Re: [Simulavr-devel] avrtest vs simulavrxx

[Joel Sherrill]

address@hidden wrote:
> On Fri May  8 13:43 , Joel Sherrill  sent:
>   
> > I think I have tracked one down to this feature in
> > avrtest that (I think) is not in simulavrxx and
> > is probably the culprit
> >
> >        "  -d           Initialize SRAM from .data (for ELF program)\n"
> >
> > This sets a flag which is used later only to do this:
> >
> >        /* Also copy in SRAM.  */
> >        if (flag_initialize_sram && vaddr >= DATA_VADDR)
> >            memcpy(cpu_data + vaddr - DATA_VADDR,
> >                   cpu_flash + addr, filesz);
> >
> > The avrtest crt0.S code doesn't appear to copy
> > initialized data into RAM. 
> >     
>
> crt0.S is avr assembly code that C programs execute before main?
>
>   
Yes. It is attached.
> > Any thoughts on how to implement this in simulavrxx?
> >     
>
> I'd expect it to look a lot like the code that initializes the flash.
>
> Perhaps the question is how to generate avr code that uses it?
> I think that with gnu tools the compilation stage could be left alone.
> The startup code could be mostly eliminated.
> I think it would just have to assign the stack pointer.
> The linker script would need to be changed.
>
>   
Josh is porting RTEMS to the AVR for the Google Summer of
Code and Eric is his mentor.  I am helping with the RTEMS issues.
RTEMS has its own tool chain (similar to avr tools) but each
Board Support Package has its own assembly language initialization.

I am beginning to think that by using the start code and linker
script that were recommended for avrtest, I have created problems.
I should move to the ones from the regular tools or at least ensure
the avrtest provided one does the same things.
> --
> Michael Hennebry
> address@hidden
> "War is only a hobby."
> ---- Msg sent via CableONE.net MyMail - http://www.cableone.net


--
Joel Sherrill, Ph.D.             Director of Research & Development
address@hidden        On-Line Applications Research
Ask me about RTEMS: a free RTOS  Huntsville AL 35805
  Support Available             (256) 722-9985


#define SPL 0x3d
#define SPH 0x3e
#define SREG 0x3f
#define RAMPZ 0x3b

#define RAMEND (64 * 1024)

        .weak   __stack
        .set    __stack, RAMEND - 1

        .weak   __heap_end
        .set    __heap_end, 0


        .section .vectors,"ax",@progbits
        .global __vectors
        .func   __vectors
__vectors:
__reset:
        jmp     __init
        .endfunc        

        .section .init0,"ax",@progbits
        .weak   __init
;       .func   __init
__init:
        
        .section .init2,"ax",@progbits
        clr     r1
        out     0x3f, r1
        ldi     r28,lo8(__stack)
        ldi     r29,hi8(__stack)
        out     SPH, r29
        out     SPL, r28

        /* Only for >64K devices with RAMPZ, replaces the default code
           provided by libgcc.S which is only linked in if necessary.  */

        .section .init4,"ax",@progbits
        .global __do_copy_data
__do_copy_data:
        .global __do_clear_bss
__do_clear_bss:
#if 0
        ldi     r17, hi8(__data_end)
        
        ldi     r26, lo8(__data_start)
        ldi     r27, hi8(__data_start)
        
        ldi     r30, lo8(__data_load_start)
        ldi     r31, hi8(__data_load_start)
        ldi     r16, hh8(__data_load_start)
        out     RAMPZ, r16

0:      
        cpi     r26, lo8(__data_end)
        cpc     r27, r17
        breq    1f
        
        elpm    r0, Z+
        st      X+, r0
        rjmp    0b
1:      
#endif

        .section .init9,"ax",@progbits
        call    main
        jmp     exit
;       .endfunc

        .global exit
        .func   exit
exit:   out 0x2f, r0
        .endfunc

        .global abort
        .func   abort
abort:  out 0x29, r0
        .endfunc