Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!uwm.edu!uwvax!natasha.cs.wisc.edu!zvr
From: zvr@natasha.cs.wisc.EDU (Alexios Zavras)
Newsgroups: comp.unix.ultrix
Subject: Re: looking for usleep() implementation for ULTRIX
Message-ID: <8896@spool.cs.wisc.edu>
Date: 19 Oct 89 02:13:17 GMT
References: <5508@shlump.nac.dec.com> <5499@shlump.nac.dec.com>
Sender: news@spool.cs.wisc.edu
Reply-To: zvr@natasha.cs.wisc.EDU (Alexios Zavras)
Organization: University of Wisconsin - Computer Sciences Department
Lines: 55

In article <5508@shlump.nac.dec.com>, michaud@decvax.dec.com (Jeff
Michaud) writes:
> 	To make this really generic it should be defined as a function.  As a
> 	macro things like:
> 		if( ... )
> 			usleep(...);
> 		else
> 			....
> 	because the "usleep(...);" is two statements, ie. a compound statement and
> 	the null statement.  This can be worked around if you use an explicit
> 	compound statement around the "usleep(...);" while keeping your code
> 	portable.

The way to #define a macro as two or more statements,
without having this problem is:

#define macro(x)	do { stmt1(x); stmt2(x); ... } while (0);

So, the definition of usleep() looks like:

/*=========================================================================*/

#ifdef  ultrix

#ifndef _TYPES_
#include    <sys/types.h>
#endif  /* _TYPES_ */
#ifndef __XTIME__
#include    <sys/time.h>
#endif  /* __XTIME__ */

#define usleep(usec)
        do                                                              \
        {                                                                \
            struct timeval  usl_delay;                                    \
            usl_delay.tv_sec  = (int) (usec) / 1000000;                    \
            usl_delay.tv_usec = (int) (usec) % 1000000;                     \
            (void) select(0,(fd_set *)0,(fd_set *)0,(fd_set *)0, &usl_delay);\
        } while (0);

#endif  /* ultrix */

/*=========================================================================*/


> |Jeff Michaud    michaud@decwrl.dec.com  michaud@decvax.dec.com|

-- zvr --
	+-----------------------+	Alexios Zavras
	| Life is once, forever |	zvr@cs.wisc.edu
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