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Merge pull request #250 from paulb-nl/window
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Window fixes, Wram bank, GBVideoPlayer, SGB joypad fix
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@sorgelig
sorgelig authored Jun 16, 2024
2 parents 51c7bae + 1258e99 commit 23dd9de
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Showing 4 changed files with 119 additions and 97 deletions.
3 changes: 2 additions & 1 deletion rtl/cart.v
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Expand Up @@ -277,11 +277,12 @@ always @(posedge clk_sys) begin
mmm01 <= 0;
{ sachen, sachen_t1, sachen_t2 } <= 0;
mapper_sel_r <= mapper_sel;
rom_mask <= 9'd0;
end

if(cart_download & ioctl_wr) begin

rom_mask <= ioctl_addr[22:14];
rom_mask <= ioctl_addr[22:14] | rom_mask;

if (megaduck) begin
cart_cgb_flag <= 0;
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15 changes: 7 additions & 8 deletions rtl/gb.v
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Original file line number Diff line number Diff line change
Expand Up @@ -135,7 +135,7 @@ wire [63:0] SaveStateBus_wired_or[0:SAVESTATE_MODULES-1];

wire [56:0] SS_Top;
wire [56:0] SS_Top_BACK;
eReg_SavestateV #(0, 31, 56, 0, 64'h0000000000800001) iREG_SAVESTATE_Top (clk_sys, SaveStateBus_Din, SaveStateBus_Adr, SaveStateBus_wren, SaveStateBus_rst, SaveStateBus_wired_or[6], SS_Top_BACK, SS_Top);
eReg_SavestateV #(0, 31, 56, 0, 64'h0000000000800000) iREG_SAVESTATE_Top (clk_sys, SaveStateBus_Din, SaveStateBus_Adr, SaveStateBus_wren, SaveStateBus_rst, SaveStateBus_wired_or[6], SS_Top_BACK, SS_Top);

wire [10:0] SS_Top2;
wire [10:0] SS_Top2_BACK;
Expand Down Expand Up @@ -861,8 +861,10 @@ wire [12:0] wram_addr_i = ~isGBC ? ext_bus_addr[12:0] :
dma_read_wram_bus ? dma_addr[12:0] :
cpu_addr[12:0];

wire [14:0] wram_addr = (wram_addr_i[12]) ? { wram_bank, wram_addr_i[11:0] } // bank 1-7 $D000-DFFF
: { 3'd0, wram_addr_i[11:0] }; // bank 0 $C000-CFFF
// 0 -> 1
wire [2:0] wram_bank_o = (!wram_bank ? 3'd1 : wram_bank);
wire [14:0] wram_addr = (wram_addr_i[12]) ? { wram_bank_o, wram_addr_i[11:0] } // bank 1-7 $D000-DFFF
: { 3'd0, wram_addr_i[11:0] }; // bank 0 $C000-CFFF

dpram #(15) wram (
.clock_a (clk_cpu),
Expand All @@ -883,12 +885,9 @@ assign SS_Top_BACK[2:0] = wram_bank;

always @(posedge clk_sys) begin
if(reset_ss)
wram_bank <= SS_Top[2:0]; // 3'd1;
wram_bank <= SS_Top[2:0]; // 3'd0;
else if(ce_cpu && sel_wram_bank && !cpu_wr_n_edge) begin
if (cpu_do[2:0]==3'd0) // 0 -> 1;
wram_bank <= 3'd1;
else
wram_bank <= cpu_do[2:0];
wram_bank <= cpu_do[2:0];
end
end

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3 changes: 2 additions & 1 deletion rtl/sgb.v
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Original file line number Diff line number Diff line change
Expand Up @@ -368,8 +368,9 @@ always @(posedge clk_sys) begin
if (reset) begin
joypad_id <= 0;
end else if (ce) begin
joypad_id <= (joypad_id & mlt_ctrl);
if (sgb_en & ~old_p15 & p15) begin
joypad_id <= (joypad_id + 1'b1) & mlt_ctrl;
joypad_id <= (joypad_id + 1'b1);
end
end
end
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195 changes: 108 additions & 87 deletions rtl/video.v
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Original file line number Diff line number Diff line change
Expand Up @@ -310,7 +310,7 @@ always @(posedge clk) begin
end

wire pcnt_reset, pcnt_end;
wire mode3_end = (lcd_clk & pcnt == 8'd167) | pcnt_end;
wire mode3_end = ~sprite_found & pcnt_end & ~(isGBC & win_first_fetch);

reg mode3_end_l;

Expand Down Expand Up @@ -570,56 +570,44 @@ assign cpu_do =
// -------------- counters & background tilemap address----------------
// --------------------------------------------------------------------

reg skip_done;
reg [2:0] skip_cnt;
reg [7:0] pcnt;
wire sprite_fetch_hold;
wire bg_shift_empty;
wire skip_end = (skip_cnt == scx[2:0] || &skip_cnt);
wire skip_en = ~skip_done & ~skip_end;
reg bg_first_fetch_done;
reg win_first_fetch;
reg bg_scroll_done;

assign pcnt_end = ( pcnt == 8'd168 );
wire bg_paused = ~bg_first_fetch_done | win_first_fetch | sprite_found | mode3_end;
wire bg_scroll_end = ~bg_paused & (bg_shift_cnt == scx[2:0]) & ~bg_scroll_done;
wire pcnt_paused = bg_paused | ~(bg_scroll_done | bg_scroll_end);

assign pcnt_end = ( pcnt == 8'd167 );
assign pcnt_reset = h_clk_en & end_of_line & ~vblank;

assign SS_Video3_BACK[ 9: 7] = skip_cnt;
assign SS_Video3_BACK[17:10] = pcnt;
assign SS_Video3_BACK[ 18] = skip_done;
assign SS_Video3_BACK[21:19] = 0;
assign SS_Video3_BACK[ 18] = bg_scroll_done;

// Pixel counter
// Pixels 0-7 are for fetching partially offscreen sprites and window.
// Pixels 8-167 are output to the display.
always @(posedge clk) begin
if (reset) begin
skip_cnt <= SS_Video3[ 9: 7]; // 3'd0;
pcnt <= SS_Video3[17:10]; // 8'd0;
skip_done <= SS_Video3[ 18]; // 1'd0;
pcnt <= SS_Video3[17:10]; // 8'd0;
bg_scroll_done <= SS_Video3[ 18]; // 1'b0;
end else if (!lcd_on) begin
skip_cnt <= 3'd0;
pcnt <= 8'd0;
skip_done <= 1'b0;
pcnt <= 8'd0;
bg_scroll_done <= 1'b0;
end else if (ce) begin
// Only skip when not paused for sprites and fifo is not empty.
// Skipping pixels must happen at pcnt = 0 to pass Wilbertpol intr2_mode0_scx_timing tests.
if (~sprite_fetch_hold & ~bg_shift_empty) begin

if (~skip_done) begin
if (~skip_end)
skip_cnt <= skip_cnt + 1'd1;
else
skip_done <= 1'd1;
end

// Pixels 0-7 are for fetching partially offscreen sprites and window.
// Pixels 8-167 are output to the display.
if(~skip_en & ~pcnt_end)
pcnt <= pcnt + 1'd1;

end

if (pcnt_reset) begin
pcnt <= 8'd0;
skip_done <= 1'b0;
skip_cnt <= 3'd0;
end else if (~pcnt_paused) begin
pcnt <= pcnt + 1'b1;
end

if (~mode3) begin
bg_scroll_done <= 1'b0;
end else if (bg_scroll_end) begin
bg_scroll_done <= 1'b1;
end
end
end

Expand Down Expand Up @@ -690,10 +678,19 @@ wire [9:0] bg_tile_map_addr = window_ena ? win_map_addr : bg_map_addr;

wire [2:0] tile_line = window_ena ? win_line[2:0] : bg_line[2:0];

reg wy_match, window_match, window_ena_d;
reg wy_match, wxy_match_d, window_match, window_ena_d;

wire wxy_match = wy_match & (pcnt == wx);

// Using the latched wxy_match_d here causes 2 Window glitches on DMG:
// 1. WX = 166 causes all following lines and the first line after VBlank to show the Window.
// This happens because the last latch is at pixel 166 and it is not reset in H/VBlank.
// 2. Window start can be delayed by 1 pixel if lcdc_win_ena goes high right after wxy_match goes low.
// This can be seen in Mealybug test m3_lcdc_win_en_change_multiple_wx.
wire win_start = ~window_match & lcdc_win_ena & ((~bg_paused & wxy_match) | wxy_match_d);
wire win_reset = pcnt_reset | ~lcdc_win_ena;

wire win_start = ~window_match & mode3 && lcdc_win_ena && ~sprite_fetch_hold && ~skip_en && ~bg_shift_empty && wy_match && (pcnt == wx) && (wx < 8'hA7);
assign window_ena = window_match & ~pcnt_reset & lcdc_win_ena;
assign window_ena = window_match & ~win_reset;

assign SS_Video3_BACK[39:33] = h_cnt ;
assign SS_Video3_BACK[41:40] = h_div_cnt ;
Expand All @@ -702,6 +699,7 @@ assign SS_Video3_BACK[ 43] = window_ena_d;
assign SS_Video3_BACK[48:44] = win_col ;
assign SS_Video3_BACK[56:49] = win_line ;
assign SS_Video3_BACK[ 63] = wy_match ;
assign SS_Video3_BACK[ 19] = wxy_match_d ;

always @(posedge clk) begin

Expand All @@ -713,6 +711,7 @@ always @(posedge clk) begin
win_col <= SS_Video3[48:44]; // 5'd0;
win_line <= SS_Video3[56:49]; // 8'd0;
wy_match <= SS_Video3[ 63]; // 1'b0;
wxy_match_d <= SS_Video3[ 19]; // 1'b0;
end else if (!lcdc_on) begin
//reset counters
h_cnt <= 7'd0;
Expand All @@ -722,6 +721,7 @@ always @(posedge clk) begin
win_col <= 5'd0;
win_line <= 8'd0;
wy_match <= 1'b0;
wxy_match_d <= 1'b0;
end else if (ce) begin

h_div_cnt <= h_div_cnt + 1'b1;
Expand All @@ -735,33 +735,32 @@ always @(posedge clk) begin
wy_match <= 1'b1;
end

if(win_start) begin
if (isGBC & ~mode3) begin
wxy_match_d <= 0;
end else if (~bg_paused) begin
wxy_match_d <= wxy_match;
end

if (win_reset) begin
window_match <= 1'b0;
end else if (win_start) begin
window_match <= 1'b1;
end

// Increment line when Window turns off. This means it is possible to increment
// multiple times per line by changing WX and toggling the Window bit in LCDC.
window_ena_d <= window_ena;
if (vblank_l)
win_line <= 8'd0;
else if (window_ena_d & ~window_ena)
win_line <= win_line + 1'b1;

if (window_match) begin
if (~mode3_end_l & mode3_end) begin
// DMG glitch: If WX = A6 then window_match stays high through VBlank
// until WY > v_cnt which means the window always appears on line 0.
if (isGBC || wx != 8'hA6 || wy > v_cnt) begin
window_match <= 1'b0; // next line starts with background
end
end

if (~lcdc_win_ena) window_match <= 1'b0;
end

// Increment when fetching is done and not waiting for sprites.
if(window_ena && ~sprite_fetch_hold && bg_fetch_done && bg_reload_shift)
if (win_reset) begin
win_col <= 5'd0;
end else if (window_ena & bg_reload_shift) begin
win_col <= win_col + 1'b1;

if (~lcdc_win_ena | pcnt_reset) win_col <= 5'd0;
end

end
end
Expand Down Expand Up @@ -806,14 +805,20 @@ reg [2:0] bg_fetch_cycle;
reg [2:0] sprite_fetch_cycle;

assign bg_fetch_done = (bg_fetch_cycle >= 3'd5);
wire sprite_fetch_done = (sprite_fetch_hold && sprite_fetch_cycle >= 3'd5);
wire sprite_fetch_done = (sprite_found && sprite_fetch_cycle >= 3'd5);

reg [2:0] bg_shift_cnt;

// The first B01 cycle does not fetch sprites so wait until the bg shift register is not empty
assign sprite_fetch_hold = sprite_found & ~bg_shift_empty;
wire bg_shift_end = &bg_shift_cnt;

reg [3:0] bg_shift_cnt;
assign bg_shift_empty = (bg_shift_cnt == 0);
assign bg_reload_shift = (bg_shift_cnt <= 1);
// The pixel shift register is reloaded when:
// 1. The first BG or Window fetch is done. (bg_shift_cnt = 5)
// 2. Last pixel is shifted out (bg_shift_cnt = 7) and not paused.
// If wxy_match is high here but the Window is disabled then the
// reload is delayed. That is what causes the extra pixel glitch
// on DMG and also the WX=0 & SCX=7 glitch.
assign bg_reload_shift = (bg_fetch_done & (~bg_first_fetch_done | win_first_fetch))
| (~bg_paused & bg_shift_end & ~(wxy_match & (lcdc_win_ena | ~isGBC)));

wire spr_prio = sprite_attr[7];
wire spr_attr_h_flip = sprite_attr[5];
Expand Down Expand Up @@ -849,14 +854,18 @@ wire bg_tile_obj1_rd = (mode3 && sprite_fetch_cycle[2:1] == 2'b10);

assign SS_Video3_BACK[59:57] = bg_fetch_cycle;
assign SS_Video3_BACK[62:60] = sprite_fetch_cycle;
assign SS_Video3_BACK[ 9: 7] = bg_shift_cnt;
assign SS_Video3_BACK[ 20] = bg_first_fetch_done;
assign SS_Video3_BACK[ 21] = win_first_fetch;

always @(posedge clk) begin

if (reset) begin

bg_fetch_cycle <= SS_Video3[59:57]; // 3'b000;
sprite_fetch_cycle <= SS_Video3[62:60]; // 3'b000;

bg_fetch_cycle <= SS_Video3[59:57]; // 3'b000;
sprite_fetch_cycle <= SS_Video3[62:60]; // 3'b000;
bg_shift_cnt <= SS_Video3[ 9: 7]; // 3'b000;
bg_first_fetch_done <= SS_Video3[ 20]; // 1'b0;
win_first_fetch <= SS_Video3[ 21]; // 1'b0;
end else if (ce) begin

// every memory access is two pixel cycles
Expand All @@ -871,7 +880,7 @@ always @(posedge clk) begin
end

// Shift sprite data out
if (~sprite_fetch_hold & ~skip_en & ~bg_shift_empty) begin
if (~pcnt_paused) begin
spr_tile_shift_0 <= spr_tile_shift_0 << 1;
spr_tile_shift_1 <= spr_tile_shift_1 << 1;
spr_pal_shift <= spr_pal_shift << 1;
Expand Down Expand Up @@ -908,39 +917,51 @@ always @(posedge clk) begin
bg_fetch_cycle <= bg_fetch_cycle + 1'b1;
end

if (~sprite_fetch_hold) begin
if (~mode3) begin
bg_first_fetch_done <= 0;
end else if (bg_fetch_done) begin
bg_first_fetch_done <= 1'b1;
end

if (~pcnt_paused) begin
// shift bg/window pixels out
tile_shift_0 <= tile_shift_0 << 1;
tile_shift_1 <= tile_shift_1 << 1;

if (|bg_shift_cnt) bg_shift_cnt <= bg_shift_cnt - 1'b1;

if (bg_fetch_done && bg_reload_shift) begin
bg_tile_attr <= bg_tile_attr_new;
tile_shift_0 <= bg_tile_data0;
// bg_tile_data1 only has valid data at cycle 6 so at cycle 5 bg_vram_data_in is loaded instead.
tile_shift_1 <= (bg_fetch_cycle == 3'd5) ? bg_vram_data_in : bg_tile_data1;
bg_shift_cnt <= 4'd8;
bg_fetch_cycle <= 0;
end
tile_shift_0 <= { tile_shift_0[6:0], 1'b0 };
tile_shift_1 <= { tile_shift_1[6:0], 1'b0 };
end

// Start sprite fetch after background fetching is done
if (bg_reload_shift) begin
bg_tile_attr <= bg_tile_attr_new;
tile_shift_0 <= bg_tile_data0;
// bg_tile_data1 only has valid data at cycle 6 so at cycle 5 bg_vram_data_in is loaded instead.
tile_shift_1 <= (bg_fetch_cycle == 3'd5) ? bg_vram_data_in : bg_tile_data1;
bg_shift_cnt <= 0;
bg_fetch_cycle <= 0;
end

if (~bg_paused) begin
if (~bg_shift_end) bg_shift_cnt <= bg_shift_cnt + 1'b1;
end

// Start sprite fetch after background fetching is done and not in BG or Window first fetch.
// Sprite fetching continues until there are no more sprites on the current x position
if (sprite_fetch_hold && bg_fetch_done) begin
if (sprite_found & bg_fetch_done & ~win_first_fetch & bg_first_fetch_done) begin
sprite_fetch_cycle <= sprite_fetch_cycle + 1'b1;
end

if (~sprite_fetch_hold || sprite_fetch_done) sprite_fetch_cycle <= 0;
if (~sprite_found || sprite_fetch_done) sprite_fetch_cycle <= 0;

// Window start, reset fetching
// DMG glitch: fetching is not reset if WX = A6. The following lines all show
// the window from the start of the line.
if ( (win_start && (isGBC || wx != 8'hA6)) || !mode3) begin
if (win_start | ~mode3) begin
bg_fetch_cycle <= 0;
bg_shift_cnt <= 0;
end

if (~lcd_on | (win_first_fetch & bg_fetch_done)) begin
win_first_fetch <= 0;
end else if (win_start) begin
win_first_fetch <= 1'b1;
end

end

end
Expand Down Expand Up @@ -1069,7 +1090,7 @@ wire [5:0] sprite_palette_index = isGBC_mode? {spr_cgb_pal_out, sprite_pixel_dat
wire [14:0] sprite_pix = isGBC ? {obpd[sprite_palette_index+1][6:0],obpd[sprite_palette_index]} : //gbc
{13'd0,obp_data};

wire lcd_clk = mode3 && ~skip_en && ~sprite_fetch_hold && ~bg_shift_empty && (pcnt >= 8);
wire lcd_clk = (~pcnt_paused & (pcnt >= 8)) | (~mode3_end_l & mode3_end);

reg [14:0] lcd_data_out;
reg [1:0] lcd_data_gb_out;
Expand Down

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