Test bench for Xoroshiro128plus:

* Update tb_xoroshiro128plus for new interface.
 * Add Makefile for testbenches with GHDL.

refimpl/Makefile

@@ -4,6 +4,7 @@
 # This makefile works with GCC under Linux.
 #
 
+.PHONY: all
 all: ref_xoroshiro ref_mt19937
 
 ref_xoroshiro: ref_xoroshiro.c

sim/Makefile

@@ -0,0 +1,27 @@
+#
+# Makefile for building test benches with GHDL (the free VHDL compiler).
+#
+
+GHDL = ghdl
+GHDLFLAGS =
+
+.PHONY: all
+all: tb_xoroshiro128plus
+
+tb_xoroshiro128plus: tb_xoroshiro128plus.o rng_xoroshiro128plus.o
+tb_xoroshiro128plus.o: tb_xoroshiro128plus.vhdl rng_xoroshiro128plus.o
+rng_xoroshiro128plus.o: ../rtl/rng_xoroshiro128plus.vhdl
+
+tb_%: tb_%.o
+	$(GHDL) $(GHDLFLAGS) -e $@
+
+%.o: %.vhdl
+	$(GHDL) $(GHDLFLAGS) -a $<
+
+%.o: ../rtl/%.vhdl
+	$(GHDL) $(GHDLFLAGS) -a $<
+
+.PHONY: clean
+clean:
+	$(GHDL) --remove
+

sim/tb_xoroshiro128plus.vhdl

@@ -2,6 +2,8 @@
 -- Test bench for PRNG "xoroshiro128+".
 --
 
+use std.textio.all;
+
 library ieee;
 use ieee.std_logic_1164.all;
 use ieee.numeric_std.all;
@@ -15,10 +17,11 @@ architecture arch of tb_xoroshiro128plus is
     signal clock_active:    boolean := false;
 
     signal s_rst:           std_logic;
-    signal s_enable:        std_logic;
     signal s_reseed:        std_logic;
     signal s_newseed:       std_logic_vector(127 downto 0);
-    signal s_output:        std_logic_vector(63 downto 0);
+    signal s_ready:         std_logic;
+    signal s_valid:         std_logic;
+    signal s_data:          std_logic_vector(63 downto 0);
 
     function to_hex_string(s: std_logic_vector)
         return string
@@ -35,31 +38,37 @@ architecture arch of tb_xoroshiro128plus is
 begin
 
     -- Instantiate PRNG.
-    inst_prng: entity work.xoroshiro128plus
+    inst_prng: entity work.rng_xoroshiro128plus
         generic map (
             init_seed => x"0123456789abcdef3141592653589793" )
         port map (
-            clk     => clk,
-            rst     => s_rst,
-            enable  => s_enable,
-            reseed  => s_reseed,
-            newseed => s_newseed,
-            output  => s_output );
+            clk         => clk,
+            rst         => s_rst,
+            reseed      => s_reseed,
+            newseed     => s_newseed,
+            out_ready   => s_ready,
+            out_valid   => s_valid,
+            out_data    => s_data );
 
     -- Generate clock.
     clk <= (not clk) after 10 ns when clock_active else '0';
 
     -- Main simulation process.
     process is
+        file outf1: text is out "sim_xoroshiro128plus_seed1.dat";
+        file outf2: text is out "sim_xoroshiro128plus_seed2.dat";
+        variable lin: line;
+        variable nskip: integer;
+        variable v: std_logic_vector(63 downto 0);
     begin
 
         report "Start test bench";
 
         -- Reset.
         s_rst       <= '1';
-        s_enable    <= '0';
         s_reseed    <= '0';
         s_newseed   <= (others => '0');
+        s_ready     <= '0';
 
         -- Start clock.
         clock_active    <= true;
@@ -69,42 +78,91 @@ begin
         wait until falling_edge(clk);
         s_rst       <= '0';
 
-        -- Produce numbers
-        for i in 0 to 150 loop
+        -- Wait 1 clock cycle to initialize generator.
+        wait until falling_edge(clk);
+        s_ready     <= '1';
 
-            if i mod 5 = 0 or i mod 7 = 0 then
-                s_enable    <= '0';
-                wait until falling_edge(clk);
-            else
-                s_enable    <= '1';
-                wait until falling_edge(clk);
-                report "Got 0x" & to_hex_string(s_output);
+        -- Produce numbers
+        for i in 0 to 999 loop
+
+            -- Check that output is valid.
+            assert s_valid = '1' report "Output not valid";
+
+            -- Write output to file.
+            write(lin, "0x" & to_hex_string(s_data));
+            writeline(outf1, lin);
+
+            -- Sometimes skip cycles.
+            if i mod 5 = 1 then
+                nskip := 1;
+                if i mod 3 = 0 then
+                    nskip := nskip + 1;
+                end if;
+                if i mod 11 = 0 then
+                    nskip := nskip + 1;
+                end if;
+
+                v := s_data;
+                s_ready <= '0';
+                for t in 1 to nskip loop
+                    wait until falling_edge(clk);
+                    assert s_valid = '1' report "Output not valid";
+                    assert s_data = v report "Output changed while not ready";
+                end loop;
+                s_ready <= '1';
             end if;
 
+            -- Go to next cycle.
+            wait until falling_edge(clk);
+
         end loop;
 
         -- Re-seed generator.
         report "Re-seed generator";
-        s_enable    <= '1';
         s_reseed    <= '1';
         s_newseed   <= x"3141592653589793fedcba9876543210";
+        s_ready     <= '0';
         wait until falling_edge(clk);
-
         s_reseed    <= '0';
         s_newseed   <= (others => '0');
 
-        -- Produce numbers
-        for i in 0 to 150 loop
+        -- Wait 1 clock cycle to re-seed generator.
+        wait until falling_edge(clk);
+        s_ready     <= '1';
 
-            if i mod 5 = 0 or i mod 7 = 0 then
-                s_enable    <= '0';
-                wait until falling_edge(clk);
-            else
-                s_enable    <= '1';
-                wait until falling_edge(clk);
-                report "Got 0x" & to_hex_string(s_output);
+        -- Produce numbers
+        for i in 0 to 999 loop
+
+            -- Check that output is valid.
+            assert s_valid = '1' report "Output not valid";
+
+            -- Write output to file.
+            write(lin, "0x" & to_hex_string(s_data));
+            writeline(outf2, lin);
+
+            -- Sometimes skip cycles.
+            if i mod 5 = 2 then
+                nskip := 1;
+                if i mod 3 = 0 then
+                    nskip := nskip + 1;
+                end if;
+                if i mod 11 = 0 then
+                    nskip := nskip + 1;
+                end if;
+
+                v := s_data;
+                s_ready <= '0';
+                for t in 1 to nskip loop
+                    wait until falling_edge(clk);
+                    assert s_valid = '1' report "Output not valid";
+                    assert s_data = v report "Output changed while not ready";
+                end loop;
+                s_ready <= '1';
             end if;
 
+            -- Go to next cycle.
+            wait until falling_edge(clk);
+
         end loop;
 
         -- End simulation.