rtl/gfx: implement fixed-point FMA

1 files changed, 48 insertions, 0 deletions

diff --git a/rtl/gfx/gfx_fixed_fma_dot.sv b/rtl/gfx/gfx_fixed_fma_dot.sv
new file mode 100644
index 0000000..2831d08
--- /dev/null
+++ b/rtl/gfx/gfx_fixed_fma_dot.sv
@@ -0,0 +1,48 @@
+`include "gfx/gfx_defs.sv"
+
+module gfx_fixed_fma_dot
+(
+	input  logic clk,
+
+	input  fixed a0,
+	             b0,
+	             a1,
+	             b1,
+	             c,
+	input  logic stall,
+
+	output fixed q
+);
+
+	fixed q0, a1_hold[`FIXED_FMA_STAGES], b1_hold[`FIXED_FMA_STAGES];
+
+	gfx_fixed_fma fma0
+	(
+		.a(a0),
+		.b(b0),
+		.q(q0),
+		.*
+	);
+
+	gfx_fixed_fma fma1
+	(
+		.a(a1_hold[`FIXED_FMA_STAGES - 1]),
+		.b(b1_hold[`FIXED_FMA_STAGES - 1]),
+		.c(q0),
+		.*
+	);
+
+	integer i;
+
+	always_ff @(posedge clk)
+		if (!stall) begin
+			a1_hold[0] <= a1;
+			b1_hold[0] <= b1;
+
+			for (i = 1; i < `FIXED_FMA_STAGES; ++i) begin
+				a1_hold[i] <= a1_hold[i - 1];
+				b1_hold[i] <= b1_hold[i - 1];
+			end
+		end
+
+endmodule