rtl/gfx; rewrite scanout

1 files changed, 45 insertions, 0 deletions

diff --git a/rtl/gfx/gfx_flush_flow.sv b/rtl/gfx/gfx_flush_flow.sv
new file mode 100644
index 0000000..a0e43d7
--- /dev/null
+++ b/rtl/gfx/gfx_flush_flow.sv
@@ -0,0 +1,45 @@
+module gfx_flush_flow
+#(parameter STAGES=0)
+(
+	input  logic clk,
+	             rst_n,
+
+	input  logic in_valid,
+	             out_ready,
+
+	output logic out_valid,
+	             commit,
+	             flush
+);
+
+	logic was_valid, was_ready;
+	logic[STAGES - 1:0] valid;
+
+	assign flush = was_valid && !was_ready;
+	assign commit = was_valid && was_ready;
+	assign out_valid = valid[STAGES - 1] && !flush;
+
+	always_ff @(posedge clk or negedge rst_n)
+		if (!rst_n) begin
+			was_ready <= 0;
+			was_valid <= 0;
+
+			for (integer i = 0; i < STAGES; ++i)
+				valid[i] <= 0;
+		end else begin
+			was_ready <= out_ready;
+			was_valid <= out_valid;
+
+			if (!flush)
+				valid[0] <= in_valid;
+			else
+				valid[0] <= 0;
+
+			for (integer i = 1; i < STAGES; ++i)
+				if (!flush)
+					valid[i] <= valid[i - 1];
+				else
+					valid[i] <= 0;
+		end
+
+endmodule