calling C sleep() using C binding

[breakgate]

Hello all,

I'm looking for a portable way to halt execution of my program for a time shorter than one second. I can't use Fortrans intrinsic sleep() function because it accepts only integer seconds.
I had thought to do this by calling the C function sleep using C binding. However, I keep getting a linker error: "unresolved external symbol _sleep referenced...".
I'm using Intel Visual Fortran Composer XE 2011.

See below for my code.
Thanks in advance for any help.

cheers,
Maarten

[fortran]module sleep_ms

interface
    function sleep_C(ms) bind(c,name="sleep")
        use iso_c_binding, only : c_int
        integer(c_int), value :: ms
        integer(c_int) :: sleep_C
    end function sleep_C
end interface

contains

    function sleep_ms(ms)
        use iso_c_binding, only: c_int
        implicit none
        integer, intent(in), value :: ms
        integer :: sleep_ms
        
        integer(c_int) :: ms_c
        
        ms_c = ms
        
        sleep_ms = sleep_C(ms_c)
        
    end function sleep_ms

end module sleep_ms[/fortran]

[TimP · Accepted solution]

You might check exactly how the sleep() linker symbol is spelled in the library you are using, by tools such as dumpbin.
There is no standard Fortran sleep function; you might find the ifort sleepqq function more convenient than the other legacy sleep function.

[breakgate]

Hi,

thanks for the fast answer. I had considered sleepqq but dismissed it because I assumed it was not portable to other compilers (specifically PGI Fortran). After some further searching I found that it *is* portable. In PGI Fortran it seems to be part of the module DFLIB, but this module seems also to be available in Intel Fortran.

cheers,
Maarten

[jimdempseyatthecove]

Maarten,

In IFPORT there is the funciton SLEEPQQ(milliseconds)

Jim Dempsey

[jimdempseyatthecove]

I see you already found SLEEPQQ...

When you program delays sometimes your interest is in the length of the delay while other times you are intersted in time intervals (IOW ~precisely every n milliseconds). In the latter case you also need to obtain the system time with sufficient resolution such that you can recompute the delay necessary to reach the desired time interval. Lookup SYSTEM_CLOCK as well as WIN32 API's which are also available.

Jim Dempsey