qi-hardware/nn-usb-fpga
1
0
Fork 0
mirror of git://projects.qi-hardware.com/nn-usb-fpga.git synced 2025-04-21 12:27:27 +03:00
Code Activity

Adding plasma example

Browse Source
This commit is contained in:
Carlos Camargo
2010-04-21 20:01:38 -05:00
parent f80360a678
commit 22c469585b
59 changed files with 18082 additions and 0 deletions
Download Patch File Download Diff File Expand all files Collapse all files

136
plasma/logic/bus_mux.vhd Normal file
View File

@@ -0,0 +1,136 @@
---------------------------------------------------------------------
-- TITLE: Bus Multiplexer / Signal Router
-- AUTHOR: Steve Rhoads (rhoadss@yahoo.com)
-- DATE CREATED: 2/8/01
-- FILENAME: bus_mux.vhd
-- PROJECT: Plasma CPU core
-- COPYRIGHT: Software placed into the public domain by the author.
-- Software 'as is' without warranty. Author liable for nothing.
-- DESCRIPTION:
-- This entity is the main signal router.
-- It multiplexes signals from multiple sources to the correct location.
-- The outputs are as follows:
-- a_bus : goes to the ALU
-- b_bus : goes to the ALU
-- reg_dest_out : goes to the register bank
-- take_branch : goes to pc_next
---------------------------------------------------------------------
library ieee;
use ieee.std_logic_1164.all;
use work.mlite_pack.all;
entity bus_mux is
port(imm_in : in std_logic_vector(15 downto 0);
reg_source : in std_logic_vector(31 downto 0);
a_mux : in a_source_type;
a_out : out std_logic_vector(31 downto 0);
reg_target : in std_logic_vector(31 downto 0);
b_mux : in b_source_type;
b_out : out std_logic_vector(31 downto 0);
c_bus : in std_logic_vector(31 downto 0);
c_memory : in std_logic_vector(31 downto 0);
c_pc : in std_logic_vector(31 downto 2);
c_pc_plus4 : in std_logic_vector(31 downto 2);
c_mux : in c_source_type;
reg_dest_out : out std_logic_vector(31 downto 0);
branch_func : in branch_function_type;
take_branch : out std_logic);
end; --entity bus_mux
architecture logic of bus_mux is
begin
--Determine value of a_bus
amux: process(reg_source, imm_in, a_mux, c_pc)
begin
case a_mux is
when A_FROM_REG_SOURCE =>
a_out <= reg_source;
when A_FROM_IMM10_6 =>
a_out <= ZERO(31 downto 5) & imm_in(10 downto 6);
when A_FROM_PC =>
a_out <= c_pc & "00";
when others =>
a_out <= c_pc & "00";
end case;
end process;
--Determine value of b_bus
bmux: process(reg_target, imm_in, b_mux)
begin
case b_mux is
when B_FROM_REG_TARGET =>
b_out <= reg_target;
when B_FROM_IMM =>
b_out <= ZERO(31 downto 16) & imm_in;
when B_FROM_SIGNED_IMM =>
if imm_in(15) = '0' then
b_out(31 downto 16) <= ZERO(31 downto 16);
else
b_out(31 downto 16) <= "1111111111111111";
end if;
b_out(15 downto 0) <= imm_in;
when B_FROM_IMMX4 =>
if imm_in(15) = '0' then
b_out(31 downto 18) <= "00000000000000";
else
b_out(31 downto 18) <= "11111111111111";
end if;
b_out(17 downto 0) <= imm_in & "00";
when others =>
b_out <= reg_target;
end case;
end process;
--Determine value of c_bus
cmux: process(c_bus, c_memory, c_pc, c_pc_plus4, imm_in, c_mux)
begin
case c_mux is
when C_FROM_ALU => -- | C_FROM_SHIFT | C_FROM_MULT =>
reg_dest_out <= c_bus;
when C_FROM_MEMORY =>
reg_dest_out <= c_memory;
when C_FROM_PC =>
reg_dest_out <= c_pc(31 downto 2) & "00";
when C_FROM_PC_PLUS4 =>
reg_dest_out <= c_pc_plus4 & "00";
when C_FROM_IMM_SHIFT16 =>
reg_dest_out <= imm_in & ZERO(15 downto 0);
when others =>
reg_dest_out <= c_bus;
end case;
end process;
--Determine value of take_branch
pc_mux: process(branch_func, reg_source, reg_target)
variable is_equal : std_logic;
begin
if reg_source = reg_target then
is_equal := '1';
else
is_equal := '0';
end if;
case branch_func is
when BRANCH_LTZ =>
take_branch <= reg_source(31);
when BRANCH_LEZ =>
take_branch <= reg_source(31) or is_equal;
when BRANCH_EQ =>
take_branch <= is_equal;
when BRANCH_NE =>
take_branch <= not is_equal;
when BRANCH_GEZ =>
take_branch <= not reg_source(31);
when BRANCH_GTZ =>
take_branch <= not reg_source(31) and not is_equal;
when BRANCH_YES =>
take_branch <= '1';
when others =>
take_branch <= '0';
end case;
end process;
end; --architecture logic