Re: [Simulavr-devel] 13-pre3 patch

[ken restivo]

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i was able to build 13-pre3, and gdb, no prob. the build system worked cleanly 
and quietly. very cool.

but i found a strange problem.

this test program successively writes the bytes "0, 0, 7, 0" to PORTC, whereas 
i was expecting it to write the bytes "0, 0, 4, 0".

/* test program for 7 != 4 bug */

#include <timer.h>
#include <io.h>
#include <pgmspace.h>

volatile int useless;

/****************
    PRINTUNSIGNED
    does unsigned hex. 
********************/
volatile void
printUnsigned(unsigned int x, unsigned char maxbuf)
{
    int xlen = 0;
    /* XXX these are volatile for debugging. gcc -O3 will remove them */
    volatile unsigned char realnum;
    do {
        realnum =  (x >> (xlen * 4)) & 0xf ;
        outp(realnum, PORTC);
        xlen++;
    } while( xlen < maxbuf);

} /* END PRINTUNSIGNED */

/************
*  MAIN
*************/
int
main( void )
{
    useless = 0x0400;

    outp(0xFF, DDRD);
    outp(0xFF, DDRC);

    printUnsigned(useless, 4);
    while(1);

    return(0);

} /* end main */

/* EOF */

i use this .avrgdbinit:
        set print pretty
        target remote localhost:1212
        load
        b printUnsigned
        display/x $sp
        display/x $pc
        c
        display xlen
        display realnum


the exact same code (with different includes, and with outp's changed to 
printf's) does the expected behaviour when compiled for linux. so it seems to 
be simulavr-specific.

the damage seems to be done in here:
        realnum =  (x >> (xlen * 4)) & 0xf ;
  8e:   8e 2f           mov r24, r30    
  90:   9f 2f           mov r25, r31
  92:   04 2e           mov r0, r20
  94:   02 c0           rjmp    .+4         ; 0x9a
  96:   96 95           lsr r25 
  98:   87 95           ror r24 
  9a:   0a 94           dec r0  
  9c:   e2 f7           brpl    .-8         ; 0x96


i compared the ror, lsr, dec, and brpl in decoder.c with the databook, and 
didn't find anything amiss.

my apologies in advance if i'm just doing something stupid here.

- -ken
- ----------
On Sun, Jan 06, 2002 at 01:11:09PM -0700, Theodore A. Roth wrote:
> The 13-pre3 patch is ready. Apply it to a clean 0.0.12 release.
> 
> Please try it out and let me know about any problems.
> 
> Here's the url:
> 
>   http://res099095.halls.colostate.edu/programs/simulavr/patches/
>     simulavr-0.0.12-0.0.13-pre3.patch.gz
> 
> 
> Ted
> 
- -- 
- ------------------
One world. Many gods. Plenty for everyone.


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