[Mesa-dev] [RFC v2 13/15] mesa/macros: add power-of-two assertions for ALIGN and ROUND_DOWN_TO

[Brian Paul]

On 06/01/2015 11:46 AM, Brian Paul wrote:
> On 06/01/2015 11:13 AM, Nanley Chery wrote:
>> From: Nanley Chery <nanley.g.chery at intel.com>
>>
>> ALIGN and ROUND_DOWN_TO both require that the alignment value passed
>> into the
>> macro be a power of two in the comments. Using software assertions
>> verifies
>> this to be the case.
>>
>> Signed-off-by: Nanley Chery <nanley.g.chery at intel.com>
>> ---
>>   src/mesa/main/macros.h | 10 ++++++++--
>>   1 file changed, 8 insertions(+), 2 deletions(-)
>>
>> diff --git a/src/mesa/main/macros.h b/src/mesa/main/macros.h
>> index c794da3..1348b08 100644
>> --- a/src/mesa/main/macros.h
>> +++ b/src/mesa/main/macros.h
>> @@ -700,7 +700,10 @@ is_power_of_two(unsigned value)
>>    *
>>    * \sa ROUND_DOWN_TO()
>>    */
>> -#define ALIGN(value, alignment)  (((value) + (alignment) - 1) &
>> ~((alignment) - 1))
>> +#define ALIGN(value, alignment) ({                        \
>> +      assert(is_power_of_two(alignment));                 \
>> +      (((value) + (alignment) - 1) & ~((alignment) - 1)); \
>> +   })
>>
>
> That construct will not compile with MSVC unfortunately (I just tested it).

I also meant to suggest- perhaps you could convert the macro to an 
inline function.

-Brian