In SX Microcontrollers, SX/B Compiler and SX-Key Tool, peterverkaik wrote:

Guenther,

I used the latest sxsim to test some taskswitching code using the secret instructions.
3 observations:

a)
When I enter the isr routine for the first time, I see the 1st entries of the shadow stacks
loaded with the states prior to the interrupt, with the 2nd entries 0.

b)
To perform a switch I then use the secret [u]pop[/u] instructions. I see the 1st level entries
being copied to W, but I don't see the 2nd level entries being copied to the 1st level entries,
which I think should be the case.

c)
 When I use the secret [u]push[/u] instructions, I see the 1st level entries being copied to the
 2nd level entries, and W being copied to the 1st level entries, as it should. 
 
Questions:
Can we assume that the shadow stack holds all 0's upon reset?
If not, why not leave the fields blank, as with the call stack.
A blank field would indicate a void value (location has never been accessed).
Could we also have blank fields in the ram area? Now they are filled with random values,
but do we really need to see these values while locations never have been accessed?
You could keep the values hidden until a location is accessed, then display it.


regards peter

---------- End of Message ----------


You can view the post on-line at:
http://forums.parallax.com/forums/default.aspx?f=7&p=9&m=53539#m183413

Need assistance? Send an email to the Forum Administrator at forumadmin@parallax.com

The Parallax Forums are powered by dotNetBB Forums, copyright 2002-2007 (http://www.dotNetBB.com)