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-------------------------------------------------------------------------------
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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 1.17 2005-05-09 22:26:08 arniml Exp $
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-- $Id: decoder.vhd,v 1.18 2005-06-09 22:18:28 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 1483... |
when others =>
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when others =>
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null;
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null;
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end case;
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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 = MSTATE2 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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alu_write_accu_o <= true;
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alu_write_accu_o <= true;
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else
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else
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-- store contents of Accumulator to BUS
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-- store contents of Accumulator to BUS
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-- to this to keep bus in output direction
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alu_read_alu_o <= true;
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alu_read_alu_o <= true;
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bus_write_bus_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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end if;
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end if;
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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 1.17 2005/05/09 22:26:08 arniml
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-- remove obsolete output stack_high_o
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--
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-- Revision 1.16 2004/10/25 19:39:24 arniml
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-- Revision 1.16 2004/10/25 19:39:24 arniml
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-- Fix bug report:
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-- Fix bug report:
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-- "RD' and WR' not asserted for INS A, BUS and OUTL BUS, A"
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-- "RD' and WR' not asserted for INS A, BUS and OUTL BUS, A"
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-- rd is asserted for INS A, BUS
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-- rd is asserted for INS A, BUS
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-- wr is asserted for OUTL BUS, A
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-- wr is asserted for OUTL BUS, A
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