Add tests for $countbits

1 files changed, 69 insertions, 0 deletions

diff --git a/tests/various/countbits.sv b/tests/various/countbits.sv
new file mode 100644
index 000000000..5762217bb
--- /dev/null
+++ b/tests/various/countbits.sv
@@ -0,0 +1,69 @@
+module top;
+
+	assert property ($countbits(15'b011xxxxzzzzzzzz, '0            ) ==  1);
+	assert property ($countbits(15'b011xxxxzzzzzzzz, '1            ) ==  2);
+	assert property ($countbits(15'b011xxxxzzzzzzzz, 'x            ) ==  4);
+	assert property ($countbits(15'b011xxxxzzzzzzzz, 'z            ) ==  8);
+	assert property ($countbits(15'b011xxxxzzzzzzzz, '0, '1        ) ==  3);
+	assert property ($countbits(15'b011xxxxzzzzzzzz, '1, '1, '0    ) ==  3);
+	assert property ($countbits(15'b011xxxxzzzzzzzz, '0, 'x        ) ==  5);
+	assert property ($countbits(15'b011xxxxzzzzzzzz, '0, 'z        ) ==  9);
+	assert property ($countbits(15'bz1x10xzxzzxzzzz, '0, 'z        ) ==  9);
+	assert property ($countbits(15'b011xxxxzzzzzzzz, 'x, 'z        ) == 12);
+	assert property ($countbits(15'b011xxxxzzzzzzzz, '1, 'z        ) == 10);
+	assert property ($countbits(15'b011xxxxzzzzzzzz, '1, 'x, 'z    ) == 14);
+	assert property ($countbits(15'b011xxxxzzzzzzzz, '1, 'x, 'z, '0) == 15);
+
+	assert property ($countbits(0,      '0) == 32); // test integers
+	assert property ($countbits(0,      '1) ==  0);
+	assert property ($countbits(80'b0,  '0) == 80); // test something bigger than integer
+	assert property ($countbits(80'bx0, 'x) == 79);
+
+	always_comb begin
+		logic       one;
+		logic [1:0] two;
+		logic [3:0] four;
+
+		// Make sure that the width of the whole expression doesn't affect the width of the shift
+		// operations inside the function.
+		one  = $countbits(3'b100, '1) & 1'b1;
+		two  = $countbits(3'b111, '1) & 2'b11;
+		four = $countbits(3'b111, '1) & 4'b1111;
+
+		assert (one  == 1);
+		assert (two  == 3);
+		assert (four == 3);
+	end
+
+	assert property ($countones(8'h00) == 0);
+	assert property ($countones(8'hff) == 8);
+	assert property ($countones(8'ha5) == 4);
+	assert property ($countones(8'h13) == 3);
+
+	logic       test1 = 1'b1;
+	logic [4:0] test5 = 5'b10101;
+
+	assert property ($countones(test1) == 1);
+	assert property ($countones(test5) == 3);
+
+	assert property ($isunknown(8'h00) == 0);
+	assert property ($isunknown(8'hff) == 0);
+	assert property ($isunknown(8'hx0) == 1);
+	assert property ($isunknown(8'h1z) == 1);
+	assert property ($isunknown(8'hxz) == 1);
+
+	assert property ($onehot(8'h00) == 0);
+	assert property ($onehot(8'hff) == 0);
+	assert property ($onehot(8'h01) == 1);
+	assert property ($onehot(8'h80) == 1);
+	assert property ($onehot(8'h81) == 0);
+	assert property ($onehot(8'h20) == 1);
+
+	assert property ($onehot0(8'h00) == 1);
+	assert property ($onehot0(8'hff) == 0);
+	assert property ($onehot0(8'h01) == 1);
+	assert property ($onehot0(8'h80) == 1);
+	assert property ($onehot0(8'h81) == 0);
+	assert property ($onehot0(8'h20) == 1);
+
+endmodule