[alsa-devel] [PATCH 07/29] mixer: remove alloca() from elem_read_enum()

[Takashi Sakamoto]

Both of alloca() and automatic variables keep 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/mixer/simple_none.c | 7 +++----
 1 file changed, 3 insertions(+), 4 deletions(-)

diff --git a/src/mixer/simple_none.c b/src/mixer/simple_none.c
index 27b5699..bd7d6b5 100644
--- a/src/mixer/simple_none.c
+++ b/src/mixer/simple_none.c
@@ -290,7 +290,7 @@ static int elem_read_route(selem_none_t *s, int dir, selem_ctl_type_t type)
 
 static int elem_read_enum(selem_none_t *s)
 {
-	snd_ctl_elem_value_t *ctl;
+	snd_ctl_elem_value_t ctl = {0};
 	unsigned int idx;
 	int err;
 	int type;
@@ -304,15 +304,14 @@ static int elem_read_enum(selem_none_t *s)
 	else if (s->selem.caps & SM_CAP_CENUM)
 		type = CTL_CAPTURE_ENUM;
 	c = &s->ctls[type];
-	snd_ctl_elem_value_alloca(&ctl);
-	if ((err = snd_hctl_elem_read(c->elem, ctl)) < 0)
+	if ((err = snd_hctl_elem_read(c->elem, &ctl)) < 0)
 		return err;
 	for (idx = 0; idx < s->str[0].channels; idx++) {
 		unsigned int idx1 = idx;
 		if (idx >= c->values)
 			idx1 = 0;
 		s->str[0].vol[idx] =
-				snd_ctl_elem_value_get_enumerated(ctl, idx1);
+				snd_ctl_elem_value_get_enumerated(&ctl, idx1);
 	}
 	return 0;
 }
-- 
2.7.4