Add explicitly-addressed memory locations.

HISTORY.markdown

@@ -26,3 +26,4 @@ in future versions.
 *   Added `repeat` loops to the language, which can repeat until a flag
     is set (or `not` set), or which can repeat `forever`.
 *   `if not` inverts the sense of the test.
+*   Added explicitly-addressed memory locations.

README.markdown

@@ -31,19 +31,25 @@ Documentation
 TODO
 ----
 
-For 0.4:
-
-*   explicitly-addressed memory locations
-
 For 0.5:
 
-*   add line number (or at least routine name) to error messages.
-*   hexadecimal literals.
-*   6502-mnemonic aliases (`sec`, `clc`)
-*   other handy aliases (`eq` for `z`, etc.)
-*   source code comments.
+*   `table` type constructor and indirect addressing.
 
 For 0.6:
 
+*   hexadecimal literals.
+*   source code comments.
+
+For 0.7:
+
 *   `word` type.
-*   `table` type constructor and indirect addressing.
+
+For 0.8:
+
+*   `vector` type.
+
+For 0.9:
+
+*   add line number (or at least routine name) to error messages.
+*   6502-mnemonic aliases (`sec`, `clc`)
+*   other handy aliases (`eq` for `z`, etc.)

doc/SixtyPical.md

@@ -75,6 +75,10 @@ by giving the type, which must be `byte`, and the name.
 
     byte pos
 
+A location in memory may be given explicitly on a user-defined memory location.
+
+    byte screen @ 1024
+
 Routines
 --------
 

eg/screen.60p

@@ -0,0 +1,8 @@
+byte screen @ 1024
+
+routine main
+  trashes a, z, n, screen
+{
+  ld a, 100
+  st a, screen
+}

src/sixtypical/compiler.py

@@ -33,6 +33,8 @@ class Compiler(object):
 
         for defn in program.defns:
             label = Label(defn.name)
+            if defn.addr is not None:
+                label.set_addr(defn.addr)
             self.labels[defn.name] = label
 
         for routine in program.routines:
@@ -48,8 +50,9 @@ class Compiler(object):
                 self.compile_routine(routine)
 
         for defn in program.defns:
-            label = self.labels[defn.name]
-            self.emitter.resolve_bss_label(label)
+            if defn.addr is None:
+                label = self.labels[defn.name]
+                self.emitter.resolve_bss_label(label)
 
     def compile_routine(self, routine):
         assert isinstance(routine, Routine)

src/sixtypical/parser.py

@@ -98,13 +98,19 @@ class Parser(object):
                 raise KeyError(name)
             self.symbols[name] = routine
             routines.append(routine)
+        self.scanner.check_type('EOF')
         return Program(defns=defns, routines=routines)
 
     def defn(self):
         self.scanner.expect('byte')
         name = self.scanner.token
         self.scanner.scan()
-        return Defn(name=name)
+        addr = None
+        if self.scanner.consume('@'):
+            self.scanner.check_type('integer literal')
+            addr = int(self.scanner.token)
+            self.scanner.scan()            
+        return Defn(name=name, addr=addr)
 
     def routine(self):
         self.scanner.expect('routine')

tests/SixtyPical Compilation.md

@@ -77,6 +77,16 @@ Access a defined memory location.
     | }
     = 00c0a0008c09c0ad09c060
 
+    | byte screen @ 1024
+    | 
+    | routine main
+    |   trashes a, z, n, screen
+    | {
+    |   ld a, 100
+    |   st a, screen
+    | }
+    = 00c0a9648d000460
+
 Some instructions.
 
     | byte foo

tests/SixtyPical Syntax.md

@@ -27,6 +27,15 @@ Syntax error
     | )
     ? SyntaxError
 
+Another syntax error
+
+    | byte glee
+    | {
+    |     ld a, 0
+    |     add a, 1
+    | }
+    ? SyntaxError
+
 Extern routines
 
     | routine chrout
@@ -92,3 +101,13 @@ Repeat with not
     |     } until not z
     | }
     = ok
+
+Extern memory locations
+
+    | byte screen @ 1024
+    | 
+    | routine main {
+    |   ld a, 100
+    |   st a, screen
+    | }
+    = ok