From 85fc7268a690e38ecb7f3b04dbfb8d70f2570a79 Mon Sep 17 00:00:00 2001
From: Alejandro Soto <alejandro@34project.org>
Date: Thu, 2 Nov 2023 20:36:51 -0600
Subject: rtl/gfx: implement perspective division

---
 rtl/gfx/gfx_perspective_flow.sv | 50 +++++++++++++++++++++++++++++++++++++++++
 1 file changed, 50 insertions(+)
 create mode 100644 rtl/gfx/gfx_perspective_flow.sv

(limited to 'rtl/gfx/gfx_perspective_flow.sv')

diff --git a/rtl/gfx/gfx_perspective_flow.sv b/rtl/gfx/gfx_perspective_flow.sv
new file mode 100644
index 0000000..ecacc65
--- /dev/null
+++ b/rtl/gfx/gfx_perspective_flow.sv
@@ -0,0 +1,50 @@
+`include "gfx/gfx_defs.sv"
+
+module gfx_perspective_flow
+(
+	input  logic clk,
+	             rst_n,
+
+	input  logic vertex_start,
+	output logic stall,
+	             in_start,
+	             out_start,
+
+	input  logic in_valid,
+	             out_ready,
+
+	output logic in_ready,
+	             out_valid
+	             stall
+);
+
+	localparam STAGES = `FP_INV_STAGES + `FP_MUL_STAGES;
+
+	logic[STAGES - 1:0] start_pipes;
+
+	assign in_start = start_pipes[`FP_INV_STAGES - 1];
+	assign out_start = start_pipes[STAGES - 1];
+
+	pipeline_flow #(.STAGES(STAGES)) flow
+	(
+		.*
+	);
+
+	always_ff @(posedge clk or negedge rst_n)
+		if (!rst_n)
+			start_pipes[0] <= 0;
+		else if (!stall)
+			start_pipes[0] <= in_valid && vertex_start;
+
+	genvar i;
+	generate
+		for (i = 1; i < STAGES; ++i) begin: pipeline
+			always_ff @(posedge clk or negedge rst_n)
+				if (!rst_n)
+					start_pipes[i] <= 0;
+				else if (!stall)
+					start_pipes[i] <= start_pipes[i - 1];
+		end
+	endgenerate
+
+endmodule
-- 
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