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-- Copyright (C) 1996 Morgan Kaufmann Publishers, Inc
-- This file is part of VESTs (Vhdl tESTs).
-- VESTs is free software; you can redistribute it and/or modify it
-- under the terms of the GNU General Public License as published by the
-- Free Software Foundation; either version 2 of the License, or (at
-- your option) any later version.
-- VESTs 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 more details.
-- You should have received a copy of the GNU General Public License
-- along with VESTs; if not, write to the Free Software Foundation,
-- Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
-- ---------------------------------------------------------------------
--
-- $Id: ch_10_alu-b.vhd,v 1.3 2001-10-26 16:29:34 paw Exp $
-- $Revision: 1.3 $
--
-- ---------------------------------------------------------------------
library bv_utilities;
use bv_utilities.bv_arithmetic.all;
architecture behavior of alu is
begin
alu_op: process (s1, s2, func) is
constant Tpd : delay_length := 10 ns;
variable bv_s1 : bit_vector(s1'range) := To_bitvector(s1);
variable bv_s2 : bit_vector(s2'range) := To_bitvector(s2);
variable temp_result : bit_vector(result'range);
constant zero_result : bit_vector(result'range) := (others => '0');
variable temp_overflow : boolean;
type boolean_to_X01_table is array (boolean) of X01;
constant boolean_to_X01 : boolean_to_X01_table
:= ( false => '0', true => '1' );
begin
case func is
when alu_add =>
bv_add(bv_s1, bv_s2, temp_result, temp_overflow);
when alu_addu =>
bv_addu(bv_s1, bv_s2, temp_result, temp_overflow);
when alu_sub =>
bv_sub(bv_s1, bv_s2, temp_result, temp_overflow);
when alu_subu =>
bv_subu(bv_s1, bv_s2, temp_result, temp_overflow);
when others =>
report "alu: illegal function code" severity error;
temp_result := X"0000_0000";
end case;
result <= To_X01(temp_result) after Tpd;
zero <= boolean_to_X01(temp_result = zero_result) after Tpd;
negative <= To_X01(temp_result(temp_result'left)) after Tpd;
overflow <= boolean_to_X01(temp_overflow) after Tpd;
end process alu_op;
end architecture behavior;
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