Subject:
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Re: NQC 2.x event processing
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Newsgroups:
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lugnet.robotics.rcx.nqc
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Date:
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Tue, 13 Jun 2000 03:04:32 GMT
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Viewed:
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1800 times
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In article <393BDEDF.3CDC@gmccomb.com>, Gordon McComb
<gmccomb@gmccomb.com> wrote:
> Dave Baum wrote:
>
> > If I get assignment working, I may then move to an array style syntax:
> >
> > UpperLimit[0] = 10;
> >
> > since "UpperLimit(0) = 10;" looks very strange to most people (although
> > some C++ programs have a lot of this sort of thing).
>
> I like UpperLimit[0] = 10; just fine. The parens look too much like
> Basic! <g>
Getting things like
Timer[0] = 100;
to work while still allowing
if (Timer(0) < 100)
{
}
is a lot harder than I had anticipated, so I'm punting on array-style
setting of the various RCX source (such as Timer(), UpperLimit(), etc).
There are presently three ways to set these things (in the
soon-to-be-released NQC 2.2.b1). Here are examples of settint timer #1
to 100
1) Assignment syntax. Any data source can be used as the target of
assignment, subject to the read/write constraints of the specific
target. Currently, only the RCX 2 allows writing of sources other than
variables, and even so, some of the sources are read-only):
Timer(1) = 100;
2) Set(dst, src). This call takes two data sources and copies the value
from the second to the first:
Set(Timer(1), 100);
This is an artifact of earlier 2.2 releases. I'm keeping it around
simply because it makes a lot of other functions in the API easier to
specify. Personally, I think it looks hideous and is likely to cause
confusion for beginners.
3) Specialized calls per data source.
SetTimer(0, 100);
I think option #3 will be the prefered method in the long run because it
affords the greatest chance of portability to other targets. #1 and #2
depend on the fact that all sources can be treated identically. #3
would allow different sources to be set with different opcodes if a
generic opcode wasn't supported. For example, although
Watch() = 123;
works on RCX 2, it doesn't work on RCX 1 (because RCX 1 doesn't support
setting of sources). However, SetWatch() works fine on both because RCX
1 does have a special opcode to set the watch.
Given the above, I'm really tempted to remove Set() from the
documentation and make it an internal-only call (there are other such
macros in the API file). I'm also tempted to disable #1 since it leads
to a programming style that isn't very C-like and is not likely to be
portable to other lego targets.
Comments?
Dave
--
reply to: dbaum at enteract dot com
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Message is in Reply To:
 | | Re: NQC 2.x event processing
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| (...) #3, which was the approach you took. (...) I think what I liked about the approach in pBrick script was that it was fairly like coding a microcontroller in assembler: set up an interrupt vector and then include a label and code for the (...) (24 years ago, 5-Jun-00, to lugnet.robotics.rcx.nqc)
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