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Re: [avr-gcc-list] Why are we using EICALL and EIJMP for AVR256?

From: Sean D'Epagnier
Subject: Re: [avr-gcc-list] Why are we using EICALL and EIJMP for AVR256?
Date: Mon, 14 Dec 2009 23:39:17 -0800

On 12/14/09, Andrew Hutchinson <address@hidden> wrote:
> The patterns for AVR mega 256 use EICALL an EIJMP
> Both require EIND to be set to provide upper address bits
> However, we are using linker trampolines for both, so in either case the
> 16 bit jump or call is to the trampolines.
> Are not the trampolines always located in first 128Kbytes? Thus we
> should be using ICALL and IJMP and not needing to set use EIND at all.
> What have I miss-understood?


Yes this confused me a lot too, but the reason is because the
trampoline is not in the first 128kbytes for a bootloader, so if the
compiler uses eijmp and eicall, then it is possible to do indirect
calls there too, but it still works fine in normal code.


> Andy
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