neorv32/sim/uart_rx.vhd

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3.6 KiB
VHDL
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2024-02-24 08:25:27 +00:00
library ieee;
use ieee.std_logic_1164.all;
use ieee.numeric_std.all;
use ieee.math_real.all;
use std.textio.all;
library vunit_lib;
context vunit_lib.vunit_context;
context vunit_lib.com_context;
context vunit_lib.vc_context;
use work.uart_rx_pkg.all;
entity uart_rx is
generic (handle : uart_rx_t);
port (
clk : in std_ulogic;
uart_txd : in std_ulogic
);
end entity;
architecture a of uart_rx is
signal uart_rx_sync : std_ulogic_vector(04 downto 0) := (others => '1');
signal uart_rx_busy : std_ulogic := '0';
signal uart_rx_sreg : std_ulogic_vector(08 downto 0) := (others => '0');
signal uart_rx_baud_cnt : real;
signal uart_rx_bitcnt : natural;
file file_uart_tx_out : text open write_mode is "neorv32.testbench_" & get_name(handle.p_logger) & ".out";
constant checker : checker_t := new_checker(handle.p_logger);
constant character_queue : queue_t := new_queue;
begin
control : process
variable request_msg, reply_msg : msg_t;
variable msg_type : msg_type_t;
procedure put_characters_in_queue(s : string) is
begin
for idx in s'range loop
push(character_queue, s(idx));
end loop;
end procedure put_characters_in_queue;
begin
receive(net, handle.p_actor, request_msg);
msg_type := message_type(request_msg);
-- Standard handling of standard wait_for_time messages = wait for the given time
-- before proceeeding
handle_wait_for_time(net, msg_type, request_msg);
if msg_type = check_uart_msg then
put_characters_in_queue(pop(request_msg));
-- Custom handling of standard wait_until_idle message
elsif msg_type = wait_until_idle_msg then
while not is_empty(character_queue) loop
wait until rising_edge(clk);
end loop;
reply_msg := new_msg(wait_until_idle_reply_msg);
reply(net, request_msg, reply_msg);
else
unexpected_msg_type(msg_type);
end if;
end process;
uart_rx_console : process(clk)
variable i : integer;
variable l : line;
variable expected_character : character;
begin
-- "UART" --
if rising_edge(clk) then
-- synchronizer --
uart_rx_sync <= uart_rx_sync(3 downto 0) & uart_txd;
-- arbiter --
if (uart_rx_busy = '0') then -- idle
uart_rx_busy <= '0';
uart_rx_baud_cnt <= round(0.5 * handle.p_baud_val);
uart_rx_bitcnt <= 9;
if (uart_rx_sync(4 downto 1) = "1100") then -- start bit? (falling edge)
uart_rx_busy <= '1';
end if;
else
if (uart_rx_baud_cnt <= 0.0) then
if (uart_rx_bitcnt = 1) then
uart_rx_baud_cnt <= round(0.5 * handle.p_baud_val);
else
uart_rx_baud_cnt <= round(handle.p_baud_val);
end if;
if (uart_rx_bitcnt = 0) then
uart_rx_busy <= '0'; -- done
i := to_integer(unsigned(uart_rx_sreg(8 downto 1)));
if is_empty(character_queue) then
check_failed(checker, "Extra characters received");
else
expected_character := pop(character_queue);
check_equal(checker, character'val(i), expected_character);
end if;
if (i = 10) then -- Linux line break
writeline(file_uart_tx_out, l);
elsif (i /= 13) then -- Remove additional carriage return
write(l, character'val(i));
end if;
else
uart_rx_sreg <= uart_rx_sync(4) & uart_rx_sreg(8 downto 1);
uart_rx_bitcnt <= uart_rx_bitcnt - 1;
end if;
else
uart_rx_baud_cnt <= uart_rx_baud_cnt - 1.0;
end if;
end if;
end if;
end process uart_rx_console;
end architecture;