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Path: utzoo!utcs!mnetor!seismo!hao!woods
From: woods@hao.UUCP
Newsgroups: net.lang.f77
Subject: Re: Startup routines for f77 and C
Message-ID: <156@hao.UUCP>
Date: Mon, 21-Jul-86 01:03:50 EDT
Article-I.D.: hao.156
Posted: Mon Jul 21 01:03:50 1986
Date-Received: Mon, 21-Jul-86 05:54:36 EDT
References: <1709@eagle.ukc.ac.uk>
Organization: High Altitude Obs./NCAR Boulder, CO
Lines: 25
Summary: main() calls MAIN_()

In article <1709@eagle.ukc.ac.uk>, map@ukc.ac.uk (M.A.Pralat) writes:
> 
> 	'......the f77 and cc commands cause slightly different loading
> sequences to be generated, since Fortran programs need a few extra libraries
> and a different startup routine than do C programs'
> 

  My understanding is that when using ld(1), the entry point is ALWAYS
called "main". In your f77 program, the main f77 routine is referred to
as MAIN_ (any PROGRAM card is ignored). The startup routine for f77 programs
is a C program that looks like

main(argc,argv,envp) int argc; char **argv,**envp; {

f_init(); MAIN_(); f_exit();

}

The f_init and f_exit set up and close the F77 I/O drivers, which
run with FORTRAN logical unit numbers on top of the usual UNIX file
descriptors. This is similar to the stdio library, which uses stream
pointers which run on top of the file descriptors, but of course the
actual routines used are different.

--Greg