module TYPES is

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type NUM is 
   range 0..7 of NAT with ==, <>, <
end type

channel NUM is (N : NUM) end channel

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type TABLE is
   array [0..7] of NAT
end type

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function ZERO : TABLE is
   return TABLE (0) -- i.e., TABLE (0, 0, 0, 0, 0, 0, 0, 0)
end function

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function ZERO_0127 : TABLE is
   return TABLE (0, 0, 0, 8, 8, 8, 8, 0)
   -- this constant is used to inform the controller that only devices
   -- 0, 1, 2, 7 are present on the SCSI bus; initializing the queue
   -- size of the other devices to their maximal limit, i.e. 8, prevents
   -- the controller from considering these other devices, since the
   -- controller believes that these devices' input queues are full
end function

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type WIRE is
   !implementedby "WIRE"
   !iteratedby "FIRST_WIRE", "NEXT_WIRE"
   array [0..7] of BOOL
end type

channel WIRE is (W : WIRE) end channel

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function ACCESS_WIRE (W: WIRE, N : NAT) : BOOL is
   !implementedby "ACCESS_WIRE" -- for external access from the .fnt file only
   return W [N]
end function

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function MAKE_WIRE (B0, B1, B2, B3, B4, B5, B6, B7 : BOOL) : WIRE is
   !implementedby "MAKE_WIRE" -- for external access from the .fnt file only
   return WIRE (B0, B1, B2, B3, B4, B5, B6, B7)
end function

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function C_PASS (W : WIRE, N : NUM) : BOOL is
   return not (W [NAT (N)])
end function

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function C_WIN (W : WIRE, N : NUM) : BOOL is
   var
      M : NAT
   in
      if not (W [NAT (N)]) then
         return FALSE
      end if;
      for M := NAT (N) + 1 while M <= 7 by M := M + 1 loop
         if W [M] then
            return FALSE
         end if
      end loop;
      return TRUE
   end var
end function

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function C_LOSS (W : WIRE, N : NUM) : BOOL is
   return not (C_PASS (W, N)) and not (C_WIN (W, N))
end function

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end module