Re: Question about digital i/o cmd buffer data format in new driver

On 01/25/05 23:58, Frank Mori Hess wrote:
> On Tuesday 25 January 2005 06:51 pm, Frank Mori Hess wrote:
>>On Monday 24 January 2005 01:15 pm, Ian Abbott wrote:
>>
>>>The second way is to pack the channel data into the minimum required
>>>number of bytes (rounding up to a whole number of bytes), storing the
>>>channels in the order they appear in the command's channel list.  So
>>>if the channel list contains 9 channels, the scan will use two bytes;
>>>bit 0 of byte 0 will contain the data for the first channel in the
>>>list; bit 1 will contain the data for the second channel in the list,
>>>etc.  If I use this method, I'll set the SDF_PACKED flag in the
>>>subdevice (nothing uses that yet!).
>>
>>You should do it the second way, except rounding up to a multiple of
>>sizeof(sampl_t) or sizeof(lsampl_t) depending on your use of SDF_LSAMPL
>>(I fixed bytes_per_scan() to do this).  You don't need a new SDF_PACKED
>>flag. The ni_pcidio driver could be thought of as a special case where
>>only chanlists starting at zero and incrementing are supported (although
>>the driver doesn't actually enforce that).
> 
> To clairify, when I say the second way, I mean with replacing most the the 
> word "byte" in your description with "sampl_t or lsampl_t".

Okay, I'll use sampl_t, using up to 2 sampl_t's per scan.

-- 
-=( Ian Abbott _at_ MEV Ltd.    E-mail: <abbotti_at_mev.co.uk>        )=-
-=( Tel: +44 (0)161 477 1898   FAX: +44 (0)161 718 3587         )=-

Received on 2005-01-26Z11:21:28