Re: TPU assembler question

Hi Attila,

This is interesting.  I don't know if the assembler is being fooled by 
the apparent sequence of :

au chan_reg = something.
chan write_mer.

That sequence is a known problem which causes contention.  Since you 
preceed it with a call, no_flush however, those two instructions won't 
be executed in sequence.  Is there a chance that the first instruction 
of your called subroutine writes ERT or MER?  Probably not but that 
would still qualify as an error.

However, there is another problem in this code snippit.  Doing a neg_MRL 
and TDL in the last instruction of a timeslot in which the channel 
register has been changed is a known problem - not detected by the 
assembler.

In any case, could you do this?

au      chan_reg := chan_reg + sr.   (* goto other channel *)
call    X_TimeLH, flush.

qty154 wrote:

>I have the following TPU code snifflet:
>
>...
>if      N = 0 then goto L_PXT00, flush.
>
>call    X_TimeLH, no_flush.
>
>au      chan_reg := chan_reg + sr.   (* goto other channel *)
>
>au      ert := a;
>chan    write_mer,          (* set up match again *)
>        neg_MRL,
>        neg_TDL;
>end.
>
>...
>The subroutine is more than 3 instructions long.
>
>I guess there is nothing spurious in this code, but tpumasm (ver 4.04
>ess release) gives an error message because of the write_mer.
>I think the error is incorrectly raised so is there an update or
>secret command-line switch of the compiler so that it generates the
>S19 file?
>I don't want to happily rewrite my otherwise highly optimised code.
>  
>
-- 
Eric McRae, Electro-Logic Machines, Inc.
511 Root St., Port Townsend WA, 98368
Phone/Fax: 360.379.0969, http://www.elmi.com



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