"FX" <coudert@[EMAIL PROTECTED]
> wrote in message
news:fudrd5$9ts$1@[EMAIL PROTECTED]
>> But you should ask the gfortran folks if they can round up some
>> do***entation about gfortran array descriptors for you. They are
>> different in every compiler.
> Yep, that's on the TODO list. Here's the short version (in C syntax).
Thanks for the do***entation, FX! Since I can never seem to get all
my ducks in a row on the first attempt, I tried a pure Fortran test
of my initial recommendation and found some syntax errors. After
fixing them up I got:
C:\gfortran\clf\repeatdouble>type repeatdouble.f90
function repeatdouble( N, d ) result( array )
use iso_c_binding
implicit none
integer, intent( in ) :: N
double precision, dimension( N ) :: array
double precision, intent( in ) :: d
integer I
print *, "repeat ", N, " times ..."
print *, "double ", d, "."
print *, "array :", array
do I = 1,N
print *, "making copy nb", i, " of ", N
array(I) = d
end do
end function repeatdouble
C:\gfortran\clf\repeatdouble>type test3.f90
program main
use ISO_C_BINDING
implicit none
type, bind(C) :: descr
type(C_PTR) address
integer(C_INTPTR_T) unknown1
integer(C_INTPTR_T) unknown2
integer(C_INTPTR_T) stride
integer(C_INTPTR_T) unknown3
integer(C_INTPTR_T) last_element
end type descr
interface
subroutine repeatdouble(DD,n,d) bind(C,name='repeatdouble_')
use ISO_C_BINDING
im****t descr
implicit none
type(descr) DD
integer(C_INT) n
real(C_DOUBLE) d
end subroutine repeatdouble
end interface
type(descr) DD
double precision, target :: buf(9)
double precision d
integer n
buf = [(n,n=1,9)]
d = 3.141592654
n = 4
DD = descr(C_LOC(buf), 0, 537, 1, 0, n-1)
call repeatdouble(DD, n, d)
write(*,'(9(f4.1))') buf
end program main
C:\gfortran\clf\repeatdouble>c:\gcc_equation\bin\x86_64-pc-mingw32-gfortran
-c r
epeatdouble.f90
C:\gfortran\clf\repeatdouble>c:\gcc_equation\bin\x86_64-pc-mingw32-gfortran
test
3.f90 repeatdouble.o -otest3
C:\gfortran\clf\repeatdouble>test3
repeat 4 times ...
double 3.1415927410125732 .
array :
making copy nb 1 of 4
So the test failed. I found the reason in test3.f90:
C:\gfortran\clf\repeatdouble>type test3.f90
program main
use ISO_C_BINDING
implicit none
type, bind(C) :: descr
type(C_PTR) address
integer(C_INTPTR_T) unknown1
integer(C_INTPTR_T) unknown2
integer(C_INTPTR_T) stride
integer(C_INTPTR_T) unknown3
integer(C_INTPTR_T) last_element
end type descr
interface
subroutine repeatdouble(DD,n,d) bind(C,name='repeatdouble_')
use ISO_C_BINDING
im****t descr
implicit none
type(descr) DD
integer(C_INT) n
real(C_DOUBLE) d
end subroutine repeatdouble
end interface
type(descr) DD
double precision, target :: buf(9)
double precision d
integer n
buf = [(n,n=1,9)]
d = 3.141592654
n = 4
DD = descr(C_LOC(buf), 0, 537, 1, 0, n-1)
! Shows the error: start
write(*,*) DD
write(*,*) C_LOC(buf)
DD%address = C_LOC(buf)
write(*,*) DD
! Shows the error: end
call repeatdouble(DD, n, d)
write(*,'(9(f4.1))') buf
end program main
C:\gfortran\clf\repeatdouble>c:\gcc_equation\bin\x86_64-pc-mingw32-gfortran
-c r
epeatdouble.f90
C:\gfortran\clf\repeatdouble>c:\gcc_equation\bin\x86_64-pc-mingw32-gfortran
test
3.f90 repeatdouble.o -otest3
C:\gfortran\clf\repeatdouble>test3
0 0 537
1 0 3
2293200
2293200 0 537
1 0 3
repeat 4 times ...
double 3.1415927410125732 .
array : 1.00000000000000000 2.0000000000000000
3.000000000000000
0 4.0000000000000000
making copy nb 1 of 4
making copy nb 2 of 4
making copy nb 3 of 4
making copy nb 4 of 4
3.1 3.1 3.1 3.1 5.0 6.0 7.0 8.0 9.0
So it seems that the structure constructor for type(descr) isn't
assigning that first member, address. If you do it by hand
everything works. This is a pretty recent version of gfortran,
so I think that the above example shows a bug in the compiler.
--
write(*,*) transfer((/17.392111325966148d0,6.5794487871554595D-85, &
6.0134700243160014d-154/),(/'x'/)); end
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