Subject:
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Re: NBC/NXC beta news
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Newsgroups:
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lugnet.robotics.nxt
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Date:
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Wed, 25 Apr 2007 22:51:01 GMT
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Viewed:
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18174 times
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In lugnet.robotics.nxt, John Hansen wrote:
> In lugnet.robotics.nxt, Doug Eaton wrote:
> > Is an array of struct expected to work? When I try to access a field within an
> > element I get an error:
> >
> > # Error: parser error
> > File "test.nxc" ; line 217
> > # val=cell[index].b
> > #----------------------------------------------------------
> > # Error: ')' expected
> >
> > Of note, the field name is truncated to the first character in the error.
>
> The problem with code of this sort is that the opcodes for manipulating values
> do not readily allow for this type of operation. To set the variable val to the
> value of the bxxx field of the structure type stored in your array of structs I
> ultimately need to generate a mov opcode.
>
> mov val, somevariablename
>
> The VM doesn't have variants of the mov opcode which allow for offsets or
> indirects of any sort. So I would need to generate code which copies out
> cell[index] into a temporary variable of the correct structure type and then I
> would need to generate the mov opcode using the temporary variable. I'd need at
> least one unique temporary for each thread and each structure type. Not
> impossible but rather complicated. The workaround is to simply declare a
> variable explicitly of the correct structure type and set it to cell[index] then
> set val in a second statement.
Well that technique does compile, but produces interesting results:
---
#include "NXCDefs.h"
struct st
{
string s1;
int i1;
}
st a1[];
st v1,v2;
task main()
{
v1.s1 = "test";
v1.i1 = 9;
NumOut(0,0,v1.i1);
TextOut(40,0,v1.s1);
ArrayInit(a1,v1,2);
v2 = a1[1];
NumOut(0,8,v1.i1);
TextOut(40,8,v1.s1);
NumOut(0,16,v2.i1);
TextOut(40,16,v2.s1);
Wait(2000);
}
---
ROSCO
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Message has 1 Reply:
 | | Re: NBC/NXC beta news
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| (...) Sorry for not getting back with you sooner about this bug, Rosco. Life comes at you fast, as they say. :-) I investigated this problem today and it looks like I've got it fixed. There were several bugs going on in NBC which were causing the (...) (18 years ago, 28-Apr-07, to lugnet.robotics.nxt)
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Message is in Reply To:
| | Re: NBC/NXC beta news
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| (...) The problem with code of this sort is that the opcodes for manipulating values do not readily allow for this type of operation. To set the variable val to the value of the bxxx field of the structure type stored in your array of structs I (...) (18 years ago, 25-Apr-07, to lugnet.robotics.nxt)
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