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Safer serialization of opcode arguments

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This commit is contained in:
Thomas Arts 2019-05-28 19:09:42 +02:00
parent 73c80e1168
commit ec0af8046a
1 changed files with 6 additions and 5 deletions
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11
src/aeb_fate_code.erl
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@ -207,7 +207,7 @@ serialize_code([{_,_}|_] = List ) ->
%% Take out the full argument list.
{Args, Rest} = lists:splitwith(fun({_, _}) -> true; (_) -> false end, List),
%% Create the appropriate number of modifier bytes.
Mods = << <<(modifier_bits(Type)):2>> || {Type, _} <- pad_args(lists:reverse(Args)) >>,
Mods = << <<(modifier_bits(Type, X)):2>> || {Type, X} <- pad_args(lists:reverse(Args)) >>,
case Mods of
<<M1:8, M2:8>> ->
[M1, M2 | [serialize_data(Type, Arg) || {Type, Arg} <- Args, Type =/= stack]] ++
@ -237,10 +237,11 @@ serialize_data(_, Data) ->
%% 01 : argN
%% 10 : varN
%% 11 : immediate
modifier_bits(immediate) -> 2#11;
modifier_bits(var) -> 2#10;
modifier_bits(arg) -> 2#01;
modifier_bits(stack) -> 2#00.
modifier_bits(immediate, _) -> 2#11;
modifier_bits(var, _) -> 2#10;
modifier_bits(arg, _) -> 2#01;
modifier_bits(stack, 0) -> 2#00;
modifier_bits(Type, X) -> error({illegal_argument, Type, X}).
bits_to_modifier(2#11) -> immediate;
bits_to_modifier(2#10) -> var;