[alsa-devel] [PATCH 18/29] mixer: remove alloca() from elem_write_route()

[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 | 11 +++++------
 1 file changed, 5 insertions(+), 6 deletions(-)

diff --git a/src/mixer/simple_none.c b/src/mixer/simple_none.c
index 0ebaf5e..d0e8963 100644
--- a/src/mixer/simple_none.c
+++ b/src/mixer/simple_none.c
@@ -514,19 +514,18 @@ static int elem_write_switch_constant(selem_none_t *s, selem_ctl_type_t type, in
 
 static int elem_write_route(selem_none_t *s, int dir, selem_ctl_type_t type)
 {
-	snd_ctl_elem_value_t *ctl;
+	snd_ctl_elem_value_t ctl = {0};
 	unsigned int idx;
 	int err;
 	selem_ctl_t *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 < c->values * c->values; idx++)
-		snd_ctl_elem_value_set_integer(ctl, idx, 0);
+		snd_ctl_elem_value_set_integer(&ctl, idx, 0);
 	for (idx = 0; idx < c->values; idx++)
-		snd_ctl_elem_value_set_integer(ctl, idx * c->values + idx,
+		snd_ctl_elem_value_set_integer(&ctl, idx * c->values + idx,
 					       !!(s->str[dir].sw & (1 << idx)));
-	if ((err = snd_hctl_elem_write(c->elem, ctl)) < 0)
+	if ((err = snd_hctl_elem_write(c->elem, &ctl)) < 0)
 		return err;
 	return 0;
 }
-- 
2.7.4