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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 1.4 2004-04-04 14:18:53 arniml Exp $
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-- $Id: decoder.vhd,v 1.5 2004-04-07 22:09:03 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 100... |
Line 100... |
psw_write_sp_o : out boolean;
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psw_write_sp_o : out boolean;
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-- ALU Interface ----------------------------------------------------------
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-- ALU Interface ----------------------------------------------------------
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alu_carry_i : in std_logic;
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alu_carry_i : in std_logic;
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alu_op_o : out alu_op_t;
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alu_op_o : out alu_op_t;
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alu_use_carry_o : out boolean;
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alu_use_carry_o : out boolean;
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alu_da_low_o : out boolean;
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alu_da_high_o : out boolean;
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alu_da_high_o : out boolean;
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alu_accu_low_o : out boolean;
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alu_accu_low_o : out boolean;
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alu_p06_temp_reg_o : out boolean;
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alu_p06_temp_reg_o : out boolean;
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alu_p60_temp_reg_o : out boolean;
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alu_p60_temp_reg_o : out boolean;
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alu_da_overflow_i : in boolean;
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alu_da_overflow_i : in boolean;
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psw_read_sp_o <= false;
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psw_read_sp_o <= false;
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psw_write_psw_o <= false;
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psw_write_psw_o <= false;
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psw_write_sp_o <= false;
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psw_write_sp_o <= false;
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alu_op_o <= ALU_NOP;
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alu_op_o <= ALU_NOP;
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alu_use_carry_o <= false;
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alu_use_carry_o <= false;
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alu_da_low_o <= false;
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alu_da_high_o <= false;
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alu_da_high_o <= false;
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alu_accu_low_o <= false;
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alu_accu_low_o <= false;
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clk_assert_prog_o <= false;
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clk_assert_prog_o <= false;
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clk_assert_rd_o <= false;
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clk_assert_rd_o <= false;
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clk_assert_wr_o <= false;
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clk_assert_wr_o <= false;
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Line 815... |
alu_p06_temp_reg_o <= true;
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alu_p06_temp_reg_o <= true;
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-- Step 2: Check Auxiliary Carry and overflow on low nibble
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-- Step 2: Check Auxiliary Carry and overflow on low nibble
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-- Add 0x06 to shadow Accumulator if one is true
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-- Add 0x06 to shadow Accumulator if one is true
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when MSTATE4 =>
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when MSTATE4 =>
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alu_da_low_o <= true;
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if psw_aux_carry_i = '1' or alu_da_overflow_i then
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if psw_aux_carry_i = '1' or alu_da_overflow_i then
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alu_read_alu_o <= true;
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alu_read_alu_o <= true;
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alu_write_shadow_o <= true;
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alu_write_shadow_o <= true;
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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 1.4 2004/04/04 14:18:53 arniml
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-- add measures to implement XCHD
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--
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-- Revision 1.3 2004/03/28 21:15:48 arniml
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-- Revision 1.3 2004/03/28 21:15:48 arniml
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-- implemented mnemonic DA
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-- implemented mnemonic DA
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--
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--
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-- Revision 1.2 2004/03/28 13:06:32 arniml
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-- Revision 1.2 2004/03/28 13:06:32 arniml
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-- implement mnemonics:
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-- implement mnemonics:
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