im_pincheck, im_poutcheck, im_piocheck - checks image descriptors for
int im_pincheck( in )
int im_poutcheck( out )
int im_piocheck( in, out)
IMAGE *in, *out;
im_pincheck(3) checks that an image descriptor is suitable for PIO
input. If the descriptor is IM_OPENOUT and the descriptor has been
written to, it is automatically ‘rewound,’ that is, it is closed and
reopened as an IM_MMAPIN descriptor.
im_poutcheck(3) checks that a descriptor is suitable for PIO output.
im_piocheck(3) simply calls in_pincheck(3) for image in and
im_poutcheck(3) for image out.
All functions returns 0 on success and -1 on error.
J. Cupitt - 23/7/93
11 April 1990 IM_IOCHECK(3)