Fortran

Displaying Fortran TypesFortran variables don't readily lend themselves to transformation by C++View, but in some cases, such as when using a common block with Cray pointer variables, it is possible to set up a corresponding C structure and then use that type to push the transformation.

Example

Consider this test case using Cray pointers in a common block, including three parts:

The Fortran code

A common block defined in an include file

The C code containing the C++View code

The Fortran Code

Here, the Fortran code sets up a common block with a few variables and then assigns them some values.

 

program pointerp

 

call stuff

 

end

 

subroutine stuff

 

include 'foop.cmn'

 

foo = 42

ix = 11

iy = 12

iz = 13

 

call doit(ix)

 

call readit

 

return

end

 

subroutine doit(ix_x)

 

include 'foop.cmn'

 

ipxp = malloc(8*ix_x*foo)

ipyp = malloc(8*iy*iz)

 

xp = 3

yp = 5

 

return

end

 

subroutine readit

 

include 'foop.cmn'

xp = 4

 

return

end

 

The include File

The Fortran include file foop.cmn sets up a common block foo1 that corresponds to the C structure extern foo1_, both in bold below.

The include file, foop.cmn:

integer :: foo, ix, iy, iz

real(kind=8) :: xp, yp

pointer (ipxp, xp(foo,ix))

pointer (ipyp, yp(iy,iz))

common /foo1/ ix, iy, iz, foo, ipxp, ipyp

 

The C Code

The C code fortranTV.c defines structure extern foo1_, aligned to the Fortran common block foo1. Then, in the TV_ttf_display_type routine for the struct foo, the calls to TV_ttf_add_row follow the layout of the data in the common block, allowing us to view the data as we want to see it

The C code, fortranTV.c:

#include <stdio.h>

 

#include "tv_data_display.h"

 

#ifdef __cplusplus

extern "C" {

#endif

 

extern struct foo { int x ; } foo1_ ;

 

#ifdef __cplusplus

}

#endif

 

// Routine data display declaration

int TV_ttf_display_type(const struct foo *parameter)

{

// Assign 'data' to the start of the common block

int *data = (int *)parameter ;

 

// Pick up the Cray pointer

double **ptr = (double **) &data[4] ;

char typeName[64] ;

 

TV_ttf_add_row("ix", "int", &data[0]) ;

TV_ttf_add_row("iy", "int", &data[1]) ;

TV_ttf_add_row("iz", "int", &data[2]) ;

TV_ttf_add_row("foo", "int", &data[3]) ;

 

sprintf(typeName, "double[%d]", data[0]*data[3]) ;

TV_ttf_add_row("ipxp", typeName, ptr[0]) ;

 

sprintf(typeName, "double[%d]", data[1]*data[2]) ;

TV_ttf_add_row("ipyp", typeName, ptr[1]) ;

 

return TV_ttf_format_ok ;

}

Compiling and Linking

First compile the TotalView tv_data_display.c routine, as described in “Compiling and linking tv_data_display.c”.

Build the program and the C program to add in the C++View transform:

ifort -g -c pointerp.f

ifort -g -c fortranTV.c -I$TVINCLUDE

Finally, link the program:

ifort -g -o crayptr pointerp.o tv_data_display.o fortranTV.o

 

Debugging

When you debug, set a breakpoint on the return statement on line 20, in subroutine doit. Run to the breakpoint and then dive on the common block foo1.

Figure 10: Using C++ View with Fortran, diving on the Fortran pointer data

if

To see the data transformed more clearly, expand the type information (downward arrow with the + sign) and change the language to C or C++.

 

Figure 11: Using C++ View with Fortran, changing language to C++

 

Then change the type from $void to foo, Figure 12.

Note that, while the original display of the common block shows the Cray pointers as integers (because a Cray pointer is actually an integer that holds only a memory address), the final, transformed display shows the data referenced by the pointers, or the arrays of doubles.

 

Figure 12: Using C++ View with Fortran, transform the type