// retroDE_ps2 — tb_gs_fog_persp // // Focused white-box TB for GS per-vertex FOG on the PERSPECTIVE-textured emit // path (persp_emit5). Forces PERSPECTIVE_CORRECT=1. The SH3 board scene runs // this build (PERSPECTIVE_CORRECT=1, COMBINED_TAZ=0, TILE_LOCAL=0), so its // geometry emits through persp_emit5 — the path round-1 left unfogged. // // A perspective-textured DECAL triangle (ST/Q supplied so ras_persp activates) // samples a SOLID texture (tex_rd_data tied constant → s1_tex_color == TEXEL // for every pixel), so the emitted color isolates the fog blend and its stage // alignment without needing to model the perspective UV walk. F is affine / // screen-linear per vertex (XYZF2[63:56]). // // Checks: // T1p — FGE=1, flat color, DISTINCT per-vertex F. At every persp_emit5: // (a) ALIGNMENT — the white-box +5-aligned s2_fog_f delay tap // (u_gs.persp_fog_f5) matches the barycentric (screen-linear) F at // the emitted pixel (persp_x5,persp_y5) within 1 LSB. A wrong delay // depth would 1-pixel-shift F and fail here. // (b) BLEND — the captured emitted RGB equals fog_blend(TEXEL, // persp_fog_f5) EXACTLY, alpha unchanged. // T2p — FGE=0, same geometry. Emitted color is BYTE-IDENTICAL to TEXEL (no // fog) — the non-negotiable invariant on the perspective path. `timescale 1ns/1ps module tb_gs_fog_persp; 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 [31:0] raster_pixel_mask_q; logic [5:0] raster_pixel_psm_q; logic raster_active; logic raster_overflow; logic raster_fifo_full; logic raster_degenerate; logic tex_rd_en; logic [31:0] tex_rd_addr; logic fb_rd_en; logic [31:0] fb_rd_addr; logic z_rd_en; logic [31:0] z_rd_addr; 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; // Solid texture: any texel address returns this ABGR word. localparam logic [31:0] TEXEL = 32'hFF_B0_60_20; // A=FF B=B0 G=60 R=20 logic [31:0] tex_texel; assign tex_texel = TEXEL; gs_stub #(.PERSPECTIVE_CORRECT(1'b1)) 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_mask_q(raster_pixel_mask_q), .raster_pixel_psm_q(raster_pixel_psm_q), .raster_active(raster_active), .raster_overflow(raster_overflow), .raster_fifo_full(raster_fifo_full), .raster_degenerate(raster_degenerate), .tex_rd_en(tex_rd_en), .tex_rd_addr(tex_rd_addr), .tex_rd_data(tex_texel), .fb_rd_en(fb_rd_en), .fb_rd_addr(fb_rd_addr), .fb_rd_data(32'd0), .z_rd_en(z_rd_en), .z_rd_addr(z_rd_addr), .z_rd_data(32'd0), .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) ); // ----- Drive helpers ----- task automatic drive_reg(input logic [7:0] num, input logic [63:0] data); @(negedge clk); gif_reg_wr_en = 1'b1; gif_reg_num = num; gif_reg_data = data; @(posedge clk); endtask task automatic drive_idle(); @(negedge clk); gif_reg_wr_en = 1'b0; gif_reg_num = 8'd0; gif_reg_data = 64'd0; @(posedge clk); endtask // XYZF2 (reg 0x04): X=[15:0] (12.4), Y=[31:16] (12.4), Z=[55:32], F=[63:56]. function automatic logic [63:0] xyzf2(input int x, input int y, input int z, input int f); return {8'(f), 24'(z), 12'(y), 4'd0, 12'(x), 4'd0}; endfunction // RGBAQ with Q in [55:32] (24-bit, FRAC=12). function automatic logic [63:0] rgbaq_q_val(input int r, input int g, input int b, input int a, input int q_fp); return {8'd0, 24'(q_fp), 8'(a), 8'(b), 8'(g), 8'(r)}; endfunction // ST (reg 0x02): S in [23:0], T in [55:32] (24-bit, FRAC=12). function automatic logic [63:0] st_val(input int s_fp, input int t_fp); return {8'd0, 24'(t_fp), 8'd0, 24'(s_fp)}; endfunction localparam logic [7:0] R_PRIM = 8'h00; localparam logic [7:0] R_RGBAQ = 8'h01; localparam logic [7:0] R_ST = 8'h02; localparam logic [7:0] R_XYZF2 = 8'h04; localparam logic [7:0] R_TEX0_1 = 8'h06; localparam logic [7:0] R_FOGCOL = 8'h3D; localparam logic [7:0] R_FRAME_1 = 8'h4C; // PRIM: TRIANGLE(3) + TME(bit4) + FGE(bit5). localparam logic [63:0] PRIM_TRI_TEX_FGE = 64'd3 | (64'd1 << 4) | (64'd1 << 5); localparam logic [63:0] PRIM_TRI_TEX = 64'd3 | (64'd1 << 4); // FGE=0 localparam logic [63:0] FRAME_1_VAL = 64'h0000_0000_0001_0000; // FBW=1, PSMCT32 // TEX0_1: TBP0=8, TBW=1, PSM=PSMCT32(0), TW=TH=0, TCC=0, TFX=DECAL(1)@[36:35]. localparam logic [63:0] TEX0_VAL = 64'd8 | (64'd1 << 14) | (64'd1 << 35); localparam int Q_ONE = 24'h001000; // 1.0 in FRAC=12 localparam int FOG_R = 8'h20, FOG_G = 8'h40, FOG_B = 8'h60; localparam logic [63:0] FOGCOL_VAL = {40'd0, 8'(FOG_B), 8'(FOG_G), 8'(FOG_R)}; function automatic int fog_ch(input int c, input int f, input int fc); return (c * f + fc * (255 - f)) >> 8; endfunction function automatic int absdiff(input int a, input int b); return (a > b) ? (a - b) : (b - a); endfunction // ----- Triangle reference (edge fn + fill rule + barycentric for F) ----- int vx0, vy0, vx1, vy1, vx2, vy2, vf0, vf1, vf2; int ref_det, sx1, sy1, sx2, sy2, sf1, sf2; function automatic int edge_f(input int px, input int py, input int ax, input int ay, input int bx, input int by); return (px - ax) * (by - ay) - (py - ay) * (bx - ax); endfunction task automatic setup_ref(); int sa; sa = (vx1 - vx0) * (vy2 - vy0) - (vy1 - vy0) * (vx2 - vx0); if (sa < 0) begin sx1 = vx2; sy1 = vy2; sf1 = vf2; sx2 = vx1; sy2 = vy1; sf2 = vf1; ref_det = -sa; end else begin sx1 = vx1; sy1 = vy1; sf1 = vf1; sx2 = vx2; sy2 = vy2; sf2 = vf2; ref_det = sa; end endtask function automatic int ref_f(input int px, input int py); int L0, L1, L2, num; L0 = -edge_f(px, py, sx1, sy1, sx2, sy2); L1 = -edge_f(px, py, sx2, sy2, vx0, vy0); L2 = -edge_f(px, py, vx0, vy0, sx1, sy1); num = L0 * vf0 + L1 * sf1 + L2 * sf2; if (ref_det == 0) return 0; return num / ref_det; endfunction int errors, align_checks, blend_checks; // Emit capture: expected color computed at persp_emit5 from the RTL's own // +5-aligned F (persp_fog_f5), plus the alignment check vs barycentric F. logic [31:0] exp_c [0:31][0:31]; bit exp_set [0:31][0:31]; bit fge_on; task automatic clear_exp(); for (int y = 0; y < 32; y++) for (int x = 0; x < 32; x++) begin exp_c[y][x] = 32'd0; exp_set[y][x] = 1'b0; end endtask // persp_emit5 monitor: alignment + record expected fogged color. always_ff @(posedge clk) begin if (rst_n && u_gs.ras_persp && u_gs.persp_emit5) begin int px, py, ef, af; logic [31:0] want; px = int'(u_gs.persp_x5); py = int'(u_gs.persp_y5); af = int'(u_gs.persp_fog_f5); if (px < 32 && py < 32) begin // (a) alignment: RTL +5-aligned F vs barycentric F at this pixel. ef = ref_f(px, py); if (absdiff(af, ef) > 1) begin $error("[persp align] (%0d,%0d) persp_fog_f5=%0d expected ~%0d", px, py, af, ef); errors = errors + 1; end else begin align_checks = align_checks + 1; end // (b) expected emitted color = fog(TEXEL, af) if FGE, else TEXEL. if (fge_on) want = {TEXEL[31:24], 8'(fog_ch(int'(TEXEL[23:16]), af, FOG_B)), 8'(fog_ch(int'(TEXEL[15:8]), af, FOG_G)), 8'(fog_ch(int'(TEXEL[7:0]), af, FOG_R))}; else want = TEXEL; exp_c[py][px] <= want; exp_set[py][px] <= 1'b1; end end end // Capture the actual emitted pixel and compare to the expected recorded above. always_ff @(posedge clk) begin if (rst_n && raster_pixel_emit && raster_pixel_x_q < 32 && raster_pixel_y_q < 32) begin if (!exp_set[raster_pixel_y_q][raster_pixel_x_q]) begin $error("[persp emit] (%0d,%0d) emitted but no persp_emit5 expected color recorded", raster_pixel_x_q, raster_pixel_y_q); errors = errors + 1; end else if (raster_pixel_color_q[31:0] !== exp_c[raster_pixel_y_q][raster_pixel_x_q]) begin $error("[persp emit] (%0d,%0d) got %08x expected %08x", raster_pixel_x_q, raster_pixel_y_q, raster_pixel_color_q[31:0], exp_c[raster_pixel_y_q][raster_pixel_x_q]); errors = errors + 1; end else begin blend_checks = blend_checks + 1; end end end task automatic drive_persp_tri(input logic [63:0] prim_word); drive_reg(R_FOGCOL, FOGCOL_VAL); drive_reg(R_PRIM, prim_word); drive_reg(R_FRAME_1, FRAME_1_VAL); drive_reg(R_TEX0_1, TEX0_VAL); drive_reg(R_RGBAQ, rgbaq_q_val(8'hFF, 8'hFF, 8'hFF, 8'hFF, Q_ONE)); drive_reg(R_ST, st_val(0, 0)); drive_reg(R_XYZF2, xyzf2(vx0, vy0, 0, vf0)); drive_reg(R_RGBAQ, rgbaq_q_val(8'hFF, 8'hFF, 8'hFF, 8'hFF, Q_ONE)); drive_reg(R_ST, st_val(0, 0)); drive_reg(R_XYZF2, xyzf2(vx1, vy1, 0, vf1)); drive_reg(R_RGBAQ, rgbaq_q_val(8'hFF, 8'hFF, 8'hFF, 8'hFF, Q_ONE)); drive_reg(R_ST, st_val(0, 0)); drive_reg(R_XYZF2, xyzf2(vx2, vy2, 0, vf2)); // closes drive_idle(); repeat (900) @(posedge clk); endtask initial begin errors = 0; align_checks = 0; blend_checks = 0; rst_n = 1'b0; gif_reg_wr_en = 1'b0; gif_reg_num = 8'd0; gif_reg_data = 64'd0; clear_exp(); repeat (4) @(posedge clk); rst_n = 1'b1; repeat (2) @(posedge clk); // ============================================================ // T1p — FGE=1, distinct per-vertex F, solid texel. Alignment + blend. // ============================================================ vx0=2; vy0=2; vf0=8'h20; vx1=12; vy1=3; vf1=8'hE0; vx2=4; vy2=9; vf2=8'h80; setup_ref(); clear_exp(); fge_on = 1'b1; drive_persp_tri(PRIM_TRI_TEX_FGE); if (align_checks == 0) begin $error("[T1p] no persp_emit5 pixels observed (persp path did not fire)"); errors = errors + 1; end if (raster_overflow || raster_degenerate) begin $error("[T1p] raster anomaly"); errors = errors + 1; end // ============================================================ // T2p — FGE=0, same geometry. Emitted MUST be byte-identical to TEXEL. // ============================================================ clear_exp(); fge_on = 1'b0; drive_persp_tri(PRIM_TRI_TEX); $display("[tb_gs_fog_persp] align_checks=%0d blend_checks=%0d errors=%0d", align_checks, blend_checks, errors); if (errors == 0) $display("[tb_gs_fog_persp] PASS"); else $display("[tb_gs_fog_persp] FAIL"); $finish; end initial begin #8000000; $error("[tb_gs_fog_persp] timeout"); $finish; end endmodule : tb_gs_fog_persp