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[/] [w11/] [tags/] [w11a_V0.61/] [rtl/] [w11a/] [pdp11_ounit.vhd] - Rev 37
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-- $Id: pdp11_ounit.vhd 427 2011-11-19 21:04:11Z mueller $ -- -- Copyright 2006-2011 by Walter F.J. Mueller <W.F.J.Mueller@gsi.de> -- -- This program is free software; you may redistribute and/or modify it under -- the terms of the GNU General Public License as published by the Free -- Software Foundation, either version 2, or at your option any later version. -- -- This program is distributed in the hope that it will be useful, but -- WITHOUT ANY WARRANTY, without even the implied warranty of MERCHANTABILITY -- or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License -- for complete details. -- ------------------------------------------------------------------------------ -- Module Name: pdp11_ounit - syn -- Description: pdp11: arithmetic unit for addresses (ounit) -- -- Dependencies: - -- Test bench: tb/tb_pdp11_core (implicit) -- Target Devices: generic -- Tool versions: xst 8.2, 9.1, 9.2, 13.1; ghdl 0.18-0.29 -- Revision History: -- Date Rev Version Comment -- 2011-11-18 427 1.1.1 now numeric_std clean -- 2010-09-18 300 1.1 renamed from abox -- 2007-06-14 56 1.0.1 Use slvtypes.all -- 2007-05-12 26 1.0 Initial version ------------------------------------------------------------------------------ library ieee; use ieee.std_logic_1164.all; use ieee.numeric_std.all; use work.slvtypes.all; use work.pdp11.all; -- ---------------------------------------------------------------------------- entity pdp11_ounit is -- offset adder for addresses (ounit) port ( DSRC : in slv16; -- 'src' data for port A DDST : in slv16; -- 'dst' data for port A DTMP : in slv16; -- 'tmp' data for port A PC : in slv16; -- PC data for port A ASEL : in slv2; -- selector for port A AZERO : in slbit; -- force zero for port A IREG8 : in slv8; -- 'ireg' data for port B VMDOUT : in slv16; -- virt. memory data for port B CONST : in slv9; -- sequencer const data for port B BSEL : in slv2; -- selector for port B OPSUB : in slbit; -- operation: 0 add, 1 sub DOUT : out slv16; -- data output NZOUT : out slv2 -- NZ condition codes out ); end pdp11_ounit; architecture syn of pdp11_ounit is -- -------------------------------------- begin process (DSRC, DDST, DTMP, PC, ASEL, AZERO, IREG8, VMDOUT, CONST, BSEL, OPSUB) variable ma : slv16 := (others=>'0'); -- effective port a data variable mb : slv16 := (others=>'0'); -- effective port b data variable sum : slv16 := (others=>'0'); -- sum variable nzo : slbit := '0'; begin if AZERO = '0' then case ASEL is when c_ounit_asel_dsrc => ma := DSRC; when c_ounit_asel_ddst => ma := DDST; when c_ounit_asel_dtmp => ma := DTMP; when c_ounit_asel_pc => ma := PC; when others => null; end case; else ma := (others=>'0'); end if; case BSEL is when c_ounit_bsel_ireg6 => mb := "000000000" & IREG8(5 downto 0) & "0"; when c_ounit_bsel_ireg8 => mb := IREG8(7) & IREG8(7) & IREG8(7) & IREG8(7) & IREG8(7) & IREG8(7) & IREG8(7) & IREG8 & "0"; when c_ounit_bsel_vmdout => mb := VMDOUT; when c_ounit_bsel_const => mb := "0000000" & CONST; when others => null; end case; if OPSUB = '0' then sum := slv(unsigned(ma) + unsigned(mb)); else sum := slv(unsigned(ma) - unsigned(mb)); end if; nzo := '0'; if unsigned(sum) = 0 then nzo := '1'; else nzo := '0'; end if; DOUT <= sum; NZOUT(1) <= sum(15); NZOUT(0) <= nzo; end process; end syn;
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