pos(bytes) ⇒ Object

Raises:

  • (RuntimeError) 


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# File 'lib/krpc/protobuf_utils.rb', line 18

def decode_varint_pos(bytes)
  raise(RuntimeError, "can't decode varint from empty byte buffer") if bytes.empty?
  pos = 0
  result = 0
  shift = 0
  loop do
    byte = bytes[pos].ord
    pos += 1
    result |= (byte & 0b0111_1111) << shift
    return [result, pos] if (byte & 0b1000_0000) == 0
    shift += 7
    raise(RuntimeError, "too many bytes when decoding varint") if shift >= 64
  end
end

.decode_zigzaged_varint(bytes) ⇒ Object Also known as: decode_sint32, decode_sint64 



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# File 'lib/krpc/protobuf_utils.rb', line 32

def decode_zigzaged_varint(bytes)
  zigzaged = decode_varint(bytes)
  (zigzaged >> 1) ^ -(zigzaged & 1)
end