> andreas> No I mean TARGETID as defined by ADIv5.2, which must be known to be 
> able to select a device on a multidrop SWD link.

Ok, i see the confusion. The TARGETID - as define by ARM, is identical to the 
JTAG-TAP-ID in style and format, thus in my mind the TARGETID = TAPID, but that 
is not the case because the DAP also has a TAPID … 

Duane> Bottom line: Are you ok with putting the DAP structure in the TAP 
structure as the first step?

andreas> No, I'm not even OK with the DAP *pointer* that's currently there.

Hmm - I must have been blind - I did not see that.  

what if I did this: use exactly that existing DAP structure pointer and remove 
the DAP STRUCTS from all other places. For example the Cortex_M has both a 
POINTER and a STRUCT, the STRUCT would go away.

duane> Then - future:  Create a TAP operations structure … full of pointers … 
it would default to JTAG tap modes, but could then be over-ridden later.

andraes>  Overridden with what? The TAP operations are necessarily implemented 
by a JTAG interface (via some convoluted wrappers to handle the complete scan 
chain... and queuing, yuk!). A DAP object can never implement a TAP. (A 
JTAG-AP, connected to a DAP, could however implement a scan chain consisting of 
a number of TAPs. But the DAP itself can't.)

I think I am not describing it well what I mean is method, or operation, or 
interface structure. If the operational goal is this: I want TAP (X) to goto IR 
state (Y), and shift data bits (Z) in and out. The function pointer that knows 
how to do that - is found via this structure chain   TARGET -> TAP -> 
SCAN_CHAIN_HEAD -> OPS_POINTER -> FUNCTION_PTR .  All of these function 
pointers should take a “TAP” pointer as parameter #1 (aka: the fake C++ this 
pointer)

andraes> I think you're after the problem caused by the lack of a scan_chain 
object (provided by a JTAG interface), with a pointer to it from each TAP in 
the chain.

Yea, you are probably correct, see above

-duane
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