[En-Nut-Discussion] Problem: read uart port

[urbi]

Adam Dybkowski wrote:
> 
> Ole Reinhardt wrote:
> 
>> Just write the code like this:
>> 
>> int got
>> int offset = 0;
>> static char inbuf[58];
>> 
>> do {
>>    got = _read(_fileno(uart), inbuf + offset, 58 - offset);
>>    if (got >= 0) offset += got;
>> } while ((got >= 0) && (offset < 58));
> 
> This will make a 100% busy loop that eats a lot of CPU power. Is that
> possible in Nut/OS to use select function to sleep between reads? Or
> maybe _read function works in blocking mode and select is not necessary?
> 
> -- 
> Adam Dybkowski
> 
> Hi, 
> 
> You can check only the buffer bevor reading it:
> 
> if (_filelength(_fileno(uart)) >= 58){
>     got = _read(_fileno(uart), inbuf, MAX_INBUFF);
> }
> 
> In this way you can polling the uart without blocking the ethernut.
> 
> Urban
> 

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