Declaring Arrays of Bits (how)?

[agate!spool.mu.edu!sdd.hp.com!cs.utexas.edu!sun-barr!west.West.Sun.COM!cr onkite.Central.Sun.COM!texsun!yorktown!young@ucbvax.Berkeley.EDU (Mark Young)]

I am trying to declare arrays of bits in Ada.  Here's my attempt:


type Array_Range_Type is range 1..128;

type Bit_Type is (OFF, ON);
for  Bit_Type use (OFF => 0, ON => 1);
for  Bit_Type'size use 1;

type Bit_Array_Type is array (Array_Range_Type) of Bit_Type;

Bit_Array : Bit_Array_Type;


This looks right to me.  I would expect Bit_Array to be represented
as an array of 128 bits (128 contiguous bits).  This is not the case,
however.  My compiler (XDADA) is representing Bit_Array as an array
of 128 bytes.  As an added note, I have been using representation clauses
for records without any problems.  

Am I missing something?  
Is there a special representation clause for arrays that I am overlooking? 
Is my compiler at fault?

Thanks for the INPUT,
Mark Young