Re: [RFC] android/hal-audio: Fix wrong memory access

[Andrei Emeltchenko <Andrei.Emeltchenko.news@gmail.com>]

Hi Andrzej,

On Thu, May 22, 2014 at 03:54:34PM +0200, Andrzej Kaczmarek wrote:
> Hi Andrei,
> 
> On 22 May 2014 15:07, Andrei Emeltchenko
> <Andrei.Emeltchenko.news@gmail.com> wrote:
> > From: Andrei Emeltchenko <andrei.emeltchenko@intel.com>
> >
> > downmix_buf is allocated to have buffer size FIXED_BUFFER_SIZE / 2, when
> > we access it as (int16_t *) we shall device index by 2.
> > ---
> >  android/hal-audio.c | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/android/hal-audio.c b/android/hal-audio.c
> > index 7305bb6..96fa5c3 100644
> > --- a/android/hal-audio.c
> > +++ b/android/hal-audio.c
> > @@ -984,7 +984,7 @@ static void downmix_to_mono(struct a2dp_stream_out *out, const uint8_t *buffer,
> >         int16_t *output = (void *) out->downmix_buf;
> >         size_t i;
> >
> > -       for (i = 0; i < bytes / 2; i++) {
> > +       for (i = 0; i < bytes / (2 * sizeof(int16_t)); i++) {
> >                 int16_t l = le16_to_cpu(get_unaligned(&input[i * 2]));
> >                 int16_t r = le16_to_cpu(get_unaligned(&input[i * 2 + 1]));
> 
> Fix is correct, but commit message does not explain properly why this
> is required. Basically we need to downmix X frames from input buffer
> and this number is "bytes / (number_of_channels * sample_size)" - so
> we were missing "sample_size" here. I think adding inline comment to
> explain this would be also good.

I my code I use frame_num instead of bytes.

Best regards 
Andrei Emeltchenko