compile-time function - (nf)

[kolstad at parsec.UUCP]

#R:hp-dcde:20000001:parsec:37300002:000:347
parsec!kolstad    Oct 15 18:35:00 1983

Here's how I did LOG2:

#define LOG2(x)  ((x)<=2?1: (x)<=4?2: (x)<=8?3: (x)<=16?4: \
	 (x)<=32?5: (x)<=64?6: (x)<=128?7:  (x)<=256?8: (x)<=512?9: \
	 (x)<=1024?10:  (x)<=2048?11:12 )

NB:  The C compiler will evaluate this expression to a single constant
	if it is supplied with a constant argument.  The preprocessor
	does NOT do the reduction.