rtl/gfx: implement triangle setup

1 files changed, 53 insertions, 0 deletions

diff --git a/rtl/gfx/gfx_setup_edge.sv b/rtl/gfx/gfx_setup_edge.sv
new file mode 100644
index 0000000..5d69a88
--- /dev/null
+++ b/rtl/gfx/gfx_setup_edge.sv
@@ -0,0 +1,53 @@
+`include "gfx/gfx_defs.sv"
+
+module gfx_setup_edge
+(
+	input  logic     clk,
+
+	input  raster_xy p,
+	                 q,
+	                 origin,
+	input  logic     stall,
+
+	output fixed     base,
+	                 inc_x,
+	                 inc_y
+);
+
+	fixed delta_x, delta_y, hold_inc_x, hold_inc_y;
+
+	gfx_pipes #(.WIDTH($bits(inc_x)), .DEPTH(`FIXED_FMA_DOT_STAGES)) inc_x_pipes
+	(
+		.in(hold_inc_x),
+		.out(inc_x),
+		.*
+	);
+
+	gfx_pipes #(.WIDTH($bits(inc_y)), .DEPTH(`FIXED_FMA_DOT_STAGES)) inc_y_pipes
+	(
+		.in(hold_inc_y),
+		.out(inc_y),
+		.*
+	);
+
+	gfx_fixed_fma_dot edge_base
+	(
+		.c(0),
+		.q(base),
+		.a0(delta_x),
+		.b0(hold_inc_x),
+		.a1(delta_y),
+		.b1(hold_inc_y),
+		.*
+	);
+
+	always_ff @(posedge clk)
+		if (!stall) begin
+			delta_x <= origin.x - q.x;
+			delta_y <= origin.y - q.y;
+
+			hold_inc_x <= p.y - q.y;
+			hold_inc_y <= q.x - p.x;
+		end
+
+endmodule