Add min/max gates

3 files changed, 70 insertions, 1 deletions

diff --git a/testsuite/formal/gates/test_minmax.sby b/testsuite/formal/gates/test_minmax.sby
new file mode 100644
index 0000000..c7d103a
--- /dev/null
+++ b/testsuite/formal/gates/test_minmax.sby
@@ -0,0 +1,12 @@
+[options]
+mode prove
+
+[engines]
+smtbmc z3
+
+[script]
+ghdl --std=08 test_minmax.vhd -e ent
+prep -top ent
+
+[files]
+test_minmax.vhd
diff --git a/testsuite/formal/gates/test_minmax.vhd b/testsuite/formal/gates/test_minmax.vhd
new file mode 100644
index 0000000..8cd760c
--- /dev/null
+++ b/testsuite/formal/gates/test_minmax.vhd
@@ -0,0 +1,57 @@
+library ieee;
+use ieee.std_logic_1164.all;
+use ieee.numeric_std.all;
+
+entity ent is
+	port (
+		clk : in std_logic;
+		a : in std_logic_vector(7 downto 0);
+		b : in std_logic_vector(7 downto 0);
+		min_sgn : out signed(7 downto 0);
+		max_sgn : out signed(7 downto 0);
+		min_uns : out unsigned(7 downto 0);
+		max_uns : out unsigned(7 downto 0)
+	);
+end;
+
+architecture a of ent is
+begin
+	process(clk)
+	begin
+		if rising_edge(clk) then
+			min_sgn <= minimum(signed(a), signed(b));
+			max_sgn <= maximum(signed(a), signed(b));
+
+			min_uns <= minimum(unsigned(a), unsigned(b));
+			max_uns <= maximum(unsigned(a), unsigned(b));
+		end if;
+	end process;
+
+	formal: block
+		signal prev_a : std_logic_vector(7 downto 0);
+		signal prev_b : std_logic_vector(7 downto 0);
+		signal has_run : std_logic := '0';
+	begin
+		process(clk)
+		begin
+			if rising_edge(clk) then
+				has_run <= '1';
+				prev_a <= a;
+				prev_b <= b;
+			end if;
+		end process;
+
+		default clock is rising_edge(clk);
+		assert eventually! has_run;
+
+		assert always has_run and signed(prev_a) <= signed(prev_b) ->
+			min_sgn = signed(prev_a) and max_sgn = signed(prev_b);
+		assert always has_run and signed(prev_a) >= signed(prev_b) ->
+			min_sgn = signed(prev_b) and max_sgn = signed(prev_a);
+
+		assert always has_run and unsigned(prev_a) <= unsigned(prev_b) ->
+			min_uns = unsigned(prev_a) and max_uns = unsigned(prev_b);
+		assert always has_run and unsigned(prev_a) >= unsigned(prev_b) ->
+			min_uns = unsigned(prev_b) and max_uns = unsigned(prev_a);
+	end block;
+end;
diff --git a/testsuite/formal/gates/testsuite.sh b/testsuite/formal/gates/testsuite.sh
index 7986d8c..d4bcf98 100755
--- a/testsuite/formal/gates/testsuite.sh
+++ b/testsuite/formal/gates/testsuite.sh
@@ -3,7 +3,7 @@
 topdir=../..
 . $topdir/testenv.sh
 
-for f in abs lsl lsr asr; do
+for f in abs minmax lsl lsr asr; do
   formal "test_${f}"
 done