X-Git-Url: http://git.joshuawise.com/fpgaboy.git/blobdiff_plain/537e1f833b8eba858c06053ea6006ea608b9a5cc..b4f3ac35e69b7d5adf57959902abe2a104b42f4f:/LCDC.v diff --git a/LCDC.v b/LCDC.v index 41b5500..7b402e4 100644 --- a/LCDC.v +++ b/LCDC.v @@ -16,13 +16,32 @@ module LCDC( inout [7:0] data, input clk, // 8MHz clock input wr, rd, - output reg irq = 0); + output wire lcdcirq, + output wire vblankirq, + output wire lcdclk, lcdvs, lcdhs, + output reg [2:0] lcdr, lcdg, output reg [1:0] lcdb); + + /***** 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; + /***** LCD control registers *****/ + 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 [7:0] rLYC = 8'b00; + reg [7:0] rDMA = 8'b00; + reg [7:0] rBGP = 8'b00; + reg [7:0] rOBP0 = 8'b00; + reg [7:0] rOBP1 = 8'b00; + reg [7:0] rWY = 8'b00; + reg [7:0] rWX = 8'b00; + /***** Sync generation *****/ /* A complete cycle takes 456 clocks. @@ -30,58 +49,145 @@ module LCDC( * * Modes: 0 -> in hblank and OAM/VRAM available - present 207 clks * 1 -> in vblank and OAM/VRAM available - * 2 -> OAM in use - present 83 clks - * 3 -> OAM/VRAM in use - present 166 clks - * So, X = 0~165 is HActive, - * X = 166-372 is HBlank, - * X = 373-455 is HWhirrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrr. + * 2 -> OAM in use - present 86 clks + * 3 -> OAM/VRAM in use - present 163 clks + * So, X = 0~162 is HActive, + * X = 163-369 is HBlank, + * X = 370-455 is HWhirrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrr. + * [02:15:10] LY is updated near the 0 -> 2 transition + * [02:15:38] it seems to be updated internally first before it is visible in the LY register itself + * [02:15:40] some kind of delay + * [02:16:19] iirc it is updated about 4 cycles prior to mode 2 */ reg [8:0] posx = 9'h000; reg [7:0] posy = 8'h00; + + 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 [1:0] mode = (posy < 144) ? - ((posx < 166) ? 2'b11 : - (posx < 373) ? 2'b00 : - 2'b10) + (vraminuse ? 2'b11 : + oaminuse ? 2'b10 : + 2'b00) : 2'b01; - always @(posedge clk) + wire [7:0] vxpos = rSCX + posx - 3; + wire [7:0] vypos = rSCY + posy; + + 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); + assign vblankirq = (posx == 0 && posy == 153); + + always @(posedge clk4) begin if (posx == 455) begin posx <= 0; - if (posy == 153) + if (posy == 153) begin posy <= 0; - else + if (0 == rLYC) + lycirq <= 1; + end else begin posy <= posy + 1; - end else + /* Check for vblank and generate an IRQ if needed. */ + if (posy == 143) begin + mode01irq <= 1; + end + if ((posy + 1) == rLYC) + lycirq <= 1; + + end + end else begin posx <= posx + 1; + if (posx == 165) + mode00irq <= 1; + else if (posx == 373) + mode10irq <= 1; + else begin + mode00irq <= 0; + mode01irq <= 0; + mode10irq <= 0; + end + lycirq <= 0; + end + + lcdr <= lcdr_; + lcdg <= lcdg_; + lcdb <= lcdb_; end + + /***** Video RAM *****/ + /* Base is 0x8000 + * + * 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] bgmap1 [1023:0]; + reg [7:0] bgmap2 [1023:0]; + + // Upper five bits are Y coord, lower five bits are X coord + // 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 [7:0] vxpos_ = vxpos + 1; + wire [9:0] bgmapaddr = {vypos[7:3], vxpos_[7:3]}; + reg [7:0] tileno; + wire [10:0] tileaddr = {tileno, vypos[2:0]}; + reg [7:0] tilehigh, tilelow; + wire [1:0] prepal = {tilehigh[7-vxpos[2:0]], tilelow[7-vxpos[2:0]]}; + assign pixdata = {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 [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 == 2) || (vxpos[2:0] == 3'b111))) || decode_bgmap1) begin + tileno <= bgmap1[bgmapaddr_in]; + if (wr && decode_bgmap1 && ~vraminuse) + bgmap1[bgmapaddr_in] <= data; + end + + always @(negedge clk) + 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 && ~vraminuse) + tiledatahigh[tileaddr_in] <= data; + if (wr && ~addr[0] && decode_tiledata && ~vraminuse) + tiledatalow[tileaddr_in] <= data; + end /***** Bus interface *****/ - reg [7:0] rLCDC = 8'h91; - reg [7:0] rSTAT = 8'h00; - reg [7:0] rSCY = 8'b00; - reg [7:0] rSCX = 8'b00; - reg [7:0] rLYC = 8'b00; - reg [7:0] rDMA = 8'b00; - reg [7:0] rBGP = 8'b00; - reg [7:0] rOBP0 = 8'b00; - reg [7:0] rOBP1 = 8'b00; - reg [7:0] rWY = 8'b00; - reg [7:0] rWX = 8'b00; - 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 : - 8'bzzzzzzzz : + ((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) : 8'bzzzzzzzz; always @(negedge clk)