[alsa-devel] [PATCH 32/34] alisp: remove alloca() from FA_hctl_elem_read()

[Takashi Sakamoto]

Both of alloca() and automatic variables keeps storages on stack, while
the former generates more instructions than the latter. It's better to use
the latter if the size of storage is computable at pre-compile or compile
time; i.e. just for structures.

This commit obsolete usages of alloca() with automatic variables.

Signed-off-by: Takashi Sakamoto <o-takashi at sakamocchi.jp>
---
 src/alisp/alisp_snd.c | 24 +++++++++++-------------
 1 file changed, 11 insertions(+), 13 deletions(-)

diff --git a/src/alisp/alisp_snd.c b/src/alisp/alisp_snd.c
index c63806b..6d5018a 100644
--- a/src/alisp/alisp_snd.c
+++ b/src/alisp/alisp_snd.c
@@ -622,8 +622,8 @@ static struct alisp_object * FA_hctl_elem_read(struct alisp_instance * instance,
 {
 	snd_hctl_elem_t *handle;
 	struct alisp_object * lexpr, * p1 = NULL, * obj;
-	snd_ctl_elem_info_t *info;
-	snd_ctl_elem_value_t *value;
+	snd_ctl_elem_info_t info = {0};
+	snd_ctl_elem_value_t value = {0};
 	snd_ctl_elem_type_t type;
 	unsigned int idx, count;
 	int err;
@@ -634,16 +634,14 @@ static struct alisp_object * FA_hctl_elem_read(struct alisp_instance * instance,
 	handle = (snd_hctl_elem_t *)get_ptr(instance, p1, item->prefix);
 	if (handle == NULL)
 		return &alsa_lisp_nil;
-	snd_ctl_elem_info_alloca(&info);
-	snd_ctl_elem_value_alloca(&value);
-	err = snd_hctl_elem_info(handle, info);
+	err = snd_hctl_elem_info(handle, &info);
 	if (err >= 0)
-		err = snd_hctl_elem_read(handle, value);
+		err = snd_hctl_elem_read(handle, &value);
 	lexpr = new_lexpr(instance, err);
 	if (err < 0)
 		return lexpr;
-	type = snd_ctl_elem_info_get_type(info);
-	count = snd_ctl_elem_info_get_count(info);
+	type = snd_ctl_elem_info_get_type(&info);
+	count = snd_ctl_elem_info_get_count(&info);
 	if (type == SND_CTL_ELEM_TYPE_IEC958) {
 		count = sizeof(snd_aes_iec958_t);
 		type = SND_CTL_ELEM_TYPE_BYTES;
@@ -651,19 +649,19 @@ static struct alisp_object * FA_hctl_elem_read(struct alisp_instance * instance,
 	for (idx = 0; idx < count; idx++) {
 		switch (type) {
 		case SND_CTL_ELEM_TYPE_BOOLEAN:
-			obj = new_integer(instance, snd_ctl_elem_value_get_boolean(value, idx));
+			obj = new_integer(instance, snd_ctl_elem_value_get_boolean(&value, idx));
 			break;
 		case SND_CTL_ELEM_TYPE_INTEGER:
-			obj = new_integer(instance, snd_ctl_elem_value_get_integer(value, idx));
+			obj = new_integer(instance, snd_ctl_elem_value_get_integer(&value, idx));
 			break;
 		case SND_CTL_ELEM_TYPE_INTEGER64:
-			obj = new_integer(instance, snd_ctl_elem_value_get_integer64(value, idx));
+			obj = new_integer(instance, snd_ctl_elem_value_get_integer64(&value, idx));
 			break;
 		case SND_CTL_ELEM_TYPE_ENUMERATED:
-			obj = new_integer(instance, snd_ctl_elem_value_get_enumerated(value, idx));
+			obj = new_integer(instance, snd_ctl_elem_value_get_enumerated(&value, idx));
 			break;
 		case SND_CTL_ELEM_TYPE_BYTES:
-			obj = new_integer(instance, snd_ctl_elem_value_get_byte(value, idx));
+			obj = new_integer(instance, snd_ctl_elem_value_get_byte(&value, idx));
 			break;
 		default:
 			obj = NULL;
-- 
2.7.4