Initial commit: retroDE_ps2 — first-of-its-kind PS2 GS FPGA core (DE25-Nano / Agilex 5)

RTL (GS rasterizer, EE core stub, platform bridge, LPDDR4B path), sim regression
(272 TBs), docs, and tooling. Copyrighted PS2 content (BIOS, game code, GS dumps,
and all dump-derived textures/traces) is excluded via .gitignore and stays local.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
This commit is contained in:
2026-06-29 20:10:50 -04:00
commit ec82764bef
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// retroDE_ps2 — tb_gs_vram_writeback (Ch89)
//
// White-box TB pinning down the Ch89 VRAM persistence contract:
// every raster_pixel_emit pulse must land 4 bytes of pixel data
// (PSMCT32 ABGR) at raster_pixel_fb_addr_q in vram_stub, and a
// later read-back at the same address must return EXACTLY the
// emitted color.
//
// Setup: gs_stub + vram_stub instantiated together; gif_reg_*
// driven directly (no DMA). Drive a single 4×4 SPRITE so 16
// pixels emit. Capture the (fb_addr, color) of each emit at the
// posedge it fires; after raster completes, walk each captured
// address and assert vram_stub.read_data == captured color.
//
// Stream:
// PRIM=SPRITE, FRAME_1 (FBP=2 FBW=10 PSMCT32), RGBAQ
// v1 = (0, 0)
// v2 = (3, 3) — close S1, sprite is 4×4 = 16 pixels
`timescale 1ns/1ps
module tb_gs_vram_writeback;
logic clk;
logic rst_n;
initial clk = 1'b0;
always #5 clk = ~clk;
logic gif_reg_wr_en;
logic [7:0] gif_reg_num;
logic [63:0] gif_reg_data;
logic [7:0] bg_r, bg_g, bg_b;
logic [63:0] prim_q, rgbaq_q, xyz2_q, xyzf2_q, frame_1_q, zbuf_1_q;
logic prim_complete;
logic [31:0] prim_complete_count;
logic [63:0] prim_v0_q, prim_v1_q, prim_v2_q;
logic [63:0] prim_color_q;
logic [63:0] prim_color_v0_q, prim_color_v1_q, prim_color_v2_q;
trace_pkg::vertex_t prim_v0_decoded_q, prim_v1_decoded_q, prim_v2_decoded_q;
trace_pkg::color_t prim_v0_color_decoded_q, prim_v1_color_decoded_q, prim_v2_color_decoded_q;
logic pixel_emit;
logic [31:0] pixel_emit_count;
logic [11:0] pixel_x_q, pixel_y_q;
logic [63:0] pixel_color_q;
logic [8:0] pixel_fbp_q;
logic [5:0] pixel_fbw_q, pixel_psm_q;
logic [31:0] pixel_fb_addr_q;
logic raster_pixel_emit;
logic [31:0] raster_pixel_emit_count;
logic [11:0] raster_pixel_x_q, raster_pixel_y_q;
logic [63:0] raster_pixel_color_q;
logic [31:0] raster_pixel_fb_addr_q;
logic [3:0] raster_pixel_be_q;
logic [5:0] raster_pixel_psm_q;
logic raster_active;
logic raster_overflow;
logic raster_degenerate;
logic ev_valid;
trace_pkg::subsys_e ev_subsys;
trace_pkg::event_e ev_event;
logic [63:0] ev_arg0, ev_arg1, ev_arg2, ev_arg3;
logic [31:0] ev_flags;
gs_stub u_gs (
.clk(clk), .rst_n(rst_n),
.reg_wr_en(1'b0), .reg_wr_addr(16'd0), .reg_wr_data(64'd0),
.gif_reg_wr_en(gif_reg_wr_en),
.gif_reg_num(gif_reg_num),
.gif_reg_data(gif_reg_data),
.bg_r(bg_r), .bg_g(bg_g), .bg_b(bg_b),
.prim_q(prim_q), .rgbaq_q(rgbaq_q),
.xyz2_q(xyz2_q), .xyzf2_q(xyzf2_q),
.frame_1_q(frame_1_q), .zbuf_1_q(zbuf_1_q),
.prim_complete(prim_complete),
.prim_complete_count(prim_complete_count),
.prim_v0_q(prim_v0_q), .prim_v1_q(prim_v1_q), .prim_v2_q(prim_v2_q),
.prim_color_q(prim_color_q),
.prim_color_v0_q(prim_color_v0_q),
.prim_color_v1_q(prim_color_v1_q),
.prim_color_v2_q(prim_color_v2_q),
.prim_v0_decoded_q(prim_v0_decoded_q),
.prim_v1_decoded_q(prim_v1_decoded_q),
.prim_v2_decoded_q(prim_v2_decoded_q),
.prim_v0_color_decoded_q(prim_v0_color_decoded_q),
.prim_v1_color_decoded_q(prim_v1_color_decoded_q),
.prim_v2_color_decoded_q(prim_v2_color_decoded_q),
.pixel_emit(pixel_emit),
.pixel_emit_count(pixel_emit_count),
.pixel_x_q(pixel_x_q), .pixel_y_q(pixel_y_q),
.pixel_color_q(pixel_color_q),
.pixel_fbp_q(pixel_fbp_q),
.pixel_fbw_q(pixel_fbw_q),
.pixel_psm_q(pixel_psm_q),
.pixel_fb_addr_q(pixel_fb_addr_q),
.raster_pixel_emit(raster_pixel_emit),
.raster_pixel_emit_count(raster_pixel_emit_count),
.raster_pixel_x_q(raster_pixel_x_q),
.raster_pixel_y_q(raster_pixel_y_q),
.raster_pixel_color_q(raster_pixel_color_q),
.raster_pixel_fb_addr_q(raster_pixel_fb_addr_q),
.raster_pixel_be_q(raster_pixel_be_q),
.raster_pixel_psm_q(raster_pixel_psm_q),
.raster_active(raster_active),
.raster_overflow(raster_overflow),
.raster_degenerate(raster_degenerate),
.ev_valid(ev_valid), .ev_subsys(ev_subsys), .ev_event(ev_event),
.ev_arg0(ev_arg0), .ev_arg1(ev_arg1),
.ev_arg2(ev_arg2), .ev_arg3(ev_arg3),
.ev_flags(ev_flags)
);
logic [31:0] vram_read_addr;
logic [31:0] vram_read_data;
vram_stub u_vram (
.clk(clk), .rst_n(rst_n),
.write_en (raster_pixel_emit),
.write_addr(raster_pixel_fb_addr_q),
.write_data(raster_pixel_color_q[31:0]),
.write_be (raster_pixel_be_q),
.write_mask(32'hFFFF_FFFF),
.read_addr (vram_read_addr),
.read_data (vram_read_data),
.read2_addr(32'd0),
.read2_data()
);
// Capture the (fb_addr, color, x, y) of every emit pulse.
int emit_count;
logic [31:0] emit_fb_addr [0:31];
logic [31:0] emit_color [0:31];
logic [11:0] emit_x [0:31];
logic [11:0] emit_y [0:31];
initial begin
emit_count = 0;
end
always_ff @(posedge clk) begin
if (rst_n && raster_pixel_emit && emit_count < 32) begin
emit_fb_addr[emit_count] <= raster_pixel_fb_addr_q;
emit_color [emit_count] <= raster_pixel_color_q[31:0];
emit_x [emit_count] <= raster_pixel_x_q;
emit_y [emit_count] <= raster_pixel_y_q;
emit_count <= emit_count + 1;
end
end
task automatic step_drive(input logic wr_en,
input logic [7:0] num,
input logic [63:0] data);
@(negedge clk);
gif_reg_wr_en = wr_en;
gif_reg_num = num;
gif_reg_data = data;
@(posedge clk);
endtask
task automatic drive_reg(input logic [7:0] num, input logic [63:0] data);
step_drive(1'b1, num, data);
endtask
task automatic drive_idle();
step_drive(1'b0, 8'd0, 64'd0);
endtask
function automatic logic [63:0] xyz2_data(input logic [11:0] x_int,
input logic [11:0] y_int);
return {32'd0, y_int, 4'd0, x_int, 4'd0};
endfunction
localparam logic [7:0] R_PRIM = 8'h00;
localparam logic [7:0] R_RGBAQ = 8'h01;
localparam logic [7:0] R_XYZ2 = 8'h05;
localparam logic [7:0] R_FRAME_1 = 8'h4C;
localparam logic [63:0] PRIM_SPRITE = 64'd6;
localparam logic [63:0] FRAME_1_VAL = 64'h0000_0000_000A_0002;
// Color: ABGR = 0x_00_00_FF_30 → A=0x00, B=0x00, G=0xFF, R=0x30.
// raster_pixel_color_q[31:0] should mirror this.
localparam logic [63:0] RGBAQ_VAL = 64'h0000_0000_0000_FF30;
localparam logic [31:0] EXPECTED_PIX = 32'h0000_FF30;
int errors;
initial begin
rst_n = 1'b0;
gif_reg_wr_en = 1'b0;
gif_reg_num = 8'd0;
gif_reg_data = 64'd0;
errors = 0;
vram_read_addr = 32'd0;
repeat (4) @(posedge clk);
rst_n = 1'b1;
repeat (2) @(posedge clk);
drive_reg(R_PRIM, PRIM_SPRITE);
drive_reg(R_FRAME_1, FRAME_1_VAL);
drive_reg(R_RGBAQ, RGBAQ_VAL);
// 4×4 SPRITE — 16 pixels.
drive_reg(R_XYZ2, xyz2_data(12'd0, 12'd0)); // v1
drive_reg(R_XYZ2, xyz2_data(12'd3, 12'd3)); // v2 — close S1
drive_idle();
repeat (40) @(posedge clk);
$display("[tb_gs_vram_writeback] emit_count=%0d raster_pixel_emit_count=%0d raster_overflow=%b",
emit_count, raster_pixel_emit_count, raster_overflow);
if (emit_count != 16) begin
$error("emit_count=%0d (expected 16)", emit_count);
errors = errors + 1;
end
if (raster_overflow !== 1'b0) begin
$error("raster_overflow=%b (expected 0)", raster_overflow);
errors = errors + 1;
end
// Walk each captured emit and verify VRAM read-back matches.
for (int i = 0; i < emit_count; i++) begin
vram_read_addr = emit_fb_addr[i];
#1; // let comb read settle
$display("[tb_gs_vram_writeback] cap[%0d] (%0d,%0d) fb=0x%08x vram=0x%08x expect=0x%08x",
i, emit_x[i], emit_y[i], emit_fb_addr[i],
vram_read_data, emit_color[i]);
if (vram_read_data !== emit_color[i]) begin
$error("VRAM mismatch @ fb=0x%08x: got 0x%08x, expected 0x%08x",
emit_fb_addr[i], vram_read_data, emit_color[i]);
errors = errors + 1;
end
if (emit_color[i] !== EXPECTED_PIX) begin
$error("emit color mismatch @ fb=0x%08x: emitted 0x%08x, expected 0x%08x",
emit_fb_addr[i], emit_color[i], EXPECTED_PIX);
errors = errors + 1;
end
end
// Sanity probe: an address NOT touched by any emit must
// still read as zero (initial mem state).
vram_read_addr = 32'h0000_0000;
#1;
if (vram_read_data !== 32'd0) begin
$error("VRAM addr 0 should be 0 (untouched), got 0x%08x", vram_read_data);
errors = errors + 1;
end
if (errors == 0) $display("[tb_gs_vram_writeback] PASS");
else $display("[tb_gs_vram_writeback] FAIL");
$finish;
end
initial begin
#5000000;
$error("[tb_gs_vram_writeback] timeout");
$finish;
end
endmodule : tb_gs_vram_writeback