Fix the initial state and polish a couple comments.

tannewt · tannewt · commit aa0ce98b3e72 · 2018-01-24T14:13:26.000-08:00
diff --git a/py/gc.c b/py/gc.c
@@ -147,7 +147,7 @@ void gc_init(void *start, void *end) {
 #endif
 
     // Set first free ATB index to the start of the heap.
-    MP_STATE_MEM(gc_last_free_atb_index) = 0;
+    MP_STATE_MEM(gc_first_free_atb_index) = 0;
     // Set last free ATB index to the end of the heap.
     MP_STATE_MEM(gc_last_free_atb_index) = MP_STATE_MEM(gc_alloc_table_byte_len) - 1;
     // Set the lowest long lived ptr to the end of the heap to start. This will be lowered as long
diff --git a/py/gc_long_lived.c b/py/gc_long_lived.c
@@ -46,7 +46,6 @@ mp_obj_fun_bc_t *make_fun_bc_long_lived(mp_obj_fun_bc_t *fun_bc, uint8_t max_dep
         mp_raw_code_t* raw_code = MP_OBJ_TO_PTR(fun_bc->const_table[i]);
         if (raw_code->kind == MP_CODE_BYTECODE) {
             raw_code->data.u_byte.bytecode = gc_make_long_lived((byte*) raw_code->data.u_byte.bytecode);
-            // TODO(tannewt): Do we actually want to recurse here?
             raw_code->data.u_byte.const_table = gc_make_long_lived((byte*) raw_code->data.u_byte.const_table);
         }
         ((mp_uint_t *) fun_bc->const_table)[i] = (mp_uint_t) make_obj_long_lived(
@@ -56,6 +55,8 @@ mp_obj_fun_bc_t *make_fun_bc_long_lived(mp_obj_fun_bc_t *fun_bc, uint8_t max_dep
     fun_bc->const_table = gc_make_long_lived((mp_uint_t*) fun_bc->const_table);
     // extra_args stores keyword only argument default values.
     size_t words = gc_nbytes(fun_bc) / sizeof(mp_uint_t*);
+    // Functions (mp_obj_fun_bc_t) have four pointers (base, globals, bytecode and const_table)
+    // before the variable length extra_args so remove them from the length.
     for (size_t i = 0; i < words - 4; i++) {
         if (fun_bc->extra_args[i] == NULL) {
             continue;
