extmod/modmarshal: Add new marshal module.

This commit implements a small subset of the CPython `marshal` module.  It
implements `marshal.dumps()` and `marshal.loads()`, but only supports
(un)marshalling code objects at this stage.  The semantics match CPython,
except that the actual marshalled bytes is not compatible with CPython's
marshalled bytes.

The module is enabled at the everything level (only on the unix coverage
build at this stage).

Signed-off-by: Damien George <damien@micropython.org>

1 files changed, 122 insertions, 0 deletions

diff --git a/tests/extmod/marshal_stress.py b/tests/extmod/marshal_stress.py
new file mode 100644
index 000000000..b52475c03
--- /dev/null
+++ b/tests/extmod/marshal_stress.py
@@ -0,0 +1,122 @@
+# Test the marshal module, stressing edge cases.
+
+try:
+    import marshal
+
+    (lambda: 0).__code__
+except (AttributeError, ImportError):
+    print("SKIP")
+    raise SystemExit
+
+ftype = type(lambda: 0)
+
+# Test a large function.
+
+
+def large_function(arg0, arg1, arg2, arg3):
+    # Arguments.
+    print(arg0, arg1, arg2, arg3)
+
+    # Positive medium-sized integer (still a small-int though).
+    print(1234)
+
+    # Negative small-ish integer.
+    print(-20)
+
+    # More than 64 constant objects.
+    x = (0,)
+    x = (1,)
+    x = (2,)
+    x = (3,)
+    x = (4,)
+    x = (5,)
+    x = (6,)
+    x = (7,)
+    x = (8,)
+    x = (9,)
+    x = (10,)
+    x = (11,)
+    x = (12,)
+    x = (13,)
+    x = (14,)
+    x = (15,)
+    x = (16,)
+    x = (17,)
+    x = (18,)
+    x = (19,)
+    x = (20,)
+    x = (21,)
+    x = (22,)
+    x = (23,)
+    x = (24,)
+    x = (25,)
+    x = (26,)
+    x = (27,)
+    x = (28,)
+    x = (29,)
+    x = (30,)
+    x = (31,)
+    x = (32,)
+    x = (33,)
+    x = (34,)
+    x = (35,)
+    x = (36,)
+    x = (37,)
+    x = (38,)
+    x = (39,)
+    x = (40,)
+    x = (41,)
+    x = (42,)
+    x = (43,)
+    x = (44,)
+    x = (45,)
+    x = (46,)
+    x = (47,)
+    x = (48,)
+    x = (49,)
+    x = (50,)
+    x = (51,)
+    x = (52,)
+    x = (53,)
+    x = (54,)
+    x = (55,)
+    x = (56,)
+    x = (57,)
+    x = (58,)
+    x = (59,)
+    x = (60,)
+    x = (61,)
+    x = (62,)
+    x = (63,)
+    x = (64,)
+
+    # Small jump.
+    x = 0
+    while x < 2:
+        print("loop", x)
+        x += 1
+
+    # Large jump.
+    x = 0
+    while x < 2:
+        try:
+            try:
+                try:
+                    print
+                except Exception as e:
+                    print
+                finally:
+                    print
+            except Exception as e:
+                print
+            finally:
+                print
+        except Exception as e:
+            print
+        finally:
+            print("loop", x)
+        x += 1
+
+
+code = marshal.dumps(large_function.__code__)
+ftype(marshal.loads(code), {"print": print})(0, 1, 2, 3)