[alsa-devel] [PATCH 2/4] topology: Change variable type to fix gcc warning

[Lin, Mengdong]

> -----Original Message-----
> From: Takashi Iwai [mailto:tiwai at suse.de]
> Sent: Wednesday, November 18, 2015 3:16 PM
> To: mengdong.lin at linux.intel.com

> On Wed, 18 Nov 2015 08:23:07 +0100,
> mengdong.lin at linux.intel.com wrote:
> >
> > From: Mengdong Lin <mengdong.lin at linux.intel.com>
> >
> > Fix warning: comparison between signed and unsigned integer
> > expressions [-Wsign-compare]
> >
> > ABI objects use type _le32, which is converted to host unsigned integer.
> > So the iterator 'i' in a loop as below should also be unsigned.
> > for (i = 0; i < pcm->num_streams; i++)
> >                 ^
> 
> Using an unsigned int for the generic loop count like i is strange.

Yes.

> Rather compare with the original value in the template, which is actually int.

Are you suggesting not change the code?

The "pcm->num_streams" here is __le32 defined in ABI:
struct snd_soc_tplg_pcm {
	...
	__le32 num_streams;	/* number of streams */
	...
} __attribute__((packed));

It seems gcc takes it as unsigned integer and so I get the warning.

Thanks
Mengdong

> 
> 
> Takashi
> 
> > Signed-off-by: Mengdong Lin <mengdong.lin at linux.intel.com>
> >
> > diff --git a/src/topology/ctl.c b/src/topology/ctl.c index
> > 7d8787f..6dc3b3d 100644
> > --- a/src/topology/ctl.c
> > +++ b/src/topology/ctl.c
> > @@ -676,7 +676,8 @@ int tplg_add_mixer(snd_tplg_t *tplg, struct
> snd_tplg_mixer_template *mixer,
> >  	struct snd_soc_tplg_private *priv = mixer->priv;
> >  	struct snd_soc_tplg_mixer_control *mc;
> >  	struct tplg_elem *elem;
> > -	int ret, i;
> > +	int ret;
> > +	unsigned int i;
> >
> >  	tplg_dbg(" Control Mixer: %s\n", mixer->hdr.name);
> >
> > @@ -743,7 +744,8 @@ int tplg_add_enum(snd_tplg_t *tplg, struct
> > snd_tplg_enum_template *enum_ctl,  {
> >  	struct snd_soc_tplg_enum_control *ec;
> >  	struct tplg_elem *elem;
> > -	int ret, i;
> > +	int ret;
> > +	unsigned int i;
> >
> >  	tplg_dbg(" Control Enum: %s\n", enum_ctl->hdr.name);
> >
> > diff --git a/src/topology/pcm.c b/src/topology/pcm.c index
> > 9b7e402..4b7c058 100644
> > --- a/src/topology/pcm.c
> > +++ b/src/topology/pcm.c
> > @@ -522,7 +522,7 @@ int tplg_add_pcm_object(snd_tplg_t *tplg,
> snd_tplg_obj_template_t *t)
> >  	struct snd_tplg_pcm_template *pcm_tpl = t->pcm;
> >  	struct snd_soc_tplg_pcm *pcm;
> >  	struct tplg_elem *elem;
> > -	int i;
> > +	unsigned int i;
> >
> >  	tplg_dbg("PCM: %s, DAI %s\n", pcm_tpl->pcm_name,
> pcm_tpl->dai_name);
> >
> > @@ -564,7 +564,7 @@ int tplg_add_link_object(snd_tplg_t *tplg,
> snd_tplg_obj_template_t *t)
> >  	struct snd_tplg_link_template *link = t->link;
> >  	struct snd_soc_tplg_link_config *lk;
> >  	struct tplg_elem *elem;
> > -	int i;
> > +	unsigned int i;
> >
> >  	if (t->type != SND_TPLG_TYPE_BE && t->type != SND_TPLG_TYPE_CC)
> >  		return -EINVAL;
> > --
> > 2.5.0
> >