-- FILE: accum.adb
-- DATE: 7/98
-- AUTHOR: Sy Wong
-- AIM: implementation of accumulator design
--pragma suppress(range_check); 
 package body ACCUM is -- .log
  procedure update (d: in out device) is
    carry_in: HDL.input:= FALSE;
    carry_out: HDL.output:= FALSE;
    slave: HDL.bus(0..n-1);
  begin
    if d.add  and then not d.state.add  then
      carry_in:= d.carry_in;
      for i in 0..n-1
      loop
        slave(i) := d.data_in(i) xor d.accumulator (i) xor carry_in;
        carry_out:= ((d.data_in(i) or d.accumulator(i)) and carry_in) or
               (d.data_in(i) and d.accumulator(i));
        carry_in:= carry_out;
      end loop;
      d.accumulator:= slave;
      d.carry_out:= carry_out;
    end if;
    d.state.add:= d.add;
  end update;
end ACCUM;