[PATCH 2/2] cli: allow users to determine history buffer allocation method

[Hanyuan Zhao]

This commit allows users to choose the appropriate memory
allocation method between static allocated and dynamically
calloc. The previous static-array way will not obviously
contribute to the final binary size since it is uninitialized,
and might have better performance than the dynamical one.
Now we provide the users with both the two options.

Signed-off-by: Hanyuan Zhao <hanyuan-z at qq.com>
---
 cmd/Kconfig           |  8 ++++++++
 common/cli_readline.c | 23 ++++++++++++++++-------
 2 files changed, 24 insertions(+), 7 deletions(-)

diff --git a/cmd/Kconfig b/cmd/Kconfig
index af4dbc95fc..d0140b6cbe 100644
--- a/cmd/Kconfig
+++ b/cmd/Kconfig
@@ -190,6 +190,14 @@ config CMD_HISTORY
 	  Show the command-line history, i.e. a list of commands that are in
 	  the history buffer.
 
+config CMD_HISTORY_USE_CALLOC
+	bool "dynamically allocate memory"
+	default y
+	depends on CMD_HISTORY
+	help
+	  Saying Y to this will use calloc to get the space for history
+	  storing. Or it will be compiled as a static array.
+
 config CMD_LICENSE
 	bool "license"
 	select BUILD_BIN2C
diff --git a/common/cli_readline.c b/common/cli_readline.c
index eec6d8b0a2..a945cbf7cf 100644
--- a/common/cli_readline.c
+++ b/common/cli_readline.c
@@ -87,26 +87,35 @@ static int hist_add_idx;
 static int hist_cur = -1;
 static unsigned hist_num;
 
+#ifndef CONFIG_CMD_HISTORY_USE_CALLOC
+static char hist_data[HIST_MAX][HIST_SIZE + 1];
+#endif
 static char *hist_list[HIST_MAX];
 
 #define add_idx_minus_one() ((hist_add_idx == 0) ? hist_max : hist_add_idx-1)
 
 static int hist_init(void)
 {
-	unsigned char *hist;
 	int i;
 
-	hist_max = 0;
-	hist_add_idx = 0;
-	hist_cur = -1;
-	hist_num = 0;
-
-	hist = calloc(HIST_MAX, HIST_SIZE + 1);
+#ifndef CONFIG_CMD_HISTORY_USE_CALLOC
+	for (i = 0; i < HIST_MAX; i++) {
+		hist_list[i] = hist_data[i];
+		hist_list[i][0] = '\0';
+	}
+#else
+	unsigned char *hist = calloc(HIST_MAX, HIST_SIZE + 1);
 	if (!hist)
 		panic("%s: calloc: out of memory!\n", __func__);
 
 	for (i = 0; i < HIST_MAX; i++)
 		hist_list[i] = hist + (i * (HIST_SIZE + 1));
+#endif
+
+	hist_max = 0;
+	hist_add_idx = 0;
+	hist_cur = -1;
+	hist_num = 0;
 
 	return 0;
 }
-- 
2.34.1