| Line 1... |
Line 1... |
-------------------------------------------------------------------------------
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-------------------------------------------------------------------------------
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--
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--
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-- The Arithmetic Logic Unit (ALU).
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-- The Arithmetic Logic Unit (ALU).
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-- It contains the ALU core plus the Accumulator and the Temp Reg.
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-- It contains the ALU core plus the Accumulator and the Temp Reg.
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--
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--
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-- $Id: alu.vhd,v 1.1 2004-03-23 21:31:52 arniml Exp $
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-- $Id: alu.vhd,v 1.2 2004-03-28 21:08:51 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 68... |
Line 68... |
carry_i : in std_logic;
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carry_i : in std_logic;
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carry_o : out std_logic;
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carry_o : out std_logic;
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aux_carry_i : in std_logic;
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aux_carry_i : in std_logic;
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aux_carry_o : out std_logic;
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aux_carry_o : out std_logic;
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alu_op_i : in alu_op_t;
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alu_op_i : in alu_op_t;
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use_carry_i : in boolean
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use_carry_i : in boolean;
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da_low_i : in boolean;
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da_high_i : in boolean;
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da_overflow_o : out boolean;
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p06_temp_reg_i : in boolean;
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p60_temp_reg_i : in boolean
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);
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);
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end alu;
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end alu;
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| Line 80... |
Line 85... |
use ieee.std_logic_arith.all;
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use ieee.std_logic_arith.all;
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|
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use work.t48_pack.clk_active_c;
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use work.t48_pack.clk_active_c;
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use work.t48_pack.res_active_c;
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use work.t48_pack.res_active_c;
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use work.t48_pack.bus_idle_level_c;
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use work.t48_pack.bus_idle_level_c;
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use work.t48_pack.nibble_t;
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use work.alu_pack.all;
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use work.alu_pack.all;
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|
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-- pragma translate_off
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-- pragma translate_off
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use work.t48_tb_pack.tb_accu_s;
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use work.t48_tb_pack.tb_accu_s;
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-- pragma translate_on
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-- pragma translate_on
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| Line 130... |
Line 136... |
else
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else
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-- default: update shadow Accumulator from real Accumulator
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-- default: update shadow Accumulator from real Accumulator
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accu_shadow_q <= accumulator_q;
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accu_shadow_q <= accumulator_q;
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end if;
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end if;
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if write_temp_reg_i then
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if p06_temp_reg_i then
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-- low nibble of DA sequence
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temp_req_q <= "00000110";
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elsif p60_temp_reg_i then
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-- high nibble of DA sequence
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temp_req_q <= "01100000";
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elsif write_temp_reg_i then
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-- normal load from T48 bus
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temp_req_q <= data_i;
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temp_req_q <= data_i;
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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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| Line 185... |
Line 198... |
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begin
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begin
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-- default assigments
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-- default assigments
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data_s <= (others => '0');
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data_s <= (others => '0');
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carry_o <= '0';
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carry_o <= '0';
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aux_carry_o <= '0';
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|
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case alu_op_i is
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case alu_op_i is
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-- Operation: AND -------------------------------------------------------
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-- Operation: AND -------------------------------------------------------
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when ALU_AND =>
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when ALU_AND =>
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data_s <= in_a_s and in_b_s;
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data_s <= in_a_s and in_b_s;
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| Line 284... |
Line 296... |
end process alu_core;
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end process alu_core;
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--
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--
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-----------------------------------------------------------------------------
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-----------------------------------------------------------------------------
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|
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-----------------------------------------------------------------------------
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-- Process aux_carry
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--
|
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-- Purpose:
|
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-- Calculates the Auxiliary Carry.
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--
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aux_carry: process (in_a_s,
|
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in_b_s,
|
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data_s)
|
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variable aux_c_v : std_logic_vector(1 downto 0);
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begin
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aux_carry_o <= '0';
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aux_c_v := in_a_s(4) & in_b_s(4);
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|
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case aux_c_v is
|
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when "00" | "11" =>
|
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if data_s(4) = '1' then
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aux_carry_o <= '1';
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end if;
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when "01" | "10" =>
|
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if data_s(4) = '0' then
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aux_carry_o <= '1';
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end if;
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when others =>
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null;
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|
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end case;
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|
|
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end process aux_carry;
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--
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-----------------------------------------------------------------------------
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|
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|
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-----------------------------------------------------------------------------
|
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-- Process da_overflow
|
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--
|
|
-- Purpose:
|
|
-- Detect overflow situation during DA sequence.
|
|
--
|
|
da_overflow: process (accu_shadow_q,
|
|
da_high_i)
|
|
|
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variable da_nibble_v : nibble_t;
|
|
|
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function da_overflow_f(data : in nibble_t) return boolean is
|
|
variable overflow_v : boolean;
|
|
begin
|
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case data is
|
|
when "1010" |
|
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"1011" |
|
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"1100" |
|
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"1101" |
|
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"1110" |
|
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"1111" =>
|
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overflow_v := true;
|
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when others =>
|
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overflow_v := false;
|
|
end case;
|
|
|
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return(overflow_v);
|
|
end;
|
|
|
|
begin
|
|
if da_high_i then
|
|
da_nibble_v := accu_shadow_q(7 downto 4);
|
|
else
|
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da_nibble_v := accu_shadow_q(3 downto 0);
|
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end if;
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|
|
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da_overflow_o <= da_overflow_f(da_nibble_v);
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|
|
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end process da_overflow;
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--
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|
-----------------------------------------------------------------------------
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|
|
|
|
-- pragma translate_off
|
-- pragma translate_off
|
-----------------------------------------------------------------------------
|
-----------------------------------------------------------------------------
|
-- Testbench support.
|
-- Testbench support.
|
-----------------------------------------------------------------------------
|
-----------------------------------------------------------------------------
|
tb_accu_s <= accumulator_q;
|
tb_accu_s <= accumulator_q;
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| Line 305... |
Line 395... |
|
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-------------------------------------------------------------------------------
|
-------------------------------------------------------------------------------
|
-- File History:
|
-- File History:
|
--
|
--
|
-- $Log: not supported by cvs2svn $
|
-- $Log: not supported by cvs2svn $
|
|
-- Revision 1.1 2004/03/23 21:31:52 arniml
|
|
-- initial check-in
|
--
|
--
|
-------------------------------------------------------------------------------
|
-------------------------------------------------------------------------------
|
|
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No newline at end of file
|
No newline at end of file
|
