CLK_TCK

[Andreas Jaeger]

The CLK_TCK definitions confuse me.

sysdeps/unix/sysv/linux/i386/bits/time.h uses:

#  if !defined __STRICT_ANSI__ && !defined __USE_XOPEN2K
/* Even though CLOCKS_PER_SEC has such a strange value CLK_TCK
   presents the real value for clock ticks per second for the system.  */
#   include <bits/types.h>
extern long int __sysconf (int);
#   define CLK_TCK ((__clock_t) __sysconf (2))  /* 2 is _SC_CLK_TCK */
#  endif

and time/time.h has:
# if defined __USE_POSIX && !defined __USE_XOPEN2K
#  ifndef CLK_TCK
#   define CLK_TCK      CLOCKS_PER_SEC
#  endif
# endif

Why do we have both definitions?

With -D_GNU_SOURCE you don't get any at all since _GNU_SOURCE implies
__USE_XOPEN2K:

t.c: In function `main':
t.c:9: `CLK_TCK' undeclared (first use in this function)
t.c:9: (Each undeclared identifier is reported only once
t.c:9: for each function it appears in.)

Using -D_POSIX_SOURCE fixes this - but that's not what I want.  IMO we
should make CLK_TCK available with _GNU_SOURCE.

What's the best way to fix this mess?

Andreas

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
#include <stdio.h>
#include <time.h>


int
main (void)
{

  printf ("CLK_TCK: %ld\n", (long)CLK_TCK);
  

  return 0;
}
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~


-- 
 Andreas Jaeger
  SuSE Labs aj@suse.de
   private aj@arthur.inka.de
    http://www.suse.de/~aj