gleb128

-module(gleb128@internal@native).
-compile([no_auto_import, nowarn_unused_vars, nowarn_unused_function, nowarn_nomatch]).

-export([get_cpu_endianness/0, decode_native_unsigned_integer/2, decode_native_signed_integer/2]).
-export_type([endianness/0]).

-type endianness() :: big | little.

-file("/home/neofox/gleb128/src/gleb128/internal/native.gleam", 13).
-spec get_cpu_endianness() -> {ok, endianness()} | {error, binary()}.
get_cpu_endianness() ->
    case <<16#01:32/native>> of
        <<16#01, 16#00, 16#00, 16#00>> ->
            {ok, little};

        <<16#00, 16#00, 16#00, 16#01>> ->
            {ok, big};

        _ ->
            {error,
                <<"Can't determine CPU's endianness. Maybe the CPU uses a mixed-endian format?"/utf8>>}
    end.

-file("/home/neofox/gleb128/src/gleb128/internal/native.gleam", 26).
-spec decode_native_unsigned_integer(bitstring(), endianness()) -> integer().
decode_native_unsigned_integer(Data, Endianness) ->
    binary:decode_unsigned(Data, Endianness).

-file("/home/neofox/gleb128/src/gleb128/internal/native.gleam", 40).
-spec decode_native_signed_integer(bitstring(), endianness()) -> integer().
decode_native_signed_integer(Data, Endianness) ->
    Size_in_bits = erlang:byte_size(Data) * 8,
    case {Endianness, Data} of
        {little, <<X:Size_in_bits/signed-little>>} ->
            X;

        {big, <<X@1:Size_in_bits/signed-big>>} ->
            X@1;

        {_, _} ->
            0
    end.