XL Fortran Enterprise Edition for AIX : User's Guide - IBM

integer
(kind=4), dimension(isize,icol), static :: a, a1
!
! Opens the file for both synchronous and asynchronous I/O.
!
open(20,form="unformatted",access="direct", &
status="scratch", recl=isize*4,asynch="yes")
!
! This loop overlaps the initialization of a(:,j) with
! asynchronous write statements.
!
! NOTE: The array is written out one column at a time.
! Since the arrays in Fortran are arranged in column
! major order, each WRITE statement writes out a
! contiguous block of the array.
!
do 200 j = 1, icol
a(:,j) = (/ (i*j,i=1,isize) /)
write(20, id=handle(j), rec=j) a(:,j)
200 end do
!
! Wait for all writes to complete before reading.
!
do 300 j = 1, icol
wait(id=handle(j))
300 end do
!
! Reads in the first record.
!
read(20, id=handle(1), rec=1) a1(:,1)
do 400 j = 2, icol
k = j - 1
!
! Waits for a previously initiated read to complete.
!
wait(id=handle(k))
!
! Initiates the next read immediately.
!
read(20, id=handle(j), rec=j) a1(:,j)
!
! While the next read is going on, we do some processing here.
!
do 350 i = 1, isize
if (a(i,k) .ne. a1(i,k)) then
print *, "(",i,",",k,") &
& expected ", a(i,k), " got ", a1(i,k)
end if
350 end do
400 end do
!
! Finish the last record.
!
wait(id=handle(icol))
do 450 i = 1, isize
if (a(i,icol) .ne. a1(i,icol)) then
print *, "(",i,",",icol,") &
& expected ", a(i,icol), " got ", a1(i,icol)
end if
Implementation Details of XL Fortran Input/Output 337