Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP
Posting-Version: version B 2.10 5/3/83; site hp-pcd.UUCP
Path: utzoo!linus!decvax!harpo!floyd!clyde!ihnp4!zehntel!hplabs!hp-pcd!hp-dcde!jack
From: jack@hp-dcde.UUCP
Newsgroups: net.lang.c
Subject: compile-time function - (nf)
Message-ID: <2079@hp-pcd.UUCP>
Date: Fri, 14-Oct-83 03:29:54 EDT
Article-I.D.: hp-pcd.2079
Posted: Fri Oct 14 03:29:54 1983
Date-Received: Sun, 16-Oct-83 08:41:36 EDT
Sender: notes_gateway@hp-pcd.UUCP
Organization: Hewlett-Packard, Fort Collins, CO
Lines: 30

#N:hp-dcde:20000001:000:517
hp-dcde!jack    Oct 12 19:00:00 1983

I want to define a compile-time function.  For example:

#define LOG2(n)	\
#if n==1	\
	0	\
#endif		\
#if n==2	\
	1	\
#endif		\
#if n==4	\
	2	\
#endif		\
... and so on ...

	i = LOG2(4);

Which I want to produce i = 2.

However, it seems that the whole macro definition gets put together
on a single line before the preprocessor checks for #if's, so the
#if's aren't recognized.  How can I (for the general case, not just LOG2)
do something like this?

					-Jack Applin
					Hewlett-Packard
					(hplabs!hp-dcd!jack)