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Subject: 
Re: Adding syscalls/opcodes to NXT-G
Newsgroups: 
lugnet.robotics.nxt
Date: 
Thu, 22 Mar 2007 07:55:10 GMT
Viewed: 
19440 times
  
In lugnet.robotics.nxt, John Hansen wrote:
In lugnet.robotics.nxt, Guy Ziv wrote:
the NXT-G compiler
has a WriteIOMap function which has as an input a binary U8 array. One can
change this syscall in the FW so when the module name is left empty (not a case
I believe ever happens in any existing NXT-G blocks) the FW takes the binary
array, wraps it and create from it a new program clump. This will allow
executing syscalls and several other opcodes from NXT-G.

Can you flesh this out a bit?  What do you have in mind when you say "create
from it a new program clump"?  The current version of the firmware limits the
size of this buffer to 64 bytes.  I increased that limit in my recent changes to
be 800 bytes.

The existing VM code is written so that it executes all the program code as it
reads the .rxe file directly from the flash memory.  Injecting a byte stream
from a jury-rigged IOMapWrite syscall into the existing FM program execution
logic seems like it would be rather complicated.  Do you envision that this code
would execute as a parallel clump or would it act more like a subroutine call?

John Hansen

John - I know you don't like this and I agree that the best solution is NI
changing their compiler to allow extending firmware with new syscalls. The way
things work, I'm afraid, this will not happen anytime soon. I'm trying to
suggest creative ways to overcome this difficulties in a "jury-rigged" way.
Since I'm not an expert in the firmware source as you are, I only scatched my
artistic concept of such solution, leaving others to check the details... Do you
have other ways to incorporate new syscalls into NXT-G with the existing NI
compiler?



Message is in Reply To:
  Re: Adding syscalls/opcodes to NXT-G
 
(...) Can you flesh this out a bit? What do you have in mind when you say "create from it a new program clump"? The current version of the firmware limits the size of this buffer to 64 bytes. I increased that limit in my recent changes to be 800 (...) (18 years ago, 21-Mar-07, to lugnet.robotics.nxt)

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