[avr-gcc-list] eicall & EIND

[Dusan Ferbas]

Hi guys,

we have 2 issues with eicall instruction on ATmega2561 platform.

1st is, that a call to a constant bootloader (BL) location is compiled
with eicall instruction without setting EIND register.
2nd is, that in BL area, indexed call /that is compiled with eicall/
seems not to work, when used from application area.
We tried both WinAVR-20071221 and WinAVR-20080610.

I noticed, that even on ATmega128, call was compiled with all unused PC
bits set to 1.
Does it mean, that we should set all "1"s in EIND ?

ad 1) same c code works on ATmega128
ATmega128 way:
-------------------------
typedef int boot_loader_send(unsigned  char *, unsigned  char
*, short);
#define boot_loader_data_send ((boot_loader_send*) 0x3F80A)

...
rslt = boot_loader_data_send(workbuf, buf, len);
(compiled with simple call)

2561 solution
------------------
- code for 128 generates eicall
- using a static inline wrap function with asm call

        

- it is
optimized (arguments are not used, so they are not prepared in
registers)

        

-
preparing registers in a "called" rtn did not work (however i
believe that is nearly the same as a next working case)
- finally we created a rtn in an external .c module (see code with asm
jmp below)
-> anyone knows an easier way ?


ad 2) works from BL area, does not from an application
following is called both from BL when XMODEM is used over a UART and also
from an application
it works from BL, but does not, when called from an application

        

- when
indexed call was replaced with a list of calls in switch-case, it works
(but we do not fit in BL area :-) )

init

        

BootInfoHeader->fn[0] = FlashPage;

        

BootInfoHeader->fn[1] = EEprom_write_page;
call

        

unsigned
char eind_local = EIND;

        

EIND =
0x3F800 >> (16 + 1); //highest bit of LoadAddr (for ATmega2561 ==
1, because in words)

        

BootInfoHeader->fn[section_id](address, (unsigned short
*)p_received_data, pagesize);

        

EIND =
eind_local;


code for ad 1) case
-------------------------------

int boot_loader_data_send(unsigned char *p_WorkBuffer, unsigned char *received_data_p, unsigned short data_length)
{
         p_WorkBuffer = p_WorkBuffer;
         received_data_p = received_data_p;
         data_length = data_length;
        
//      int      rslt;

//      asm volatile (  "movw r20,%3" "\n\t"
//                                          "movw r22,%2" "\n\t"
//                                          "movw r24,%1" "\n\t"
//                                          "call 0x3F00A" "\n\t"
//                                          "movw %0,r24" :
//                                          "=r" (rslt) :
//                                          "r" (p_WorkBuffer),
//                                          "r" (received_data_p),
//                                          "r" (data_length));

        asm volatile ("jmp 0x3F00A");

//      return rslt;
}

======================================
At 02:27 4.6.2008, Andy H wrote:
> I cant answer your question
> fully. ...
>
> Anatoly is adding support for 256 on version gcc 4.3 and gcc 4.4. He or
> Eric may provide you a better way to do call. (Even if it needs asm
> /macro wrapper)
>
> Dusan Ferbas wrote:
> > Hi,
> >
> > I am using WinAVR-20071221, because none of the most recent toolchains
> > produces a runnable code for our application.
> >
> > Our bootloader starts at 0x3f800 (2kB).
> > In its code, we are using function[id](...) construction.
> > This is compiled with eicall instruction, but no EIND register is
> > set.
> > Is there a way, how to tell the compiler, that code is linked in upper
> > half of flash ?
> > In bootloader code we can live with EIND=1 at its init.
> >
> > But when we have a call from our application, neither EIND is set, even
> > address is not divided by 2 (WinAVR bug #1959227).
> > Probably some far attribute should be applied ?
> > When compiled for ATmega128 (with 0x1f806), it works ...
> >
> > typedef void boot_loader_init(unsigned  char *);
> > #define
> > boot_loader_data_init          
> > ((boot_loader_init *)0x3F806)
> > ...
> >   boot_loader_data_init(buffer);
> > ...
> >
> >
> > Dusan 
>
>
> Dusan Ferbas
> www.etech.cz