Re: [avr-gcc-list] PC (ProgrammCounter) problems

[Larry Barello]

Besides the obvious:

lo8()
hi8()

which are the first and second byte of a "short" or "long"

There are the Program Memory equivalents:

pm_lo8()
pm_hi8()

which do the divide by 2.  There is also

hlo8()    Third byte of long
hhi8()    fourth byte of long

There is also the hh8() and pm_hh8() which I have no clue what they do.  
Probably the
third byte for future addressing in future avr's...

This isn't documented anywhere.

Cheers!

----- Original Message ----- 
From: "Andreas Buhr" <address@hidden>
To: <address@hidden>
Sent: Monday, July 28, 2003 6:42 PM
Subject: [avr-gcc-list] PC (ProgrammCounter) problems


> Hello all!
>
> Could you please help me?
>
> I write assembler-apps and want to compile them with avr-as/avr-ld.
> I often use lapels as arguments.
> For example I wan to push the address of a function on the stack:
>
> In AVRStudio this works:
>
> myfunction:
> nop
> nop
> ldi r16, low(myfunction)
> push r16
> ldi r16, high(myfunction)
> push r16
> ret
>
> (it is a loop)
>
> How to do this with avr-as? In avr-as 'myfunction' is exactly twice what
> it should be. So this is working code for avr-as:
>
> myfunction:
> nop
> nop
>
> ldi r16, lo8(myfunction)
> ldi r17, hi8(myfunction)
> lsr r17
> ror r16
> push r17
> push r16
> ret
>
> But I don't want to have the lsr and ror. There are two instructions
> wasted. I am searching for something like:
> ldi r16, lo8(myfunction>>1)
> or
> ldi r16, lo8(myfunction/2)
>
> These two instructions give errors:
> Error: invalid sections for operation on `myfunction' and `L0
'
>
> any help?
>
> thanks in advance
>
> Andreas Buhr
>
>
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