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More WIP on PPU

This commit is contained in:
Koray Yanik 2023-10-31 22:48:14 +00:00
parent 3c3dbd2175
commit 82584dab34
5 changed files with 179 additions and 70 deletions
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2
build/tb_top.Makefile
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@ -1,5 +1,5 @@
TB = tb_top
SOURCES = gb.sv cpu.sv ppu.sv idec.sv ctrl.sv alu.sv alu16.sv regbank.sv rom.sv ram.sv cart.sv display.sv tb_top.sv vgasim.sv clkgen.sv
SOURCES = gb.sv cpu.sv ppu.sv ppu_ioregs.sv idec.sv ctrl.sv alu.sv alu16.sv regbank.sv rom.sv ram.sv cart.sv display.sv tb_top.sv vgasim.sv clkgen.sv
INCLUDES = cpu_pkg.svh sva_common.svh
DPI_SOURCES = vgasim.c

158
rtl/ppu/ppu.sv
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@ -11,93 +11,114 @@ module ppu (
input logic cpu_we_i,
input logic [ 7:0] cpu_wdata_i,
output logic [15:0] ppu_addr_o,
input logic [ 7:0] ppu_rdata_i,
output logic [ 1:0] pixel_o,
output logic vsync_o,
output logic hsync_o
);
`define IOREG_DECL(name) \
logic [ 7:0] name``_r; \
logic [ 7:0] name``_next; \
logic name``_we; \
logic name``_sel;
`define REG_DECL(t, name) \
t name``_r; \
t name``_next; \
logic name``_we;
`define IOREG_DEF(name, addr, rstval) \
`define REG_DEF(name, rstval) \
always_ff @(posedge clk or negedge nreset) begin \
if (!nreset) \
name``_r <= rstval; \
else if (name``_we) \
name``_r <= name``_next; \
end \
assign name``_sel = (cpu_addr_i == addr); \
assign name``_we = name``_sel & cpu_we_i;
end
typedef struct packed {
logic lcd_en;
logic win_tilemap_sel;
logic win_en;
logic tiledata_sel;
logic bg_tilemap_sel;
logic obj_size;
logic obj_display;
logic bgwin_display;
} lcdc_t;
typedef enum {
ST_RESET,
ST_OAM_SCAN,
ST_FETCH_TILE_INDEX,
ST_FETCH_TILE_DATA0,
ST_FETCH_TILE_DATA1,
ST_PUSH_PIXELS,
ST_HBLANK
} state_t;
lcdc_t lcdc;
logic [3:0] [1:0] bgp;
`REG_DECL(state_t, state);
`REG_DECL(logic [7:0], oam);
// LX is not read/writeable
logic [ 8:0] lx_r;
logic [ 8:0] lx_next;
logic lx_end_of_line;
`REG_DECL(logic [7:0], tile);
`REG_DECL(logic [7:0], tile_no);
`REG_DECL(logic [7:0], ly);
logic ly_sel;
logic ly_end_of_frame;
`IOREG_DECL(lcdc);
`IOREG_DECL(ly);
`IOREG_DECL(sy);
`IOREG_DECL(bgp);
logic [ 8:0] lx_r;
logic [ 8:0] lx_next;
logic lx_we;
logic lx_end_of_line;
`IOREG_DEF (lcdc, 16'hFF40, '0);
`IOREG_DEF ( sy, 16'hFF42, '0);
`IOREG_DEF ( bgp, 16'hFF47, '0);
logic tilemap_base_sel;
logic [ 7:0] ioregs_rdata;
assign lcdc_next = cpu_wdata_i;
assign sy_next = cpu_wdata_i;
assign bgp_next = cpu_wdata_i;
`REG_DEF(state, ST_RESET);
assign state_we = 1'b1;
assign lcdc = lcdc_r;
assign bgp = bgp_r;
always_ff @(posedge clk or negedge nreset) begin
if (!nreset) begin
ly_r <= '0;
lx_r <= '0;
end else begin
ly_r <= ly_next;
lx_r <= lx_next;
end
always_comb begin
state_next = state_r;
case (state_r)
ST_RESET: state_next = ST_OAM_SCAN;
ST_OAM_SCAN: state_next = oam_we ? ST_OAM_SCAN : ST_FETCH_TILE_INDEX; // 80 cycles per row
ST_FETCH_TILE_INDEX: state_next = ST_FETCH_TILE_DATA0; // 1 cycle x 20 per row
ST_FETCH_TILE_DATA0: state_next = ST_FETCH_TILE_DATA1; // 1 cycle x 20 per row
ST_FETCH_TILE_DATA1: state_next = ST_PUSH_PIXELS; // 1 cycle x 20 per row
ST_PUSH_PIXELS: state_next = (tile_no_r == 5'd20) ? ST_HBLANK : ST_PUSH_PIXELS; // 8 cycles x 20 per row
ST_HBLANK: state_next = lx_end_of_line ? ST_FETCH_TILE_INDEX : ST_HBLANK;
endcase
end
`REG_DEF(tile, '0);
assign tile_we = (state_r == ST_FETCH_TILE_INDEX);
assign tile_next = ppu_rdata_i;
`REG_DEF(tile_no, '0);
assign tile_no_we = (state_next == ST_FETCH_TILE_INDEX);
assign tile_no_next = (state_r == ST_OAM_SCAN) ? '0 :
(tile_no_r + 8'h01);
`REG_DEF(oam, '0)
assign oam_we = (state_r == ST_OAM_SCAN) & (oam_r < 7'd80);
assign oam_next = (oam_r + 7'h01);
`REG_DEF(ly, '0)
assign ly_sel = (cpu_addr_i == 16'hFF44);
assign ly_next = (ly_sel & cpu_we_i) ? 8'h00 : // Clear on write
(lx_end_of_line & ly_end_of_frame) ? 8'h00 :
(lx_end_of_line & ~ly_end_of_frame) ? (ly_r + 8'h01) :
ly_r;
assign ly_end_of_frame = ly_r > 8'd153;
`REG_DEF(lx, '0)
assign lx_we = 1'b1;
assign lx_next = lx_end_of_line ? 9'h0 : (lx_r + 9'h01);
assign ly_end_of_frame = ly_r > 8'd153;
assign lx_end_of_line = lx_r > 9'd456;
assign cpu_rdata_o =
{8{lcdc_sel}} & lcdc_r |
`ifdef VSYNC_HACK
{8{ ly_sel}} & 8'h90 |
`else
{8{ ly_sel}} & ly_r |
`endif
{8{ sy_sel}} & sy_r;
ppu_ioregs ppu_ioregs_inst (
.clk (clk),
.nreset(nreset),
.cpu_addr_i (cpu_addr_i),
.cpu_rdata_o(ioregs_rdata),
.cpu_we_i (cpu_we_i),
.cpu_wdata_i(cpu_wdata_i),
.display_enable_o(display_enable_o),
.tilemap_base_sel_o(tilemap_base_sel)
);
assign pixel_o = ((lx_r < 8'd160) & (ly_r < 8'd144)) ? ly_r[1:0] : // should create a nice line-pattern for now
2'h00;
@ -105,17 +126,26 @@ assign pixel_o = ((lx_r < 8'd160) & (ly_r < 8'd144)) ? ly_r[1:0] : // should cr
assign vsync_o = ly_r >= 8'd144;
assign hsync_o = lx_r >= 8'd160;
assign display_enable_o = lcdc_r[7];
assign cpu_rdata_o =
ioregs_rdata |
`ifdef VSYNC_HACK
{8{ ly_sel}} & 8'h90;
`else
{8{ ly_sel}} & ly_r;
`endif
logic [7:0] tilemap_base_addr;
assign tilemap_base_addr = tilemap_base_sel ? 8'h9C : 8'h98;
assign ppu_addr_o = {tilemap_base_addr, tile_no_r};//(state_next == ST_FETCH_TILE_INDEX) ? {tilemap_base_addr, tile_no} :
//(state_next == ST_PUSH_PIXELS & lx_r[])
`undef IOREG_DEF
`undef IOREG_DECL
`ifdef SVA_ENABLE
logic sva_ppu_sel;
assign sva_ppu_sel = lcdc_sel | ly_sel | sy_sel;
logic sva_sel;
assign sva_sel = ly_sel;
`endif /* SVA_ENABLE */
endmodule : ppu

76
rtl/ppu/ppu_ioregs.sv Normal file
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@ -0,0 +1,76 @@
module ppu_ioregs (
input logic clk,
input logic nreset,
input logic [15:0] cpu_addr_i,
output logic [ 7:0] cpu_rdata_o,
input logic cpu_we_i,
input logic [ 7:0] cpu_wdata_i,
output logic display_enable_o,
output logic tilemap_base_sel_o,
output logic [ 8:0] ly_o,
output logic [ 7:0] lx_o
);
`define IOREG_DECL(name) \
logic [ 7:0] name``_r; \
logic [ 7:0] name``_next; \
logic name``_we; \
logic name``_sel;
`define IOREG_DEF(name, addr, rstval) \
always_ff @(posedge clk or negedge nreset) begin \
if (!nreset) \
name``_r <= rstval; \
else if (name``_we) \
name``_r <= name``_next; \
end \
assign name``_sel = (cpu_addr_i == addr); \
assign name``_we = name``_sel & cpu_we_i;
typedef struct packed {
logic lcd_en;
logic win_tilemap_sel;
logic win_en;
logic tiledata_sel;
logic bg_tilemap_sel;
logic obj_size;
logic obj_display;
logic bgwin_display;
} lcdc_t;
lcdc_t lcdc;
logic [3:0] [1:0] bgp;
`IOREG_DECL(lcdc);
`IOREG_DECL(ly);
`IOREG_DECL(sy);
`IOREG_DECL(bgp);
`IOREG_DEF (lcdc, 16'hFF40, '0);
`IOREG_DEF ( sy, 16'hFF42, '0);
`IOREG_DEF ( bgp, 16'hFF47, '0);
assign lcdc_next = cpu_wdata_i;
assign sy_next = cpu_wdata_i;
assign bgp_next = cpu_wdata_i;
assign lcdc = lcdc_r;
assign bgp = bgp_r;
assign cpu_rdata_o =
{8{lcdc_sel}} & lcdc_r |
{8{ sy_sel}} & sy_r;
assign display_enable_o = lcdc.lcd_en;
assign tilemap_base_sel_o = lcdc.bg_tilemap_sel;
`ifdef SVA_ENABLE
logic sva_sel;
assign sva_sel = lcdc_sel | sy_sel;
`endif /* SVA_ENABLE */
endmodule : ppu_ioregs

2
sim/tb_top.sv
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@ -138,7 +138,7 @@ assign we = gb_inst.cpu_we;
assign vram_sel = gb_inst.vram_sel;
assign hiram_sel = gb_inst.hiram_sel;
assign ppu_sel = gb_inst.ppu_inst.sva_ppu_sel;
assign ppu_sel = gb_inst.ppu_inst.ppu_ioregs_inst.sva_sel;
always_ff @(posedge gb_clk or negedge nreset) begin
if (!nreset)

11
sim/vgasim.sv
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@ -17,15 +17,18 @@ import "DPI-C" function int vgasim_init(input int screen_h, input int screen_w,
import "DPI-C" function int vgasim_reset();
import "DPI-C" function int vgasim_tick(input int r, input int g, input int b, input int hsync, input int vsync);
logic vgasim_initialised = 0;
initial begin
automatic int ret = vgasim_init(SCREEN_W, SCREEN_H, DEPTH);
assert (ret == 0) else begin
if (ret != 0) begin
$display($sformatf("[%0t] vgasim init failed: %d", $time, ret));
$fatal();
end else begin
vgasim_initialised = '1;
end
end
always @(negedge nreset) begin
always @(negedge nreset iff vgasim_initialised) begin
automatic int ret = vgasim_reset();
assert (ret == 0) else begin
$display($sformatf("[%0t] vgasim reset failed: %d", $time, ret));
@ -33,7 +36,7 @@ always @(negedge nreset) begin
end
end
always @(posedge clk iff nreset) begin
always @(posedge clk iff nreset && vgasim_initialised) begin
automatic int ret = vgasim_tick(r_i, g_i, b_i, hsync_i, vsync_i);
assert (ret == 0) else begin
$display($sformatf("[%0t] vgasim tick failed: %d", $time, ret));