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Line 1... |
-------------------------------------------------------------------------------
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-------------------------------------------------------------------------------
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--
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--
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-- The Decoder unit.
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-- The Decoder unit.
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-- It decodes the instruction opcodes and executes them.
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-- It decodes the instruction opcodes and executes them.
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--
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--
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-- $Id: decoder.vhd,v 1.9 2004-04-24 11:22:55 arniml Exp $
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-- $Id: decoder.vhd,v 1.10 2004-04-25 16:22:03 arniml Exp $
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--
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--
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-- Copyright (c) 2004, Arnim Laeuger (arniml@opencores.org)
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-- Copyright (c) 2004, Arnim Laeuger (arniml@opencores.org)
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--
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--
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-- All rights reserved
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-- All rights reserved
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--
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--
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| Line 1412... |
Line 1412... |
else
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else
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clk_assert_wr_o <= true;
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clk_assert_wr_o <= true;
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end if;
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end if;
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if not clk_second_cycle_i then
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if not clk_second_cycle_i then
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case clk_mstate_i is
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-- read dmem and put contents on BUS as external address
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-- read dmem and put contents on BUS as external address
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if clk_mstate_i = MSTATE3 then
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when MSTATE3 =>
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dm_read_dmem_o <= true;
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dm_read_dmem_o <= true;
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bus_write_bus_o <= true;
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bus_write_bus_o <= true;
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-- store contents of Accumulator to BUS
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when MSTATE5 =>
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if opc_opcode_s(4) = '1' then
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alu_read_alu_o <= true;
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bus_write_bus_o <= true;
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end if;
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end if;
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when others =>
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null;
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end case;
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else
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else
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if clk_mstate_i = MSTATE1 then
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if clk_mstate_i = MSTATE1 then
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if opc_opcode_s(4) = '0' then
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if opc_opcode_s(4) = '0' then
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-- store contents of BUS in Accumulator
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-- store contents of BUS in Accumulator
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add_read_bus_s <= true;
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add_read_bus_s <= true;
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Line 1883... |
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-------------------------------------------------------------------------------
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-------------------------------------------------------------------------------
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-- File History:
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-- File History:
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--
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--
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-- $Log: not supported by cvs2svn $
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-- $Log: not supported by cvs2svn $
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-- Revision 1.9 2004/04/24 11:22:55 arniml
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-- removed superfluous signal from sensitivity list
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--
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-- Revision 1.8 2004/04/18 18:57:43 arniml
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-- Revision 1.8 2004/04/18 18:57:43 arniml
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-- + enhance instruction strobe generation
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-- + enhance instruction strobe generation
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-- + rework address output under EA=1 conditions
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-- + rework address output under EA=1 conditions
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--
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--
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-- Revision 1.7 2004/04/15 22:06:05 arniml
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-- Revision 1.7 2004/04/15 22:06:05 arniml
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