Annotate Lua packer with more comments

src/script/common/c_packer.h

@@ -39,30 +39,31 @@ extern "C" {
 #define INSTR_PUSHREF  (-12)
 
 /**
- * Represents a single instruction that pushes a new value or works with existing ones.
+ * Represents a single instruction that pushes a new value or operates with existing ones.
  */
 struct PackedInstr
 {
 	s16 type; // LUA_T* or INSTR_*
 	u16 set_into; // set into table on stack
-	bool keep_ref; // is referenced later by INSTR_PUSHREF?
+	bool keep_ref; // referenced later by INSTR_PUSHREF?
 	bool pop; // remove from stack?
+	// Note: the remaining members are named by type, not usage
 	union {
 		bool bdata; // boolean: value
 		lua_Number ndata; // number: value
 		struct {
-			u16 uidata1, uidata2; // table: narr, nrec
+			u16 uidata1, uidata2; // table: narr | nrec
 		};
 		struct {
 			/*
-				SETTABLE: key index, value index
+				SETTABLE: key index | value index
 				POP: indices to remove
-				otherwise w/ set_into: numeric key, -
+				PUSHREF: index of referenced instr | unused
+				otherwise w/ set_into: numeric key | unused
 			*/
 			s32 sidata1, sidata2;
 		};
 		void *ptrdata; // userdata: implementation defined
-		s32 ref; // PUSHREF: index of referenced instr
 	};
 	/*
 		- string: value
@@ -78,7 +79,7 @@ struct PackedInstr
 /**
  * A packed value can be a primitive like a string or number but also a table
  * including all of its contents. It is made up of a linear stream of
- * 'instructions' that build the final value when executed.
+ * instructions that build the final value when executed.
  */
 struct PackedValue
 {