On 10/05/10 13:06, Hennerich, Michael wrote: > Jonathan Cameron wrote on 2010-10-05: >> On 10/05/10 12:52, Hennerich, Michael wrote: >>> Jonathan Cameron wrote on 2010-10-05: >>>> On 10/05/10 12:24, Hennerich, Michael wrote: >>>>> /** >>>>> * IIO_CONST_ATTR_SCAN_EL_TYPE - attr to specify the data format >>>>> of a scan el * @name: the scan el name (may be more general and >>>>> cover a set of scan elements * @_sign: either s or u for signed >>>>> or unsigned * >>>>> @_bits: number of actual bits occuplied by the value * >>>>> @_storagebits: number of bits _bits is padded to when read out of >>>>> buffer **/ >>>>> #define IIO_CONST_ATTR_SCAN_EL_TYPE(_name, _sign, _bits, >>>>> _storagebits) \ >>>>> IIO_CONST_ATTR(_name##_type, >>>>> #_sign#_bits"/"#_storagebits); There are cases where bits < >>>>> storagebits and the result is not alligned to the LSB. Lets say we >>>>> have an 10-bit ADC. The output is stored in a 16-bit word, with >>>>> four leading zeros, then the 10-bit datum, followed by 2 don't care bits. >>>>> >>>>> So it would be good to provide an additional shift value? >>>>> Or how shall we handle these cases? >>>> This was discussed in the original debate and we simply proposed >>>> leaving it until we had a user. So the question is how to describe >>>> the shift. >>>> >>>> So taking your example, how about: >>>> >>>> u10/16>>2 >>>> >>>> Where the shift is optional. >>>> >>>> Other suggestions welcome given I made that up with 2 seconds >> thought. >>> >>> I think this is sufficient. I can only think about right shifts being >>> useful. This notation would consistently allow both, that's why I like >>> it. It would be decidedly odd for right shift to make sense. >>> >>> A bit off topic - some common defines for signed/unsigned types might >>> also be useful. >>> >>> #define IIO_SCAN_EL_TYPE_SIGNED 's' #define >>> IIO_SCAN_EL_TYPE_UNSIGNED 'u' Fine with me. > > Shall we add the shift option to the existing macro? > Or shall we create a new one? How would you name it? Create a new one (as this is optional and as of yet, not that common) IIO_CONST_ATTR_SCAN_EL_TYPE_WITH_SHIFT should do the job. > > Greetings, > Michael > > Analog Devices GmbH Wilhelm-Wagenfeld-Str. 6 80807 Muenchen > Sitz der Gesellschaft Muenchen, Registergericht Muenchen HRB 4036 Geschaeftsfuehrer Thomas Wessel, William A. Martin, Margaret Seif > > > -- To unsubscribe from this list: send the line "unsubscribe linux-iio" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
