From 09016f7e2ece0435b042119622e0024a0784f68c Mon Sep 17 00:00:00 2001
From: Mikael Pettersson <mikpelinux@gmail.com>
Date: Sun, 12 Jan 2020 21:00:27 +0100
Subject: [PATCH] as: parse: handle symbol +/- offset exprs

---
 erlang/apps/as/src/parse.erl | 23 ++++++++++++++++++++---
 erlang/apps/as/src/scan.erl  |  3 ++-
 erlang/apps/as/src/token.erl |  1 +
 erlang/apps/as/src/token.hrl |  2 ++
 4 files changed, 25 insertions(+), 4 deletions(-)

diff --git a/erlang/apps/as/src/parse.erl b/erlang/apps/as/src/parse.erl
index a0fb153..f1d4eee 100644
--- a/erlang/apps/as/src/parse.erl
+++ b/erlang/apps/as/src/parse.erl
@@ -639,16 +639,33 @@ do_expr(ScanState, First) ->
     {ok, {_Location, {?T_UINTEGER, UInt}}} ->
       {ok, mk_integer_expr(UInt)};
     {ok, {_Location, {?T_LOCAL_LABEL, Number, Direction}}} ->
-      {ok, mk_local_label_expr(Number, Direction)};
+      do_expr_maybe_offset(ScanState, _Symbol = {Number, Direction});
     {ok, {_Location, {?T_SYMBOL, Symbol}}} ->
-      {ok, mk_symbol_expr(Symbol)};
+      do_expr_maybe_offset(ScanState, Symbol);
     _ ->
       badtok("invalid start of expr", First)
   end.
 
+do_expr_maybe_offset(ScanState, Symbol) ->
+  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, _Token} = First} ->
+     scan:pushback(ScanState, First),
+     {ok, mk_symbol_expr(Symbol)};
+   {error, _Reason} = Error -> Error
+  end.
+
+do_expr_offset(ScanState, Symbol, IsMinus) ->
+  case scan:token(ScanState) of
+    {ok, {_Location, {?T_UINTEGER, UInt}}} ->
+      {ok, mk_symbol_expr(Symbol, if IsMinus -> -UInt; true -> UInt end)};
+    ScanRes -> badtok("expected <uinteger> after <sign>", ScanRes)
+  end.
+
 mk_integer_expr(Value) -> #expr{symbol = false, offset = Value}.
-mk_local_label_expr(Number, Direction) -> mk_symbol_expr({Number, Direction}).
 mk_symbol_expr(Symbol) -> #expr{symbol = Symbol, offset = 0}.
+mk_symbol_expr(Symbol, Offset) -> #expr{symbol = Symbol, offset = Offset}.
 
 %% String Lists ----------------------------------------------------------------
 
diff --git a/erlang/apps/as/src/scan.erl b/erlang/apps/as/src/scan.erl
index d955140..87c0ac5 100644
--- a/erlang/apps/as/src/scan.erl
+++ b/erlang/apps/as/src/scan.erl
@@ -1,7 +1,7 @@
 %%% -*- erlang-indent-level: 2 -*-
 %%%
 %%% scanner for pdp10-elf as
-%%% Copyright (C) 2013-2019  Mikael Pettersson
+%%% Copyright (C) 2013-2020  Mikael Pettersson
 %%%
 %%% This file is part of pdp10-tools.
 %%%
@@ -169,6 +169,7 @@ do_token(ScanState) ->
         $/  -> do_slash(ScanState);
         $\" -> do_string(ScanState, Location, []);
         $-  -> {ok, {Location, ?T_MINUS}};
+        $+  -> {ok, {Location, ?T_PLUS}};
         _   ->
           if $0 =< Ch, Ch =< $9 -> do_number(ScanState, Location, Ch);
              ($A =< Ch andalso Ch =< $Z) orelse
diff --git a/erlang/apps/as/src/token.erl b/erlang/apps/as/src/token.erl
index f595d55..457c5b9 100644
--- a/erlang/apps/as/src/token.erl
+++ b/erlang/apps/as/src/token.erl
@@ -84,6 +84,7 @@ format(Token) ->
     ?T_DOT              -> ".";
     ?T_LPAREN           -> "(";
     ?T_MINUS            -> "-";
+    ?T_PLUS             -> "+";
     ?T_RPAREN           -> ")";
     ?T_NEWLINE          -> "<newline>";
     ?T_EOF              -> "<eof>"
diff --git a/erlang/apps/as/src/token.hrl b/erlang/apps/as/src/token.hrl
index 51f48cb..5b31d9f 100644
--- a/erlang/apps/as/src/token.hrl
+++ b/erlang/apps/as/src/token.hrl
@@ -61,6 +61,7 @@
 -define(T_DOT,          'T_DOT').       % .
 -define(T_LPAREN,       'T_LPAREN').    % (
 -define(T_MINUS,        'T_MINUS').     % -
+-define(T_PLUS,         'T_PLUS').      % +
 -define(T_RPAREN,       'T_RPAREN').    % )
 
 %% synthetic symbols
@@ -96,6 +97,7 @@
                | ?T_DOT
                | ?T_LPAREN
                | ?T_MINUS
+               | ?T_PLUS
                | ?T_RPAREN
                | ?T_NEWLINE
                | ?T_EOF