[PATCH xf86-input-synaptics 07/10] Add touch valuator mask to hw state structure

[Chase Douglas]

On 02/09/2012 03:27 PM, Peter Hutterer wrote:
> On Wed, Feb 08, 2012 at 06:35:16PM -0800, Chase Douglas wrote:
>> Signed-off-by: Chase Douglas <chase.douglas at canonical.com>
>> ---
>>  src/synaptics.c    |   78 ++++++++++++++++++++++++++++++++++++++++++++++++++-
>>  src/synapticsstr.h |    1 +
>>  src/synproto.h     |    5 +++
>>  3 files changed, 82 insertions(+), 2 deletions(-)
>>
>> diff --git a/src/synaptics.c b/src/synaptics.c
>> index c0398fb..b01be59 100644
>> --- a/src/synaptics.c
>> +++ b/src/synaptics.c
>> @@ -1151,6 +1151,8 @@ DeviceInit(DeviceIntPtr dev)
>>  #ifdef HAVE_MULTITOUCH
>>      if (priv->has_touch)
>>      {
>> +        priv->num_slots = priv->max_touches ? : 10;
> 
> whoah, didn't know that was legal. is this gcc or std C?
> either way, I'd rather not do that because of this behaviour:
> 
>     int a = 12;
>     a = (a > 10) ? : 10;
>     → a is now 1
>     
> Not quite what one would expect.

I think it is standard C. It's not seen too often because many times
you're checking a value against something non-zero. A better example of
how not to do it is:

a = (b > 0) ? : 10;

I don't see any reason why what I have is bad, but I'll change it if it
makes you cringe. People writing C need to know what they are doing, and
this isn't one of those areas where what really happens is different
than what one might think.

-- Chase