[patch][rfa] SID cpu tracing -- attempt #2

[Dave Brolley]

Approved by fche and committed.

Dave Brolley wrote:

> Hi,
>
> Reponding to Frank's concerns about my previous patch, here is an 
> implementation along the lines he suggested. The idea is that each 
> CGEN 'set' handler and each component which is the target of a store 
> operation is responsible to annotating the cpu trace with the actual 
> value stored, if desired. In order to accomplish this, two changes 
> were necessary.
>
> 1) The tracing code generated by CGEN is now generated before the code 
> for the semantic operation. That way any annotation appears after the 
> original cpu trace.
>
> 2) basic_cpu now has a "trace" pin for use by other components. Each 
> value driven on the pin will be echoed as a character into the cpu's 
> trace_stream. This way annotation by other components are merged 
> properly with the cpu trace whether it be to cout or to a file.
>
> I've attached sid-trace-cgen.patch.txt which shows the CGEN changes 
> and a partial diff of the resulting changes to xstormy16-sem.cxx. I've 
> also attached sid-trace.patch.txt which shows the changes to basic_cpu.
>
> Tested on an internal port which requirs this functionality.
>
> OK to commit?
>
> Dave