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as: parse: handle :modifier(symbol+offset) exprs, improve docs

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This commit is contained in:
Mikael Pettersson 2020-01-25 19:36:03 +01:00
parent 0f6449d237
commit d6eef91276
2 changed files with 78 additions and 27 deletions
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104
erlang/apps/as/src/parse.erl
View File

@ -73,7 +73,7 @@ stmt(ScanState) ->
%%
%% <address> ::= "@"? <displacement>? <index>?
%%
%% <displacement> ::= <uinteger> | <symbol> | <uinteger>[bf]
%% <displacement> ::= <expr>
%%
%% <index> ::= "(" <accumulator> ")"
%%
@ -85,9 +85,6 @@ stmt(ScanState) ->
%% movei 1,@fum(2)
%% jump bar
%%
%% TODO: <displacement> should be <expr> and permit parentheses and
%% various operators.
%%
%% Ambiguous example:
%%
%% <symbol> (<uinteger>) <newline>
@ -137,7 +134,7 @@ insn_uint(ScanState, Location, Name, Location2, UInt) ->
%% Seen "<symbol> <first>" where <first> is not "@", or <uinteger> followed by ",".
%% <first> is the start of the <displacement>.
insn_disp(ScanState, Location, Name, First) ->
case do_expr(ScanState, {ok, First}) of
case do_expr(ScanState, {ok, First}, ifiw) of
{ok, Displacement} ->
insn_ea_disp(ScanState, Location, Name, _AccOrDev = false, _At = false, Displacement);
{error, _Reason} = Error -> Error
@ -150,7 +147,7 @@ insn_ea(ScanState, Location, Name, AccOrDev) ->
make_insn(Location, Name, AccOrDev, _At = false, _Displacement = false, _Index = false);
{ok, {_Location, ?T_AT}} -> insn_ea_at(ScanState, Location, Name, AccOrDev);
{ok, {_Location, _Token}} = ScanRes ->
case do_expr(ScanState, ScanRes) of
case do_expr(ScanState, ScanRes, ifiw) of
{ok, Displacement} ->
insn_ea_disp(ScanState, Location, Name, AccOrDev, _At = false, Displacement);
{error, _Reason} = Error -> Error
@ -160,7 +157,7 @@ insn_ea(ScanState, Location, Name, AccOrDev) ->
%% <symbol> [<accordev> ","] "@" . <displacement> ["(" <index> ")"] <newline>
insn_ea_at(ScanState, Location, Name, AccOrDev) ->
case expr(ScanState) of
case expr(ScanState, ifiw) of
{ok, Displacement} ->
insn_ea_disp(ScanState, Location, Name, AccOrDev, _At = true, Displacement);
{error, _Reason} = Error -> Error
@ -208,7 +205,7 @@ make_insn(Location, Name, AccOrDev, At, Displacement, Index) ->
Stmt = #s_insn{ high13 = FinalHigh13
, at = At
, address = case Displacement of
false -> mk_integer_expr(0);
false -> mk_integer_expr(0, ifiw);
_ -> Displacement
end
, index = if Index =:= false -> 0; true -> Index end
@ -602,13 +599,26 @@ section_name(ScanState) ->
end.
%% Expressions -----------------------------------------------------------------
%%
%% <expr> ::= ":" <modifier> "(" <plain_expr> ")"
%% | <plain_expr>
%%
%% <plain_expr> ::= "(" <plain_expr> ")"
%% | "-"? <uinteger>
%% | (<symbol> | <local_label>) (("+" | "-") <uinteger>)?
%%
%% <modifier> ::= "ifiw" | "w" | "b" | "h"
%%
%% Note: <modifier> defaults to "ifiw" in <insn> and "w" in data directives.
%% It describes how the value should be represented, which also determines
%% which relocation to use for it.
%% <expr_list> ::= (<expr> ("," <expr>)*)? \n
expr_list(ScanState) ->
case scan:token(ScanState) of
{ok, {_Location, ?T_NEWLINE}} -> {ok, []};
First ->
case do_expr(ScanState, First) of
case do_expr(ScanState, First, _DefaultModifier = w) of
{ok, Expr} -> expr_list(ScanState, [Expr]);
{error, _Reason} = Error -> Error
end
@ -617,7 +627,7 @@ expr_list(ScanState) ->
expr_list(ScanState, Exprs) ->
case scan:token(ScanState) of
{ok, {_Location, ?T_COMMA}} ->
case expr(ScanState) of
case expr(ScanState, _DefaultModifier = w) of
{ok, Expr} -> expr_list(ScanState, [Expr | Exprs]);
{error, _Reason} = Error -> Error
end;
@ -625,13 +635,44 @@ expr_list(ScanState, Exprs) ->
ScanRes -> badtok("expected comma or newline", ScanRes)
end.
expr(ScanState) ->
do_expr(ScanState, scan:token(ScanState)).
expr(ScanState, DefaultModifier) ->
do_expr(ScanState, scan:token(ScanState), DefaultModifier).
do_expr(ScanState, First) ->
do_expr(ScanState, First, DefaultModifier) ->
case First of
{ok, {_Location, ?T_COLON}} -> modifier_expr(ScanState);
_ -> do_plain_expr(ScanState, First, DefaultModifier)
end.
modifier_expr(ScanState) ->
case scan:token(ScanState) of
{ok, {_Location1, {?T_SYMBOL, Symbol}}} = ScanRes1 ->
case symbol_modifier(Symbol) of
false -> badtok("invalid modifier", ScanRes1);
Modifier ->
case scan:token(ScanState) of
{ok, {_Location2, ?T_LPAREN}} ->
case plain_expr(ScanState, Modifier) of
{ok, _Expr} = Result ->
case scan:token(ScanState) of
{ok, {_Location3, ?T_RPAREN}} -> Result;
ScanRes3 -> badtok("expected right parenthesis", ScanRes3)
end;
{error, _Reason} = Error -> Error
end;
ScanRes2 -> badtok("expected left parenthesis", ScanRes2)
end
end;
ScanRes1 -> badtok("expected modifier <symbol>", ScanRes1)
end.
plain_expr(ScanState, Modifier) ->
do_plain_expr(ScanState, scan:token(ScanState), Modifier).
do_plain_expr(ScanState, First, Modifier) ->
case First of
{ok, {_Location1, ?T_LPAREN}} ->
case expr(ScanState) of
case plain_expr(ScanState, Modifier) of
{ok, Expr} ->
case scan:token(ScanState) of
{ok, {_Location2, ?T_RPAREN}} -> {ok, Expr};
@ -642,39 +683,48 @@ do_expr(ScanState, First) ->
{ok, {_Location1, ?T_MINUS}} ->
case scan:token(ScanState) of
{ok, {_Location2, {?T_UINTEGER, UInt}}} ->
{ok, mk_integer_expr(-UInt)};
{ok, mk_integer_expr(-UInt, Modifier)};
ScanRes -> badtok("expected <uinteger> after -", ScanRes)
end;
{ok, {_Location, {?T_UINTEGER, UInt}}} ->
{ok, mk_integer_expr(UInt)};
{ok, mk_integer_expr(UInt, Modifier)};
{ok, {_Location, {?T_LOCAL_LABEL, Number, Direction}}} ->
do_expr_maybe_offset(ScanState, _Symbol = {Number, Direction});
do_expr_maybe_offset(ScanState, _Symbol = {Number, Direction}, Modifier);
{ok, {_Location, {?T_SYMBOL, Symbol}}} ->
do_expr_maybe_offset(ScanState, Symbol);
do_expr_maybe_offset(ScanState, Symbol, Modifier);
_ ->
badtok("invalid start of expr", First)
end.
do_expr_maybe_offset(ScanState, Symbol) ->
do_expr_maybe_offset(ScanState, Symbol, Modifier) ->
case scan:token(ScanState) of
{ok, {_Location, ?T_MINUS}} -> do_expr_offset(ScanState, Symbol, _IsMinus = true);
{ok, {_Location, ?T_PLUS}} -> do_expr_offset(ScanState, Symbol, _IsMinus = false);
{ok, {_Location, ?T_MINUS}} -> do_expr_offset(ScanState, Symbol, _IsMinus = true, Modifier);
{ok, {_Location, ?T_PLUS}} -> do_expr_offset(ScanState, Symbol, _IsMinus = false, Modifier);
{ok, {_Location, _Token} = First} ->
scan:pushback(ScanState, First),
{ok, mk_symbol_expr(Symbol)};
{ok, mk_symbol_expr(Symbol, Modifier)};
{error, _Reason} = Error -> Error
end.
do_expr_offset(ScanState, Symbol, IsMinus) ->
do_expr_offset(ScanState, Symbol, IsMinus, Modifier) ->
case scan:token(ScanState) of
{ok, {_Location, {?T_UINTEGER, UInt}}} ->
{ok, mk_symbol_expr(Symbol, if IsMinus -> -UInt; true -> UInt end)};
{ok, mk_symbol_expr(Symbol, if IsMinus -> -UInt; true -> UInt end, Modifier)};
ScanRes -> badtok("expected <uinteger> after <sign>", ScanRes)
end.
mk_integer_expr(Value) -> #expr{symbol = false, offset = Value}.
mk_symbol_expr(Symbol) -> #expr{symbol = Symbol, offset = 0}.
mk_symbol_expr(Symbol, Offset) -> #expr{symbol = Symbol, offset = Offset}.
symbol_modifier(Symbol) ->
case Symbol of
"ifiw" -> ifiw;
"w" -> w;
"b" -> b;
"h" -> h;
_ -> false
end.
mk_integer_expr(Value, Modifier) -> #expr{symbol = false, offset = Value, modifier = Modifier}.
mk_symbol_expr(Symbol, Modifier) -> #expr{symbol = Symbol, offset = 0, modifier = Modifier}.
mk_symbol_expr(Symbol, Offset, Modifier) -> #expr{symbol = Symbol, offset = Offset, modifier = Modifier}.
%% String Lists ----------------------------------------------------------------

1
erlang/apps/as/src/tunit.hrl
View File

@ -26,6 +26,7 @@
-record(expr,
{ symbol :: false | string() | {non_neg_integer(), $b | $f}
, offset :: integer()
, modifier :: ifiw | w | b | h
}).
-type expr() :: #expr{}.