Skip to content

P
Platform-independent core collection
Commit c8205156 authored by Tristan Gingold's avatar Tristan Gingold
Browse files
Options

gc_sync_word_wr: improve speed (use toggling).

parent 17a1843c
Hide whitespace changes
Inline Side-by-side
Showing with 31 additions and 30 deletions
modules/common/gc_sync_word_wr.vhd
View file @ c8205156
......@@ -10,7 +10,7 @@
-- Used to transfer a word from the input clock domain to the output clock
-- domain. User provides the data and a pulse write signal to transfer the
-- data. When the data are transfered, a write pulse is generated on the
-- output side along with the data, and an acknowledge is geenrated on the
-- output side along with the data, and an acknowledge is generated on the
-- input side. Once the user request a transfer, no new data should be
-- requested for a transfer until the ack was received.
--
......@@ -52,44 +52,46 @@ entity gc_sync_word_wr is
end entity;
architecture behav of gc_sync_word_wr is
signal data : std_logic_vector (width - 1 downto 0);
signal in_busy : std_logic;
signal in_progress : std_logic;
signal ack_start, ack_done : std_logic;
signal data : std_logic_vector (width - 1 downto 0);
signal in_busy : std_logic;
signal start_wr : std_logic;
-- Synchronized extended wr_i signal.
signal wr_out : std_logic;
-- Internal pulse for wr_o, active one cycle before wr_o.
signal wr_out_p : std_logic;
signal wr_out : std_logic;
signal last_wr_out : std_logic;
signal wr_out_fb : std_logic;
signal last_wr_out_fb : std_logic;
begin
-- Handle incoming request.
process(clk_in_i)
begin
if rising_edge(clk_in_i) then
if rst_in_n_i = '0' then
in_progress <= '0';
start_wr <= '0';
in_busy <= '0';
data <= (others => '0');
ack_o <= '0';
last_wr_out_fb <= '0';
else
ack_o <= '0';
if in_busy = '0' then
if wr_i = '1' then
in_progress <= '1';
-- Write requested.
-- Toggle start_wr ...
start_wr <= not start_wr;
in_busy <= '1';
data <= data_i;
end if;
else
assert wr_i = '0' report "request while previous one not completed"
severity error;
if ack_start = '1' then
in_progress <= '0';
end if;
if ack_done = '1' then
assert in_progress = '0';
in_busy <= '0';
-- ... and wait until wr_out_fb has been toggled.
if (wr_out_fb xor last_wr_out_fb) = '1' then
-- Set ack (for one cycle).
ack_o <= '1';
last_wr_out_fb <= wr_out_fb;
-- Ready for a new request.
in_busy <= '0';
end if;
end if;
end if;
......@@ -100,9 +102,8 @@ begin
port map (
clk_i => clk_out_i,
rst_n_i => rst_out_n_i,
data_i => in_progress,
synced_o => wr_out,
ppulse_o => wr_out_p);
data_i => start_wr,
synced_o => wr_out);
-- Outputs.
process (clk_out_i)
......@@ -111,11 +112,13 @@ begin
if rst_out_n_i = '0' then
data_o <= (others => '0');
wr_o <= '0';
last_wr_out <= '0';
else
if wr_out_p = '1' then
if (wr_out xor last_wr_out) = '1' then
-- Data are stable.
data_o <= data;
wr_o <= '1';
last_wr_out <= wr_out;
else
wr_o <= '0';
end if;
......@@ -129,6 +132,5 @@ begin
clk_i => clk_in_i,
rst_n_i => rst_in_n_i,
data_i => wr_out,
ppulse_o => ack_start,
npulse_o => ack_done);
synced_o => wr_out_fb);
end behav;
sim/gc_sync_word_wr/run.do
View file @ c8205156
......@@ -11,5 +11,5 @@ radix -hexadecimal
#add wave *
do wave.do
run 4 us
run 400ns
wave zoomfull
sim/gc_sync_word_wr/wave.do
View file @ c8205156
......@@ -10,12 +10,11 @@ add wave -noupdate /tb_gc_sync_word_wr/wri
add wave -noupdate /tb_gc_sync_word_wr/wro
add wave -noupdate /tb_gc_sync_word_wr/ack
add wave -noupdate /tb_gc_sync_word_wr/cmp_tb/in_busy
add wave -noupdate /tb_gc_sync_word_wr/cmp_tb/in_progress
add wave -noupdate /tb_gc_sync_word_wr/cmp_tb/ack_start
add wave -noupdate /tb_gc_sync_word_wr/cmp_tb/ack_done
add wave -noupdate /tb_gc_sync_word_wr/cmp_tb/wr_out
add wave -noupdate /tb_gc_sync_word_wr/cmp_tb/last_wr_out
TreeUpdate [SetDefaultTree]
WaveRestoreCursors {{Cursor 1} {0 ps} 0}
quietly wave cursor active 0
WaveRestoreCursors {{Cursor 1} {90000 ps} 0}
quietly wave cursor active 1
configure wave -namecolwidth 150
configure wave -valuecolwidth 100
configure wave -justifyvalue left
......@@ -30,4 +29,4 @@ configure wave -griddelta 40
configure wave -timeline 0
configure wave -timelineunits ps
update
WaveRestoreZoom {0 ps} {262500 ps}
WaveRestoreZoom {0 ps} {420 ns}
Markdown is supported
0% or
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment