Lpc2000

> 
> There are two forms of stm: stm(1) and stm(2)
> There are three forms of ldm: 1,2,3.
> 
> The stm(1) form seems to be generally safe whereas the stm(2) 
> form is only 
> safe in certain cases (saving the SYS/user register bank while 
> not in that 
> mode).

> How you determine which you get, perhaps someone else knows...

There is the slight syntacical difference between a context
restore sequence, eg. 

  ldmfd sp!,{r0-r12,lr,pc}^   // pop new task's r0-r12,lr & pc

versus not including pc in the register list. In that case
the user/sys registers are updated. (I think thats right,
I don't have my ARM-ARM open).

So I was wondering whether the 'safety' issues with using
ldm from user/sys mode are related to this particular use
only, or were in general not useable from user/sys mode.

If this is the case, then I suspect Jean Labrosse's uCOS
port was based on caution, and that the ldm instructions
can be used to speed up the context save/restore sequence
slightly.

At some point I'll just boot the LPC board I have with
one version of the code or the other and see if I break
anything :)  (Busy on other things at the moment tho).

Dave