[fpc-pascal] two small ?s - high(real) and nearest 2^x

[David Emerson]

Thanks, guys!

hrm, I am a little disappointed to realize that, although I'm on a 
32-bit system, 'real' maps to 'double' rather than 'single' ... and it 
is a bit slower, too. So I guess I'll use single for now.

an fpc bsr function would be nice, but I'm gonna stick with compatible 
code.

I do realize that allocating by doubling size is memory intensive, but 
it's just for the rapid growth part-- once the array is populated, I 
shrink it down to its precise size.

Cheers,
David.


On Sat 10 Oct 2009, David Emerson wrote:
> 1. Is there a way to get the highest and lowest real values? I can do 
> high(longint) but high(real) gives me an error. Also of interest is a 
> low(real) value (-m * 10^n) as distinct from the smallest real value
> (m * 10^-n)
> 
> 2. For the purposes of reserving memory in block sizes that can be 
> easily reallocated, I like to use powers of two. So if I have, e.g., a 
> dynamic array, I might start with a size of 1024 and then double it 
> when it hits capacity. Hopefully this smoothes memory management, as I 
> am using a lot of memory...
> 
> Anyway, what I'd like is a simple function that can quickly identify 
the 
> next power-of-two larger than an arbitrary number. So if I feed the 
> function 472, it will return 512. Thus far I haven't been able to 
> figure out how to do this without a big if-then-else nest. Is there 
> some clever way to request that the processor return the position of 
> the leftmost '1' in 00101101?
> 
> Thanks!
> ~David.
> 
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