Re: [ECOS] Problems with port to Hitex HiCO.SH-4 board.

["Gary D. Thomas" <gary dot thomas at mind dot be>]

On Mon, 2003-07-21 at 05:17, Francois Retief wrote:
> Hello,
> 
> I am busy with an eCos port of the Hitex HiCO.SH-4 board (Hitachi SH7750 
> processor).  My problem is that Redboot freezes during startup, as seen by 
> the captured output below.
> 
> ---------8<---------------------------------8<--------------
> +
> RedBoot(tm) bootstrap and debug environment [ROM]
> Non-certified release, version v2_0 - built 12:12:54, Jul 21 2003
> 
> Platform: HiCO.SH-4 (SH7750)
> Copyright (C) 2000, 2001, 2002, Red Hat, Inc.
> 
> RAM: 0x
> ---------8<---------------------------------8<--------------
> 
> I traced to freese to the diag.cxx file. Now the strange part is the program 
> hangs in either of the following two pieces of code: 
> 
> In function: diag_write_long_num(..)
> ...
> /* construct digits into buffer in reverse order */
> if( n == 0 ) buf[bpos++] = '0';
> else while ( n != 0 )
> {
> 	cyg_ucount8 d = n % base;
> 	buf[bpos++] = digits[d];
> 	n /= base;
> }
> ...  <<---- never gets here
> 
> 
> In function: _cvt(..)
> ...
> if (val == 0) {
> 	/* Special case */
> 	*cp++ = ' 0';
> } else {
> 	while (val) {
> 		*cp++ = digits[val % radix];
> 		val /= radix;
> 	}
> }
> ...  <<---- never gets here
> 
> Does anybody have any hints about what is going on here?  
> 
> It looks to me that the division operation is not working propperly and that 
> the variable never reaches zero.  The SH7750 chip has a floating point unit.  
> Can it be that the gcc compiler is using floating point division?  The value 
> would get smaller, but never reaches zero.   How do I fix this?

There should not be any floating point operations going on at this 
point.  I'd suggest looking at the actual code generated for this
function - maybe it can shed some light.  

What sort of debugging tools do you have available?  If you have
hardware debugging (stepping, breakpoints, etc), perhaps you can
see what's happening more fully.

-- 
Gary D. Thomas <gary.thomas@mind.be>


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