RTC(3I) Last changed: 1-6-98
NAME
_rtc, RTC, IRTC, IRTC_RATE - Returns clock register contents
SYNOPSIS
C/C++:
#include <intrinsics.h>
long _rtc (void);
Fortran:
INTRINSIC RTC
RTC ()
INTRINSIC IRTC
IRTC ()
EXTERNAL RTC()
REAL(KIND=8) time
CALL RTC(time)
EXTERNAL IRTC()
INTEGER(KIND=8) itime
CALL IRTC(itime)
INTEGER(KIND=8) IRTC_RATE, NCYCPSEC
NCYCPSEC = IRTC_RATE()IMPLEMENTATION
C/C++: UNICOS and UNICOS/mk systems
Fortran: UNICOS, UNICOS/mk, and IRIX systems
STANDARDS
C/C++: Cray Research extension
Fortran: CF90 and MIPSpro 7 Fortran 90 compiler extension to Fortran
90
DESCRIPTION
The _rtc, RTC, and IRTC intrinsic functions return a real-time clock
value. The value is expressed as the number of clock ticks. The
IRTC_RATE function returns the clock rate of the IRTC and RTC
functions.
C/C++ NOTES
Because _rtc is an intrinsic function, no externally visible library
function is available for it. The compiler generates inline code to
produce the result.
FORTRAN NOTES
The names of these intrinsics cannot be passed as arguments.
When RTC is called as a subroutine, it accepts the following argument:
time The real-time clock value is returned as a REAL(KIND=8) value.
When IRTC is called as a subroutine, it accepts the following
argument:
itime The real-time clock value is returned as an INTEGER(KIND=8)
value.
The RTC intrinsic function is outmoded. For information on outmoded
features and their preferred standard alternatives, see the Fortran
Language Reference Manual, Volume 3, publication SR-3905.
The use of RTC is not recommended on UNICOS or IRIX systems. See the
standard SYSTEM_CLOCK(3I) intrinsic subroutine for the preferred
alternative.
FORTRAN RETURN VALUES
RTC returns a 64-bit real value. IRTC returns a 64-bit integer value.
When using CF90 on a UNICOS system, RTC returns the low-order 46 bits
of the clock register as a REAL(KIND=8) value. IRTC returns the
current content of the clock re46ster as an INTEGER(KIND=8) value.
The result of IRTC may exceed 2 -1 and must not be used in
multiplication, division, or conversion to real unless the values is
typed as a 64-bit integer in the CF90 program or -i 64 is specified on
the f90(1) command line. Addition and subtraction are unaffected.
On IRIX systems, RTC returns the low-order 52 bits of the system clock
expressed as a REAL(KIND=8) value. IRTC returns the system clock as
an INTEGER(KIND=8) value. IRTC_RATE returns the number of IRTC and
RTC clock ticks per second in an INTEGER(KIND=8) value. IRTC is the
fastest nonwrapping clock.
SEE ALSO
A complete list of C/C++ intrinsic functions available on Cray
Research systems is in the Cray C/C++ Reference Manual, publication SR
-2179.
f90(1), SECOND(3F), SYSCLOCK(3F), SYSTEM_CLOCK(3I), TSECND(3F)
Intrinsic Procedures Reference Manual, publication SR-2138, for the
printed version of this man page.
