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nn-usb-fpga/plasma/logic/reg_bank.vhd
Carlos Camargo 22c469585b Adding plasma example
2010-04-21 20:01:38 -05:00

324 lines
14 KiB
VHDL
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---------------------------------------------------------------------
-- TITLE: Register Bank
-- AUTHOR: Steve Rhoads (rhoadss@yahoo.com)
-- DATE CREATED: 2/2/01
-- FILENAME: reg_bank.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:
-- Implements a register bank with 32 registers that are 32-bits wide.
-- There are two read-ports and one write port.
---------------------------------------------------------------------
library ieee;
use ieee.std_logic_1164.all;
use ieee.std_logic_unsigned.all;
use work.mlite_pack.all;
--library UNISIM; --May need to uncomment for ModelSim
--use UNISIM.vcomponents.all; --May need to uncomment for ModelSim
entity reg_bank is
generic(memory_type : string := "XILINX_16X");
port(clk : in std_logic;
reset_in : in std_logic;
pause : in std_logic;
rs_index : in std_logic_vector(5 downto 0);
rt_index : in std_logic_vector(5 downto 0);
rd_index : in std_logic_vector(5 downto 0);
reg_source_out : out std_logic_vector(31 downto 0);
reg_target_out : out std_logic_vector(31 downto 0);
reg_dest_new : in std_logic_vector(31 downto 0);
intr_enable : out std_logic);
end; --entity reg_bank
--------------------------------------------------------------------
-- The ram_block architecture attempts to use TWO dual-port memories.
-- Different FPGAs and ASICs need different implementations.
-- Choose one of the RAM implementations below.
-- I need feedback on this section!
--------------------------------------------------------------------
architecture ram_block of reg_bank is
signal intr_enable_reg : std_logic;
type ram_type is array(31 downto 0) of std_logic_vector(31 downto 0);
--controls access to dual-port memories
signal addr_read1, addr_read2 : std_logic_vector(4 downto 0);
signal addr_write : std_logic_vector(4 downto 0);
signal data_out1, data_out2 : std_logic_vector(31 downto 0);
signal write_enable : std_logic;
begin
reg_proc: process(clk, rs_index, rt_index, rd_index, reg_dest_new,
intr_enable_reg, data_out1, data_out2, reset_in, pause)
begin
--setup for first dual-port memory
if rs_index = "101110" then --reg_epc CP0 14
addr_read1 <= "00000";
else
addr_read1 <= rs_index(4 downto 0);
end if;
case rs_index is
when "000000" => reg_source_out <= ZERO;
when "101100" => reg_source_out <= ZERO(31 downto 1) & intr_enable_reg;
--interrupt vector address = 0x3c
when "111111" => reg_source_out <= ZERO(31 downto 8) & "00111100";
when others => reg_source_out <= data_out1;
end case;
--setup for second dual-port memory
addr_read2 <= rt_index(4 downto 0);
case rt_index is
when "000000" => reg_target_out <= ZERO;
when others => reg_target_out <= data_out2;
end case;
--setup write port for both dual-port memories
if rd_index /= "000000" and rd_index /= "101100" and pause = '0' then
write_enable <= '1';
else
write_enable <= '0';
end if;
if rd_index = "101110" then --reg_epc CP0 14
addr_write <= "00000";
else
addr_write <= rd_index(4 downto 0);
end if;
if reset_in = '1' then
intr_enable_reg <= '0';
elsif rising_edge(clk) then
if rd_index = "101110" then --reg_epc CP0 14
intr_enable_reg <= '0'; --disable interrupts
elsif rd_index = "101100" then
intr_enable_reg <= reg_dest_new(0);
end if;
end if;
intr_enable <= intr_enable_reg;
end process;
--------------------------------------------------------------
---- Pick only ONE of the dual-port RAM implementations below!
--------------------------------------------------------------
-- Option #1
-- One tri-port RAM, two read-ports, one write-port
-- 32 registers 32-bits wide
tri_port_mem:
if memory_type = "TRI_PORT_X" generate
ram_proc: process(clk, addr_read1, addr_read2,
addr_write, reg_dest_new, write_enable)
variable tri_port_ram : ram_type := (others => ZERO);
begin
data_out1 <= tri_port_ram(conv_integer(addr_read1));
data_out2 <= tri_port_ram(conv_integer(addr_read2));
if rising_edge(clk) then
if write_enable = '1' then
tri_port_ram(conv_integer(addr_write)) := reg_dest_new;
end if;
end if;
end process;
end generate; --tri_port_mem
-- Option #2
-- Two dual-port RAMs, each with one read-port and one write-port
dual_port_mem:
if memory_type = "DUAL_PORT_" generate
ram_proc2: process(clk, addr_read1, addr_read2,
addr_write, reg_dest_new, write_enable)
variable dual_port_ram1 : ram_type := (others => ZERO);
variable dual_port_ram2 : ram_type := (others => ZERO);
begin
data_out1 <= dual_port_ram1(conv_integer(addr_read1));
data_out2 <= dual_port_ram2(conv_integer(addr_read2));
if rising_edge(clk) then
if write_enable = '1' then
dual_port_ram1(conv_integer(addr_write)) := reg_dest_new;
dual_port_ram2(conv_integer(addr_write)) := reg_dest_new;
end if;
end if;
end process;
end generate; --dual_port_mem
-- Option #3
-- RAM16X1D: 16 x 1 positive edge write, asynchronous read dual-port
-- distributed RAM for all Xilinx FPGAs
-- From library UNISIM; use UNISIM.vcomponents.all;
xilinx_16x1d:
if memory_type = "XILINX_16X" generate
signal data_out1A, data_out1B : std_logic_vector(31 downto 0);
signal data_out2A, data_out2B : std_logic_vector(31 downto 0);
signal weA, weB : std_logic;
signal no_connect : std_logic_vector(127 downto 0);
begin
weA <= write_enable and not addr_write(4); --lower 16 registers
weB <= write_enable and addr_write(4); --upper 16 registers
reg_loop: for i in 0 to 31 generate
begin
--Read port 1 lower 16 registers
reg_bit1a : RAM16X1D
port map (
WCLK => clk, -- Port A write clock input
WE => weA, -- Port A write enable input
A0 => addr_write(0), -- Port A address[0] input bit
A1 => addr_write(1), -- Port A address[1] input bit
A2 => addr_write(2), -- Port A address[2] input bit
A3 => addr_write(3), -- Port A address[3] input bit
D => reg_dest_new(i), -- Port A 1-bit data input
DPRA0 => addr_read1(0), -- Port B address[0] input bit
DPRA1 => addr_read1(1), -- Port B address[1] input bit
DPRA2 => addr_read1(2), -- Port B address[2] input bit
DPRA3 => addr_read1(3), -- Port B address[3] input bit
DPO => data_out1A(i), -- Port B 1-bit data output
SPO => no_connect(i) -- Port A 1-bit data output
);
--Read port 1 upper 16 registers
reg_bit1b : RAM16X1D
port map (
WCLK => clk, -- Port A write clock input
WE => weB, -- Port A write enable input
A0 => addr_write(0), -- Port A address[0] input bit
A1 => addr_write(1), -- Port A address[1] input bit
A2 => addr_write(2), -- Port A address[2] input bit
A3 => addr_write(3), -- Port A address[3] input bit
D => reg_dest_new(i), -- Port A 1-bit data input
DPRA0 => addr_read1(0), -- Port B address[0] input bit
DPRA1 => addr_read1(1), -- Port B address[1] input bit
DPRA2 => addr_read1(2), -- Port B address[2] input bit
DPRA3 => addr_read1(3), -- Port B address[3] input bit
DPO => data_out1B(i), -- Port B 1-bit data output
SPO => no_connect(32+i) -- Port A 1-bit data output
);
--Read port 2 lower 16 registers
reg_bit2a : RAM16X1D
port map (
WCLK => clk, -- Port A write clock input
WE => weA, -- Port A write enable input
A0 => addr_write(0), -- Port A address[0] input bit
A1 => addr_write(1), -- Port A address[1] input bit
A2 => addr_write(2), -- Port A address[2] input bit
A3 => addr_write(3), -- Port A address[3] input bit
D => reg_dest_new(i), -- Port A 1-bit data input
DPRA0 => addr_read2(0), -- Port B address[0] input bit
DPRA1 => addr_read2(1), -- Port B address[1] input bit
DPRA2 => addr_read2(2), -- Port B address[2] input bit
DPRA3 => addr_read2(3), -- Port B address[3] input bit
DPO => data_out2A(i), -- Port B 1-bit data output
SPO => no_connect(64+i) -- Port A 1-bit data output
);
--Read port 2 upper 16 registers
reg_bit2b : RAM16X1D
port map (
WCLK => clk, -- Port A write clock input
WE => weB, -- Port A write enable input
A0 => addr_write(0), -- Port A address[0] input bit
A1 => addr_write(1), -- Port A address[1] input bit
A2 => addr_write(2), -- Port A address[2] input bit
A3 => addr_write(3), -- Port A address[3] input bit
D => reg_dest_new(i), -- Port A 1-bit data input
DPRA0 => addr_read2(0), -- Port B address[0] input bit
DPRA1 => addr_read2(1), -- Port B address[1] input bit
DPRA2 => addr_read2(2), -- Port B address[2] input bit
DPRA3 => addr_read2(3), -- Port B address[3] input bit
DPO => data_out2B(i), -- Port B 1-bit data output
SPO => no_connect(96+i) -- Port A 1-bit data output
);
end generate; --reg_loop
data_out1 <= data_out1A when addr_read1(4)='0' else data_out1B;
data_out2 <= data_out2A when addr_read2(4)='0' else data_out2B;
end generate; --xilinx_16x1d
-- Option #4
-- Altera LPM_RAM_DP
altera_mem:
if memory_type = "ALTERA_LPM" generate
signal clk_delayed : std_logic;
signal addr_reg : std_logic_vector(4 downto 0);
signal data_reg : std_logic_vector(31 downto 0);
signal q1 : std_logic_vector(31 downto 0);
signal q2 : std_logic_vector(31 downto 0);
begin
-- Altera dual port RAMs must have the addresses registered (sampled
-- at the rising edge). This is very unfortunate.
-- Therefore, the dual port RAM read clock must delayed so that
-- the read address signal can be sent from the mem_ctrl block.
-- This solution also delays the how fast the registers are read so the
-- maximum clock speed is cut in half (12.5 MHz instead of 25 MHz).
clk_delayed <= not clk; --Could be delayed by 1/4 clock cycle instead
dpram_bypass: process(clk, addr_write, reg_dest_new)
begin
if rising_edge(clk) and write_enable = '1' then
addr_reg <= addr_write;
data_reg <= reg_dest_new;
end if;
end process; --dpram_bypass
-- Bypass dpram if reading what was just written (Altera limitation)
data_out1 <= q1 when addr_read1 /= addr_reg else data_reg;
data_out2 <= q2 when addr_read2 /= addr_reg else data_reg;
lpm_ram_dp_component1 : lpm_ram_dp
generic map (
LPM_WIDTH => 32,
LPM_WIDTHAD => 5,
--LPM_NUMWORDS => 0,
LPM_INDATA => "REGISTERED",
LPM_OUTDATA => "UNREGISTERED",
LPM_RDADDRESS_CONTROL => "REGISTERED",
LPM_WRADDRESS_CONTROL => "REGISTERED",
LPM_FILE => "UNUSED",
LPM_TYPE => "LPM_RAM_DP",
USE_EAB => "ON",
INTENDED_DEVICE_FAMILY => "UNUSED",
RDEN_USED => "FALSE",
LPM_HINT => "UNUSED")
port map (
RDCLOCK => clk_delayed,
RDCLKEN => '1',
RDADDRESS => addr_read1,
RDEN => '1',
DATA => reg_dest_new,
WRADDRESS => addr_write,
WREN => write_enable,
WRCLOCK => clk,
WRCLKEN => '1',
Q => q1);
lpm_ram_dp_component2 : lpm_ram_dp
generic map (
LPM_WIDTH => 32,
LPM_WIDTHAD => 5,
--LPM_NUMWORDS => 0,
LPM_INDATA => "REGISTERED",
LPM_OUTDATA => "UNREGISTERED",
LPM_RDADDRESS_CONTROL => "REGISTERED",
LPM_WRADDRESS_CONTROL => "REGISTERED",
LPM_FILE => "UNUSED",
LPM_TYPE => "LPM_RAM_DP",
USE_EAB => "ON",
INTENDED_DEVICE_FAMILY => "UNUSED",
RDEN_USED => "FALSE",
LPM_HINT => "UNUSED")
port map (
RDCLOCK => clk_delayed,
RDCLKEN => '1',
RDADDRESS => addr_read2,
RDEN => '1',
DATA => reg_dest_new,
WRADDRESS => addr_write,
WREN => write_enable,
WRCLOCK => clk,
WRCLKEN => '1',
Q => q2);
end generate; --altera_mem
end; --architecture ram_block
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