// retroDE_ps2 — tb_gs_raster_psmct16 (Ch95) // // Locks the contract for gs_stub's WRITE-side PSMCT16 emit. The // raster pipeline (Ch88: S0/S1/S2) now packs ABGR → RGB5A1 when // FRAME_1.PSM = PSMCT16 (= 0x02), and emits a 4-bit `write_be` // alongside the data so vram_stub commits exactly 2 bytes per // pixel without stomping the neighboring halfword. // // Setup: // PRIM = SPRITE // FRAME_1: FBP=0, FBW=1, PSM=PSMCT16 // The PSM bits are at FRAME_1[29:24]. PSMCT16 = 0x02. // RGBAQ: pick channels with distinct high-5-bit values so the // packed RGB5A1 is non-degenerate. Use R=0x84, G=0xC6, B=0x42, // A=0x80 (matches the Ch94 read-side test colors after 5→8 // expansion, except A=0x80 instead of 0; the alpha bit is // informational). // v1 = (0, 0); v2 = (3, 3) → 4×4 sprite. // // Expected per-pixel pack: // r5 = 0x84[7:3] = 0x10 // g5 = 0xC6[7:3] = 0x18 // b5 = 0x42[7:3] = 0x08 // a1 = 0x80[7] = 1 // pix16 = {a1, b5, g5, r5} = (1 << 15) | (0x08 << 10) | (0x18 << 5) | 0x10 // = 0x8000 | 0x2000 | 0x0300 | 0x10 = 0xA310 // // Expected VRAM after raster (FBW=1 → 64 pixels/row × 2 bytes // = 128 bytes/row stride; sprite 4 wide × 4 tall): // Row 0 at byte 0: [pix0=0xA310 | pix1=0xA310 | pix2=0xA310 | pix3=0xA310] // = mem[0..7] = {0x10,0xA3, 0x10,0xA3, 0x10,0xA3, 0x10,0xA3} // Row 1 at byte 128: same pattern at bytes 128..135 // Row 2 at byte 256: bytes 256..263 // Row 3 at byte 384: bytes 384..391 // Bytes 8..127 of row 0 (and similarly for other rows) MUST // stay zero (no halfword leak from the next row's writes or // from the sprite's own boundary). // // PASS criteria: // - 16 raster_pixel_emit pulses // - Every expected sprite halfword reads back as 0xA310 // - Specifically, the halfword right after the sprite on each // row (byte 8..9 / 136..137 / etc.) reads as 0 — proves the // write_be byte gating works (without it, a 32-bit write at // byte 6 would stomp bytes 8..9 with the duplicate halfword). `timescale 1ns/1ps module tb_gs_raster_psmct16; logic clk; logic rst_n; initial clk = 1'b0; always #5 clk = ~clk; // gs_stub IO 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] pmode_q, dispfb1_q, display1_q; 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 gs_ev_valid; trace_pkg::subsys_e gs_ev_subsys; trace_pkg::event_e gs_ev_event; logic [63:0] gs_ev_arg0, gs_ev_arg1, gs_ev_arg2, gs_ev_arg3; logic [31:0] gs_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), .pmode_q(pmode_q), .dispfb1_q(dispfb1_q), .display1_q(display1_q), .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(gs_ev_valid), .ev_subsys(gs_ev_subsys), .ev_event(gs_ev_event), .ev_arg0(gs_ev_arg0), .ev_arg1(gs_ev_arg1), .ev_arg2(gs_ev_arg2), .ev_arg3(gs_ev_arg3), .ev_flags(gs_ev_flags) ); logic [31:0] vram_read_addr; logic [31:0] vram_read_data; vram_stub #(.BYTES(4096)) 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() ); int errors; int psmct16_emit_seen; initial begin errors = 0; psmct16_emit_seen = 0; end // Sanity: while emitting PSMCT16, raster_pixel_be_q should be // 4'b0011 (gs_stub uses byte-addressed write_addr so the same // be works for both even and odd pixels), and raster_pixel_psm_q // should be 6'h02. always_ff @(posedge clk) begin if (rst_n && raster_pixel_emit) begin psmct16_emit_seen <= psmct16_emit_seen + 1; if (raster_pixel_psm_q !== 6'h02) begin $error("emit %0d: raster_pixel_psm_q=0x%02x (expected 0x02 PSMCT16)", psmct16_emit_seen, raster_pixel_psm_q); errors <= errors + 1; end if (raster_pixel_be_q !== 4'b0011) begin $error("emit %0d: raster_pixel_be_q=%b (expected 4'b0011 for PSMCT16)", psmct16_emit_seen, raster_pixel_be_q); errors <= errors + 1; end 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 task automatic check_halfword(input logic [31:0] byte_addr, input logic [15:0] expected, input string tag); logic [15:0] got; // vram_stub returns 4 bytes starting at read_addr; read at // a 4-byte-aligned address that contains the target // halfword, then mux based on byte_addr[1]. vram_read_addr = byte_addr & ~32'd3; #1; got = byte_addr[1] ? vram_read_data[31:16] : vram_read_data[15:0]; if (got !== expected) begin $error("[%s] @byte 0x%08x got 0x%04x expected 0x%04x", tag, byte_addr, got, expected); errors = errors + 1; end endtask 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; // FRAME_1: FBP[8:0]=0, FBW[21:16]=1, PSM[29:24]=PSMCT16(0x02). // FBW=1 at bit 16 → 0x0001_0000 // PSM=2 at bit 24 → 0x0200_0000 localparam logic [63:0] FRAME_1_VAL = 64'h0000_0000_0201_0000; // RGBAQ: A=0x80 B=0x42 G=0xC6 R=0x84. // Lower 32 bits {A, B, G, R} = 0x8042_C684. localparam logic [63:0] RGBAQ_VAL = 64'h0000_0000_8042_C684; // Expected packed PSMCT16 pixel. localparam logic [4:0] EXP_R5 = 5'h10; localparam logic [4:0] EXP_G5 = 5'h18; localparam logic [4:0] EXP_B5 = 5'h08; localparam logic EXP_A1 = 1'b1; localparam logic [15:0] EXP_PIX = {EXP_A1, EXP_B5, EXP_G5, EXP_R5}; localparam int SPRITE_W = 4; localparam int SPRITE_H = 4; // FBW=1 → 64 pixels/row × 2 bytes = 128 bytes/row stride. localparam int ROW_STRIDE_BYTES = 128; initial begin rst_n = 1'b0; gif_reg_wr_en = 1'b0; gif_reg_num = 8'd0; gif_reg_data = 64'd0; 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); drive_reg(R_XYZ2, xyz2_data(12'd0, 12'd0)); drive_reg(R_XYZ2, xyz2_data(12'(SPRITE_W - 1), 12'(SPRITE_H - 1))); drive_idle(); wait (raster_active == 1'b1); wait (raster_active == 1'b0); repeat (10) @(posedge clk); if (raster_pixel_emit_count != 32'(SPRITE_W * SPRITE_H)) begin $error("expected %0d emits, got %0d", SPRITE_W * SPRITE_H, raster_pixel_emit_count); errors = errors + 1; end if (psmct16_emit_seen != SPRITE_W * SPRITE_H) begin $error("PSMCT16 emit observer count=%0d (expected %0d)", psmct16_emit_seen, SPRITE_W * SPRITE_H); errors = errors + 1; end // Verify each sprite pixel landed as the right RGB5A1 halfword. for (int y = 0; y < SPRITE_H; y++) begin for (int x = 0; x < SPRITE_W; x++) begin logic [31:0] byte_addr; byte_addr = (y * ROW_STRIDE_BYTES) + (x * 2); check_halfword(byte_addr, EXP_PIX, "sprite-pixel"); end end // Load-bearing: the halfword RIGHT AFTER the sprite on // each row must be 0. Without write_be byte gating, a // 32-bit write at the rightmost sprite pixel (e.g. byte 6 // for row 0) would stomp bytes 8..9 with the duplicate // halfword. With write_be active, those bytes stay 0. for (int y = 0; y < SPRITE_H; y++) begin logic [31:0] right_of_sprite; right_of_sprite = (y * ROW_STRIDE_BYTES) + (SPRITE_W * 2); check_halfword(right_of_sprite, 16'h0000, "right-of-sprite-must-be-zero"); end // Also: bytes between rows (e.g. bytes 8..127 on row 0) // should mostly be zero. Spot-check one. check_halfword(32'd64, 16'h0000, "mid-row-must-be-zero"); $display("[tb_gs_raster_psmct16] sprite=%0dx%0d pix16=0x%04x emits=%0d", SPRITE_W, SPRITE_H, EXP_PIX, raster_pixel_emit_count); if (errors == 0) $display("[tb_gs_raster_psmct16] PASS"); else $display("[tb_gs_raster_psmct16] FAIL"); $finish; end initial begin #5000000; $error("[tb_gs_raster_psmct16] timeout"); $finish; end endmodule : tb_gs_raster_psmct16