# Xmavlink case required for `mix xmavlink ...` to work
defmodule Mix.Tasks.Xmavlink do
use Mix.Task
import XMAVLink.Parser
import DateTime
import Enum,
only: [any?: 2, count: 1, join: 2, map: 2, filter: 2, reduce: 3, reverse: 1, sort: 1, into: 3]
import String, only: [trim: 1, replace: 3, split: 2, capitalize: 1, downcase: 1]
import XMAVLink.Utils
import Mix.Generator, only: [create_file: 3]
import Path, only: [rootname: 1, basename: 1]
import Bitwise
@doc """
"""
@shortdoc "Generate Elixir Module from MAVLink dialect XML"
@spec run([String.t()]) :: :ok
@impl Mix.Task
def run([dialect_xml_path]) do
run([dialect_xml_path, "#{dialect_xml_path |> rootname |> basename}.ex"])
end
def run([dialect_xml_path, output_ex_source_path]) do
run([
dialect_xml_path,
output_ex_source_path,
dialect_xml_path
|> rootname
|> basename
|> module_case
])
end
def run([dialect_xml_path, output_ex_source_path, module_name]) do
case parse_mavlink_xml(dialect_xml_path) do
{:error, message} ->
IO.puts(message)
%{version: version, dialect: dialect, enums: enums, messages: messages} ->
enum_code_fragments = get_enum_code_fragments(enums, module_name)
message_code_fragments = get_message_code_fragments(messages, enums, module_name)
unit_code_fragments = get_unit_code_fragments(messages)
true =
create_file(
output_ex_source_path,
"""
defmodule #{module_name}.Types do
@typedoc "A MAVLink message"
@type message :: #{map(messages, &"#{module_name}.Message.#{&1[:name] |> module_case}") |> join(" | ")}
@typedoc "An atom representing a MAVLink enumeration type"
@type enum_type :: #{map(enums, &":#{&1[:name]}") |> join(" | ")}
@typedoc "An atom representing a MAVLink enumeration type value"
@type enum_value :: #{map(enums, &"#{&1[:name]}") |> join(" | ")}
@typedoc "Measurement unit of field value"
@type field_unit :: #{unit_code_fragments |> join(~s( | )) |> trim}
#{enum_code_fragments |> map(& &1[:type]) |> join("\n\n ")}
end
#{message_code_fragments |> map(& &1.module) |> join("\n\n") |> trim}
defmodule #{module_name} do
import String, only: [replace_trailing: 3]
import XMAVLink.Utils, only: [unpack_array: 2, unpack_float: 1]
import Bitwise
@moduledoc ~s(#{module_name} #{version}.#{dialect} generated by MAVLink mix task from #{dialect_xml_path} on #{utc_now()})
@doc "MAVLink version"
@spec mavlink_version() :: #{version}
def mavlink_version(), do: #{version}
@doc "MAVLink dialect"
@spec mavlink_dialect() :: #{dialect}
def mavlink_dialect(), do: #{dialect}
@doc "Return a String description of a MAVLink enumeration"
@spec describe(#{module_name}.Types.enum_type | #{module_name}.Types.enum_value) :: String.t
#{enum_code_fragments |> map(& &1[:describe]) |> join("\n ") |> trim}
@doc "Return keyword list of mav_cmd parameters"
@spec describe_params(#{module_name}.Types.mav_cmd) :: XMAVLink.Types.param_description_list
#{enum_code_fragments |> map(& &1[:describe_params]) |> join("\n ") |> trim}
@doc "Return encoded integer value used in a MAVLink message for an enumeration value"
#{enum_code_fragments |> map(& &1[:encode_spec]) |> join("\n ") |> trim}
#{enum_code_fragments |> map(& &1[:encode]) |> join("\n ") |> trim}
@doc "Return the atom representation of a MAVLink enumeration value from the enumeration type and encoded integer"
#{enum_code_fragments |> map(& &1[:decode_spec]) |> join("\n ") |> trim}
#{enum_code_fragments |> map(& &1[:decode]) |> join("\n ") |> trim}
def decode(value, _enum), do: value
@doc "Return the message checksum and size in bytes for a message with a specified id"
@typep target_type :: :broadcast | :system | :system_component | :component
@spec msg_attributes(XMAVLink.Types.message_id) :: {:ok, XMAVLink.Types.crc_extra, pos_integer, target_type} | {:error, :unknown_message_id}
#{message_code_fragments |> map(& &1.msg_attributes) |> join("") |> trim}
def msg_attributes(_), do: {:error, :unknown_message_id}
@doc "Helper function for messages to pack bitmask fields"
@spec pack_bitmask(MapSet.t(#{module_name}.Types.enum_value), #{module_name}.Types.enum_type, (#{module_name}.Types.enum_value, #{module_name}.Types.enum_type -> integer)) :: integer
def pack_bitmask(flag_set, enum, encode), do: Enum.reduce(flag_set, 0, & Bitwise.bxor(&2, encode.(&1, enum)))
@doc "Helper function for decode() to unpack bitmask fields"
@spec unpack_bitmask(integer, #{module_name}.Types.enum_type, (integer, #{module_name}.Types.enum_type -> #{module_name}.Types.enum_value), MapSet.t, integer) :: MapSet.t(#{module_name}.Types.enum_value)
def unpack_bitmask(value, enum, decode, acc \\\\ MapSet.new(), pos \\\\ 1) do
case {decode.(pos, enum), (value &&& pos) != 0} do
{not_atom, _} when not is_atom(not_atom) ->
acc
{entry, true} ->
unpack_bitmask(value, enum, decode, MapSet.put(acc, entry), pos <<< 1)
{_, false} ->
unpack_bitmask(value, enum, decode, acc, pos <<< 1)
end
end
@doc "Unpack a MAVLink message given a MAVLink frame's message id and payload"
@spec unpack(XMAVLink.Types.message_id, binary) :: #{module_name}.Types.message | {:error, :unknown_message}
#{message_code_fragments |> map(& &1.unpack) |> join("") |> trim}
def unpack(_, _), do: {:error, :unknown_message}
end
""",
[]
)
IO.puts("Generated #{module_name} in '#{output_ex_source_path}'.")
:ok
end
end
@type enum_detail :: %{
type: String.t(),
describe: String.t(),
describe_params: String.t(),
encode: String.t(),
decode: String.t()
}
@spec get_enum_code_fragments([XMAVLink.Parser.enum_description()], String.t()) :: [enum_detail]
defp get_enum_code_fragments(enums, module_name) do
for enum <- enums do
%{
name: name,
description: description
} = enum
entry_code_fragments = get_entry_code_fragments(enum)
%{
type:
~s/@typedoc "#{description}"\n / <>
~s/@type #{name} :: / <>
(map(entry_code_fragments, &":#{&1[:name]}") |> join(" | ")),
describe:
~s/def describe(:#{name}), do: "#{escape(description)}"\n / <>
(map(entry_code_fragments, & &1[:describe])
|> join("\n ")),
describe_params:
filter(entry_code_fragments, &(&1 != nil))
|> map(& &1[:describe_params])
|> join("\n "),
encode_spec:
"@spec encode(#{module_name}.Types.#{name}, :#{name}) :: " <>
(map(entry_code_fragments, & &1[:value])
|> join(" | ")),
encode:
map(entry_code_fragments, & &1[:encode])
|> join("\n "),
decode_spec:
"@spec decode(" <>
(map(entry_code_fragments, & &1[:value])
|> join(" | ")) <> ", :#{name}) :: #{module_name}.Types.#{name}",
decode:
map(entry_code_fragments, & &1[:decode])
|> join("\n ")
}
end
end
@type entry_detail :: %{
name: String.t(),
describe: String.t(),
describe_params: String.t(),
encode: String.t(),
decode: String.t()
}
@spec get_entry_code_fragments(XMAVLink.Parser.enum_description()) :: [entry_detail]
defp get_entry_code_fragments(enum = %{name: enum_name, entries: entries}) do
bitmask? = looks_like_a_bitmask?(enum)
{details, _} =
reduce(
entries,
{[], 0},
fn entry, {details, next_value} ->
%{
name: entry_name,
description: entry_description,
value: entry_value,
params: entry_params
} = entry
# Use provided value or continue monotonically from last value: in common.xml MAV_STATE uses this
{entry_value, next_value} =
case entry_value do
nil ->
{next_value, next_value + 1}
_ ->
{entry_value, entry_value + 1}
end
entry_value_string =
if bitmask?,
do: "0b#{Integer.to_string(entry_value, 2)}",
else: Integer.to_string(entry_value)
{
[
%{
name: entry_name,
describe: ~s/def describe(:#{entry_name}), do: "#{escape(entry_description)}"/,
describe_params: get_param_code_fragments(entry_name, entry_params),
encode: ~s/def encode(:#{entry_name}, :#{enum_name}), do: #{entry_value_string}/,
decode: ~s/def decode(#{entry_value_string}, :#{enum_name}), do: :#{entry_name}/,
value: entry_value_string
}
| details
],
next_value
}
end
)
reverse(details)
end
@spec get_param_code_fragments(String.t(), [XMAVLink.Parser.param_description()]) :: String.t()
defp get_param_code_fragments(entry_name, entry_params) do
cond do
count(entry_params) == 0 ->
nil
true ->
~s/def describe_params(:#{entry_name}), do: [/ <>
(map(entry_params, &~s/{#{&1[:index]}, "#{&1[:description]}"}/) |> join(", ")) <>
~s/]/
end
end
@spec get_message_code_fragments(
[XMAVLink.Parser.message_description()],
[enum_detail],
String.t()
) :: [String.t()]
defp get_message_code_fragments(messages, enums, module_name) do
# Lookup used by looks_like_a_bitmask?()
enums_by_name = into(enums, %{}, fn enum -> {Atom.to_string(enum.name), enum} end)
for message <- messages do
message_module_name = message.name |> module_case
enforce_field_names =
Enum.filter(message.fields, &(!&1.is_extension))
|> map(&(":" <> downcase(&1.name)))
|> join(", ")
field_names = message.fields |> map(&(":" <> downcase(&1.name))) |> join(", ")
field_types =
message.fields
|> map(&(downcase(&1.name) <> ": " <> field_type(&1, module_name)))
|> join(", ")
wire_order = message.fields |> wire_order
target =
case {any?(message.fields, &(&1.name == "target_system")),
any?(message.fields, &(&1.name == "target_component"))} do
{false, false} ->
:broadcast
{true, false} ->
:system
{true, true} ->
:system_component
{false, true} ->
# Does this happen?
:component
end
# Have to append "_f" to stop clash with reserved elixir words like "end"
[unpack_binary_pattern, unpack_binary_pattern_ext] =
for field_list <- wire_order do
field_list
|> map(
&(downcase(&1.name) <>
"_f::" <>
if(&1.ordinality > 1,
do: "binary-size(#{type_to_binary(&1.type).size * &1.ordinality})",
else: type_to_binary(&1.type).pattern
))
)
|> join(",")
end
[unpack_struct_fields, unpack_struct_fields_ext] =
for field_list <- wire_order do
field_list
|> map(&(downcase(&1.name) <> ": " <> unpack_field_code_fragment(&1, enums_by_name)))
|> join(", ")
end
[pack_binary_pattern, pack_binary_pattern_ext] =
for field_list <- wire_order do
field_list
|> map(&pack_field_code_fragment(&1, enums_by_name, module_name))
|> join(",")
end
crc_extra = calculate_message_crc_extra(message)
# Including extension fields - currently only used for MAVLink 2 payload truncation
expected_payload_size =
reduce(
message.fields,
0,
# Before MAVLink 2 trailing 0 truncation
fn field, sum -> sum + type_to_binary(field.type).size * field.ordinality end
)
if message.has_ext_fields do
%{
msg_attributes: """
def msg_attributes(#{message.id}), do: {:ok, #{crc_extra}, #{expected_payload_size}, :#{target}}
""",
unpack: """
def unpack(#{message.id}, 1, <<#{unpack_binary_pattern}>>), do: {:ok, %#{module_name}.Message.#{message_module_name}{#{unpack_struct_fields}}}
def unpack(#{message.id}, 2, <<#{unpack_binary_pattern},#{unpack_binary_pattern_ext}>>), do: {:ok, %#{module_name}.Message.#{message_module_name}{#{unpack_struct_fields},#{unpack_struct_fields_ext}}}
""",
module: """
defmodule #{module_name}.Message.#{message_module_name} do
@enforce_keys [#{enforce_field_names}]
defstruct [#{field_names}]
@typedoc "#{escape(message.description)}"
@type t :: %#{module_name}.Message.#{message_module_name}{#{field_types}}
defimpl XMAVLink.Message do
def pack(msg, 1), do: {:ok, #{message.id}, #{module_name}.msg_attributes(#{message.id}), <<#{pack_binary_pattern}>>}
def pack(msg, 2), do: {:ok, #{message.id}, #{module_name}.msg_attributes(#{message.id}), <<#{pack_binary_pattern},#{pack_binary_pattern_ext}>>}
end
end
"""
}
else
%{
msg_attributes: """
def msg_attributes(#{message.id}), do: {:ok, #{crc_extra}, #{expected_payload_size}, :#{target}}
""",
unpack: """
def unpack(#{message.id}, _, <<#{unpack_binary_pattern}>>), do: {:ok, %#{module_name}.Message.#{message_module_name}{#{unpack_struct_fields}}}
""",
module: """
defmodule #{module_name}.Message.#{message_module_name} do
@enforce_keys [#{enforce_field_names}]
defstruct [#{field_names}]
@typedoc "#{escape(message.description)}"
@type t :: %#{module_name}.Message.#{message_module_name}{#{field_types}}
defimpl XMAVLink.Message do
def pack(msg, _), do: {:ok, #{message.id}, #{module_name}.msg_attributes(#{message.id}), <<#{pack_binary_pattern}>>}
end
end
"""
}
end
end
end
@spec calculate_message_crc_extra(XMAVLink.Parser.message_description()) ::
XMAVLink.Types.crc_extra()
defp calculate_message_crc_extra(message) do
reduce(
# Do not include extension fields
message.fields |> wire_order |> hd,
x25_crc(message.name <> " "),
fn field, crc ->
case field.ordinality do
1 ->
crc |> x25_crc(field.type <> " ") |> x25_crc(field.name <> " ")
_ ->
crc
|> x25_crc(field.type <> " ")
|> x25_crc(field.name <> " ")
|> x25_crc([field.ordinality])
end
end
)
|> eight_bit_checksum
end
# Unpack Message Fields
defp unpack_field_code_fragment(%{name: name, ordinality: 1, enum: "", type: "float"}, _) do
"unpack_float(#{downcase(name)}_f)"
end
defp unpack_field_code_fragment(%{name: name, ordinality: 1, enum: "", type: "double"}, _) do
"unpack_double(#{downcase(name)}_f)"
end
defp unpack_field_code_fragment(%{name: name, ordinality: 1, enum: ""}, _) do
downcase(name) <> "_f"
end
defp unpack_field_code_fragment(%{name: name, ordinality: 1, enum: enum, display: :bitmask}, _)
when enum != "" do
"unpack_bitmask(#{downcase(name)}_f, :#{enum}, &decode/2)"
end
defp unpack_field_code_fragment(%{name: name, ordinality: 1, enum: enum}, enums_by_name) do
case looks_like_a_bitmask?(enums_by_name[enum]) do
true ->
IO.puts(~s[Warning: assuming #{enum} is a bitmask although display="bitmask" not set])
"unpack_bitmask(#{downcase(name)}_f, :#{enum}, &decode/2)"
false ->
"decode(#{downcase(name)}_f, :#{enum})"
end
end
defp unpack_field_code_fragment(%{name: name, type: "char"}, _) do
~s[replace_trailing(#{downcase(name)}_f, <<0>>, "")]
end
defp unpack_field_code_fragment(%{name: name, type: type}, _) do
"unpack_array(#{downcase(name)}_f, fn(<<elem::#{type_to_binary(type).pattern},rest::binary>>) -> {elem, rest} end)"
end
# Pack Message Fields
defp pack_field_code_fragment(%{name: name, ordinality: 1, enum: "", type: "float"}, _, _) do
"XMAVLink.Utils.pack_float(msg.#{downcase(name)})::binary-size(4)"
end
defp pack_field_code_fragment(%{name: name, ordinality: 1, enum: "", type: "double"}, _, _) do
"XMAVLink.Utils.pack_double(msg.#{downcase(name)})::binary-size(8)"
end
defp pack_field_code_fragment(%{name: name, ordinality: 1, enum: "", type: type}, _, _) do
"msg.#{downcase(name)}::#{type_to_binary(type).pattern}"
end
defp pack_field_code_fragment(
%{name: name, ordinality: 1, enum: enum, display: :bitmask, type: type},
_,
module_name
)
when enum != "" do
"#{module_name}.pack_bitmask(msg.#{downcase(name)}, :#{enum}, &#{module_name}.encode/2)::#{type_to_binary(type).pattern}"
end
defp pack_field_code_fragment(
%{name: name, ordinality: 1, enum: enum, type: type},
enums_by_name,
module_name
) do
case looks_like_a_bitmask?(enums_by_name[enum]) do
true ->
"#{module_name}.pack_bitmask(msg.#{downcase(name)}, :#{enum}, &#{module_name}.encode/2)::#{type_to_binary(type).pattern}"
false ->
"#{module_name}.encode(msg.#{downcase(name)}, :#{enum})::#{type_to_binary(type).pattern}"
end
end
defp pack_field_code_fragment(%{name: name, ordinality: ordinality, type: "char"}, _, _) do
"XMAVLink.Utils.pack_string(msg.#{downcase(name)}, #{ordinality})::binary-size(#{ordinality})"
end
defp pack_field_code_fragment(%{name: name, ordinality: ordinality, type: type}, _, _) do
"XMAVLink.Utils.pack_array(msg.#{downcase(name)}, #{ordinality}, fn(elem) -> <<elem::#{type_to_binary(type).pattern}>> end)::binary-size(#{type_to_binary(type).size * ordinality})"
end
@spec get_unit_code_fragments([XMAVLink.Parser.message_description()]) :: [String.t()]
defp get_unit_code_fragments(messages) do
reduce(
messages,
MapSet.new(),
fn message, units ->
reduce(
message.fields,
units,
fn %{units: next_unit}, units ->
cond do
next_unit == nil ->
units
Regex.match?(~r/^[a-zA-Z0-9@_]+$/, Atom.to_string(next_unit)) ->
MapSet.put(units, ~s(:#{next_unit}))
true ->
MapSet.put(units, ~s(:"#{next_unit}"))
end
end
)
end
)
|> MapSet.to_list()
|> Enum.sort()
end
@spec module_case(String.t()) :: String.t()
defp module_case(name) do
name
|> split("_")
|> map(&capitalize/1)
|> join("")
end
# Some bitmask fields e.g. EkfStatusReport.flags are not marked with display="bitmask". This function
# returns true if the enum entry values start with 1, 2, 4 and then continue increasing through powers of 2.
defp looks_like_a_bitmask?(%{entries: entries}),
do: looks_like_a_bitmask?(entries |> map(& &1.value) |> sort)
defp looks_like_a_bitmask?([1, 2, 4 | rest]), do: looks_like_a_bitmask?(rest)
defp looks_like_a_bitmask?([8 | rest]), do: looks_like_a_bitmask?(rest |> map(&(&1 >>> 1)))
defp looks_like_a_bitmask?([]), do: true
defp looks_like_a_bitmask?(_), do: false
# Have to deal with some overlap between MAVLink and Elixir types
defp field_type(%{type: type, ordinality: ordinality, enum: enum}, module_name)
when ordinality > 1,
do: "[ #{field_type(%{type: type, ordinality: 1, enum: enum}, module_name)} ]"
defp field_type(%{enum: enum, display: :bitmask}, module_name) when enum != "",
do: "MapSet.t(#{module_name}.Types.#{enum})"
defp field_type(%{enum: enum}, module_name) when enum != "", do: "#{module_name}.Types.#{enum}"
defp field_type(%{type: "char"}, _), do: "char"
defp field_type(%{type: "float"}, _), do: "Float32"
defp field_type(%{type: "double"}, _), do: "Float64"
defp field_type(%{type: type}, _), do: "XMAVLink.Types.#{type}"
# Map field types to a binary pattern code fragment and a size
defp type_to_binary("char"), do: %{pattern: "integer-size(8)", size: 1}
defp type_to_binary("uint8_t"), do: %{pattern: "integer-size(8)", size: 1}
defp type_to_binary("int8_t"), do: %{pattern: "signed-integer-size(8)", size: 1}
defp type_to_binary("uint16_t"), do: %{pattern: "little-integer-size(16)", size: 2}
defp type_to_binary("int16_t"), do: %{pattern: "little-signed-integer-size(16)", size: 2}
defp type_to_binary("uint32_t"), do: %{pattern: "little-integer-size(32)", size: 4}
defp type_to_binary("int32_t"), do: %{pattern: "little-signed-integer-size(32)", size: 4}
defp type_to_binary("uint64_t"), do: %{pattern: "little-integer-size(64)", size: 8}
defp type_to_binary("int64_t"), do: %{pattern: "little-signed-integer-size(64)", size: 8}
# Delegate to (un)pack_float to handle :nan
defp type_to_binary("float"), do: %{pattern: "binary-size(4)", size: 4}
# " " (un)pack_double
defp type_to_binary("double"), do: %{pattern: "binary-size(8)", size: 8}
@spec escape(String.t()) :: String.t()
defp escape(s) do
replace(s, ~s("), ~s(\\"))
end
end
