[squeak-dev] Re: [ANN] Number comparison, hash, NaN, Point, and other partially ordered sets

John M McIntosh johnmci at smalltalkconsulting.com
Fri Jan 9 22:21:55 UTC 2009


years back we coded up a FloatMathPlugin to do IEEE math  a front end  
to http://www.netlib.org/fdlibm/  in april of 06

Testing showed we could do IEEE math using the plugin on linux/windows/ 
mac (powerpc).

I believe Qwaq took over building this for macintel.

Also note the unix and carbon VM do fiddle with the FP unit control  
register via this code I've a copy of
you would need to check the build tree for the unix version to see if  
it is different.

#if defined(__GNUC__) && ( defined(i386) || defined(__i386) ||  
defined(__i386__)  \
			|| defined(i486) || defined(__i486) || defined (__i486__) \
			|| defined(intel) || defined(x86) || defined(i86pc) )
   static void fldcw(unsigned int cw)
   {
     __asm__("fldcw %0" :: "m"(cw));
   }
#else
# define fldcw(cw)
#endif

#if defined(__GNUC__) && ( defined(ppc) || defined(__ppc) ||  
defined(__ppc__)  \
			|| defined(POWERPC) || defined(__POWERPC) || defined (__POWERPC__) )
void mtfsfi(unsigned long long fpscr);
void mtfsfi(unsigned long long fpscr)
   {
     __asm__("lfd   f0, %0" :: "m"(fpscr));
     __asm__("mtfsf 0xff, f0");
   }
#else
# define mtfsfi(fpscr)
#endif



On 9-Jan-09, at 7:20 AM, Bert Freudenberg wrote:

>
> On 09.01.2009, at 16:16, Tim Olson wrote:
>
>>
>> On Jan 8, 2009, at 9:30 AM, Hans-Martin Mosner wrote:
>>
>>> AFAIK, the Croquet project needs to have exactly reproducible float
>>> arithmetics on all platforms.
>>
>> Are you using the exact same code on all platforms for   
>> trancendentals and other floating-point functions?  If not, that is  
>> going to be the greatest source of different results.  They tend to  
>> vary widely on accuracy, since there is no 1/2 ULP accuracy  
>> requirement for those functions, unlike for the defined IEEE  
>> operations (+,-,*,/,sqrt)
>
>
> Yes, Andreas wrote a new plugin to ensure bit-identical floating  
> point ops across platforms.
>
> - Bert -
>
>
>

--
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John M. McIntosh <johnmci at smalltalkconsulting.com>
Corporate Smalltalk Consulting Ltd.  http://www.smalltalkconsulting.com
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