Armory format: Free the tests' memory allocation before actual cracking

doc/README-Armory

@@ -60,8 +60,6 @@ target wallet's settings.
 Since our built-in test vectors currently include 32 MiB test wallet data
 extracts, the self-test at startup will potentially (depending on number
 of threads and SIMD) consume a lot of memory (and take much time, too).
-That memory currently remains allocated further during the run even if
-your actual target wallet's data extract needs less memory.  If this is
-a problem (perhaps if you're on a system supporting a lot of hardware
-threads, but having little RAM), you may remove some test vectors from
-the "tests" array in armory_fmt_plug.c and re-run "make".
+If this is a problem (perhaps if you're on a system supporting a lot of
+hardware threads, but having little RAM), you may remove some test
+vectors from the "tests" array in armory_fmt_plug.c and re-run "make".

src/armory_fmt_plug.c

@@ -141,6 +141,24 @@ static void done(void)
 	secp256k1_context_destroy(secp256k1_ctx);
 }
 
+/*
+ * Free the tests' memory allocation before actual cracking, so that it doesn't
+ * affect long-term memory usage in case the actual targets need less memory
+ * than the tests.  However, don't do this when proceeding from self-test to
+ * benchmark, so that memory (de)allocation time doesn't affect the speeds.
+ */
+void reset(struct db_main *db)
+{
+	if (benchmark_running)
+		return;
+
+	int i;
+	for (i = 0; i < max_threads; i++) {
+		free_region_t(&memory[i]);
+		init_region_t(&memory[i]);
+	}
+}
+
 static void *get_salt(char *ciphertext)
 {
 	uint8_t decoded[BINARY_SIZE + SALT_SIZE];
@@ -486,7 +504,7 @@ struct fmt_main fmt_armory = {
 	}, {
 		init,
 		done,
-		fmt_default_reset,
+		reset,
 		fmt_default_prepare,
 		valid,
 		fmt_default_split,