[XCSSA] Propeller Demo at Breakpoint...

[X-otic Computer Systems of San Antonio]

X-otic Computer Systems of San Antonio wrote:
> Wow.. really takes me back to the C=64 demo days of old... right down to the 
> polyphonic waveform sound and rotating cubes and Mandelbrots! hehe..
>
> Pretty impressive!  And in just 32k?!
>   
I guess he does use some kind of compression, but still very impressive.
> But thinking about it..  the C64 was just ONE 1MHz proc doing all this fancy 
> video and the Prop runs at what.. 80MHz x 8 cogs = 160MIPS?!
> 	http://xcssa.org/files/2008-08_Propeller_Presentation_Fredrik.pdf
> That's 160 times more powerful than my Amiga 500!  Although to put it in 
> perspective, the C=64 (and Amiga) DID have their own separate dedicated video 
> generation hardware and circuitry, and the Propeller does it ALL on board (at 
> VGA resolution no less).  So I guess my reply is more a "prop to the prop  
> designers" than to the old C=64 hacks. :)  
>   
Yes, it's hard to compare C64 and Amiga to the prop...
And keep in mind that even the C64 have more memory than the prop... ;-)

> Although.. I didn't realize that the propeller didn't have a simple 
> multiplication instruction.  How do you deal with the Fredrik (and don't just 
> say multiple additions! ;) 
>   
Actually yes... ;-)
However there is a shift involved so the worst case have as many add as 
there are bits in the  number so to say.

This is how the multiplication actually looks likes,

                mov   r,#0
loop
                shr   y,#1   wc
        if_c    add   r,x
                shl   x,#1
                tjnz  y,#loop


There are also log and anti-log tables in the Propeller ROM that can be 
used.
Convert the two numbers to their log, add and then do an anti-log.
This has been suggested on the Propeller Forums, I don't know if anyone 
is using it though...

/Fredrik