Flop the clock polarity of the LCDC around.

[fpgaboy.git] / LCDC.v

diff --git a/LCDC.v b/LCDC.v
index 9a111f7bd2de8fa3a37a1c1895a6fbf0532f0fab..f951d3a15ba7ea5af16709d6d7dd8b3446397009 100644 (file)
--- a/LCDC.v
+++ b/LCDC.v
@@ -19,7 +19,7 @@ module LCDC(
        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);
        
        /***** Needed prototypes *****/
        wire [1:0] pixdata;
@@ -28,10 +28,9 @@ module LCDC(
        reg clk4 = 0;
        always @(posedge clk)
                clk4 = ~clk4;
-       assign lcdclk = 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;
@@ -63,8 +62,8 @@ module LCDC(
        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);
        
@@ -77,17 +76,19 @@ module LCDC(
        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);
        assign vblankirq = (posx == 0 && posy == 153);
        
-       always @(posedge clk4)
+       always @(negedge clk4)
        begin
                if (posx == 455) begin
                        posx <= 0;
@@ -118,6 +119,10 @@ module LCDC(
                        end
                        lycirq <= 0;
                end
+               
+               lcdr <= lcdr_;
+               lcdg <= lcdg_;
+               lcdb <= lcdb_;
        end
        
        /***** Video RAM *****/
@@ -135,11 +140,13 @@ module LCDC(
        // 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]};
+       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;
-       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 = {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);
@@ -147,20 +154,20 @@ module LCDC(
        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
+       always @(posedge clk)
+               if ((vraminuse && ((posx == 2) || (vxpos[2:0] == 3'b111))) || decode_bgmap1) begin
                        tileno <= bgmap1[bgmapaddr_in];
-                       if (wr && decode_bgmap1)
+                       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
+       always @(posedge 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)
+                       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
   
@@ -183,7 +190,7 @@ module LCDC(
                         8'bzzzzzzzz) :
                8'bzzzzzzzz;
   
-       always @(negedge clk)
+       always @(posedge clk)
        begin
                if (wr)
                        case (addr)