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[/] [potato/] [trunk/] [src/] [pp_csr_alu.vhd] - Rev 65
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-- The Potato Processor - A simple processor for FPGAs -- (c) Kristian Klomsten Skordal 2014 <kristian.skordal@wafflemail.net> -- Report bugs and issues on <http://opencores.org/project,potato,bugtracker> library ieee; use ieee.std_logic_1164.all; use ieee.numeric_std.all; use work.pp_csr.all; --! @brief ALU used for calculating new values of control and status registers. entity pp_csr_alu is port( x, y : in std_logic_vector(31 downto 0); result : out std_logic_vector(31 downto 0); immediate : in std_logic_vector(4 downto 0); use_immediate : in std_logic; write_mode : in csr_write_mode ); end entity pp_csr_alu; architecture behaviour of pp_csr_alu is signal a, b : std_logic_vector(31 downto 0); begin a <= x; b <= y when use_immediate = '0' else std_logic_vector(resize(unsigned(immediate), b'length)); calculate: process(a, b, write_mode) begin case write_mode is when CSR_WRITE_NONE => result <= a; when CSR_WRITE_SET => result <= a or b; when CSR_WRITE_CLEAR => result <= a and (not b); when CSR_WRITE_REPLACE => result <= b; end case; end process calculate; end architecture behaviour;
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