Video RAM cut 1 -- on distributed ram

diff --git a/LCDC.v b/LCDC.v
index 444fb85b02792a7055e84f49fe356b87e2563654..8f237eb1aae11a5e11271ec28b00a52dfc3143ab 100644 (file)
--- a/LCDC.v
+++ b/LCDC.v
@@ -21,22 +21,15 @@ module LCDC(
        output wire lcdclk, lcdvs, lcdhs,
        output wire [2:0] lcdr, lcdg, output wire [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;
        assign lcdclk = clk4;
        
-       /***** Video RAM *****/
-       /* Base is 0x8000
-        *
-        * Tile data from 8000-8FFF or 8800-97FF
-        * Background tile maps 9800-9BFF or 9C00-9FFF
-        */
-       reg [7:0] tiledata [6143:0];
-       reg [7:0] bgmap1 [1023:0];
-       reg [7:0] bgmap2 [1023:0];
-       
        /***** LCD control registers *****/
        reg [7:0] rLCDC = 8'h91;
        reg [7:0] rSTAT = 8'h00;
@@ -57,11 +50,11 @@ 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] <Judge_> LY is updated near the 0 -> 2 transition
         * [02:15:38] <Judge_> it seems to be updated internally first before it is visible in the LY register itself
         * [02:15:40] <Judge_> some kind of delay
@@ -69,17 +62,23 @@ module LCDC(
         */
        reg [8:0] posx = 9'h000;
        reg [7:0] posy = 8'h00;
+       
+       wire vraminuse = (posx < 163);
+       wire oaminuse = (posx > 369);
+       
+       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;
        
        assign lcdvs = (posy == 153) && (posx == 455);
        assign lcdhs = (posx == 455);
-       assign lcdr = (posx < 160) && (posy < 144) ? {posy == rLYC ? 3'b111 : 3'b000} : 3'b000;
-       assign lcdg = (posx < 160) && (posy < 144) ? {posy < rSCY ? 3'b111 : 3'b000} : 3'b000;
-       assign lcdb = (posx < 160) && (posy < 144) ? {2'b11} : 2'b00;
+       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 ? {posy < rSCY ? 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);
@@ -116,8 +115,56 @@ module LCDC(
                        end
                        lycirq <= 0;
                end
-               
        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] tiledata [6143:0];
+       reg [7:0] bgmap1 [1023:0];
+       reg [7:0] bgmap2 [1023:0];
+       
+       // Upper five bits are Y coord, lower five bits are X coord
+       wire [7:0] vxpos = rSCX + posx - 3;
+       wire [7:0] vypos = rSCY + posy;
+       
+       // The new tile number is loaded when vxpos[2:0] is 3'b101
+       // The new tile data low is loaded when vxpos[2:0] is 3'b110
+       // The new tile data high 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]};
+       reg [7:0] tilelowtmp, tilehigh, tilelow;
+       assign pixdata = {tilehigh[vxpos[2:0]], tilelow[vxpos[2:0]]};
+       
+       wire decode_tiledata = (addr >= 16'h8000) && (addr <= 16'h97FF);
+       wire decode_bgmap1 = (addr >= 16'h9800) && (addr <= 16'h9BFF);
+       
+       always @(negedge clk)
+               if (vraminuse) begin
+                       if ((posx == 0) || ((posx > 2) && (vxpos[2:0] == 3'b101)))
+                               tileno <= bgmap1[bgmapaddr];
+                       else if ((posx == 1) || ((posx > 2) && (vxpos[2:0] == 3'b110)))
+                               tilelowtmp <= tiledata[{tileaddr, 1'b0}];
+                       else if ((posx == 2) || ((posx > 2) && (vxpos[2:0] == 3'b111))) begin
+                               tilehigh <= tiledata[{tileaddr, 1'b1}];
+                               tilelow <= tilelowtmp;
+                       end
+               end else begin
+                       if (decode_tiledata) begin
+                               tilelowtmp <= tiledata[addr[12:0]];
+                               if (wr)
+                                       tiledata[addr[12:0]] <= data;
+                       end else if (decode_bgmap1) begin
+                               tileno <= bgmap1[addr[12:0]];
+                               if (wr)
+                                       bgmap1[addr[12:0]] <= data;
+                       end
+               end
   
        /***** Bus interface *****/
        assign data = rd ?
@@ -132,6 +179,8 @@ module LCDC(
                        (addr == `ADDR_OBP1) ? rOBP1 :
                        (addr == `ADDR_WY) ? rWY :
                        (addr == `ADDR_WX) ? rWX :
+                       (decode_tiledata) ? tilelowtmp :
+                       (decode_bgmap1) ? tileno :
                        8'bzzzzzzzz :
                8'bzzzzzzzz;
   

diff --git a/diag.asm b/diag.asm
index 8e09874baaf06cdb9b6472508f81a2cbff6a8dda..7f06de0ce42223f19f4dc2b67a74a5497592e8c8 100644 (file)
--- a/diag.asm
+++ b/diag.asm
@@ -32,6 +32,8 @@ main:
        
        ld hl, signon
        call puts
+
+       call putscreen
        
        ei
 
@@ -48,6 +50,25 @@ main:
 signon:
        db $0D,$0A,$1B,"[1mFPGABoy Diagnostic ROM",$1B,"[0m",$0D,$0A,0
 
+putscreen:
+       ld a, $FF               ; Copy two tiles.
+       ld hl, $8000
+       ld [hli], a
+       ld [hli], a
+       xor a
+       ld [hli], a
+       ld [hli], a
+       
+       ld hl, $9800
+.loop: ld a, $FF
+       ld [hli], a
+       xor a
+       ld [hli], a
+       ld a, h
+       cp $9C
+       jp nz,.loop
+       ret
+
 vbl:
        PUSH AF
        PUSH BC