[fpc-devel] Arm Thumb2 - Stellaris status

[David Welch]

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> The great strength of ARM is that the peripherals, even if in different locations in different manufacturers parts, are identical in hardware terms if they are all cortex m3; that is the IP which they license from ARM.com. So maybe that is another reason for keeping the peripheral offset definitions and peripheral drivers separate and out of the compiler.
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> Geoffrey
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Not sure what you are saying here, almost none of the peripherals are 
the same from vendor to vendor.  With the cortex-m3 the systick timer 
and the VNIC for example are from ARM, sure, but the majority of the 
items you are going to use timers, dma, pwm, gpio, clocks and enables, 
etc are vendor specific and vastly different from vendor to vendor. 
Within a vendor they are very similar if not the same but from ti to st 
most of the items are not compatible, likewise from ti to lpc/nxp or ti 
to atmel, etc.

Normally these are libraries and not buried in the compiler proper, I 
agree with that.  Perhaps that is what you were saying and I misunderstood.

And as with libraries you can take them or leave them, that would want 
to be the case here (without having to dig into the compiler proper). 
Would need to roll your own target to avoid/modify a library.  Ideally 
with the compiler you want to specify the arm core to take advantages of 
instructions each newer core supports.  Not use them to tie to boards or 
systems.

I was hoping for thumb support but I now see that the choices are 
limited to arm and thumb+thumb2 (without any separation between thumb 
and thumb2).  Actually thumb2 wasnt working for me, I got an arm+thumb2 
mix, so I will ride this along for a while and see what comes up, 
otherwise limit my use to ARM targets, or start working on a thumb 
backend.  Adding backends as well as arm embedded are of interest to me 
so I may work on a little of both.

So far it seems to be very straight forward to add a platform/device to 
fpc arm embedded, so if the stock support is too bulky or confusing 
individuals can cherry pick items they want and make their own simpler 
target.

Actually what we definitely need here in the near term is an arm generic 
target and a thumb2 generic target that does not have any of the vendor 
specific items in it, perhaps not even core specific peripherals.

I understand this is a work in progress and sorting everything out will 
take some time.

David