From ec7274034775dc5e053ff3c96bd141ac50b4fc81 Mon Sep 17 00:00:00 2001
From: Joshua Wise <joshua@nyus.joshuawise.com>
Date: Sat, 19 Apr 2008 03:03:16 -0400
Subject: [PATCH] Fix some sync issues? Maybe?

---
 LCDC.v   | 26 ++++++++++++++++----------
 diag.asm | 30 +++++++++++++++---------------
 2 files changed, 31 insertions(+), 25 deletions(-)

diff --git a/LCDC.v b/LCDC.v
index 0e1b569..5089129 100644
--- 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;
@@ -77,11 +77,12 @@ 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 || vxpos < 8) ? 2'b11 : 2'b00} : 2'b00;
+	assign lcdvs = (posy == 153) && (posx == 2);
+	assign lcdhs = (posx == 2);
+	
+	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);
@@ -118,6 +119,10 @@ module LCDC(
 			end
 			lycirq <= 0;
 		end
+		
+		lcdr <= lcdr_;
+		lcdg <= lcdg_;
+		lcdb <= lcdb_;
 	end
 	
 	/***** Video RAM *****/
@@ -135,11 +140,12 @@ 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]]};
+	assign pixdata = {tilehigh[7-vxpos[2:0]], tilelow[7-vxpos[2:0]]};
 	
 	wire decode_tiledata = (addr >= 16'h8000) && (addr <= 16'h97FF);
 	wire decode_bgmap1 = (addr >= 16'h9800) && (addr <= 16'h9BFF);
@@ -148,14 +154,14 @@ module LCDC(
 	wire [11:0] tileaddr_in = vraminuse ? tileaddr : addr[12:1];
 	
 	always @(negedge clk)
-		if ((vraminuse && ((posx == 1) || (vxpos[2:0] == 3'b110))) || decode_bgmap1) begin
+		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 == 2) || (vxpos[2:0] == 3'b111))) || decode_tiledata) begin
+		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)
diff --git a/diag.asm b/diag.asm
index 77c5202..c832ff2 100644
--- a/diag.asm
+++ b/diag.asm
@@ -51,22 +51,22 @@ signon:
 	db $0D,$0A,$1B,"[1mFPGABoy Diagnostic ROM",$1B,"[0m",$0D,$0A,0
 
 tiles:
-	db %11111111
-	db %11111111
-	db %11000011
-	db %11000011
-	db %11000011
-	db %11000011
-	db %11111111
-	db %11111111
-	
-	db %00000000
-	db %00000000
-	db %00000000
-	db %00000000
-	db %00000000
-	db %00000000
+	db %01111100
+	db %11000110
+	db %11000110
+	db %11111110
+	db %11000110
+	db %11000110
+	db %11000110
 	db %00000000
+	
+	db %11111100
+	db %11000110
+	db %11000110
+	db %11111100
+	db %11000110
+	db %11000110
+	db %11111100
 	db %00000000
 
 putscreen:
-- 
2.43.0