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. 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' 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
