output wire lcdcirq,
output wire vblankirq,
output wire lcdclk, lcdvs, lcdhs,
- output wire [2:0] lcdr, lcdg, output wire [1:0] lcdb);
+ output reg [2:0] lcdr, lcdg, output reg [1:0] lcdb);
+
+ /***** Bus latches *****/
+ reg rdlatch = 0;
+ reg [15:0] addrlatch = 0;
/***** Needed prototypes *****/
wire [1:0] pixdata;
/***** Internal clock that is stable and does not depend on CPU in single/double clock mode *****/
reg clk4 = 0;
always @(posedge clk)
- clk4 = ~clk4;
- assign lcdclk = clk4;
+ clk4 <= ~clk4;
/***** LCD control registers *****/
- reg [7:0] rLCDC = 8'h91;
+ reg [7:0] rLCDC = 8'h00;
reg [7:0] rSTAT = 8'h00;
reg [7:0] rSCY = 8'b00;
reg [7:0] rSCX = 8'b00;
reg [8:0] posx = 9'h000;
reg [7:0] posy = 8'h00;
- wire vraminuse = (posx < 163);
- wire oaminuse = (posx > 369);
+ wire vraminuse = (posx < 163) && (posy < 144) && rLCDC[7];
+ wire oaminuse = (posx > 369) && (posy < 144) && rLCDC[7];
wire display = (posx > 2) && (posx < 163) && (posy < 144);
wire [7:0] vxpos = rSCX + posx - 3;
wire [7:0] vypos = rSCY + posy;
- assign lcdvs = (posy == 153) && (posx == 455);
- assign lcdhs = (posx == 455);
- assign lcdr = display ? {pixdata[1] ? 3'b111 : 3'b000} : 3'b000;
- assign lcdg = display ? {pixdata[0] ? 3'b111 : 3'b000} : 3'b000;
- assign lcdb = display ? {(vypos < 8) ? 2'b11 : 2'b00} : 2'b00;
+ assign lcdvs = (posy == 153) && (posx == 2) && rLCDC[7];
+ assign lcdhs = (posx == 2) && rLCDC[7];
+ assign lcdclk = clk4;
+
+ wire [2:0] lcdr_ = display ? {pixdata[1] ? 3'b111 : 3'b000} : 3'b000;
+ wire [2:0] lcdg_ = display ? {pixdata[0] ? 3'b111 : 3'b000} : 3'b000;
+ wire [1:0] lcdb_ = display ? {(vypos < 8 || vxpos < 8) ? 2'b11 : 2'b00} : 2'b00;
reg mode00irq = 0, mode01irq = 0, mode10irq = 0, lycirq = 0;
assign lcdcirq = (rSTAT[3] & mode00irq) | (rSTAT[4] & mode01irq) | (rSTAT[5] & mode10irq) | (rSTAT[6] & lycirq);
end
lycirq <= 0;
end
+
+ lcdr <= lcdr_;
+ lcdg <= lcdg_;
+ lcdb <= lcdb_;
end
/***** Video RAM *****/
* Tile data from 8000-8FFF or 8800-97FF
* Background tile maps 9800-9BFF or 9C00-9FFF
*/
- reg [7:0] tiledatahigh [3071:0];
- reg [7:0] tiledatalow [3071:0];
+ reg [7:0] tiledatahigh [6143:0];
+ reg [7:0] tiledatalow [6143:0];
reg [7:0] bgmap1 [1023:0];
reg [7:0] bgmap2 [1023:0];
// The new tile number is loaded when vxpos[2:0] is 3'b110
// The new tile data is loaded when vxpos[2:0] is 3'b111
// The new tile data is latched and ready when vxpos[2:0] is 3'b000!
- wire [9:0] bgmapaddr = {vypos[7:3], vxpos[7:3]};
- reg [7:0] tileno;
- wire [10:0] tileaddr = {tileno, vypos[2:1]};
+ wire [7:0] vxpos_ = vxpos + 1;
+ wire [9:0] bgmapaddr = {vypos[7:3], vxpos_[7:3]};
+ reg [7:0] tileno1;
+ reg [7:0] tileno2;
+ wire [7:0] tileno = rLCDC[3] ? tileno2 : tileno1;
+ wire [11:0] tileaddr =
+ {(rLCDC[4] ? {1'b0,tileno} : (9'b100000000 + {tileno[7],tileno})),
+ vypos[2:0]};
reg [7:0] tilehigh, tilelow;
- assign pixdata = {tilehigh[vxpos[2:0]], tilelow[vxpos[2:0]]};
+ wire [1:0] prepal = {tilehigh[7-vxpos[2:0]], tilelow[7-vxpos[2:0]]};
+ assign pixdata = 2'b11-{rBGP[{prepal,1'b1}],rBGP[{prepal,1'b0}]};
wire decode_tiledata = (addr >= 16'h8000) && (addr <= 16'h97FF);
wire decode_bgmap1 = (addr >= 16'h9800) && (addr <= 16'h9BFF);
+ wire decode_bgmap2 = (addr >= 16'h9C00) && (addr <= 16'h9FFF);
wire [9:0] bgmapaddr_in = vraminuse ? bgmapaddr : addr[9:0];
wire [11:0] tileaddr_in = vraminuse ? tileaddr : addr[12:1];
- always @(negedge clk)
- if ((vraminuse && ((posx == 1) || ((posx > 2) && (vxpos[2:0] == 3'b110)))) || decode_bgmap1) begin
- tileno <= bgmap1[bgmapaddr_in];
- if (wr && decode_bgmap1)
+ always @(posedge clk)
+ begin
+ if ((vraminuse && ((posx == 2) || (vxpos[2:0] == 3'b111))) || decode_bgmap1) begin
+ tileno1 <= bgmap1[bgmapaddr_in];
+ if (wr && decode_bgmap1 && ~vraminuse)
bgmap1[bgmapaddr_in] <= data;
end
-
- always @(negedge clk)
- if ((vraminuse && ((posx == 2) || ((posx > 2) && (vxpos[2:0] == 3'b111)))) || decode_tiledata) begin
+ if ((vraminuse && ((posx == 2) || (vxpos[2:0] == 3'b111))) || decode_bgmap2) begin
+ tileno2 <= bgmap2[bgmapaddr_in];
+ if (wr && decode_bgmap2 && ~vraminuse)
+ bgmap2[bgmapaddr_in] <= data;
+ end
+ if ((vraminuse && ((posx == 3) || (vxpos[2:0] == 3'b000))) || decode_tiledata) begin
tilehigh <= tiledatahigh[tileaddr_in];
tilelow <= tiledatalow[tileaddr_in];
- if (wr && addr[0] && decode_tiledata)
+ if (wr && addr[0] && decode_tiledata && ~vraminuse)
tiledatahigh[tileaddr_in] <= data;
- if (wr && ~addr[0] && decode_tiledata)
+ if (wr && ~addr[0] && decode_tiledata && ~vraminuse)
tiledatalow[tileaddr_in] <= data;
end
+ end
/***** Bus interface *****/
- assign data = rd ?
- (addr == `ADDR_LCDC) ? rLCDC :
- (addr == `ADDR_STAT) ? {rSTAT[7:3], (rLYC == posy) ? 1'b1 : 1'b0, mode} :
- (addr == `ADDR_SCY) ? rSCY :
- (addr == `ADDR_SCX) ? rSCX :
- (addr == `ADDR_LY) ? posy :
- (addr == `ADDR_LYC) ? rLYC :
- (addr == `ADDR_BGP) ? rBGP :
- (addr == `ADDR_OBP0) ? rOBP0 :
- (addr == `ADDR_OBP1) ? rOBP1 :
- (addr == `ADDR_WY) ? rWY :
- (addr == `ADDR_WX) ? rWX :
- (decode_tiledata && addr[0]) ? tilehigh :
- (decode_tiledata && ~addr[0]) ? tilelow :
- (decode_bgmap1) ? tileno :
- 8'bzzzzzzzz :
+ assign data = rdlatch ?
+ ((addrlatch == `ADDR_LCDC) ? rLCDC :
+ (addrlatch == `ADDR_STAT) ? {rSTAT[7:3], (rLYC == posy) ? 1'b1 : 1'b0, mode} :
+ (addrlatch == `ADDR_SCY) ? rSCY :
+ (addrlatch == `ADDR_SCX) ? rSCX :
+ (addrlatch == `ADDR_LY) ? posy :
+ (addrlatch == `ADDR_LYC) ? rLYC :
+ (addrlatch == `ADDR_BGP) ? rBGP :
+ (addrlatch == `ADDR_OBP0) ? rOBP0 :
+ (addrlatch == `ADDR_OBP1) ? rOBP1 :
+ (addrlatch == `ADDR_WY) ? rWY :
+ (addrlatch == `ADDR_WX) ? rWX :
+ (decode_tiledata && addrlatch[0]) ? tilehigh :
+ (decode_tiledata && ~addrlatch[0]) ? tilelow :
+ (decode_bgmap1) ? tileno :
+ 8'bzzzzzzzz) :
8'bzzzzzzzz;
- always @(negedge clk)
+ always @(posedge clk)
begin
+ rdlatch <= rd;
+ addrlatch <= addr;
if (wr)
case (addr)
`ADDR_LCDC: rLCDC <= data;
git.joshuawise.com / fpgaboy.git / blobdiff