60 lines
2.2 KiB
Erlang
60 lines
2.2 KiB
Erlang
%% @author Loïc Hoguin <essen@dev-extend.eu>
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%% @copyright 2010 Loïc Hoguin.
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%% @doc EGS script compiler.
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%%
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%% This file is part of EGS.
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%%
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%% EGS is free software: you can redistribute it and/or modify
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%% it under the terms of the GNU Affero General Public License as
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%% published by the Free Software Foundation, either version 3 of the
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%% License, or (at your option) any later version.
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%%
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%% EGS is distributed in the hope that it will be useful,
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%% but WITHOUT ANY WARRANTY; without even the implied warranty of
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%% MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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%% GNU Affero General Public License for more details.
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%%
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%% You should have received a copy of the GNU Affero General Public License
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%% along with EGS. If not, see <http://www.gnu.org/licenses/>.
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-module(egs_script_compiler).
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-export([compile/1]).
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%% @doc Compile a script parsed using egs_script_lexer and egs_script_parser.
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compile(ParseTree) ->
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RootBin = root(ParseTree),
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FooterPos = byte_size(RootBin),
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FooterSize = 0, %% @todo
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<< $T, $S, $B, $2, FooterPos:32/little, FooterSize:32/little, RootBin/binary >>.
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root(Routines) ->
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root(Routines, 0, []).
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root(nil, _Pos, Acc) ->
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iolist_to_binary(lists:reverse(Acc));
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root({Routine, Next}, Pos, Acc) ->
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Bin = routine(Routine),
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Pos2 = case Next of nil -> 0; _ -> Pos + byte_size(Bin) + 4 end,
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root(Next, Pos2, [<< Pos2:32/little, Bin/binary >>|Acc]).
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routine({Type, Name, Instructions}) ->
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TypeBin = case Type of event -> << $E, $V, $E, $N, $T, $. >>; function -> << >> end,
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NameBin = list_to_binary(Name),
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Padding = 8 * (32 - byte_size(TypeBin) - byte_size(NameBin)),
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InstrsBin = instructions(Instructions),
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InstrsSize = byte_size(InstrsBin) + 4,
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VarsBin = << 76:32/little, 0:32/little >>, %% @todo 0 vars for now.
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<< TypeBin/binary, NameBin/binary, 0:Padding,
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InstrsSize:32/little, VarsBin/binary, InstrsBin/binary, 0:32 >>.
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instructions(Instrs) ->
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instructions(Instrs, []).
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instructions(nil, Acc) ->
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iolist_to_binary(lists:reverse(Acc));
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instructions({Instr, Next}, Acc) ->
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instructions(Next, [instruction(Instr)|Acc]).
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instruction({push, N}) when is_integer(N) ->
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<< 2:32/little, N:32/little >>;
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instruction({syscall, N}) when is_integer(N) ->
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<< 97:32/little, N:32/little >>.
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