implement offsets for constants

README.md

@@ -91,8 +91,6 @@ my_label:
     lw      s1, (s0)
     lw      s2, 256(s0)
     lw      s3, label(s0)
-
-; this is currently unsupported however
     sw      s2, label+4
     sw      s3, label+4(s0)
 

lips/Dumper.lua

@@ -138,21 +138,25 @@ function Dumper:desym(t)
         end
         return rel % 0x10000
     elseif type(t.tok) == 'number' then
+        if t.offset then
+            return t.tok + t.offset
+        end
         return t.tok
     elseif t.tt == 'REG' then
         assert(data.all_registers[t.tok], 'Internal Error: unknown register')
         return data.registers[t.tok] or data.fpu_registers[t.tok] or data.sys_registers[t.tok]
-    elseif t.tt == 'LABELSYM' then
+    elseif t.tt == 'LABELSYM' or t.tt == 'LABELREL' then
         local label = self.labels[t.tok]
         if label == nil then
             self:error('undefined label')
         end
-        return label
+        if t.offset then
-    elseif t.tt == 'LABELREL' then
+            label = label + t.offset
-        local label = self.labels[t.tok]
-        if label == nil then
-            self:error('undefined label')
         end
+        if t.tt == 'LABELSYM' then
+            return label
+        end
+
         label = label % 0x80000000
         local pos = self.pos % 0x80000000
         local rel = floor(label/4) - 1 - floor(pos/4)

lips/Lexer.lua

@@ -379,6 +379,10 @@ function Lexer:lex(_yield)
                 local n = self:read_number()
                 if n then
                     yield('NUM', sign*n)
+                elseif #buff == 1 then
+                    -- this could be a RELLABELSYM
+                    -- we'll have to let the preproc figure it out
+                    yield('UNARY', sign)
                 else
                     yield('RELLABELSYM', sign*#buff)
                 end

lips/Parser.lua

@@ -179,6 +179,7 @@ function Parser:instruction()
     elseif overrides[name] then
         overrides[name](self, name)
     elseif h[2] == 'tob' then -- TODO: or h[2] == 'Tob' then
+        -- handle all the addressing modes for lw/sw-like instructions
         local lui = data.instructions['LUI']
         local addu = data.instructions['ADDU']
         local args = {}
@@ -191,6 +192,9 @@ function Parser:instruction()
             local lui_args = {}
             local addu_args = {}
             local o = self:const()
+            if self.tt == 'NUM' then
+                o:set('offset', self:const().tok)
+            end
             args.offset = self:token(o)
             if not o.portion then
                 args.offset:set('portion', 'lower')

lips/Preproc.lua

@@ -17,11 +17,24 @@ function Preproc:process(tokens)
     local plus_labels = {} -- constructed forwards
     local minus_labels = {} -- constructed backwards
 
-    -- first pass: resolve defines, collect relative labels
+    -- first pass: resolve unary ops, defines, and collect relative labels
     local new_tokens = {}
     self.i = 0
     while self.i < #self.tokens do
         local t = self:advance()
+        local sign = 1
+        if t.tt == 'UNARY' then
+            local peek = self.tokens[self.i + 1]
+            if peek.tt == 'UNARY' then
+                self:error('unary operators cannot be chained')
+            elseif peek.tt == 'EOL' or peek.tt == 'SEP' then
+                t.tt = 'RELLABEL'
+            elseif peek.tt == 'DEFSYM' then
+                sign = t.tok
+            else
+                self:error('expected a symbolic constant after unary operator')
+            end
+        end
         if t.tt == nil then
             error('Internal Error: missing token')
         elseif t.tt == 'DEF' then
@@ -36,7 +49,7 @@ function Preproc:process(tokens)
             if tok == nil then
                 self:error('undefined define') -- uhhh nice wording
             end
-            insert(new_tokens, self:token(tt, tok))
+            insert(new_tokens, self:token(tt, tok * sign))
         elseif t.tt == 'RELLABEL' then
             if t.tok == '+' then
                 insert(plus_labels, #new_tokens + 1)