Start repo, claude & kimi still vibing tho
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283
lib/odinsea/net/packet/in.ex
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283
lib/odinsea/net/packet/in.ex
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defmodule Odinsea.Net.Packet.In do
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@moduledoc """
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Incoming packet reader ported from Java InPacket.
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Handles little-endian decoding of MapleStory packet data.
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"""
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defstruct data: <<>>, index: 0, length: 0
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alias Odinsea.Constants.Server
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@type t :: %__MODULE__{
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data: binary(),
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index: non_neg_integer(),
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length: non_neg_integer()
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}
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@doc """
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Creates a new incoming packet from binary data.
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"""
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@spec new(binary()) :: t()
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def new(data) when is_binary(data) do
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%__MODULE__{
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data: data,
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index: 0,
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length: byte_size(data)
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}
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end
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@doc """
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Returns the remaining bytes in the packet.
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"""
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@spec remaining(t()) :: non_neg_integer()
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def remaining(%__MODULE__{length: length, index: index}), do: length - index
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@doc """
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Returns true if the packet has been fully read.
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"""
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@spec empty?(t()) :: boolean()
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def empty?(%__MODULE__{length: length, index: index}), do: index >= length
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@doc """
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Returns the current read position.
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"""
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@spec get_index(t()) :: non_neg_integer()
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def get_index(%__MODULE__{index: index}), do: index
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@doc """
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Sets the read position.
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"""
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@spec set_index(t(), non_neg_integer()) :: t()
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def set_index(packet, index) when index >= 0 do
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%{packet | index: min(index, packet.length)}
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end
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@doc """
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Skips the specified number of bytes.
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"""
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@spec skip(t(), non_neg_integer()) :: t()
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def skip(packet, count) when count >= 0 do
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%{packet | index: min(packet.index + count, packet.length)}
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end
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@doc """
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Reads a byte and returns {value, updated_packet}.
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"""
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@spec decode_byte(t()) :: {integer(), t()} | :error
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def decode_byte(%__MODULE__{data: data, index: index, length: length}) do
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if index + 1 <= length do
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<<_::binary-size(index), value::signed-integer-little-8, _::binary>> = data
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{value, %__MODULE__{data: data, index: index + 1, length: length}}
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else
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:error
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end
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end
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@doc """
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Reads a byte and returns only the value, raising on error.
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"""
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@spec decode_byte!(t()) :: integer()
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def decode_byte!(packet) do
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case decode_byte(packet) do
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{value, _} -> value
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:error -> raise "Packet underrun reading byte"
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end
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end
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@doc """
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Reads a short (2 bytes) and returns {value, updated_packet}.
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"""
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@spec decode_short(t()) :: {integer(), t()} | :error
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def decode_short(%__MODULE__{data: data, index: index, length: length}) do
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if index + 2 <= length do
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<<_::binary-size(index), value::signed-integer-little-16, _::binary>> = data
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{value, %__MODULE__{data: data, index: index + 2, length: length}}
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else
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:error
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end
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end
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@doc """
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Reads a short and returns only the value, raising on error.
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"""
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@spec decode_short!(t()) :: integer()
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def decode_short!(packet) do
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case decode_short(packet) do
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{value, _} -> value
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:error -> raise "Packet underrun reading short"
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end
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end
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@doc """
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Reads an int (4 bytes) and returns {value, updated_packet}.
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"""
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@spec decode_int(t()) :: {integer(), t()} | :error
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def decode_int(%__MODULE__{data: data, index: index, length: length}) do
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if index + 4 <= length do
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<<_::binary-size(index), value::signed-integer-little-32, _::binary>> = data
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{value, %__MODULE__{data: data, index: index + 4, length: length}}
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else
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:error
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end
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end
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@doc """
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Reads an int and returns only the value, raising on error.
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"""
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@spec decode_int!(t()) :: integer()
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def decode_int!(packet) do
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case decode_int(packet) do
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{value, _} -> value
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:error -> raise "Packet underrun reading int"
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end
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end
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@doc """
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Reads a long (8 bytes) and returns {value, updated_packet}.
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"""
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@spec decode_long(t()) :: {integer(), t()} | :error
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def decode_long(%__MODULE__{data: data, index: index, length: length}) do
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if index + 8 <= length do
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<<_::binary-size(index), value::signed-integer-little-64, _::binary>> = data
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{value, %__MODULE__{data: data, index: index + 8, length: length}}
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else
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:error
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end
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end
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@doc """
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Reads a long and returns only the value, raising on error.
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"""
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@spec decode_long!(t()) :: integer()
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def decode_long!(packet) do
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case decode_long(packet) do
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{value, _} -> value
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:error -> raise "Packet underrun reading long"
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end
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end
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@doc """
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Reads a MapleStory ASCII string (length-prefixed).
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Format: [2-byte length][ASCII bytes]
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"""
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@spec decode_string(t()) :: {String.t(), t()} | :error
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def decode_string(packet) do
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case decode_short(packet) do
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{length, packet} when length >= 0 ->
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decode_buffer(packet, length) |> decode_string_result()
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_ ->
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:error
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end
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end
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defp decode_string_result({bytes, packet}) do
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{bytes, packet}
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end
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@doc """
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Reads a string and returns only the value, raising on error.
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"""
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@spec decode_string!(t()) :: String.t()
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def decode_string!(packet) do
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case decode_string(packet) do
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{value, _} -> value
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:error -> raise "Packet underrun reading string"
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end
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end
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@doc """
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Reads a specified number of bytes and returns {bytes, updated_packet}.
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"""
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@spec decode_buffer(t(), non_neg_integer()) :: {binary(), t()} | :error
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def decode_buffer(%__MODULE__{data: data, index: index, length: total_length}, count)
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when count >= 0 do
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if index + count <= total_length do
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<<_::binary-size(index), buffer::binary-size(count), _::binary>> = data
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{buffer, %__MODULE__{data: data, index: index + count, length: total_length}}
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else
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:error
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end
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end
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@doc """
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Reads a buffer and returns only the bytes, raising on error.
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"""
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@spec decode_buffer!(t(), non_neg_integer()) :: binary()
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def decode_buffer!(packet, count) do
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case decode_buffer(packet, count) do
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{value, _} -> value
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:error -> raise "Packet underrun reading buffer"
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end
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end
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@doc """
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Reads a boolean (1 byte, 0 = false, 1 = true).
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"""
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@spec decode_bool(t()) :: {boolean(), t()} | :error
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def decode_bool(packet) do
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case decode_byte(packet) do
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{0, packet} -> {false, packet}
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{_, packet} -> {true, packet}
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:error -> :error
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end
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end
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@doc """
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Reads a boolean, raising on error.
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"""
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@spec decode_bool!(t()) :: boolean()
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def decode_bool!(packet) do
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case decode_bool(packet) do
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{value, _} -> value
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:error -> raise "Packet underrun reading bool"
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end
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end
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@doc """
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Reads the remaining bytes in the packet.
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"""
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@spec read_remaining(t()) :: {binary(), t()}
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def read_remaining(%__MODULE__{data: data, index: index, length: length}) do
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remaining = length - index
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<<_::binary-size(index), buffer::binary-size(remaining), _::binary>> = data
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{buffer, %__MODULE__{data: data, index: length, length: length}}
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end
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@doc """
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Converts the packet to a hex string for debugging.
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"""
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@spec to_hex_string(t()) :: String.t()
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def to_hex_string(%__MODULE__{data: data}), do: Odinsea.Net.Hex.encode(data)
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@doc """
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Converts the packet to a hex string with position markers.
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"""
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@spec to_hex_string(t(), boolean()) :: String.t()
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def to_hex_string(%__MODULE__{data: data, index: index}, true) do
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hex_str = Odinsea.Net.Hex.encode(data)
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"[pos=#{index}] " <> hex_str
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end
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def to_hex_string(packet, false), do: to_hex_string(packet)
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@doc """
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Returns the raw packet data.
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"""
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@spec to_buffer(t()) :: binary()
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def to_buffer(%__MODULE__{data: data}), do: data
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@doc """
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Returns a slice of the packet data.
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"""
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@spec slice(t(), non_neg_integer(), non_neg_integer()) :: binary()
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def slice(%__MODULE__{data: data}, start, length) do
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binary_part(data, start, length)
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end
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@doc """
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Returns the packet length.
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"""
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@spec length(t()) :: non_neg_integer()
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def length(%__MODULE__{length: length}), do: length
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end
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