1 files changed, 54 insertions, 0 deletions
diff --git a/rtl/legacy_gfx/gfx_fold.sv b/rtl/legacy_gfx/gfx_fold.sv
new file mode 100644
index 0000000..616d868
--- /dev/null
+++ b/rtl/legacy_gfx/gfx_fold.sv
@@ -0,0 +1,54 @@
+`include "gfx/gfx_defs.sv"
+
+module gfx_fold
+(
+	input  logic  clk,
+
+	input  vec4   vec,
+	input  logic  stall,
+	              feedback,
+	              feedback_last,
+
+	output fp     q
+);
+
+	fp q_add;
+	vec2 feedback_vec, queued[`FP_ADD_STAGES];
+
+	assign feedback_vec = queued[`FP_ADD_STAGES - 1];
+
+	gfx_fp_add add
+	(
+		.a(feedback ? q_add : vec[0]),
+		.b(feedback ? feedback_vec[feedback_last] : vec[1]),
+		.q(q_add),
+		.*
+	);
+
+	gfx_skid_buf #(.WIDTH($bits(q))) skid
+	(
+		.in(q_add),
+		.out(q),
+		.*
+	);
+
+	always_ff @(posedge clk)
+		if (!stall) begin
+			if (feedback)
+				queued[0] <= feedback_vec;
+			else begin
+				queued[0][0] <= vec[2];
+				queued[0][1] <= vec[3];
+			end
+		end
+
+	genvar i;
+	generate
+		for (i = 1; i < `FP_ADD_STAGES; ++i) begin: stages
+			always_ff @(posedge clk)
+				if (!stall)
+					queued[i] <= queued[i - 1];
+		end
+	endgenerate
+
+endmodule