rtl/vdc: initial commit of video display controller

1 files changed, 184 insertions, 0 deletions

diff --git a/rtl/vdc/vdc_io.sv b/rtl/vdc/vdc_io.sv
new file mode 100644
index 0000000..88b19e3
--- /dev/null
+++ b/rtl/vdc/vdc_io.sv
@@ -0,0 +1,184 @@
+module vdc_io
+import vdc_pkg::*;
+(
+	input  logic      clk,
+	                  rst_n,
+
+	input  logic      frame_start,
+	input  ptr        front_base,
+	input  geom_dim   lines,
+	                  stride,
+	                  line_len,
+	output logic      frame_done,
+
+	       if_axib.m  stream,
+
+	       vdc_dac.tx dac
+);
+
+	localparam int BURST_BITS = 4;
+
+	enum int unsigned
+	{
+		ORDER_B_RGB,
+		ORDER_GB_RG,
+		ORDER_RGB_R,
+		ORDER_BUBBLE
+	} word_order;
+
+	ptr araddr, stride_jump, stride_save;
+	logic bubble, burst_ar_last, first_pix, last_pix, next_bubble, word_r_last;
+	geom_dim line_ar_count, line_r_count, word_r_count;
+	pix_rgb24 dac_pix, next_pix;
+	logic[3:0][7:0] in_cur, in_prev;
+	logic[$bits(geom_dim) - BURST_BITS - 1:0] burst_ar_count, bursts_per_line;
+
+	assign stream.arid = '0;
+	assign stream.arlen = ($bits(stream.arlen))'((1 << BURST_BITS) - 1);
+	assign stream.arsize = 3'b010; // 4 bytes/beat
+	assign stream.araddr = {araddr, 2'b00};
+	assign stream.arburst = 2'b01; // Incremental mode
+
+	assign stream.rready = (~dac.valid | dac.ready) & ~bubble;
+
+	assign stream.awid = 'x;
+	assign stream.awlen = 'x;
+	assign stream.awsize = 'x;
+	assign stream.awaddr = 'x;
+	assign stream.awburst = 'x;
+	assign stream.awvalid = 0;
+
+	assign stream.wdata = 'x;
+	assign stream.wlast = 'x;
+	assign stream.wstrb = 'x;
+	assign stream.wvalid = 0;
+
+	assign stream.bready = 0;
+
+	assign dac.pix.b = rgb8to10(dac_pix.b);
+	assign dac.pix.g = rgb8to10(dac_pix.g);
+	assign dac.pix.r = rgb8to10(dac_pix.r);
+
+	assign in_cur = stream.rdata;
+	assign last_pix = bubble & word_r_last & (line_r_count == '0);
+	assign stride_jump = stride_save + {{($bits(araddr) - $bits(stride)){1'b0}}, stride};
+	assign word_r_last = word_r_count == '0;
+	assign burst_ar_last = burst_ar_count == '0;
+	assign bursts_per_line = line_len[$bits(line_len) - 1:BURST_BITS];
+
+	always_comb begin
+		unique case (word_order)
+			ORDER_RGB_R: next_bubble = 1;
+			default:     next_bubble = 0;
+		endcase
+
+		unique case (word_order)
+			ORDER_BUBBLE: bubble = 1;
+			default:      bubble = 0;
+		endcase
+
+		unique case (word_order)
+			ORDER_B_RGB: begin
+				next_pix.b = in_cur[0];
+				next_pix.g = in_cur[1];
+				next_pix.r = in_cur[2];
+			end
+
+			ORDER_GB_RG: begin
+				next_pix.b = in_prev[3];
+				next_pix.g = in_cur[0];
+				next_pix.r = in_cur[1];
+			end
+
+			ORDER_RGB_R: begin
+				next_pix.b = in_prev[2];
+				next_pix.g = in_prev[3];
+				next_pix.r = in_cur[0];
+			end
+
+			ORDER_BUBBLE: begin
+				next_pix.b = in_prev[1];
+				next_pix.g = in_prev[2];
+				next_pix.r = in_prev[3];
+			end
+		endcase
+	end
+
+	always_ff @(posedge clk) begin
+		if (stream.arvalid & stream.arready) begin
+			araddr <= araddr + ($bits(araddr))'(1 << BURST_BITS);
+
+			burst_ar_count <= burst_ar_count - 1;
+			if (burst_ar_last) begin
+				araddr <= stride_jump;
+				stride_save <= stride_jump;
+
+				burst_ar_count <= bursts_per_line;
+				line_ar_count <= line_ar_count - 1;
+			end
+		end
+
+		if (stream.rvalid & stream.rready)
+			in_prev <= in_cur;
+
+		if (~dac.valid | dac.ready) begin
+			dac_pix <= next_pix;
+			dac.last <= last_pix;
+			dac.first <= first_pix;
+		end
+
+		if (dac.valid & dac.ready) begin
+			first_pix <= 0;
+
+			unique case (word_order)
+				ORDER_B_RGB:  word_order <= ORDER_GB_RG;
+				ORDER_GB_RG:  word_order <= ORDER_RGB_R;
+				ORDER_RGB_R:  word_order <= ORDER_BUBBLE;
+				ORDER_BUBBLE: word_order <= ORDER_B_RGB;
+			endcase
+
+			if (~next_bubble) begin
+				word_r_count <= word_r_count - 1;
+				if (word_r_last) begin
+					line_r_count <= line_r_count - 1;
+					word_r_count <= line_len;
+				end
+			end
+		end
+
+		if (frame_start) begin
+			araddr <= front_base;
+			stride_save <= front_base;
+			line_ar_count <= lines;
+			burst_ar_count <= bursts_per_line;
+
+			first_pix <= 1;
+			word_order <= ORDER_B_RGB;
+
+			line_r_count <= lines;
+			word_r_count <= line_len;
+		end
+	end
+
+	always_ff @(posedge clk or negedge rst_n)
+		if (~rst_n) begin
+			dac.valid <= 0;
+			frame_done <= 0;
+			stream.arvalid <= 0;
+		end else begin
+			dac.valid <= (dac.valid & ~dac.ready) | bubble | stream.rvalid;
+
+			unique case (1'b1)
+				frame_start:
+					stream.arvalid <= 1;
+
+				stream.arvalid & stream.arready & burst_ar_last & (line_ar_count == '0):
+					stream.arvalid <= 0;
+
+				default: ;
+			endcase
+
+			frame_done <= dac.valid & dac.ready & last_pix;
+		end
+
+endmodule