newlib/libc/time/clock.c

   1 /* NetWare can not use this implementation of clock, since it does not
   2    have times or any similar function.  It provides its own version of
   3    clock in clib.nlm.  If we can not use clib.nlm, then we must write
   4    clock in sys/netware.  */
   5
   6 #ifdef CLOCK_PROVIDED
   7
   8 int _dummy_clock = 1;
   9
  10 #else
  11
  12 /*
  13  * clock.c
  14  * Original Author:     G. Haley
  15  *
  16  * Determines the processor time used by the program since invocation. The time
  17  * in seconds is the value returned divided by the value of the macro CLK_TCK.
  18  * If the processor time used is not available, (clock_t) -1 is returned.
  19  */
  20
  21 /*
  22 FUNCTION
  23 <<clock>>---cumulative processor time
  24
  25 INDEX
  26         clock
  27
  28 SYNOPSIS
  29         #include <time.h>
  30         clock_t clock(void);
  31
  32 DESCRIPTION
  33 Calculates the best available approximation of the cumulative amount
  34 of time used by your program since it started.  To convert the result
  35 into seconds, divide by the macro <<CLOCKS_PER_SEC>>.
  36
  37 RETURNS
  38 The amount of processor time used so far by your program, in units
  39 defined by the machine-dependent macro <<CLOCKS_PER_SEC>>.  If no
  40 measurement is available, the result is (clock_t)<<-1>>.
  41
  42 PORTABILITY
  43 ANSI C requires <<clock>> and <<CLOCKS_PER_SEC>>.
  44
  45 Supporting OS subroutine required: <<times>>.
  46 */
  47
  48 #include <time.h>
  49 #include <sys/times.h>
  50 #include <reent.h>
  51
  52 clock_t
  53 clock ()
  54 {
  55   struct tms tim_s;
  56   clock_t res;
  57
  58   if ((res = (clock_t) _times_r (_REENT, &tim_s)) != (clock_t) -1)
  59     res = (clock_t) (tim_s.tms_utime + tim_s.tms_stime +
  60                      tim_s.tms_cutime + tim_s.tms_cstime);
  61
  62   return res;
  63 }
  64
  65 #endif /* CLOCK_PROVIDED */