update: using stack char array

src/core/core.cc

@@ -35,6 +35,17 @@
 
 ////////////////////////////////////////
 
+#define RELEASE(NEXT_CODE, FILTER) \
+cache_t next_case = { \
+    .code = NEXT_CODE, \
+    .mask = F_1x1 << next_addr, \
+    .filter = FILTER, \
+    .addr = next_addr \
+}; \
+cache_insert(next_case);
+
+////////////////////////////////////////
+
 #define BFS_INIT \
 int next_addr; \
 int current = 0; \
@@ -49,17 +60,6 @@ int filter = cache[current++].filter;
 
 ////////////////////////////////////////
 
-#define RELEASE(NEXT_CODE, FILTER) \
-cache_t next_case = { \
-    .code = NEXT_CODE, \
-    .mask = F_1x1 << next_addr, \
-    .filter = FILTER, \
-    .addr = next_addr \
-}; \
-cache_insert(next_case);
-
-////////////////////////////////////////
-
 inline void Core::cache_insert(Core::cache_t &next_case) { // try to insert into cache
     auto *cache_ptr = cache;
     for (; cache_ptr < cache + cache_size; ++cache_ptr) {

src/short_code/serialize.cc

@@ -8,7 +8,8 @@ ShortCode ShortCode::from_string(const std::string &short_code) {
 
 std::string ShortCode::to_string() const { // encode as 5-bits string
     uint32_t short_code = code;
-    std::string result(5, '\0'); // short code length 5
+    char result[6]; // short code length 5
+    result[5] = '\0'; // string ending flag
     for (int n = 0; n < 5; ++n) {
         result[4 - n] = SHORT_CODE_TABLE[short_code & 0b11111]; // aka _ % 32
         short_code >>= 5; // aka _ / 32