Given this,

´´´
import std.bitmanip;
import core.stdc.limits;

void main()
{
	BitArray ba;
	ba.length = size_t.sizeof * CHAR_BIT; // enough length, known at compile time
	size_t arbitrary; // = random size_t, not known at compile time

	// ba ???assign??? arbitrary;
        assert(cast(size_t[])ba == [arbitrary]);
}
´´´

how to convert a number to a BitArray as fast as possible, given that the BitArray is already allocated to the needed length?
Is bit checking the way to go, or is there a way to cast one to the other somehow?

On Sunday, 25 March 2018 at 11:32:56 UTC, Alex wrote:
> how to convert a number to a BitArray as fast as possible, given that the BitArray is already allocated to the needed length?
> Is bit checking the way to go, or is there a way to cast one to the other somehow?

Via bit checking I would end with this:

´´´
void assign(BitArray ba, size_t val) //@nogc
{
	import std.algorithm : each;

	assert(ba.length == size_t.sizeof * CHAR_BIT);

	val.bitsSet.each!(b => ba.flip(b));
}
´´´