getting gnu as to check the current location

[Harvey Chapman]

Is it possible with gnu as to do something like this?

.if (. - _start1) < 0x100 || (. - _start1) > 0x1ff
	.error	"some_label must be between 0x100 and 0x1FF!"
.endif
some_label:

I'm trying to just let the label exist where it may, but if anyone adds/removes code that causes that condition to change, I'd like them to know about it at compile time.

Thanks,
Harvey