WIP: write atom to string

Signed-off-by: Davide Bettio <davide@uninstall.it>
atomvm · Nov 3, 2023 · d8044b6 · d8044b6
1 parent cc2e352
commit d8044b6
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Showing 3 changed files with 54 additions and 14 deletions.
diff --git a/src/libAtomVM/atom_table.c b/src/libAtomVM/atom_table.c
@@ -197,32 +197,41 @@ long atom_table_get_index(struct AtomTable *table, AtomString string)
     return result;
 }
 
-// TODO: this function needs to be optimized
-AtomString atom_table_get_atom_string(struct AtomTable *table, long index)
+static struct HNode *get_node_using_index(struct AtomTable *table, long index)
 {
-    SMP_RDLOCK(table);
-
     if (UNLIKELY(index >= table->count)) {
-        SMP_UNLOCK(table);
         return NULL;
     }
 
     struct HNodeGroup *node_group = table->first_node_group;
     while (node_group) {
         long first_index = node_group->first_index;
         if (first_index + node_group->len > index) {
-            AtomString found_key = node_group->nodes[index - first_index].key;
-            SMP_UNLOCK(table);
-            return found_key;
+            return &node_group->nodes[index - first_index];
         }
 
         node_group = node_group->next;
     }
 
-    SMP_UNLOCK(table);
     return NULL;
 }
 
+// TODO: this function needs to be optimized
+AtomString atom_table_get_atom_string(struct AtomTable *table, long index)
+{
+    SMP_RDLOCK(table);
+
+    struct HNode *node = get_node_using_index(table, index);
+    if (IS_NULL_PTR(node)) {
+        return NULL;
+    }
+
+    AtomString found_key = node->key;
+
+    SMP_UNLOCK(table);
+    return found_key;
+}
+
 int atom_table_cmp_using_atom_index(struct AtomTable *table, int t_atom_index, int other_atom_index)
 {
     AtomString t_atom_string = atom_table_get_atom_string(table, t_atom_index);
@@ -250,6 +259,31 @@ int atom_table_cmp_using_atom_index(struct AtomTable *table, int t_atom_index, i
     return memcmp_result;
 }
 
+atom_ref_t atom_table_get_atom_ptr_and_len(struct AtomTable *table, long index, size_t *out_len)
+{
+    SMP_RDLOCK(table);
+
+    struct HNode *node = get_node_using_index(table, index);
+    if (IS_NULL_PTR(node)) {
+        return NULL;
+    }
+
+    *out_len = atom_string_len(node->key);
+
+    SMP_UNLOCK(table);
+    return node;
+}
+
+void atom_table_write_cstring(struct AtomTable *table, atom_ref_t atom, int buf_len, char *outbuf)
+{
+    SMP_RDLOCK(table);
+
+    struct HNode *node = (struct HNode *) atom;
+    atom_string_to_c(node->key, outbuf, buf_len);
+
+    SMP_UNLOCK(table);
+}
+
 static inline void init_node(struct HNode *node, AtomString atom, long index)
 {
     node->key = atom;

diff --git a/src/libAtomVM/atom_table.h b/src/libAtomVM/atom_table.h
@@ -35,6 +35,8 @@ enum AtomTableCopyOpt
     AtomTableAlreadyExisting = 2
 };
 
+typedef const void *atom_ref_t;
+
 struct AtomTable *atom_table_new();
 void atom_table_destroy(struct AtomTable *table);
 
@@ -49,5 +51,7 @@ long atom_table_ensure_atoms(
 
 int atom_table_cmp_using_atom_index(
     struct AtomTable *table, int t_atom_index, int other_atom_index);
+atom_ref_t atom_table_get_atom_ptr_and_len(struct AtomTable *table, long index, size_t *out_len);
+void atom_table_write_cstring(struct AtomTable *table, atom_ref_t atom, int buf_len, char *outbuf);
 
 #endif
diff --git a/src/libAtomVM/nifs.c b/src/libAtomVM/nifs.c
@@ -2024,17 +2024,19 @@ static term nif_erlang_atom_to_binary_2(Context *ctx, int argc, term argv[])
         RAISE_ERROR(BADARG_ATOM);
     }
 
-    int atom_index = term_to_atom_index(atom_term);
-    AtomString atom_string = atom_table_get_atom_string(ctx->global->atom_table, atom_index);
+    GlobalContext *glb = ctx->global;
 
-    int atom_len = atom_string_len(atom_string);
+    int atom_index = term_to_atom_index(atom_term);
+    size_t atom_len;
+    atom_ref_t atom_ref = atom_table_get_atom_ptr_and_len(glb->atom_table, atom_index, &atom_len);
 
     if (UNLIKELY(memory_ensure_free_opt(ctx, term_binary_heap_size(atom_len), MEMORY_CAN_SHRINK) != MEMORY_GC_OK)) {
         RAISE_ERROR(OUT_OF_MEMORY_ATOM);
     }
 
-    const char *atom_data = (const char *) atom_string_data(atom_string);
-    return term_from_literal_binary(atom_data, atom_len, &ctx->heap, ctx->global);
+    term binary = term_create_uninitialized_binary(atom_len, &ctx->heap, glb);
+    atom_table_write_cstring(glb->atom_table, atom_ref, atom_len, (char *) term_binary_data(binary));
+    return binary;
 }
 
 static term nif_erlang_atom_to_list_1(Context *ctx, int argc, term argv[])