Data_as

Hi

I need to pass a DLL a pointer to an array of pointers to c arrays of unsigned 16 bit integers.

I started to do this using data_as(POINTER( type ) on sub-arrays.  This caused access violations. When I looked at what was in the pointer arrays I discovered that they all pointed to the same location.  After poking around a bit is seems that the problem is not to do with using sub-arrays as I expected but with the way in which I have approached the problem and I can't see what I'm doing wrong.  Here is a very simple example

from ctypes import POINTER, c_uint16
import numpy as  np

if __name__ == '__main__':

   pointerArrayType = POINTER( c_uint16 ) * 2      # an array of pointers type length 2
   pointers = pointerArrayType()                           # the actual array

   frame1 = np.zeros(( 100, 100 ), dtype = np.uint16, order = 'C' )   # Ensure C contiguous layout
   frame2 = np.zeros(( 100, 100 ), dtype = np.uint16, order = 'C' )

   pointers[ 0 ] = frame1.ctypes.data_as( POINTER( c_uint16 ))
   pointers[ 1 ] = frame2.ctypes.data_as( POINTER( c_uint16 ))

   print pointers[ 0 ]
   print pointers[ 1 ]

This prints 
<__main__.LP_c_ushort object at 0x00000000025132C8>
<__main__.LP_c_ushort object at 0x00000000025132C8>

This suggests that the data arrays for frame1 and frame2 are at the same location.  Clearly I've done something wrong but can't see what.  

Any help would be gratefully received.
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