rtl/gfx: implement SP writeback

1 files changed, 65 insertions, 0 deletions

diff --git a/rtl/gfx/gfx_sp_writeback.sv b/rtl/gfx/gfx_sp_writeback.sv
new file mode 100644
index 0000000..1195910
--- /dev/null
+++ b/rtl/gfx/gfx_sp_writeback.sv
@@ -0,0 +1,65 @@
+`include "gfx/gfx_defs.sv"
+
+module gfx_sp_writeback
+(
+	input  logic    clk,
+	                rst_n,
+
+	input  wb_op    stream_wb,
+	input  logic    stream_wb_valid,
+	output logic    stream_wb_ready,
+
+	input  wb_op    combiner_wb,
+	input  logic    combiner_wb_valid,
+	output logic    combiner_wb_ready,
+
+	input  wb_op    shuffler_wb,
+	input  logic    shuffler_wb_valid,
+	output logic    shuffler_wb_ready,
+
+	output logic    wr,
+	output vreg_num wr_reg,
+	output mat4     wr_data
+);
+
+	wb_op wb_in, wb_out;
+
+	assign wr_reg = wb_out.dst;
+	assign wr_data = wb_out.data;
+
+	gfx_pipeline_flow #(.STAGES(`GFX_SP_WB_STAGES)) flow
+	(
+		.stall(),
+		.in_ready(),
+		.in_valid(stream_wb_valid || combiner_wb_valid || shuffler_wb_valid),
+		.out_ready(1),
+		.out_valid(wr),
+		.*
+	);
+
+	gfx_pipes #(.WIDTH($bits(wb_out)), .DEPTH(`GFX_SP_WB_STAGES)) pipes
+	(
+		.in(wb_in),
+		.out(wb_out),
+		.stall(0),
+		.*
+	);
+
+	always_comb begin
+		stream_wb_ready = 0;
+		combiner_wb_ready = 0;
+		shuffler_wb_ready = 0;
+
+		if (stream_wb_valid) begin
+			wb_in = stream_wb;
+			stream_wb_ready = 1;
+		end else if (shuffler_wb_valid) begin
+			wb_in = shuffler_wb;
+			shuffler_wb_ready = 1;
+		end else begin
+			wb_in = combiner_wb;
+			combiner_wb_ready = 1;
+		end
+	end
+
+endmodule