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

[Jürgen Hestermann]

> 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...

I have done this too. I maintain 2 values, one for the *allocated* 
memory and one for the *used*. This way I don't need to reallocate 
unless I hit the border. If this happens, I simply allocate a new chunk 
of memory of double size (which is then again a power of 2) and 
move(copy) the data to the new memory. This way I don't have to 
reallocate very often because the additional memory increases by a 
factor of 2 which makes it less propably for large numbers of bytes.

> Is there 
> some clever way to request that the processor return the position of 
> the leftmost '1' in 00101101?

The only way I can think of is a shr (or shl) loop which should run as 
often as number of bits exist in the worst case;

i := 0;
while x<>0 do
    begin
    x := x shr 1;
    inc(i);
    end;
if i<>0 then
   x := 1 shl i
else
   error
if X=0 then overflow;