Details (mostly comments)
diff --git a/lgc.c b/lgc.c
index cf62a45..db519c6 100644
--- a/lgc.c
+++ b/lgc.c
@@ -1565,6 +1565,7 @@
*/
void luaC_step (lua_State *L) {
global_State *g = G(L);
+ lua_assert(!g->gcemergency);
if (g->gcrunning) { /* running? */
if(isdecGCmodegen(g))
genstep(L, g);
diff --git a/lobject.h b/lobject.h
index a22148c..0c38aff 100644
--- a/lobject.h
+++ b/lobject.h
@@ -17,11 +17,12 @@
/*
-** Extra tags for non-values
+** Extra tags for collectable non-values
*/
#define LUA_TUPVAL LUA_NUMTAGS /* upvalues */
#define LUA_TPROTO (LUA_NUMTAGS+1) /* function prototypes */
+
/*
** number of all possible tags (including LUA_TNONE)
*/
@@ -30,7 +31,7 @@
/*
** tags for Tagged Values have the following use of bits:
-** bits 0-3: actual tag (a LUA_T* value)
+** bits 0-3: actual tag (a LUA_T* constant)
** bits 4-5: variant bits
** bit 6: whether value is collectable
*/
@@ -86,24 +87,35 @@
/* Macros for internal tests */
+
+/* collectable object has the same tag as the original value */
#define righttt(obj) (ttypetag(obj) == gcvalue(obj)->tt)
+/*
+** Any value being manipulated by the program either is non
+** collectable, or the collectable object has the right tag
+** and it is not dead.
+*/
#define checkliveness(L,obj) \
((void)L, lua_longassert(!iscollectable(obj) || \
(righttt(obj) && (L == NULL || !isdead(G(L),gcvalue(obj))))))
/* Macros to set values */
+
+/* set a value's tag */
#define settt_(o,t) ((o)->tt_=(t))
+/* main macro to copy values (from 'obj1' to 'obj2') */
#define setobj(L,obj1,obj2) \
{ TValue *io1=(obj1); const TValue *io2=(obj2); \
- io1->value_ = io2->value_; io1->tt_ = io2->tt_; \
- checkliveness(L,io1); lua_assert(!isreallyempty(io1)); }
+ io1->value_ = io2->value_; settt_(io1, io2->tt_); \
+ checkliveness(L,io1); lua_assert(!isnonstrictnil(io1)); }
/*
-** different types of assignments, according to destination
+** Different types of assignments, according to source and destination.
+** (They are mostly equal now, but may be different in the future.)
*/
/* from stack to stack */
@@ -118,13 +130,16 @@
#define setobj2t setobj
-
+/*
+** Entries in the Lua stack
+*/
typedef union StackValue {
TValue val;
} StackValue;
-typedef StackValue *StkId; /* index to stack elements */
+/* index to stack elements */
+typedef StackValue *StkId;
/* convert a 'StackValue' to a 'TValue' */
#define s2v(o) (&(o)->val)
@@ -166,7 +181,7 @@
/*
** macro to detect non-standard nils (used only in assertions)
*/
-#define isreallyempty(v) (ttisnil(v) && !ttisstrictnil(v))
+#define isnonstrictnil(v) (ttisnil(v) && !ttisstrictnil(v))
/*
diff --git a/ltable.c b/ltable.c
index 5561d45..4c7ae99 100644
--- a/ltable.c
+++ b/ltable.c
@@ -155,6 +155,9 @@
}
+/*
+** Returns the main position of an element given as a 'TValue'
+*/
static Node *mainpositionTV (const Table *t, const TValue *key) {
return mainposition(t, rawtt(key), valraw(key));
}
diff --git a/ltests.c b/ltests.c
index 0d4ec93..bb5dad5 100644
--- a/ltests.c
+++ b/ltests.c
@@ -80,7 +80,7 @@
/*
-** Warning function for tests. Fist, it concatenates all parts of
+** Warning function for tests. First, it concatenates all parts of
** a warning in buffer 'buff'. Then, it has three modes:
** - 0.normal: messages starting with '#' are shown on standard output;
** - other messages abort the tests (they represent real warning
