* Re: Re: [ECOS] Termios and waiting for character input
@ 2006-08-25 16:13 Andre-John Mas
2006-08-25 16:16 ` Gary Thomas
0 siblings, 1 reply; 2+ messages in thread
From: Andre-John Mas @ 2006-08-25 16:13 UTC (permalink / raw)
To: Jonathan Larmour, Gary Thomas; +Cc: Andre-John Mas, ecos-discuss
Where do I change the VMIN value? I'll change the value to see
if this helps.
BTW I had worked around the issue by simply doing a loop until
the input value was not 0x0. Not very elegant when CPU cycles
matter. I also made the same observation as Gary that the code
worked on other systems. I had tested the same code on MacOS X.
Andre
Jonathan Larmour wrote:
>
> Gary Thomas wrote:
> > Jonathan Larmour wrote:
> >> Gary Thomas wrote:
> >>> Jonathan Larmour wrote:
> >>>> Non-canonical mode processing was only implemented to support
> >>>> VMIN=0,TIME=0. Support for VMIN>0 is rudimentary and I wouldn't
> >>>> trust it. But VMIN defaults to 0, and that sample code posted
> >>>> doesn't attempt to set it to anything else.
> >>>>
> >>>> I imagine it defaults to something else on Linux, hence the
> >>>> difference in behaviour. <fx: goes and checks> Aha, in fact it
> >>>> defaults to 6. The POSIX standard does not set any requirements for
> >>>> the default value, so eCos is fine on this count.
> >>>
> >>> Thanks for looking into this.
> >>>
> >>> Perhaps we should make the default values for VMIN/VMAX configurable,
> >>> possibly with settings that match other systems?
> >>
> >> Maybe so if I had more confidence it worked! If Andre-John (or
> >> yourself) can play around with VMIN>0 and don't find any problems,
> >> then we could change the default for VMIN. NB there is no VMAX, but if
> >> you meant TIME, then TIME>0 is definitely unsupported in the current
> >> code.
> >
> > It does work correctly (or at least the same as Linux) when VMIN=1.
> > If I set VMIN=6, then I have to type 6 characters before the first one
> > is seen.
> > Perhaps that's where a setting of TIME>0 would matter...
>
> Yes indeed, that's the correct behaviour for TIME=0. So maybe it does work,
> and we could set default VMIN to 1.
>
> > At least we could have a way to default the value of VMIN and document
> > the fact that TIME>0 is not implemented (if not already in the docs)
>
> Since VMIN can be set in a well-known and standard way at run-time, I'm not
> sure there's much value in a configuration option for the default.
>
> Termios is unfortunately undocumented. This was in the days when making doc
> edits happen was like pulling teeth. And it became one of those things that
> just never happened.
>
> Jifl
>
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^ permalink raw reply [flat|nested] 2+ messages in thread
* Re: [ECOS] Termios and waiting for character input
2006-08-25 16:13 Re: [ECOS] Termios and waiting for character input Andre-John Mas
@ 2006-08-25 16:16 ` Gary Thomas
0 siblings, 0 replies; 2+ messages in thread
From: Gary Thomas @ 2006-08-25 16:16 UTC (permalink / raw)
To: Andre-John Mas; +Cc: Jonathan Larmour, ecos-discuss
Andre-John Mas wrote:
> Where do I change the VMIN value? I'll change the value to see
> if this helps.
>
> BTW I had worked around the issue by simply doing a loop until
> the input value was not 0x0. Not very elegant when CPU cycles
> matter. I also made the same observation as Gary that the code
> worked on other systems. I had tested the same code on MacOS X.
It's just another parameter to the termios structure. Simply
add this line:
term = termsave; /* termsave contains old termios */
term.c_lflag &= ~ECHO; /* turn off echo if it's set */
term.c_lflag &= ~ECHOE; /* turn off echoe if it's set */
term.c_lflag &= ~ICANON; /* turn off echoe if it's set */
term.c_cc[VMIN] = 1;
> Andre
>
> Jonathan Larmour wrote:
>> Gary Thomas wrote:
>>> Jonathan Larmour wrote:
>>>> Gary Thomas wrote:
>>>>> Jonathan Larmour wrote:
>>>>>> Non-canonical mode processing was only implemented to support
>>>>>> VMIN=0,TIME=0. Support for VMIN>0 is rudimentary and I wouldn't
>>>>>> trust it. But VMIN defaults to 0, and that sample code posted
>>>>>> doesn't attempt to set it to anything else.
>>>>>>
>>>>>> I imagine it defaults to something else on Linux, hence the
>>>>>> difference in behaviour. <fx: goes and checks> Aha, in fact it
>>>>>> defaults to 6. The POSIX standard does not set any requirements for
>>>>>> the default value, so eCos is fine on this count.
>>>>> Thanks for looking into this.
>>>>>
>>>>> Perhaps we should make the default values for VMIN/VMAX configurable,
>>>>> possibly with settings that match other systems?
>>>> Maybe so if I had more confidence it worked! If Andre-John (or
>>>> yourself) can play around with VMIN>0 and don't find any problems,
>>>> then we could change the default for VMIN. NB there is no VMAX, but if
>>>> you meant TIME, then TIME>0 is definitely unsupported in the current
>>>> code.
>>> It does work correctly (or at least the same as Linux) when VMIN=1.
>>> If I set VMIN=6, then I have to type 6 characters before the first one
>>> is seen.
>>> Perhaps that's where a setting of TIME>0 would matter...
>> Yes indeed, that's the correct behaviour for TIME=0. So maybe it does work,
>> and we could set default VMIN to 1.
>>
>>> At least we could have a way to default the value of VMIN and document
>>> the fact that TIME>0 is not implemented (if not already in the docs)
>> Since VMIN can be set in a well-known and standard way at run-time, I'm not
>> sure there's much value in a configuration option for the default.
>>
>> Termios is unfortunately undocumented. This was in the days when making doc
>> edits happen was like pulling teeth. And it became one of those things that
>> just never happened.
>>
>> Jifl
>>
--
------------------------------------------------------------
Gary Thomas | Consulting for the
MLB Associates | Embedded world
------------------------------------------------------------
--
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and search the list archive: http://ecos.sourceware.org/ml/ecos-discuss
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2006-08-25 16:13 Re: [ECOS] Termios and waiting for character input Andre-John Mas
2006-08-25 16:16 ` Gary Thomas
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