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Diffstat (limited to 'testsuite/vests/vhdl-93/ashenden/compliant/ch_06_pas-b.vhd')
-rw-r--r-- | testsuite/vests/vhdl-93/ashenden/compliant/ch_06_pas-b.vhd | 53 |
1 files changed, 53 insertions, 0 deletions
diff --git a/testsuite/vests/vhdl-93/ashenden/compliant/ch_06_pas-b.vhd b/testsuite/vests/vhdl-93/ashenden/compliant/ch_06_pas-b.vhd new file mode 100644 index 000000000..8d0dfd26c --- /dev/null +++ b/testsuite/vests/vhdl-93/ashenden/compliant/ch_06_pas-b.vhd @@ -0,0 +1,53 @@ + +-- 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_06_pas-b.vhd,v 1.2 2001-10-26 16:29:34 paw Exp $ +-- $Revision: 1.2 $ +-- +-- --------------------------------------------------------------------- + +architecture behavioral of product_adder_subtracter is +begin + + behavior : process (a, b) is + + constant Tpd_in_out : time := 3 ns; + variable op2 : std_ulogic_vector(b'range); + variable carry_in : std_ulogic; + variable carry_out : std_ulogic; + + begin + carry_out := To_X01(mode); + if To_X01(mode) = '1' then + op2 := not b; + else + op2 := b; + end if; + for index in 0 to 31 loop + carry_in := carry_out; -- of previous bit + s(index) <= a(index) xor op2(index) xor carry_in after Tpd_in_out; + carry_out := (a(index) and op2(index)) + or (carry_in and (a(index) xor op2(index))); + end loop; + s(32) <= a(31) xor op2(31) xor carry_out after Tpd_in_out; + end process behavior; + +end architecture behavioral; |