rtl/legacy_gfx: rename gfx -> legacy_gfx

1 files changed, 34 insertions, 0 deletions

diff --git a/rtl/legacy_gfx/gfx_fifo_overflow.sv b/rtl/legacy_gfx/gfx_fifo_overflow.sv
new file mode 100644
index 0000000..c9cb3de
--- /dev/null
+++ b/rtl/legacy_gfx/gfx_fifo_overflow.sv
@@ -0,0 +1,34 @@
+`include "gfx/gfx_defs.sv"
+
+module gfx_fifo_overflow
+#(parameter DEPTH=0)
+(
+	input  logic clk,
+	             rst_n,
+
+	input  logic down,
+	             out_ready,
+	             out_valid,
+
+	output logic empty,
+	             down_safe
+);
+
+	logic up;
+	logic[$clog2(DEPTH + 1) - 1:0] pending;
+
+	assign up = out_ready && out_valid;
+	assign empty = pending == 0;
+	assign down_safe = up || pending < DEPTH - 1;
+
+	always_ff @(posedge clk or negedge rst_n)
+		if (!rst_n)
+			pending <= 0;
+		else begin
+			if (up && !down)
+				pending <= pending - 1;
+			else if (!up && down)
+				pending <= pending + 1;
+		end
+
+endmodule