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From: lim@iris.ucdavis.edu (Lloyd Lim)
Newsgroups: comp.sys.mac.programmer
Subject: Re: C/LSC question
Message-ID: <5834@ucdavis.ucdavis.edu>
Date: 6 Nov 89 00:02:36 GMT
References: <113@fornax.UUCP>
Sender: uucp@ucdavis.ucdavis.edu
Reply-To: lim@iris.ucdavis.edu (Lloyd Lim)
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Organization: U.C. Davis - Department of Electrical Engineering and Computer Science
Lines: 48

In article <113@fornax.UUCP> mcdonald@fornax.UUCP (Ken Mcdonald) writes:
>I'm writing a program in C which requires lots of calls to a small number
>of very small functions.  Because of the number of calls made to them,
>these functions need to be as fast as possible; because of their size,
>it would be quite worthwhile to have the code for these functions
>inserted by the compiler directly wherever said function is called,
>rather than having the compiler generate all the necessary stack
>manipulations and JSRs involved in a "real" function call.  Is there
>any way to have C do this?  Is there any way to have Lightspeed C (okay,
>okay, THINK C, but I liked the old name better) do this?  If not, is 
>there any good way to fake it?  How about any bad way?  Please don't
>say I have to use the built in assembler, I'd prefer to avoid going down
>to that level.

I know you don't want to but as a reminder for those that don't mind assembly
you can define a assembly language routine as inline.

My only other suggestion would be to code it as a macro.  Just put the same
statements into a macro with a backslash at the end of each line and
parentheses around each occurence of a macro argument.  I've coded some of the
more basic QuickDraw routines this way for slight speed increases.  If you need
local storage you can just put your statements in a block and declare some
variables.  Make sure you don't do anything funny in the macro calls which
would be have side effects (e.g. SWAP(++a, ++b)).  Here's a very simple example
that I just made up and which seems to run through THINK's syntax checker ok.

#define SWAP(x, y)   \
   {                 \
      short temp;    \
                     \
      temp = (x);    \
      (x) = (y);     \
      (y) = temp;    \
   }

void main(void);

void main()
{
   short a, b;
   
   SWAP(a, b);
}

+++
Lloyd Lim     Internet: lim@iris.ucdavis.edu (128.120.57.20)
              Compuserve: 72647,660
              US Mail: 146 Lysle Leach Hall, U.C. Davis, Davis, CA 95616