update docs a bit.

docs/TODO.txt

@@ -6,7 +6,6 @@ How can you help?
 If you're interested in M1 and M0, contributions in the following
 areas are particularly welcome:
 * writing tests (try to break M1!).
-* figure out how to do function calls and parameters. 
 * figure out how to do modules (multi-file programs)
 * figure out how to do pointers and/or references (Java-like).
 * can we do exceptions at this level/
@@ -37,10 +36,11 @@ What's working?
 * unary minus op.
 * array access (x[42] = 3; x = y[3])
 * field access (x.y = 3; )
+* function calls and returns.
 
 What's not working?
 -------------------
-* function calls (mostly the returns); parameters/arguments.
+* parameters/arguments.
 * namespaces
 * PMC definitions (incl methods)
 * return statements
@@ -55,7 +55,6 @@ What's not working?
 
 short-term roadmap:
 -------------------
-* implement function calls properly (including returning from a function) HIGH PRIORITY
 * look into vtable implementation for PMCs for calling member functions x.y();
 * think about a module management system. No preprocessor please. Maybe similar to Java's import statement. This might include namespaces, and also private and public scopes for modules (keywords needed?)
 * generate instructions (struct instances) rather than print directly to stdout. This will allow analysis and optimization.
@@ -64,7 +63,7 @@ random list of items:
 ---------------------
 * implement parameter and argument handling
 * implement namespaces and their handling
-* implement structs or other aggregate types; PMCs native?
+* implement PMCs
 * any other keywords? e.g., continue? 
 * implement semantic checker (a thorough one!)
 * finish code generator

docs/pddxx_m1.pod

@@ -8,8 +8,13 @@ M1 refers to a C-like language targeting the M0 "virtual machine". That is,
 M0 can be considered as a virtual machine which defines an instruction set
 and a computation model. Details of M0 can be found in [1].
 
+The M1 compiler is reentrant, which means it is thread-safe. This allows to 
+invoke the M1 compiler if it's already running.
+
 =head2 Status
 
+See the TODO file for the current status.
+
 =head2 Design Principles of M1
 
 A few basic design principles (so-called I<key drivers>) drove the design
@@ -70,14 +75,14 @@ Completed milestones:
 
 =item * simple structs; read and write
 
+=item * function calls and returns
+
 =back
 
 Incomplete milestones:
 
 =over 4
 
-=item * function calls and returns
-
 =item * Enumerations
 
 =item * PMC definitions