Re: [MiNT] Alignment

[Alan Hourihane <alanh@fairlite.demon.co.uk>]

On Sat, 2008-01-26 at 22:35 +0100, Vincent Rivière wrote:
> > Question 1: On a standard TT or Falcon with 68030, is it faster to do a 
> > move.l to an address multiple of 4 than to an address not multiple of 4 ?
> 
> Thank you for your answers.
> So the conclusion is:
> Aligning the longs on multiples of 4 is faster only inside the FastRAM.
> 
> There are 2 cases:
> 
> 1) Standard ST and Falcon 030
> Aligning the longs on multiples of 4 is useless, because these machines 
> have only ST-RAM, which is always wired on a 16-bit data bus. The 
> biggest useful (and required) alignment is 2 bytes for words and longs 
> (and maybe FPU floats ?)
> 
> 2) Standard TT and accelerator cards for ST and Falcon with FastRAM
> The FastRAM is wired on a 32-bit data bus, and can only be accessed by 
> the CPU. Thus it can work at full-speed when the longs are aligned on a 
> 4-byte boundary.
> 
> Does anyone agree ?

Yes. 

Alan.